Aircraft crash in WNY

[lengro]

The company took the decision the day after an SAS turboprop made by the Canadian company crash-landed with 44 people on board in Denmark when part of its landing gear collapsed.

The plane slid down the runway on its belly after the landing gear collapsed, with one wing scraping the ground in a shower of sparks. All passengers and crew were evacuated safely.

the images...

[ODBAL]

The pilot of the plane is the Brother of our I.T. guy.  Sad day at work...

[Dawger]

This is most likely icing that could not be controlled with the anti-ice and de-ice systems installed on the aircraft.

When the horizontal stabilizer stalls the nose pitches down. This can be aggravated depending on particular design features. There is evidence of accumulations of ice on the CVR. Ice can cause a tailplane stall especially during flap extension.

Several aircraft have crashed because of tailplane icing. Most notably an Embraer 120 in Detroit.

The ATR-72 crash in Roselawn, Indiana was attributed to icing. Specifically icing aft of the ice protection on the leading edge the wing.

Icing is tricky. If you get into severe icing you only have a few minutes or seconds before it makes the airplane un-flyable. But icing that severe is very rare. And modern airplanes are well equipped to deal with it, especially if the ice protection is heat from bleed air instead of inflatable boots.

I'm not familiar with the Q400 but I doubt it had hot wings and tail. Probably pneumatic boots.

[humble]

Roselawn was pilot error, he had engaged flaps during hold and then when he got clearance he forgot about them and got an overspeed warning...things went fubar when he retracted them...

I'm curious if the approach was manual or AP....

Great video
http://video.google.com/videoplay?docid=2238323060735779946

[SFRT - Frenchy]

Roselawn was not a pilot error. If it was, why would they force the wing leading edge modification on all ATRs?

As far as the Q400, my personal guess is that they had the autopilot on, picked up so much ice that the autopilot reached it's limit and disconected ... or they disconected it themselves to manually shoot the ILS. The autopilot gave back the plane to the creew with flight controls in extreme and awckward positions, throw the plane out of balance before the unsuspecting/unprepared creew could spell "mama". 

[trigger2]

My theory...

After staying up all night watching MSNBC and talking to a couple of investigators on this sorta thing, I've devised my own theory...

After seeing pictures of the percipitation in the area, I don't believe that to have caused too much of an issue, it wouldn't be anything that the planes boots (Inflatable rubber tubes on the front end of the wing that break off ice on a smaller planes that can't produce the extra air a jet engine can to feed it through heated tubes to act as a de-icer) couldn't handle. What's more interesting to me is that SEVERAL eye witnesses saw an engine on fire prior to "touch down", which, historically is EXTREMELY rare... I believe that on approach (they were ~4-5 mi out) a large gust of wind (also reported, a couple witnesses saying roughly 25 - 30 mph gusts on the ground) was able to alter the airflow over the wings causing a stall, and at ~1500 - 2000 feet, you don't have much time to recover. The pilot then was forced to take the extreme angle of attack he was at (estimated to be > 45 degrees) and increase engine power to regain airflow and airspeed. The pilot could have instinctually added full power to an engine (although a no-no, with little room to recover, I'd be wanting all the help I could get) causing one of the engines to overheat and catch fire (backed up by a couple eye witnesses saying they heard a high-pitched noise, one describing it as a "high pitched squeal, similar to an earthquake" which, sounds like a weird way to describe it, but if you've ever heard a turbo runnin on decent power, you know something of what he's talking about.). Before you reply going "Overheating an engine takes a while!!" think also that this plane was a dual engine turbo prop, and was almost through with its flight, who knows what the engine temperature was before the incident, and how quickly an engine of this particular model heats at full power... Although that would be a result of the initial stall. I'm forseeing this crash to be labled as a weather related incident...

Another possibility though...

Pilot went through a dense pack of cold air causing near instantanious icing which the boots couldn't break through (that's ALOT of ice in case you don't know... although possible, unlikely) causing an airflow disturbance over the top of the wings, again, resulting in an annoying voice saying "Stall Stall Stall" And maybe later... "Sink rate... Pull Up."

I'm making speculations here, but I believe that both cases that I bring up (although having the same result...stall) are supported by eye-witness accounts and the little evidence we have so far.

My thoughts and prayers go out to the families, and to the heroic men and women who responded to this tragedy...


Another interesting tidbit here though...
Looking through different things, it seems that plane crashes seem to come in threes...Right now we're at two, one heroic story of amazing piloting, and one mystery tragedy...

This is most likely icing that could not be controlled with the anti-ice and de-ice systems installed on the aircraft.

I'm not familiar with the Q400 but I doubt it had hot wings and tail. Probably pneumatic boots.

I'm quite familier with the Q400, it has, as I mentions, pneumatic boots.
It also has the best service record, with the only blot on it being the slight landing gear issue in Europe which was promptly fixed.

[SFRT - Frenchy]

Trigger, turbine overheat theory?  I'll be very surprised if the Q400 turbines don't have a fuel bypass valve to prevent ITT redlining. Don't those have the 5000HP PW with FADEC anyway?

[humble]

Roselawn was not a pilot error. If it was, why would they force the wing leading edge modification on all ATRs?

As far as the Q400, my personal guess is that they had the autopilot on, picked up so much ice that the autopilot reached it's limit and disconected ... or they disconected it themselves to manually shoot the ILS. The autopilot gave back the plane to the creew with flight controls in extreme and awckward positions, throw the plane out of balance before the unsuspecting/unprepared creew could spell "mama". 

NTSB finding was that misconfiguration was a key component of the crash. Doesnt mean that the icing wasnt a major factor and that corrections werent called for. However the full deployment of the flaps and subsequent overspeeding/retraction directly caused the crash. I thought recommended procedures anytime ice was observed was to disengage AP and fly the approach manually. Even GA pilots are taught you never engage flaps with visible ice on the leading wing edges? I know U've got thousands of hours in all kinds of stuff...from the comparatively little I know it sure seems like some fundamental errors...assuming AP was engaged up till final.

[trigger2]

Trigger, turbine overheat theory?  I'll be very surprised if the Q400 turbines don't have a fuel bypass valve to prevent ITT redlining. Don't those have the 5000HP PW with FADEC anyway?

The aircraft is powered by two turboprop engines type PW1 50A supplied by Pratt & Whitney Canada. Each engine develops 5,071shp or 3,800kW. The turboprop engines, mounted in Shorts engine nacelles, have full authority digital engine control (FADEC).

The engines drive six-bladed reversible-pitch composite propellers, type R408, supplied by Dowty. The propeller blades are fitted with an electrical de-icing system.

The total fuel capacity is 6,526l giving a maximum range of 2,519km carrying 74 passengers. The maximum cruise speed is just under 403mph.



Although, yes, it does have blocks, I do believe that at full power, a number of things could have gone wrong. A plane isn't made to be run full power unless ABSOLUTLY need be. I'm not strong with this theory, this is just me trying to explain as why an engine would be on fire AGL...

Although at full power, a number of mechanical issues could have also caused an engine to ignite...

[humble]

Dash 8 has had significant issues with runaway props, if levers were in flight idle and pilot initiated checklist it would cause the severe dip/rotation/occillation as well (from account above) however I think NTSB would have commented on engine power settings or voice comments in that regard. Given the planes extensive use in Europe/Canada I cant see how the icing would bring it down unless they screwed the pooch by the numbers. Would require AP till final then flap deployment in known icing etc...

[texasmom]

Read an article talking about the woman & her daughter who made it out of the house, and the husband who was killed. It stated that the woman still hadn't been told about the fate of her husband. If that's accurate, it was pretty insensitive to report his death in the article for the whole world to read about first.

[Cobra516]

Very sad day in aviation, RIP to all onboard.

Here's the tapes from Buffalo ATC - callsign Colgan 3407

Abbreviated version
Download Crash - MP3 Crash by Colgan Free Music Hosting

Full version - 15 mins in they're cleared for the ILS 23
http://event.liveatc.net/kbuf/KBUF-Feb-13-2009-0300Z.mp3

Hearing the cheer in the FO's voice just minutes before they went down, then hearing ATC not being able to contact them again is gut-wrenching  

There was another Colgan crew cleared for the approach a few minutes after, and they asked the tower if they knew what was going on down there, I imagine they saw the fire, that had to be tough to stomach. 

Many pilots reporting icing conditions while in the approach area.  Not the time to speculate, but the NTSB said that after 15 degrees of flaps was selected, there was severe pitch down and roll.  Very likely that it was a tail stall, as a result of the ice it had accumulated.  In an icing situation like this it's usually always encountered when adding flaps.

When the horizontal stabilizer stalls the nose pitches down. This can be aggravated depending on particular design features. There is evidence of accumulations of ice on the CVR. Ice can cause a tailplane stall especially during flap extension.

That's what I'm thinking.  To recover from a tail stall the recovery actions are almost completely opposite of a wing stall, you want to pull the stick back to re-attatch the flow on the horizontal stab and maintain power or reduce power. Basically to recover from a tail stall you want to "undo what you just did".   

Since the thrust line on the Dash 8 is above the center of gravity - any sudden increase in power will cause a nose down pitching moment, that will be aggravated by the already compromised lifting surface of the horizontal stab as a result of the ice accumulation.  Like you said it's most likely to happen during flap extension, especially if you're close to the max speed for flap extension - as I'm guessing he may have been, trying to fly the approach a little faster because of the icing. 

[Serenity]

Hearing the cheer in the FO's voice just minutes before they went down, then hearing ATC not being able to contact them again is gut-wrenching   

Yeah... there's a reason I guess they don't play THAT particular part on the news... god that was painful to hear...

Sorry, but this stands out to me as being just... bizarre: "Um... uh... what do you mean they went down?"

[Dawger]

Having several thousand hours flying in icing country in pneumatic boot protected airplane I can tell you that they only protect a small part of the airfoil.

While the ATR-42 and ATR-72 aircraft are now compliant with all icing condition requirements imposed by those 18 ADs, the de-icing boots still only reach back to 12.5% of the chord. Prior to the accident, they had extended only to 5% and 7%, respectively. They still fail to deal with the findings of the Boscombe-Down tests, conducted by the British, which demonstrated ice could form as far back on the wing as 23% of the chord, and on the tail at 30% of chord. Both percentages remain well beyond the limits of the extended deicing boots, installed in compliance with those FAA ADs.

Ice accumulation on an airplane is an emergency yet many pilots have a false sense of security because the airplane has ice protection features. At best they only keep the airplanes flying until it can get out of icing conditions. Some are better at it than others.

I am currently flying a modern jet with bleed heat but that doesn't mean I would hang around in icing. When we know there is icing on an approach we do our best to stay high and descend continuously through it. It doesn't take much to take down an airplane.

Here is how little it takes......

http://www.tsb.gc.ca/eng/rapports-reports/aviation/1997/a97h0011/a97h0011_index.asp

The flight was unremarkable until the aircraft was on final approach to the Fredericton airport. The autopilot was controlling the aircraft based on commands from the crew, the flight management system, and signals from the ground-based instrument landing system (ILS) for runway 15 at Fredericton. The aircraft's landing lights were on for the approach and landing. The captain saw the glow from the runway approach lights through the fog at about 300 feet above ground level (agl), 100 feet above decision height for the approach. At decision height, 200 feet above the runway, the captain, the pilot-not-flying (PNF), called the lights in sight and the first officer responded that he was landing. The first officer disconnected the autopilot, at about 165 feet above ground, to hand fly the rest of the approach and landing.

After the autopilot was disconnected, the aircraft drifted above the glide path, and twice the captain coached the first officer to get the aircraft down to the glide path. The first officer reduced thrust in response to the captain's first mention to get the aircraft down, and he reduced thrust to idle at about 80 feet agl. Moments later, the captain, aware that the aircraft was left of the centre line but not knowing the distance travelled down the runway, and not sure that a safe landing could be made, ordered a go-around, which the first officer acknowledged. The thrust levers were advanced, the first officer selected the go-around mode for the flight director, and he started to increase the pitch of the aircraft to the command bar indications, 10 degrees nose up. About one second after the first officer acknowledged the go-around, the stick shaker (stall warning) activated. As the aircraft reached 10 degrees nose up, about one and one-half seconds after the stick shaker activated, the captain called flaps and selected them to the go-around setting, the warbler tone associated with the stall protection system (SPS) sounded, and the aircraft stalled aerodynamically.

The area forecast for the New Brunswick area behind the warm front indicated that, for the time of the occurrence, there would be light, occasionally moderate icing in cloud. The freezing level would be at the surface, with above-freezing layers between 3000 and 6000 feet asl. The Caribou, Maine, tephigram9 for 16/2000 indicated a sharp temperature inversion aloft. The upper-level winds forecast for the Fredericton area, valid for use between 16/1700 and 17/0200, indicated above-freezing temperatures up to and including 9000 feet asl. The Surface Weather record for Fredericton indicates that at 16/2300 the dry-bulb/dew-point temperatures were -7.7șC/-8.3șC, and at 16/2357, -7.6șC/-8.1șC.

The crew reported that the flight was not in cloud until the final stages of the approach into Fredericton, where they entered cloud at between 500 and 1000 feet agl, and that there were no indications of icing throughout the flight. In the two hours before the occurrence, two flights had landed at Fredericton in similar weather conditions. During the investigation, the crew of one flight indicated that on final approach, after entering cloud, there was some light icing, and after landing there was some light rime icing on the leading edge of the wing. The crew of the other flight did not see ice during the approach or on the wings after landing. A person driving from Edmundston to Fredericton on the evening of the accident reported encountering freezing fog north of Fredericton.

The ice accretion studies concluded that the aircraft was in an icing environment for at least 60 seconds prior to the stall, and that during this period a thin layer of mixed ice with some degree of roughness likely accumulated on the leading edges of the wings. The engineering simulator comparison indicated that aerodynamic "events" occurred at 400 and 150 feet agl that reduced the aircraft lift, and that the lift losses were a result of local flow separation in the area of the leading edge cap, located between WS 247 and WS 253.

The drag coefficient calculated for the accident flight (while the aircraft was on approach below 1000 feet) was significantly higher than the drag coefficients calculated for the previous flights. This difference in coefficients indicates increased drag while the aircraft was on approach, and, therefore, reduced performance.

The ice accretion study by Bombardier Inc. also stated that for the ice roughness, height, and density predicted, a reduction in lift of as much as 0.43±0.04 in CLmax with a corresponding change in maximum AOA of 5±1.25 degrees could be expected. The contributions of sealant and ground effect to the performance degradation have been estimated in previous sections, and, when combined, amount to between 2 and 3.3 degrees reduction in maximum AOA. The aircraft stalled at an AOA which was approximately 4.5 degrees lower than expected for the natural stall. The estimated effects of ice accretion, therefore, would be a reduction in maximum AOA of 2.5 degrees (4.5 - 2) to 1.2 degrees (4.5 - 3.3); a thin layer of ice could account for this degradation.

Notwithstanding that no ice was found on the aircraft following the accident, there is no phenomenon other than ice accretion that could account for performance deficits of this magnitude, particularly when progressive performance reductions occurred while the aircraft was on final approach in weather conditions conducive to icing. The most likely scenario is that in addition to ice accretion along the leading edge, ice also accumulated on the extruded sealant at WS 247 and WS 253.

An estimated .020 inches of ice would cause a five degree reduction in critical angle of attack in the CRJ. Admittedly the wing on a CRJ is swept.

The accident this week shows evidence that the crew saw ice accumulating and then extended flaps. That is the danger point in any airplane, the point most likely to cause tailplane stall. The flap extension causes the angle of attack of the tail to increase, pushing it closer to stall. Changing airflow over the wing changes airflow over the tail, possibly exacerbating the angle of attack increase. Finally, flow separation on the bottom of the horizontal stabilizer could create a low pressure bubble far aft and actually pull the elevator down. Airplanes with a flying tail instead of a hinged elevator are less susceptible to this. I don't know if the Q400 flight controls include a fully movable horizontal stabilizer or a hinged elevator.



NASA Icing video with good explanations of tail stall.
http://video.google.com/videoplay?docid=2238323060735779946

A summary of the Roselawn accident.
http://www.airlinesafety.com/letters/atr.htm

Another Summary with a link in it to the full report
http://aviation-safety.net/database/record.php?id=19941031-1



An AOPA PDF with wise words for GA airplanes.
http://www.aopa.org/asf/publications/sa11.pdf

[CAP1]

Another interesting tidbit here though...
Looking through different things, it seems that plane crashes seem to come in threes...Right now we're at two, one heroic story of amazing piloting, and one mystery tragedy...

no......we're at one.

the one in the hudson wasn't a crash. that was a perfect landing, considering the circumstances.