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island_airphoto
June 12, 2025, 22:50:00 GMT permalink Post: 11899808 |
Knowing nothing else but watching that, it looked like the plane was very heavy, got out of ground effect, and started sinking again. The pilot, if that was true, needed to level off and gain speed.
Subjects: None |
island_airphoto
June 15, 2025, 02:49:00 GMT permalink Post: 11902064 |
Subjects: None |
island_airphoto
June 15, 2025, 13:17:00 GMT permalink Post: 11902459 |
Maybe a dumb question - A DA-42 went in with double engine failure when the gear was retracted, the additional load of the gear pump was enough to drop the bus voltages low enough to shut down both FADECs. They took off with a very low battery and no one had tested this scenario previously. Obviously a very different airplane, but still raising the gear probably is a significant load and may have caused an electrical problem to get worse.
* or Boeing thought of that, DA-42s got rewired and won't do that now. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Dual Engine Failure Engine Failure (All) |
island_airphoto
June 20, 2025, 15:50:00 GMT permalink Post: 11907076 |
Re water in fuel - how often do 787 operators usually check the water drains? It seems like the water scavenger would normally deal with it, but if it gets clogged or otherwise doesn't work you'll get water out of the sump drains.
Subjects: None |
island_airphoto
June 29, 2025, 13:29:00 GMT permalink Post: 11913034 |
I got the idea that with no (or very little) thrust, and with the aircraft falling, the pilot (may have) realized that he was in
out of control flight
, and falling.
In a pedantic sense: if you make control inputs, and the aircraft won't or can't respond to them, you are in out of control flight . The whole event happened pretty quickly. How far into "we are doomed" that his senses told him they were can have informed his decision to say something about it. (the human mind is an interesting thing). There's also the matter of temporal distortion which can happen during stress or high adrenalin events. (I experienced that during the course of an aircraft accident: not on topic for this thread). As to conformance with ICAO, not all investigations make good on that.
Spoiler
I sincerely hope that this one does. (Note: some of what I refer to as out of control flight seems to be called upset in commercial transport jargon). Subjects (links are to this post in the relevant subject page so that this post can be seen in context): ICAO |
island_airphoto
June 29, 2025, 15:18:00 GMT permalink Post: 11913084 |
I distinguish between "upset" and "out of control" for any airplane. "Upset" to me implies an unusual attitude, headed for worse if a correction is not made quickly. An airplane can be stalled, and out of control, but not upset. The pilot may no longer have any control effectiveness available to pitch up, so the airplane is not in control in that sense, though it otherwise is stable (for the moment). I saw in the video an airplane which, after suffering a [total] power loss in a climb pitch attitude, and a climb speed, did not noticeably pitch down, so it certainly would have been slowing down, and approaching a stall. If the pilot maintained the attempt to pitch up, and the airplane was not aerodynamically able to respond, it was not in control, so, out of control.
I encountered this thinking while flight testing a modified GA plane in the company of an experienced test pilot. The airplane would bob across an airspeed range with full nose up pitch control. It was a very stable bob, but the indicated airspeed would increase and decrease about 5 knots during this bobbing, while the controls were held against the nose up stop. I asked him, was the indicated stall speed the faster, or slow of the two airspeeds? His reply: "Can you control the airspeed while the airplane is slower than the faster speed?". "No" I replied. Then the airplane is out of control at the faster airspeed, and that is the stall speed. The fact that it would fly slower was not in my control, though the airplane was still controllable in roll and yaw. It's a fine point, but this event is well into fine point territory! Did you have the extended pitot tube for your test? On a lot of Cessnas, one can get them down to 0 KIAS if you are good with your feet. Beyond a certain angle of attack the regular pitot gets very inaccurate. Subjects: None |
island_airphoto
June 30, 2025, 01:56:00 GMT permalink Post: 11913325 |
OK, from my standpoint as a curious observer, what would their options be? They don't have engines to provide thrust, they don't have altitude to lower the nose and gain speed, and they don't have the speed to pull the nose up and extend the glide? All while trying to troubleshoot the same problem we've collectively taken 2 weeks to not understand. What would you do?
Subjects: None |
island_airphoto
June 30, 2025, 13:12:00 GMT permalink Post: 11913614 |
* as for why not before, probably because it didn't happen that way or in Boeing's worst nightmare some weird corner case in the software that does this if certain parameters are in rare combination. Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Parameters |
island_airphoto
June 30, 2025, 13:24:00 GMT permalink Post: 11913622 |
Thank you for that answer, edge cases do abound in complex systems, but would not moving the throttles forward by hand (as the thrust was beginning to reduce {for that strange reason}) overcome that and restore thrust?
(As I don't fly the 787, I may be missing something basic on how the systems work). Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FADEC |
island_airphoto
June 30, 2025, 14:55:00 GMT permalink Post: 11913678 |
So it has an automated VMC departure preventer? That is pretty clever as long it never goes off when not needed.
Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FCOM |
island_airphoto
July 10, 2025, 11:53:00 GMT permalink Post: 11918969 |
787 pilots, If throttles are NOT at idle, will their respective fuel cut off switches still trigger a shutdown?
The above checklist procedure implies throttle lever angle and cutoff switches are independant for resetting FADECs. If so, is it time for this convention from the days where throttles and cutoffs were mechanical systems, not resolvers and switches, to end? Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Fuel (All) Fuel Cutoff Fuel Cutoff Switches |
island_airphoto
July 12, 2025, 19:55:00 GMT permalink Post: 11920790 |
We have a very disturbing choice: Either Boeing designed planes that will randomly shut off for no reason or we have pilots that will do so. Neither one is a happy thought.
Subjects: None |
island_airphoto
July 12, 2025, 20:09:00 GMT permalink Post: 11920800 |
I know.......it could turn out to be some way out cause no one has thought off. A buddy went down with double engine failure in an Aztec, when he switched tanks water that had leaked into the airplane formed an ice ball that jammed the cables to the actual switches between tanks and cut off all fuel. If he hadn't landed in a field and gotten an A&P on it before the temps went above freezing maybe no one would have ever known why 2 engines with totally separate fuel systems died at the same time. Last edited by T28B; 12th July 2025 at 20:12 . Reason: split out the novel failure story in its own paragraph Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Dual Engine Failure Engine Failure (All) Fuel (All) Fuel Cutoff Switches |
island_airphoto
July 12, 2025, 20:32:00 GMT permalink Post: 11920816 |
Subjects: None |
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