Philadelphia Learjet crash

[Oldman731]

https://www.inquirer.com/news/philadelphia/a/timeline-plane-crash-northeast-philadelphia-20250203.html

...so...runaway trim?  Only my speculation, never flew a jet.  For those of you who have, when do you engage autopilot after takeoff?

- oldman

[TyFoo]

Depends on their OPSPECS, the SID, how busy the airspace is, wx conditions and personal preference.

Definitely a Loss of Control. First glance it looks like it could have stalled. It could be a runaway trim, but with two Disconnects and the circuit breaker, that should easily be mitigated. That Lear was an oldy, built before they went to Glass in the mid 80s. If it had the old Six pack for avionics, perhaps a vacuum failure? If it had a Glass upgrade, then could be plugged Pitot/ Static port, broken pitot line, which would affect the ADC if it had one. Hard to speculate considering the plane wasnt airborne 60 seconds.

[Busher]

https://www.inquirer.com/news/philadelphia/a/timeline-plane-crash-northeast-philadelphia-20250203.html

...so...runaway trim?  Only my speculation, never flew a jet.  For those of you who have, when do you engage autopilot after takeoff?

- oldman

I have never flown any of the Lear models but I have spoken to former First Officers that had a lot of Lear experience. They told me that elevator trim must be properly set before take-off... if not, the control pressure after lift off can be impossible to override... and can lead to disaster. It might not have been a trim "runaway".

As to autopilot engagement, it varies from jet to jet. I retired from flying 16 years ago but the minimum altitude for my retirement airplane was 600 feet AGL. The Lear is a very old design so I suspect it's minimum altitude is at least that high but I will try to find out for you.

[TyFoo]

That makes perfect sense too.

On the older Citations circa mid 80's, upon advancing the throttles, if you were out of trim, you would get a Master Warning/ Caution. It wasn't always easy to identify the issue, and usually required an exit off the runway and figuring out what one of the 3 - 4  items gave you the Warning.

The newer mid 90s models and on - you got a Master Warning and an EICAS message. Making it easier to identify and correct.

In either plane you did not continue the takeoff.

[Busher]

https://www.inquirer.com/news/philadelphia/a/timeline-plane-crash-northeast-philadelphia-20250203.html

...so...runaway trim?  Only my speculation, never flew a jet.  For those of you who have, when do you engage autopilot after takeoff?

- oldman

I finally found it for you.... the minimum altitude for autopilot engagement is 1000 ft AGL.

[Oldman731]

I finally found it for you.... the minimum altitude for autopilot engagement is 1000 ft AGL.

Thanks, guys.  They found the black box (in the crater), so we'll see what that says.  Given the small size of the crater, it almost looks like the plane was vertical when it hit.

As Bullwinkle might have said, "I hate takeoffs that begin like this."

- oldman

[nopoop]

I follow this guy on FB, but he's on utube also. Breaks down crashes. A good watch. He breaks down the DC crash with what is known so far.

https://youtube.com/@pilot-debrief?si=ffpb86MHmy00s-zc

[icepac]

I don’t see a departure to stall scenario specifically because of the high speed of the plane coming down. 

It only climbed to 1600 feet maximum so why the speed? 

My theory is that they lost the horizon and spent the entire time accelerating while trying to “feel their way to upright and level”.     Well that’s not really possible to do without attitude reference whether from a gauge or the actual horizon.   

[Maverick]

I watched a couple of the videos of the Philly crash. There was a lot of light at the plane, possibly on fire, as it went down. The down angle was severe and you could see it change to go just past vertical before impact. Really small crater.

I'm wondering if an engine fire or grenaded engine may have cut the controls. I don't see trim levels being responsible for loss of attitude / altitude as the pilots should have been able to mitigate a lot of that just by pulling on the yoke. Not having flown one of those I can't say for sure.

[Puma44]

Or, spatialize disorientation after takeoff, pulling up into a low cloud deck while acceleration?

[Shuffler]

Spatial disorientation............... ......................

[Eagler]

Jet seemed to be on fire to me also...rip

Eagler

[MajWoody]

It looked like a meteor coming down. Perhaps the oxygen bottles exploded.

[Busher]

While talking to a former First Officer who accumulated almost 5000 hours on various Lear models (he is also interested in this accident), he referred me to this AD that applies to all models, While we are all speculating this was interesting to read.

https://www.duncanaviation.aero/intelligence/bombardier-learjet-flap-component-airworthiness-directive-2018-19-04#:~:text=This%20AD%20requires%20the%20replacement,models%20is%20Oct%2023%2C%202018.

[TyFoo]

I didn't see the aircraft on fire. I saw the Takeoff/ Landing lights lit up and reflecting off the clouds as it came down.