Aces High Bulletin Board

General Forums => Aircraft and Vehicles => Topic started by: earl1937 on November 26, 2013, 09:45:51 AM

Title: Heavy Aircraft Stall Training
Post by: earl1937 on November 26, 2013, 09:45:51 AM
 :airplane: The Federal Aviation Agency has come out with a new "proposed" stall warning and recovery procedure, for aircraft operated under FAR part 121, which covers heavy aircraft, jet liners of all descriptions. Anyone operating as a part 121 operator is covered by this regulation. Here is a copy from the FAA on excathly their proposed change!
Pilots of transport-category airplanes should be taught to reduce the angle of attack as their first response to a stall warning, the FAA said on Tuesday. In a new proposed advisory circular, the FAA says it aims to provide "best practices and guidance for training, testing, and checking for pilots to ensure correct and consistent response to unexpected stall warnings, and/or stick pusher activations."

Duh! Is there any "Transport Rated Pilots", or Commercial rated pilots in the world who have not had stall training and recovery? The Buffalo crash a few years back should have pointed out what really needed to be done to correct this problem, "Pilot Training" and related issues. The captain of that aircraft had failed many flight tests while in school and the lady co-pilot was very inexperienced!
If a pilot fails a flight test more than 2 times, on his or her 3rd try, they should be advised to enter a different line of work. Not all people have the coordination and SA, when on instruments to be a safe pilot, when hauling fare paying passengers!
Don't mean to get on my "soap box", but to many people are passed on flight progress tests, just to get more of the almighty dollar!
Which brings me to Aces High landings! Guys, for gosh sakes, slow the aircraft down to no more than 100 IAS over the end of the runway when landing. I still see people trying to land when approaching way to fast, and they either crash or run off the other end of the runway.
Get your favorite ride, climb to 5K or so  and slow the thing down, (maybe 110 IAS), learn to maintain heading and altitude by using the flight controls and power management. Just a few flights of practice will make a big difference in safe landings and scoring your kills or damage points.
Title: Re: Heavy Aircraft Stall Training
Post by: colmbo on November 26, 2013, 11:02:48 AM

Pilots of transport-category airplanes should be taught to reduce the angle of attack as their first response to a stall warning,


Well shoot, I too could be an ATP!!

I'm guessing a case of politicians wanting "something done".
Title: Re: Heavy Aircraft Stall Training
Post by: Oldman731 on November 26, 2013, 11:06:00 AM
I'm guessing a case of politicians wanting "something done".


Agreed.

- oldman
Title: Re: Heavy Aircraft Stall Training
Post by: earl1937 on November 26, 2013, 11:15:19 AM
Well shoot, I too could be an ATP!!

I'm guessing a case of politicians wanting "something done".
:airplane: Unless the FAA has changed, its more political than the U.S. congress!
Title: Re: Heavy Aircraft Stall Training
Post by: pembquist on November 26, 2013, 11:56:17 AM
You'll have to bear with my poor memory but I thought one of the factors that contributed to the buffalo crash was that the pilot had been flying (maybe had most of his transport time?) in a plane known to be especially subsceptable to tailplane icing and consequent tailplane stall (a Saab?). The notion is that his reaction to the situation was to pull hard to to recover the aircraft he wasn't flying in a situation he wasn't in. If I recall correctly the cockpit was not sterile and they didn't seem to be paying very good attention, when the plane began to stall he didn't know what was going on and fell back on a panicky recollection of what to do about the scariest thing that came to mind. (My memory tailplane stall in the Saab or whatever, is that you don't get a second chance if it departs.) So if my memory is correct I can see why they would write down what is staggeringly obvious, though I don't see how it would make any difference.

I think the strange thing is that it is as if the system thinks flying commuter planes in north east winter weather is somehow less demanding than flying JFK to Paris in a wide body.
Title: Re: Heavy Aircraft Stall Training
Post by: Puma44 on November 26, 2013, 03:17:21 PM
:airplane: Unless the FAA has changed, its more political than the U.S. congress!
Not to mention the real problem wasn't addressed and corrected.
Title: Re: Heavy Aircraft Stall Training
Post by: Brooke on November 27, 2013, 12:10:39 AM
By the way, any folks who are having problems slowing down from a fast approach:
1.  If you are coming in really fast (300-400 mph, say), chop throttle and do a hard 270 or 360 degree turn to bleed off speed.
2.  If you are lining up and are too fast (but not so fast to need a 360 degree hard turn), stomp full rudder and keep on your approach.  This adds a lot of drag (crossed controls as you keep it on a straight heading).  Gently release rudder once you get to flaps-down speed for your aircraft, and start putting in flaps.
Title: Re: Heavy Aircraft Stall Training
Post by: earl1937 on November 27, 2013, 03:09:28 AM
You'll have to bear with my poor memory but I thought one of the factors that contributed to the buffalo crash was that the pilot had been flying (maybe had most of his transport time?) in a plane known to be especially subsceptable to tailplane icing and consequent tailplane stall (a Saab?). The notion is that his reaction to the situation was to pull hard to to recover the aircraft he wasn't flying in a situation he wasn't in. If I recall correctly the cockpit was not sterile and they didn't seem to be paying very good attention, when the plane began to stall he didn't know what was going on and fell back on a panicky recollection of what to do about the scariest thing that came to mind. (My memory tailplane stall in the Saab or whatever, is that you don't get a second chance if it departs.) So if my memory is correct I can see why they would write down what is staggeringly obvious, though I don't see how it would make any difference.

I think the strange thing is that it is as if the system thinks flying commuter planes in north east winter weather is somehow less demanding than flying JFK to Paris in a wide body.
:airplane:  Copy from NTSB's final report on cause of accident!

Probable Cause
The National Transportation Safety Board determines that the probable cause of this accident was the captain's inappropriate response to the activation of the stick shaker, which led to an aerodynamic stall from which the airplane did not recover. Contributing to the accident were (1) the flight crew's failure to monitor airspeed in relation to the rising position of the lowspeed cue, (2) the flight crew's failure to adhere to sterile cockpit procedures, (3) the captain's failure to effectively manage the flight, and (4) Colgan Air's inadequate procedures for airspeed selection and management during approaches in icing conditions.

Web site for full report and recommendations:     http://www.ntsb.gov/investigations/summary/AAR1001.html
Title: Re: Heavy Aircraft Stall Training
Post by: pembquist on November 27, 2013, 02:21:32 PM
From the recommendations that Earl linked to:

Identify which airplanes operated under 14 Code of Federal Regulations Part 121, 135, and 91K are susceptible to tailplane stalls and then (1) require operators of those airplanes to provide an appropriate airplane-specific tailplane stall recovery procedure in their training manuals and company procedures and (2) direct operators of those airplanes that are not susceptible to tailplane stalls to ensure that training and company guidance for the airplanes explicitly states this lack of susceptibility and contains no references to tailplane stall recovery procedures. (A-10-25)

I get the impression that the captain had never been exposed to the stick shaker which seems like totally inadequate training. My memory about the Saab was correct. Here is a link to a NY Times article on the crash http://www.nytimes.com/2009/02/19/nyregion/19crash.html?_r=0 (http://www.nytimes.com/2009/02/19/nyregion/19crash.html?_r=0)

The predominant impression that's given is of pilot incompetence but the reality is that training and standards were lousy and if there had been a safety culture of any merit at that operator this particular accident would not have occurred.
Title: Re: Heavy Aircraft Stall Training
Post by: DaveBB on November 27, 2013, 04:39:31 PM
So the horizontal stabilizers are stalling before the wings?
Title: Re: Heavy Aircraft Stall Training
Post by: colmbo on November 27, 2013, 08:18:42 PM
So the horizontal stabilizers are stalling before the wings?

And a fun time was had by all.
Title: Re: Heavy Aircraft Stall Training
Post by: pembquist on November 27, 2013, 09:06:14 PM
So the horizontal stabilizers are stalling before the wings?

Yes, because of icing. See the videohttp://youtu.be/_ifKduc1hE8 (http://youtu.be/_ifKduc1hE8)
Title: Re: Heavy Aircraft Stall Training
Post by: earl1937 on November 28, 2013, 02:29:41 PM
From the recommendations that Earl linked to:

Identify which airplanes operated under 14 Code of Federal Regulations Part 121, 135, and 91K are susceptible to tailplane stalls and then (1) require operators of those airplanes to provide an appropriate airplane-specific tailplane stall recovery procedure in their training manuals and company procedures and (2) direct operators of those airplanes that are not susceptible to tailplane stalls to ensure that training and company guidance for the airplanes explicitly states this lack of susceptibility and contains no references to tailplane stall recovery procedures. (A-10-25)

I get the impression that the captain had never been exposed to the stick shaker which seems like totally inadequate training. My memory about the Saab was correct. Here is a link to a NY Times article on the crash http://www.nytimes.com/2009/02/19/nyregion/19crash.html?_r=0 (http://www.nytimes.com/2009/02/19/nyregion/19crash.html?_r=0)

The predominant impression that's given is of pilot incompetence but the reality is that training and standards were lousy and if there had been a safety culture of any merit at that operator this particular accident would not have occurred.
:furious This one of many accidents caused by what I said before, "lack of training" by operators who cut corners to save money!
Title: Re: Heavy Aircraft Stall Training
Post by: Valkyrie on November 29, 2013, 07:09:35 PM
I am working on a commercial rating now 243 hours and an aerospace space engineering degree. I feel the failure is in the PTS, and the design of the stalling regime.

Stalls going into spins are not well understood by todays ATP commercial or CFI, and the regulation in the PTS standards are to blame. They call for a recovery with minimal altitude loss and its that second part is the problem. When training in trainers for ratings the full power stall procedure is to cut the power, nose up to bleed speed, then full power nose up into the stall. ALL effort is focused on stopping the stall before it develops, not allowing the stall to occur, then recovering, but recovering only from an incipient stall. Much would be gained by requiring a full stall demonstration allowing the stall to develop and not worrying about busting the alt on the recovery, many testing failures have resulted from accelerated stalls on the recovery trying not to drop alt in the stall. This may come from a misread altitude loss requirement, but the way it is enforced is a nearly a failure to allow the stall happen. The ultimate lesson that needs to be learned is that you MUST FIRST break the stall, then initiate recovery. I would care if every applicant lost 300 feet so long as they knew that they had to get the AOA under critical first. I think it is very likely that the Colgan Air Capt. never saw more than 4 intentional stalls in his life. Today pilots are taught that stalls are impossible to recover from (Cirus pull the chute), and are taught cookbook style stalls that will likely never happen in real life.

This started with the FAA getting away from spin training years ago and has moved to the point where while training even a stall is to be avoided at all costs because they turn into spins which are now only taught once during CFI training and not even done on that check ride. Combine this with an overreliance on automation (see 777 SFO, Colgan Buffalo, UPS Birmingham) and its a very real issue of basic piloting skills being totally lost. Extremely low time CFI's who don't know much of anything and its a case of the blind leading the blind. I'll be a CFI before long and I won't ever have been in ice before making it to a transport aircraft. I would much rather have gone to a cargo carrier and flown nights in the right seat than get my 1250 hours instructing, and it would have been far safer, than the current Rube Goldberg style regulations.

I would much rather have the FAA allow very low time 500 hour CPL pilots in cargo aircraft than the current 1500 atp requirements that wouldn't have stopped the buffalo crash.
Title: Re: Heavy Aircraft Stall Training
Post by: earl1937 on November 30, 2013, 12:01:53 PM
I am working on a commercial rating now 243 hours and an aerospace space engineering degree. I feel the failure is in the PTS, and the design of the stalling regime.

Stalls going into spins are not well understood by today's ATP commercial or CFI, and the regulation in the PTS standards are to blame. They call for a recovery with minimal altitude loss and its that second part is the problem. When training in trainers for ratings the full power stall procedure is to cut the power, nose up to bleed speed, then full power nose up into the stall. ALL effort is focused on stopping the stall before it develops, not allowing the stall to occur, then recovering, but recovering only from an incipient stall. Much would be gained by requiring a full stall demonstration allowing the stall to develop and not worrying about busting the alt on the recovery, many testing failures have resulted from accelerated stalls on the recovery trying not to drop alt in the stall. This may come from a misread altitude loss requirement, but the way it is enforced is a nearly a failure to allow the stall happen. The ultimate lesson that needs to be learned is that you MUST FIRST break the stall, then initiate recovery. I would care if every applicant lost 300 feet so long as they knew that they had to get the AOA under critical first. I think it is very likely that the Colgan Air Capt. never saw more than 4 intentional stalls in his life. Today pilots are taught that stalls are impossible to recover from (Cirrus pull the chute), and are taught cookbook style stalls that will likely never happen in real life.


This started with the FAA getting away from spin training years ago and has moved to the point where while training even a stall is to be avoided at all costs because they turn into spins which are now only taught once during CFI training and not even done on that check ride. Combine this with an overreliance on automation (see 777 SFO, Colgan Buffalo, UPS Birmingham) and its a very real issue of basic piloting skills being totally lost. Extremely low time CFi who don't know much of anything and its a case of the blind leading the blind. I'll be a CFI before long and I won't ever have been in ice before making it to a transport aircraft. I would much rather have gone to a cargo carrier and flown nights in the right seat than get my 1250 hours instructing, and it would have been far safer, than the current Rube Goldberg style regulations.

I would much rather have the FAA allow very low time 500 hour CPL pilots in cargo aircraft than the current 1500 ATP requirements that wouldn't have stopped the buffalo crash.
:airplane: You make some valid points and as a one time FAA designated pilot examiner for Private, Commercial and Instrument ratings and Multi-engine rating, we were required to strictly stick to the current FAA flight standards. As far as stall requirements, the recognize of an impending stall was the most important thing, but like you, I think that falls short of finding out if the applicator was truly, "the master of that aircraft". After the usual check maneuvers, I always had the applicant demonstrate a 45 and 60 degree banked turn, VFR, with a plus or minus 100 foot altitude loss or gain. (I wonder how many pilots in AH could do that in the game). Most could not do it in a satisfactorily manner, so usually retraining was required before I would pass the applicant's check ride. Very few flight instructors had completed the demonstrated spin recovery technique which I think was very important pilot training. Slow flight was another pet peeve of mine, as most couldn't maintain altitude and airspeed at the same time.
The pilot of the Buffalo crash had failed instrument flight tests 2 or 3 times in his career, but he was allowed to cont flying as PIC of transport aircraft. While that aircraft model had a history
of zonal icing problems, I think the pilots incompetence in IFR conditions had more to do with that accident than anything. The fact that the crew was engaged in idle "chit chat" was also a factor in this accident.
At any rate, if a PIC doesn't stay "ahead" of his aircraft at all times, its just a matter of time before he is involved in an accident! Instrument flight on partial panel is another thing I always insisted on. If a pilot cannot fly on "needle, ball, airspeed and altimeter, then he or she shouldn't flying on instruments. All the new bells and whistles are well and good for safe flight, but what happens when you have complete electrical failure? Fortunately most good airlines insist on "raw" date instruments in the event of Elect failure, but then comes the question, can the PIC fly on raw data alone.
As a chief flight instructor for largest flight school in Atlanta, I flew with every potential new instructor and only hired about 5 out 10 because of the lack of understanding and training for the things which I have mentioned in this reply.
On your Ice comment, just remember, if it is freezing rain, climb, because there is warm air above you. If you have clear or rime ice, use your deice boots, if you have them on that aircraft, manually, not on automatic.
Title: Re: Heavy Aircraft Stall Training
Post by: icepac on December 01, 2013, 11:15:40 AM
Then new rhetoric of "decrease the angle of attack" is directly related to the buffalo crash and the former (and really stupid) "zero altitude loss stall recovery" that somehow became procedure.

One thing not mentioned often concerning the buffalo crash is the engine intake icing that caused compressor stall only when they asked for more power but flew before that with zero symptoms because low power settings often will  not show the symptoms of icing.

Witnesses heard the popping noise you get with compressor stall as the plane mushed in.

Had it not been for the intake icing, even that badly piloted plane would likely have powered out of the stall using the flawed procedure they adhered to.

Plenty of guys in general aviation piston planes get into trouble when they have carb icing during descent because they didn't turn on the carburetor heat.

On a successful approach that doesn't require bringing high power to correct the glideslope, these guys often simply make a safe landing not knowing that they would have been in trouble had they called for higher power.
Title: Re: Heavy Aircraft Stall Training
Post by: GScholz on December 01, 2013, 11:28:32 AM
The Air France accident in the South Atlantic shows that commercial pilots need more basic stick & rudder time. That crew flew into a thunderstorm, lost autopilot due to systems failures and stalled their airliner. They kept it in a deep stall all the way down to the sea.
Title: Re: Heavy Aircraft Stall Training
Post by: Karnak on December 01, 2013, 11:32:58 AM
The Air France accident in the South Atlantic shows that commercial pilots need more basic stick & rudder time. That crew flew into a thunderstorm, lost autopilot due to systems failures and stalled their airliner. They kept it in a deep stall all the way down to the sea.
IIRC the captain got back to the cockpit before they hit the water and he rapidly recognized what was happening and started to recover the plane but didn't have enough altitude left to do so.
Title: Re: Heavy Aircraft Stall Training
Post by: GScholz on December 01, 2013, 11:44:58 AM
Yes, because he was an older pilot who had a lot of stick & rudder time on older, less automated aircraft.
Title: Re: Heavy Aircraft Stall Training
Post by: GScholz on December 01, 2013, 11:52:52 AM
At 1h 36m, the flight enters the outer extremities of a tropical storm system. Unlike other planes' crews flying through the region, AF447's flight crew has not changed the route to avoid the worst of the storms. The outside temperature is much warmer than forecast, preventing the still fuel-heavy aircraft from flying higher to avoid the effects of the weather. Instead, it ploughs into a layer of clouds.

At 1h51m, the cockpit becomes illuminated by a strange electrical phenomenon. The co-pilot in the right-hand seat, an inexperienced 32-year-old named Pierre-Cédric Bonin, asks, "What's that?" The captain, Marc Dubois, a veteran with more than 11,000 hours of flight time, tells him it is St. Elmo's fire, a phenomenon often found with thunderstorms at these latitudes.

At approximately 2 am, the other co-pilot, David Robert, returns to the cockpit after a rest break. At 37, Robert is both older and more experienced than Bonin, with more than double his colleague's total flight hours. The head pilot gets up and gives him the left-hand seat. Despite the gap in seniority and experience, the captain leaves Bonin in charge of the controls.

At 2:02 am, the captain leaves the flight deck to take a nap. Within 15 minutes, everyone aboard the plane will be dead.]

02:03:44 (Bonin) La convergence inter tropicale… voilà, là on est dedans, entre 'Salpu' et 'Tasil.' Et puis, voilà, on est en plein dedans…
The inter-tropical convergence... look, we're in it, between 'Salpu' and 'Tasil.' And then, look, we're right in it...

The intertropical convergence, or ITC, is an area of consistently severe weather near the equator. As is often the case, it has spawned a string of very large thunderstorms, some of which stretch into the stratosphere. Unlike some of the other planes's crews flying in the region this evening, the crew of AF447 has not studied the pattern of storms and requested a divergence around the area of most intense activity. (Salpu and Tasil are two air-traffic-position reporting points.)

02:05:55 (Robert) Oui, on va les appeler derrière... pour leur dire quand même parce que...
Yes, let's call them in the back, to let them know...

Robert pushes the call button.

02:05:59 (flight attendant, heard on the intercom) Oui? Marilyn.
Yes? Marilyn.

02:06:04 (Bonin) Oui, Marilyn, c'est Pierre devant... Dis-moi, dans deux minutes, on devrait attaquer une zone où ça devrait bouger un peu plus que maintenant. Il faudrait vous méfier là.
Yes, Marilyn, it's Pierre up front... Listen, in 2 minutes, we're going to be getting into an area where things are going to be moving around a little bit more than now. You'll want to take care.

02:06:13 (flight attendant) D'accord, on s'assoit alors?
Okay, we should sit down then?

02:06:15 (Bonin) Bon, je pense que ce serait pas mal… tu préviens les copains!
Well, I think that's not a bad idea. Give your friends a heads-up.

02:06:18 (flight attendant) Ouais, OK, j'appelle les autres derrière. Merci beaucoup.
Yeah, okay, I'll tell the others in the back. Thanks a lot.

02:06:19 (Bonin) Mais je te rappelle dès qu'on est sorti de là.
I'll call you back as soon as we're out of it.

02:06:20 (flight attendant) OK.
Okay.

The two copilots discuss the unusually elevated external temperature, which has prevented them from climbing to their desired altitude, and express happiness that they are flying an Airbus 330, which has better performance at altitude than an Airbus 340.

02:06:50 (Bonin) Va pour les anti-ice. C'est toujours ça de pris.
Let's go for the anti-icing system. It's better than nothing.

Because they are flying through clouds, the pilots turn on the anti-icing system to try to keep ice off the flight surfaces; ice reduces the plane's aerodynamic efficiency, weighs it down, and in extreme cases, can cause it to crash.

02:07:00 (Bonin) On est apparemment à la limite de la couche, ça devrait aller.
We seem to be at the end of the cloud layer, it might be okay.

In the meantime Robert has been examining the radar system and has found that it has not been set up in the correct mode. Changing the settings, he scrutinizes the radar map and realizes that they are headed directly toward an area of intense activity.

02:08:03 (Robert) Tu peux éventuellement le tirer un peu à gauche.
You can possibly pull it a little to the left.

02:08:05 (Bonin) Excuse-moi?
Sorry, what?

02:08:07 (Robert) Tu peux éventuellement prendre un peu à gauche. On est d'accord qu'on est en manuel, hein?
You can possibly pull it a little to the left. We're agreed that we're in manual, yeah?

Bonin wordlessly banks the plane to the left. Suddenly, a strange aroma, like an electrical transformer, floods the cockpit, and the temperature suddenly increases. At first, the younger pilot thinks that something is wrong with the air-conditioning system, but Robert assures him that the effect is from the severe weather in the vicinity. Bonin seems ill at ease. Then the sound of slipstream suddenly becomes louder. This, presumably, is due to the accumulation of ice crystals on the exterior of the fuselage. Bonin announces that he is going to reduce the speed of the aircraft, and asks Robert if he should turn on a feature that will prevent the jet engines from flaming out in the event of severe icing.

Just then an alarm sounds for 2.2 seconds, indicating that the autopilot is disconnecting. The cause is the fact that the plane's pitot tubes, externally mounted sensors that determine air speed, have iced over, so the human pilots will now have to fly the plane by hand.

Title: Re: Heavy Aircraft Stall Training
Post by: GScholz on December 01, 2013, 11:53:32 AM
Note, however, that the plane has suffered no mechanical malfunction. Aside from the loss of airspeed indication, everything is working fine. Otelli reports that many airline pilots (and, indeed, he himself) subsequently flew a simulation of the flight from this point and were able to do so without any trouble. But neither Bonin nor Roberts has ever received training in how to deal with an unreliable airspeed indicator at cruise altitude, or in flying the airplane by hand under such conditions.

02:10:06 (Bonin) J'ai les commandes.
I have the controls.

02:10:07 (Robert) D'accord.
Okay.

Perhaps spooked by everything that has unfolded over the past few minutes—the turbulence, the strange electrical phenomena, his colleague's failure to route around the potentially dangerous storm—Bonin reacts irrationally. He pulls back on the side stick to put the airplane into a steep climb, despite having recently discussed the fact that the plane could not safely ascend due to the unusually high external temperature.

Bonin's behavior is difficult for professional aviators to understand. "If he's going straight and level and he's got no airspeed, I don't know why he'd pull back," says Chris Nutter, an airline pilot and flight instructor. "The logical thing to do would be to cross-check"—that is, compare the pilot's airspeed indicator with the co-pilot's and with other instrument readings, such as groundspeed, altitude, engine settings, and rate of climb. In such a situation, "we go through an iterative assessment and evaluation process," Nutter explains, before engaging in any manipulation of the controls. "Apparently that didn't happen."

Almost as soon as Bonin pulls up into a climb, the plane's computer reacts. A warning chime alerts the cockpit to the fact that they are leaving their programmed altitude. Then the stall warning sounds. This is a synthesized human voice that repeatedly calls out, "Stall!" in English, followed by a loud and intentionally annoying sound called a "cricket." A stall is a potentially dangerous situation that can result from flying too slowly. At a critical speed, a wing suddenly becomes much less effective at generating lift, and a plane can plunge precipitously. All pilots are trained to push the controls forward when they're at risk of a stall so the plane will dive and gain speed.

The Airbus's stall alarm is designed to be impossible to ignore. Yet for the duration of the flight, none of the pilots will mention it, or acknowledge the possibility that the plane has indeed stalled—even though the word "Stall!" will blare through the cockpit 75 times. Throughout, Bonin will keep pulling back on the stick, the exact opposite of what he must do to recover from the stall.

02:10:07 (Robert) Qu'est-ce que c'est que ça?
What's this?

02:10:15 (Bonin) On n'a pas une bonne… On n'a pas une bonne annonce de vitesse.
There's no good... there's no good speed indication.

02:10:16 (Robert) On a perdu les, les, les vitesses alors?
We've lost the, the, the speeds, then?

The plane is soon climbing at a blistering rate of 7000 feet per minute. While it is gaining altitude, it is losing speed, until it is crawling along at only 93 knots, a speed more typical of a small Cessna than an airliner. Robert notices Bonin's error and tries to correct him.

02:10:27 (Robert) Faites attention à ta vitesse. Faites attention à ta vitesse.
Pay attention to your speed. Pay attention to your speed.

He is probably referring to the plane's vertical speed. They are still climbing.

02:10:28 (Bonin) OK, OK, je redescends.
Okay, okay, I'm descending.

02:10:30 (Robert) Tu stabilises...
Stabilize…

02:10:31 (Bonin) Ouais.
Yeah.

02:10:31 (Robert) Tu redescends... On est en train de monter selon lui… Selon lui, tu montes, donc tu redescends.
Descend... It says we're going up... It says we're going up, so descend.

02:10:35 (Bonin) D'accord.
Okay.

Thanks to the effects of the anti-icing system, one of the pitot tubes begins to work again. The cockpit displays once again show valid speed information.

02:10:36 (Robert) Redescends!
Descend!

02:10:37 (Bonin) C'est parti, on redescend.
Here we go, we're descending.

02:10:38 (Robert) Doucement!
Gently!

Bonin eases the back pressure on the stick, and the plane gains speed as its climb becomes more shallow. It accelerates to 223 knots. The stall warning falls silent. For a moment, the co-pilots are in control of the airplane.

02:10:41(Bonin) On est en… ouais, on est en "climb."
We're... yeah, we're in a climb.

Yet, still, Bonin does not lower the nose. Recognizing the urgency of the situation, Robert pushes a button to summon the captain.

02:10:49 (Robert) Putain, il est où... euh?
Damn it, where is he?
Title: Re: Heavy Aircraft Stall Training
Post by: GScholz on December 01, 2013, 11:54:48 AM
The plane has climbed to 2512 feet above its initial altitude, and though it is still ascending at a dangerously high rate, it is flying within its acceptable envelope. But for reasons unknown, Bonin once again increases his back pressure on the stick, raising the nose of the plane and bleeding off speed. Again, the stall alarm begins to sound.

Still, the pilots continue to ignore it, and the reason may be that they believe it is impossible for them to stall the airplane. It's not an entirely unreasonable idea: The Airbus is a fly-by-wire plane; the control inputs are not fed directly to the control surfaces, but to a computer, which then in turn commands actuators that move the ailerons, rudder, elevator, and flaps. The vast majority of the time, the computer operates within what's known as normal law, which means that the computer will not enact any control movements that would cause the plane to leave its flight envelope. The flight control computer under normal law will not allow an aircraft to stall, aviation experts say.

But once the computer lost its airspeed data, it disconnected the autopilot and switched from normal law to "alternate law," a regime with far fewer restrictions on what a pilot can do. In alternate law, pilots can stall an airplane.

It's quite possible that Bonin had never flown an airplane in alternate law, or understood its lack of restrictions. Therefore, Bonin may have assumed that the stall warning was spurious because he didn't realize that the plane could remove its own restrictions against stalling and, indeed, had done so.

02:10:55 (Robert) Putain!
Damn it!

Another of the pitot tubes begins to function once more. The cockpit's avionics are now all functioning normally. The flight crew has all the information that they need to fly safely, and all the systems are fully functional. The problems that occur from this point forward are entirely due to human error.

02:11:03 (Bonin) Je suis en TOGA, hein?
I'm in TOGA, huh?

Bonin's statement here offers a crucial window onto his reasoning. TOGA is an acronym for Take Off, Go Around. When a plane is taking off or aborting a landing—"going around"—it must gain both speed and altitude as efficiently as possible. At this critical phase of flight, pilots are trained to increase engine speed to the TOGA level and raise the nose to a certain pitch angle.

Clearly, here Bonin is trying to achieve the same effect: He wants to increase speed and to climb away from danger. But he is not at sea level; he is in the far thinner air of 37,500 feet. The engines generate less thrust here, and the wings generate less lift. Raising the nose to a certain angle of pitch does not result in the same angle of climb, but far less. Indeed, it can—and will—result in a descent.

While Bonin's behavior is irrational, it is not inexplicable. Intense psychological stress tends to shut down the part of the brain responsible for innovative, creative thought. Instead, we tend to revert to the familiar and the well-rehearsed. Though pilots are required to practice hand-flying their aircraft during all phases of flight as part of recurrent training, in their daily routine they do most of their hand-flying at low altitude—while taking off, landing, and maneuvering. It's not surprising, then, that amid the frightening disorientation of the thunderstorm, Bonin reverted to flying the plane as if it had been close to the ground, even though this response was totally ill-suited to the situation.

02:11:06 (Robert) Putain, il vient ou il vient pas?
Damn it, is he coming or not?

The plane now reaches its maximum altitude. With engines at full power, the nose pitched upward at an angle of 18 degrees, it moves horizontally for an instant and then begins to sink back toward the ocean.

02:11:21 (Robert) On a pourtant les moteurs! Qu'est-ce qui se passe bordel? Je ne comprends pas ce que se passe.
We still have the engines! What the hell is happening? I don't understand what's happening.

Unlike the control yokes of a Boeing jetliner, the side sticks on an Airbus are "asynchronous"—that is, they move independently. "If the person in the right seat is pulling back on the joystick, the person in the left seat doesn't feel it," says Dr. David Esser, a professor of aeronautical science at Embry-Riddle Aeronautical University. "Their stick doesn't move just because the other one does, unlike the old-fashioned mechanical systems like you find in small planes, where if you turn one, the [other] one turns the same way." Robert has no idea that, despite their conversation about descending, Bonin has continued to pull back on the side stick.

The men are utterly failing to engage in an important process known as crew resource management, or CRM. They are failing, essentially, to cooperate. It is not clear to either one of them who is responsible for what, and who is doing what. This is a natural result of having two co-pilots flying the plane. "When you have a captain and a first officer in the cockpit, it's clear who's in charge," Nutter explains. "The captain has command authority. He's legally responsible for the safety of the flight. When you put two first officers up front, it changes things. You don't have the sort of traditional discipline imposed on the flight deck when you have a captain."

The vertical speed toward the ocean accelerates. If Bonin were to let go of the controls, the nose would fall and the plane would regain forward speed. But because he is holding the stick all the way back, the nose remains high and the plane has barely enough forward speed for the controls to be effective. As turbulence continues to buffet the plane, it is nearly impossible to keep the wings level.

02:11:32 (Bonin) Putain, j'ai plus le contrôle de l'avion, là! J'ai plus le contrôle de l'avion!
Damn it, I don't have control of the plane, I don't have control of the plane at all!

02:11:37 (Robert) Commandes à gauche!
Left seat taking control!

At last, the more senior of the pilots (and the one who seems to have a somewhat better grasp of the situation) now takes control of the airplane. Unfortunately, he, too, seems unaware of the fact that the plane is now stalled, and pulls back on the stick as well. Although the plane's nose is pitched up, it is descending at a 40-degree angle. The stall warning continues to sound. At any rate, Bonin soon after takes back the controls.

A minute and a half after the crisis began, the captain returns to the cockpit. The stall warning continues to blare.

02:11:43 (Captain) Eh… Qu'est-ce que vous foutez?
What the hell are you doing?

02:11:45 (Bonin) On perd le contrôle de l'avion, là!
We've lost control of the plane!

02:11:47 (Robert) On a totalement perdu le contrôle de l'avion... On comprend rien... On a tout tenté...
We've totally lost control of the plane. We don't understand at all... We've tried everything.

Title: Re: Heavy Aircraft Stall Training
Post by: GScholz on December 01, 2013, 11:55:25 AM
By now the plane has returned to its initial altitude but is falling fast. With its nose pitched 15 degrees up, and a forward speed of 100 knots, it is descending at a rate of 10,000 feet per minute, at an angle of 41.5 degrees. It will maintain this attitude with little variation all the way to the sea. Though the pitot tubes are now fully functional, the forward airspeed is so low—below 60 knots—that the angle-of-attack inputs are no longer accepted as valid, and the stall-warning horn temporarily stops. This may give the pilots the impression that their situation is improving, when in fact it signals just the reverse.

Another of the revelations of Otelli's transcript is that the captain of the flight makes no attempt to physically take control of the airplane. Had Dubois done so, he almost certainly would have understood, as a pilot with many hours flying light airplanes, the insanity of pulling back on the controls while stalled. But instead, he takes a seat behind the other two pilots.

This, experts say, is not so hard to understand. "They were probably experiencing some pretty wild gyrations," Esser says. "In a condition like that, he might not necessarily want to make the situation worse by having one of the crew members actually disengage and stand up. He was probably in a better position to observe and give his commands from the seat behind."

But from his seat, Dubois is unable to infer from the instrument displays in front of him why the plane is behaving as it is. The critical missing piece of information: the fact that someone has been holding the controls all the way back for virtually the entire time. No one has told Dubois, and he hasn't thought to ask.

02:12:14 (Robert) Qu'est-ce que tu en penses? Qu'est-ce que tu en penses? Qu'est-ce qu'il faut faire?
What do you think? What do you think? What should we do?

02:12:15 (Captain) Alors, là, je ne sais pas!
Well, I don't know!

As the stall warning continues to blare, the three pilots discuss the situation with no hint of understanding the nature of their problem. No one mentions the word "stall." As the plane is buffeted by turbulence, the captain urges Bonin to level the wings—advice that does nothing to address their main problem. The men briefly discuss, incredibly, whether they are in fact climbing or descending, before agreeing that they are indeed descending. As the plane approaches 10,000 feet, Robert tries to take back the controls, and pushes forward on the stick, but the plane is in "dual input" mode, and so the system averages his inputs with those of Bonin, who continues to pull back. The nose remains high.

02:13:40 (Robert) Remonte... remonte... remonte... remonte...
Climb... climb... climb... climb...

02:13:40 (Bonin) Mais je suis à fond à cabrer depuis tout à l'heure!
But I've had the stick back the whole time!

At last, Bonin tells the others the crucial fact whose import he has so grievously failed to understand himself.

02:13:42 (Captain) Non, non, non... Ne remonte pas... non, non.
No, no, no... Don't climb... no, no.

02:13:43 (Robert) Alors descends... Alors, donne-moi les commandes... À moi les commandes!
Descend, then... Give me the controls... Give me the controls!

Bonin yields the controls, and Robert finally puts the nose down. The plane begins to regain speed. But it is still descending at a precipitous angle. As they near 2000 feet, the aircraft's sensors detect the fast-approaching surface and trigger a new alarm. There is no time left to build up speed by pushing the plane's nose forward into a dive. At any rate, without warning his colleagues, Bonin once again takes back the controls and pulls his side stick all the way back.

02:14:23 (Robert) Putain, on va taper... C'est pas vrai!
Damn it, we're going to crash... This can't be happening!

02:14:25 (Bonin) Mais qu'est-ce que se passe?
But what's happening?

02:14:27 (Captain) 10 degrès d'assiette...
Ten degrees of pitch...

Exactly 1.4 seconds later, the cockpit voice recorder stops.
Title: Re: Heavy Aircraft Stall Training
Post by: Karnak on December 01, 2013, 12:13:37 PM
Yeah.  I've read it.  The whole thing boggled my mind.  Even as just a stupid sim pilot I can't imagine taking the actions Bonin did.  It is just so ingrained in me to do nose down to escape a stall.  I can't imagine holding the nose up like that in a plane where the computer prevents it from spinning by limiting the angle of attack.
Title: Re: Heavy Aircraft Stall Training
Post by: GScholz on December 01, 2013, 12:20:17 PM
Apparently it is not so ingrained in the younger generations of commercial pilots today. In many ways the pilots are there as a backup in case the automation fails, but they're useless if they cannot fly the airplane under difficult circumstances without automation. The automation rarely fails in any other circumstance than "difficult".
Title: Re: Heavy Aircraft Stall Training
Post by: earl1937 on December 01, 2013, 02:56:59 PM
Apparently it is not so ingrained in the younger generations of commercial pilots today. In many ways the pilots are there as a backup in case the automation fails, but they're useless if they cannot fly the airplane under difficult circumstances without automation. The automation rarely fails in any other circumstance than "difficult".
:airplane: A great post sir! How about the Japanese guys who flew, or didn't fly, that 787, I think it was, into the support end of the runway at San Franisco not to long ago?

Again, it goes back to one of my other posts: the worst time to practice emergency procedures is in a real emergency!
Title: Re: Heavy Aircraft Stall Training
Post by: Karnak on December 01, 2013, 03:43:31 PM
:airplane: A great post sir! How about the Japanese guys who flew, or didn't fly, that 787, I think it was, into the support end of the runway at San Franisco not to long ago?

Again, it goes back to one of my other posts: the worst time to practice emergency procedures is in a real emergency!
Korean guys and  it was a 777.  First fatalities on a 777 actually.

I understand Japanese airlines are much safer than Korean, having made significant improvements since the '70s and '80s.
Title: Re: Heavy Aircraft Stall Training
Post by: Valkyrie on December 01, 2013, 03:53:04 PM
JAL is extremely competent both in aircraft pilotage and engineering. The Koreans have an extreme cultural problem with flying and seniority. Junior pilots on crews won't correct a senior airmen or even announce trouble. This was a major issue in the 90s for them. They will follow a senior into a hills side or into the ground if that is what the man chooses to do. Korean Aor has implemented major saftey programs to correct his, but it can still be and issue.

The 777 SFO was. Failure to understand the auto throttles by an experienced crew new to the 777. They relied on the auto throttle to maintain speed even she the mode selected didn't offer that feature. A major failure I thier scan to make sure they were on speed. That why American and others Mandate that the autopilot is all on or all off and not something in between. Hence the phraseology push push click click.

Here again is my point the FAA needs to clarify what it wants in the pts standards. Do they want a stall and recovery, or a close representation of a stall and recovery?

If it is the first clear up the minimum altitude loss language. demostrate an actual stall and recovery without mentioning the loss in altitude, or clarifiying what you need to do. If its the second make sure you get close to the stall but to not stall and no altitude loss.

Lastly start spin training again seriously for ATP candidates. Let the stall develope and see what they are really about from various angles example banked 60 degrees, so pilots will understand critical angle of attack.
Title: Re: Heavy Aircraft Stall Training
Post by: Karnak on December 01, 2013, 03:59:57 PM
JAL is extremely competent both in aircraft pilotage and engineering. The Koreans have an extreme cultural problem with flying and seniority. Junior pilots on crews won't correct a senior airmen or even announce trouble. This was a major issue in the 90s for them. They will follow a senior into a hills side or into the ground if that is what the man chooses to do. Korean Aor has implemented major saftey programs to correct his, but it can still be and issue.
I seem to recall that a Japanese air liner or cargo plane crashed in the UK in the '80s due to the copilot being absolutely deferential to the pilot.  I would guess, if I am correct, that the Japanese took steps to address that problem.
Title: Re: Heavy Aircraft Stall Training
Post by: Valkyrie on December 01, 2013, 07:16:03 PM
No it was Korean airlines 747. Capt attitude indicator failed and no one corrected him. He was a capt but low time on 747s. Prior to that he was an air force Col commanding f-16 squadrons. It was out of stanstead uk 50km north of london.
Title: Re: Heavy Aircraft Stall Training
Post by: Karnak on December 01, 2013, 07:50:47 PM
No it was Korean airlines 747. Capt attitude indicator failed and no one corrected him. He was a capt but low time on 747s. Prior to that he was an air force Col commanding f-16 squadrons. It was out of stanstead uk 50km north of london.
Ah.  Thanks for the correction.  The Koreans need to do something about that.

I recall looking at the crash of JAL 123 and the flight crew did a good job with what they had to work with, but there just wasn't enough for them given the terrain.
Title: Re: Heavy Aircraft Stall Training
Post by: hitech on December 07, 2013, 12:01:21 PM
If you stall while flying inverted is it technique increasing or deceasing AOA what you go from -10 to -9 degrees of AOA?

One thing I am always amazed by is the fairly hi % of pilots who have never even done a roll in an aircraft. I was teaching a friend of my who has about 3000 hours of flight time including unusual attitude training.

I was teaching him hammer heads. I had talked him threw it before we left the ground, the up was no problem, I assisted a little on the kick and corner of the stick. But as soon as we were on the down line he was already pulling back on the stick, I was letting him make the mistake assuming he would feel what was happening, but he kept pulling to the point of the tail starting to slide out at which time i pushed forward and did the recovery. But what surprised me is that he never sensed the onset of the spin , nore did he sense the stall at very slow speeds even though we where headed straight down.

Another time when I was getting my check out in the RV from base to final I was a little nose hi, I simply increased the bank with a slight unload to let the nose settle. My instructor practically freaked thinking we would stall with a high bank angle not understanding what a "Knife in" Pitch down maneuver is.


HiTech

Title: Re: Heavy Aircraft Stall Training
Post by: colmbo on December 07, 2013, 12:10:54 PM
If you stall while flying inverted is it technique increasing or deceasing AOA what you go from -10 to -9 degrees of AOA?




Say again, over.
Title: Re: Heavy Aircraft Stall Training
Post by: pembquist on December 07, 2013, 12:23:52 PM
If you stall while flying inverted is it technique increasing or deceasing AOA what you go from -10 to -9 degrees of AOA



Hey Chief, what?
Title: Re: Heavy Aircraft Stall Training
Post by: earl1937 on December 08, 2013, 07:59:08 AM
If you stall while flying inverted is it technique increasing or deceasing AOA what you go from -10 to -9 degrees of AOA?

One thing I am always amazed by is the fairly hi % of pilots who have never even done a roll in an aircraft. I was teaching a friend of my who has about 3000 hours of flight time including unusual attitude training.

I was teaching him hammer heads. I had talked him threw it before we left the ground, the up was no problem, I assisted a little on the kick and corner of the stick. But as soon as we were on the down line he was already pulling back on the stick, I was letting him make the mistake assuming he would feel what was happening, but he kept pulling to the point of the tail starting to slide out at which time i pushed forward and did the recovery. But what surprised me is that he never sensed the onset of the spin , nore did he sense the stall at very slow speeds even though we where headed straight down.

Another time when I was getting my check out in the RV from base to final I was a little nose hi, I simply increased the bank with a slight unload to let the nose settle. My instructor practically freaked thinking we would stall with a high bank angle not understanding what a "Knife in" Pitch down maneuver is.


HiTech


:airplane: :x If you stall while flying inverted:  It no longer matters, your wing is through flying and you really don't have any control until the wing recovers flying speed!
Title: Re: Heavy Aircraft Stall Training
Post by: Puma44 on December 08, 2013, 05:22:04 PM
 :confused:  Say what?
Title: Re: Heavy Aircraft Stall Training
Post by: Valkyrie on December 08, 2013, 09:22:30 PM
The problem with pilots is the understanding of critical angle of attack. To people everything is a relation to what they know, people relate everything back to the horizon. What pilots need to talk about is relative wind, angle of attack, and flight path. All are very different animals. And in talking stall recovery it should be in terms of decreasing angle of attack.

Angle of attack as related to relative wind as related to flight path.

Many pilots see it as angle of attack as related flight path, without the understanding of relative wind. My jeppeson book didn't talk about relative wind, only angle of attack and the critical angle of attack. Took my aerodynamics one book to get the relative wing concept.

Inveted or upright you have to understand  relative wind and the angle of attack as a function of relative wind. Having the aopa at a negative angle could work inverted providing the lift in the aero foil, much like and extra 300 with a near symetirical aero foil.

HiTech I think that is where your friend is missing a concept.
:airplane: :x If you stall while flying inverted:  It no longer matters, your wing is through flying and you really don't have any control until the wing recovers flying speed!

Earl you too are missing the point it's about how the critical angle of attack is defined, it's got nothing to do with speed. But the angle between relative wind, and angle of attack. Speed just works on the relative wind. You need to work all those variables to get the desired flight path.
Title: Re: Heavy Aircraft Stall Training
Post by: Oldman731 on December 08, 2013, 09:32:14 PM
The problem with pilots is the understanding of critical angle of attack. To people everything is a relation to what they know, people relate everything back to the horizon. What pilots need to talk about is relative wind, angle of attack, and flight path. All are very different animals. And in talking stall recovery it should be in terms of decreasing angle of attack.

Angle of attack as related to relative wind as related to flight path.

Many pilots see it as angle of attack as related flight path, without the understanding of relative wind. My jeppeson book didn't talk about relative wind, only angle of attack and the critical angle of attack. Took my aerodynamics one book to get the relative wing concept.

Inveted or upright you have to understand  relative wind and the angle of attack as a function of relative wind. Having the aopa at a negative angle could work inverted providing the lift in the aero foil, much like and extra 300 with a near symetirical aero foil.

HiTech I think that is where your friend is missing a concept.
Earl you too are missing the point it's about how the critical angle of attack is defined, it's got nothing to do with speed. But the angle between relative wind, and angle of attack.


Well thank goodness that all of this has been made clear to me now.

- oldman
Title: Re: Heavy Aircraft Stall Training
Post by: Puma44 on December 08, 2013, 11:26:02 PM

Well thank goodness that all of this has been made clear to me now.

- oldman
Been wondering how long it would take you to figure it out, Oldman.   :lol
Title: Re: Heavy Aircraft Stall Training
Post by: Puma44 on December 08, 2013, 11:42:21 PM
The problem with pilots is the understanding of critical angle of attack. To people everything is a relation to what they know, people relate everything back to the horizon. What pilots need to talk about is relative wind, angle of attack, and flight path. All are very different animals. And in talking stall recovery it should be in terms of decreasing angle of attack.

Angle of attack as related to relative wind as related to flight path.

Many pilots see it as angle of attack as related flight path, without the understanding of relative wind.


I'm guessing most "pilots" that are formally trained and licensed/rated understand the relationship between AOA and relative wind. 

Earl you too are missing the point it's about how the critical angle of attack is defined, it's got nothing to do with speed. But the angle between relative wind, and angle of attack. Speed just works on the relative wind. You need to work all those variables to get the desired flight path.

Just a guess, but, I think Earl probably has the concept down pretty well, considering his vast aviation experience....to include those as an instructor. 

How would you analyze the AOA, relative wind, airspeed, and stall potential here (just for the sake of discussion)?

(http://i906.photobucket.com/albums/ac270/puma44/4230d6c9d78495b3a93b72ef84aa4a69.jpg)

Title: Re: Heavy Aircraft Stall Training
Post by: earl1937 on December 09, 2013, 11:42:05 AM
I'm guessing most "pilots" that are formally trained and licensed/rated understand the relationship between AOA and relative wind. 

Just a guess, but, I think Earl probably has the concept down pretty well, considering his vast aviation experience....to include those as an instructor. 

How would you analyze the AOA, relative wind, airspeed, and stall potential here (just for the sake of discussion)?

(http://i906.photobucket.com/albums/ac270/puma44/4230d6c9d78495b3a93b72ef84aa4a69.jpg)


:airplane: Well put sir! Sometimes there is a lot of difference in the "text book" and what really happens in the real thing! I understand exactly what Hi Tech is asking and I was just making the point that the "hip bone" is connected to the "thigh bone", so what difference does it make if you are right side up or not, if that darn wing quits flying, you are going to have to make a recovery post haste. In an inverted "flat" spin, you better know what you are doing, but most times, instinct takes over, backed up by a lot of piratical experience. If you are on the "gauges" is one thing, but VFR, you are going to have visual clues as to your reaction during recovery.
Title: Re: Heavy Aircraft Stall Training
Post by: Puma44 on December 09, 2013, 11:59:36 AM
Exactly, Earl!  The training and survival instinct take over and in the vast majority of cases, all is well and more valuable experience is gained.  Then, there are those times when buffoonery takes over and things don't work out quite so well.   :salute


(http://i906.photobucket.com/albums/ac270/puma44/00bf6f4d7d245d1d193e69f6faed9b4c_zps8796b669.jpg) (http://s906.photobucket.com/user/puma44/media/00bf6f4d7d245d1d193e69f6faed9b4c_zps8796b669.jpg.html)
Title: Re: Heavy Aircraft Stall Training
Post by: Valkyrie on December 09, 2013, 03:06:10 PM
9.5 out of 10 pilots today couldn't even begin to understand what is being discused here. If we could go back in time and ask the Cologan Air capt he couldn't explain it.

All pilots understand that a stall is the point at which the aero foil exceeds its given critical angle of attack and fails to produce lift.

All pilots will understand that to stop a stall you must break the stall first, where confusion sets in is how this relates to the flight path and speed.

Cl = L/qs

L is lift
Q is the dynamic pressure
S is the wing surface area
Cl is the lift coeficinet

So what I am getting at here is the speed does effect the stall but only as it relates to the relative wind, and needed lift produced.
A wing at a certain speed must produce a Cl to maintian the desired flight path.
Title: Re: Heavy Aircraft Stall Training
Post by: Valkyrie on December 09, 2013, 03:11:09 PM
If the needed Cl exceeds the maximum Cl the wing can produce, the flight path will descend until enough energy Q is attained to come back into equilibrium. Assuming standard configuration. In effect the stall.

The Stall itself is the phenomenon of the the AOA exceeding the critical angle of attack and the flow becoming turbulent and not producing the needed Cl to lift the airplane.

Cl for a wing is a function of its angle of attack.

Cl * Q * S = L which works to produce the disired flight path along with Drag, Thrust, and weight.

Hence the accelerated stall, where its the flow over the wing that is turbulent and no longer producing lift.

So the stall is independent of the speed, but directly related to angle of attack, and the flow over the wing.
Title: Re: Heavy Aircraft Stall Training
Post by: Puma44 on December 09, 2013, 03:38:40 PM
9.5 out of 10 pilots today couldn't even begin to understand what is being discused here.

Where do you get that statistic?   :headscratch:
Title: Re: Heavy Aircraft Stall Training
Post by: Oldman731 on December 09, 2013, 03:49:50 PM
Where do you get that statistic?  


Oh sit down and be quiet, Puma, you can't even begin to understand these things.

- oldman
Title: Re: Heavy Aircraft Stall Training
Post by: Puma44 on December 09, 2013, 06:31:35 PM
Yeah, you're right, Oldman......pretty technical stuff.   :rofl
Title: Re: Heavy Aircraft Stall Training
Post by: hitech on December 09, 2013, 06:40:47 PM
Restated for colmbo
If you stall while flying inverted is it technically increasing or deceasing AOA what you go from -10 to -9 degrees of AOA?

HiTech



was a typo also.

To stall inverted , you are pulling negative AOA decreasing AOA would mean having less aoa, less aoa then -10 is - 11. So is the key to stall recover always decreasing AOA?

HiTech
Title: Re: Heavy Aircraft Stall Training
Post by: FLS on December 09, 2013, 07:09:51 PM
Restated for colmbo
was a typo also.

To stall inverted , you are pulling negative AOA decreasing AOA would mean having less aoa, less aoa then -10 is - 11. So is the key to stall recover always decreasing AOA?

HiTech


Depends on your reference point.  -11 degrees is a greater angle than -10 degrees.
Title: Re: Heavy Aircraft Stall Training
Post by: pembquist on December 09, 2013, 07:16:10 PM
I still don't understand. If the aoa is the angle between the mean chord line and the relative wind it's the absolute value of the angle not the sign that is significant.
Title: Re: Heavy Aircraft Stall Training
Post by: Valkyrie on December 09, 2013, 08:12:19 PM
It's relative.

Inverted you would need to increase the aoa. B/c the separation in due to the large negative aoa getting your lift vector in the right direction. To correct that separation increasing aoa will correct the separation and inverted flight can continue with an air foil with the flow attached.

I have neve Rome aerobatics before, but that would be interesting as the Cm might not be in your favor, almost like an out of balance f-16 at test pilot school where they turned off the light computer and stalled it 600 lbs tail heavy.

Yes the absolute value is only importent if dealing with a symmetrical airfoil. Sign is important if the is as symmetrical.
Title: Re: Heavy Aircraft Stall Training
Post by: pembquist on December 09, 2013, 09:24:05 PM
I don't understand, inverted or not, symmetrical or not you are reducing the angle between the direction of relative wind to get the flow reattached. Isn't it correct to say that -10 is a larger angle than +5?
Title: Re: Heavy Aircraft Stall Training
Post by: Valkyrie on December 09, 2013, 10:03:22 PM
Correct.
Title: Re: Heavy Aircraft Stall Training
Post by: pembquist on December 09, 2013, 10:42:23 PM
OK so I think my confusion is semantic and about nomenclature. If I was flying inverted pushing on the stick to climb and began to stall I would not say or conceptualize recovery to be "increase angle of attack" by letting the stick come back. I would say and conceptualize that I was lowering the angle of attack by letting the stick come back. So now I think I understand Hitech's question.
Title: Re: Heavy Aircraft Stall Training
Post by: hitech on December 10, 2013, 12:57:41 PM
OK so I think my confusion is semantic and about nomenclature. If I was flying inverted pushing on the stick to climb and began to stall I would not say or conceptualize recovery to be "increase angle of attack" by letting the stick come back. I would say and conceptualize that I was lowering the angle of attack by letting the stick come back. So now I think I understand Hitech's question.

Yep you understand the question.

Also from experience, the RV has a nasty snap when you stall inverted. It's stall speed is about 30 knots higher flying inverted then right side up.

I also found that the first time you use your climb rate indicator while inverted, for some reason it messes with your head which way is which.

Also, no matter how hard you try to clean the plane before planned sustained inverted flight, there will always be a special piece of dirt in the correct position to drop into your nose.

HiTech
Title: Re: Heavy Aircraft Stall Training
Post by: earl1937 on December 10, 2013, 01:01:17 PM
Yep you understand the question.

Also from experience, the RV has a nasty snap when you stall inverted. It's stall speed is about 30 knots higher flying inverted then right side up.

I also found that the first time you use your climb rate indicator while inverted, for some reason it messes with your head which way is which.

Also, no matter how hard you try to clean the plane before planned sustained inverted flight, there will always be a special piece of dirt in the correct position to drop into your nose.

HiTech
:airplane: Good point! Ever watch it while a student is doing an outside loop in a S2 Pitts? That will blow your mind!
Title: Re: Heavy Aircraft Stall Training
Post by: Citabria on December 18, 2013, 04:49:00 PM
...Also, no matter how hard you try to clean the plane before planned sustained inverted flight, there will always be a special piece of dirt in the correct position to drop into your nose.

HiTech

I try to keep the dirt suspended in mid air or pinned to the floor if I am upside down at all after seeing how much dirt can get airborne in an SNJ texan.
Title: Re: Heavy Aircraft Stall Training
Post by: Citabria on December 18, 2013, 08:52:52 PM
I will play devils advocate to the origional discussion in this thread that deals with basic stick and rudder skills or lack thereof.

how do these things keep happening?

Colgan captain does a stall pancakes kills everyone.

Airfrance copilots crash while captain takes a nap. Berlon had the stick held full back the entire time the aircraft was stalled and decending and the entire time kept saying "whats happening? I dont understand" and never mentioned to the rest of the crew his fatal actions with the controls.

situational awareness was completely lost by a fatigued and undertrained and/or underskilled crew with the usual result of death to all onboard. both planes could have recovered easily with max power and pushing the yoke forward but the controls were held full back until the crash was unavoidable.

the general conclusion of these accidents is the crews were inexperienced and deficient in their abilities to safely command an airliner under the worst conditions when at their weakest most fatigued and debilitated cognitive state. had they been fresh well rested they might have reacted more correctly but they did not and everybody died as usual.

humans will always find a way to screw up and because humans make and service the computers and components of aircraft they will screw up sooner or later as well so there really is no ironclad humanproof airplane because even if computers fly the aircraft from gate to gate those computers were made and maintained by humans and also have the chance to break down.

Title: Re: Heavy Aircraft Stall Training
Post by: Karnak on December 18, 2013, 10:01:16 PM
China Airlines Flight 006 is another example, though the pilot did manage to recover the aircraft once he dropped below the clouds.  He didn't believe his ADIs because what they were telling him was so unbelievable compared to what he thought was happening that his first assumption was that they were broken.