|
PWS
Originally Posted by hunbet
(Post 10212795)
Looks like a very violent and brief squall with hail and windshear. The predictive windshear would have been inhibited just prior to the time they encountered it . Many warnings are inhibited during T/O until established in climb.
Note that the after crash videos don't show any rain. PWS is available up to 100 kts on most aircraft as that’s the whole point, and the WX radar should have given quite a distinct picture. Having said all that, we don’t know if PWS was fitted on this aircraft. |
:ugh:
Originally Posted by TangoAlphad
(Post 10212808)
While I agree most would of been inhibited by take off it doesn't say much for the system if it didn't pick up a cell capable of putting an aircraft back on the deck during the early roll.. (assuming the cell theory)
|
Radar View
The on board radar shows what's ahead in a narrow cone. There's a lot of sky and possible nastiness in the hemisphere surrounding the aircraft that's not in that cone.
If the Mexican government offers weather radar images on the web, the pax might have better SA with their phones (airplane mode off) ;) |
The microburst could have formed directly above the airport just as they were on the takeoff roll.The weather radar would have been incapable of detecting anything close.
Moments later it wasn't even raining at the crash site. |
Watching the LiveLeaks video from the left side, you can hear what sounds like wind whistling right when the aircraft rotated and leaves the ground. Soon after, the wind sounds stops and the plane comes back down sans gear. Reminds me of DAL 191: “you’re gonna lose it all of a sudden” when the L1011 enters the rain shaft and encounters a strong headwind. The headwind shears to a downdraft, and all the airspeed is gone. For both aircraft, the time betweeen headwind and downdraft is quite short. Anyone have the expertise to tell if the rotation point is before what would be expected of a plane at this weight in those conditions? If it rotated too soon, it may be because the pilots got the headwind and thought they got a nice “bonus” on takeoff only to lose it. |
If you can set aside the music and narration and just watch the video, we can see what some (not all) microbursts look like and how they behave.
At the start of the takeoff run the vis is good off to the right, (slightly less so to the left) in these videos, but rain & wind increase just prior to rotation. The aircraft gets briefly airborne and settles back, hard, onto the runway. It is apparent in the video that the leading-edge devices are deployed as expected. Could be classic windshear, or "rain-roughened" wing surfaces or a combination of these factors. Regarding reduced-thrust and assumed temperature power settings, this would have been a full-thrust takeoff given the METARS. But, as always, what we think should be the case doesn't explain the accident, (Sid Dekker, Field Guide to Understanding Human Factors). This aircraft type has very good recorders and the QAR may have an even more detailed set of parameters so determining aircraft energy, system & power settings, control inputs, accelerations and so on will be (or should be!) straightforward. The CVR will be interesting in terms of any discussions regarding awareness of weather and the decision to takeoff. NOTE: Bear in mind that this is time lapse work and the speed with which this "rain bomb" moves may be exaggerated. |
Re the evacuation, what strikes me most about the on-board video/audio is that - admittedly in the absence of pictures after the severe impact - the degree of audible panic among the passengers is much lower than I would have expected in the circumstances.
It will be interesting to find out in due course, perhaps, what the thumping noises were. Sounds as if someone near the camera was trying to fight past or through an obstruction. Was the fuselage breached even before the fire destroyed it? |
Originally Posted by Chris Scott
(Post 10213028)
It will be interesting to find out in due course, perhaps, what the thumping noises were. Sounds as if someone near the camera was trying to fight past or through an obstruction. Was the fuselage breached even before the fire destroyed it?
|
Wind shear warnings in the aircraft I fly are prohibited until 15'agl radar altimeter. Why o why they didn't sit at the end of the runway 20 minutes and takeoff in the clear. TEM threat-error-management. |
As a reminder, a microburst after take-off put a Pan Am 727 into the ground from 150 feet altitude (Flt. 759, Kenner (New Orleans), 1982). No survivors. In a weird way, this flight was "lucky" if the microburst (if real - high probability) prevented it from getting significantly airborne, if at all. Of course, 36 years ago we were only just starting to get a handle on detecting and handling microburst threats.
______________________ Any followup on the original reports of engine failure? Was that just "fog of war?" If real, what are the odds it was caused by hail or rain ingestion from the same weather event? cf: take-off video. On the positive side, AvHerald quotes hospital as saying the captain is recovering from spinal surgery and can move arms and legs. :ok: |
..the authorities are already stating it can be a lengthy investigation, depending on the condition of the recorders and that the captain is assisting in the investigation..
..that already sounds like the recorders are good enough, but that they are now preparing the "actual happening" of the accident to hold water reg. insurance and upcoming passenger law suits.. ..lure me - if indeed it was a windshear - that they are already preparing to put all blame on the captain for a takeoff into a windshear "which he is expected to be able to predict from the current WX situation based on education, experience and good judgement" ..just my guess - we've seen it all before.. |
Originally Posted by er340790
(Post 10212210)
True... though most incidents I have seen over the last 42 years involved the pushing of that luck.... right up until it ran out. :sad:
It's so nice to hear of a serendipitous outcome in these tines of angst, trouble and strife pretty well everywhere around the world. |
Originally Posted by HarryMann
(Post 10213429)
Same here, very wise words. I know I've had my 9 lives !
It's so nice to hear of a serendipitous outcome in these tines of angst, trouble and strife pretty well everywhere around the world. OAP |
Flex
Originally Posted by TangoAlphad
(Post 10212929)
These days with assumed temp and derates etc etc very hard too tell. Only guide I'd have is if we aren't rotating by the time I'm getting into 900m (alt red white) I'd be getting twitchy.
|
Video of takeoff from port side passenger window. Also clearly shows smoke direction after the crash. Audio of distressed victims following the evacuation https://www.buzzfeed.com/briannasack...e9#.yoyMkq37e9 mjb |
Originally Posted by Onceapilot
(Post 10213477)
Yes, less than worst case. :ok: However, this was not serendipitous, if this was primarily caused by downburst, ignoring the adverse conditions and taking-off was pure risk taking. Unfortunately, I have witnessed similar many times from the flightdeck. :oh:
OAP Does Mexico have such a 'blame the crew' culture like 3rd world countries such as Bolivia, Italy and France? |
Originally Posted by daelight
(Post 10214124)
/
Does Mexico have such a 'blame the crew' culture like 3rd world countries such as Bolivia, Italy and France? |
Originally Posted by N90-EWR
(Post 10214128)
Taking off under those conditions was an extremely poor judgement call, and as so often I am reminded in these forums, the captain is the ultimate authority in deciding whether to go or not to go, so yes, the blame is on the crew on this one, and the "culture" over there has nothing to do with that.
|
Originally Posted by daelight
(Post 10214124)
/
Does Mexico have such a 'blame the crew' culture like 3rd world countries such as Bolivia, Italy and France? |
It's way too early to talk of blame and such talk un-nerves future passengers from flying.
As an aviation forum we must be aware that it's corrective actions that count towards calming passengers. Best to concentrate on getting facts and lessons learned |
| All times are GMT. The time now is 15:58. |
Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.