|
Originally Posted by KARFA
(Post 30874307)
the memory actions for a runaway stabiliser trim are very clear and short and include disengaging the autopilot (if engaged), moving both stab trim cutout switches to cutout, and trimming manually. i haven’t see anything which suggests the auto throttle system was malfunctioning for the lion air incident so no reason to touch that. |
Originally Posted by T8191
(Post 30874487)
I got the feeling that MCAS still operated even in the circumstances you describe. I got somewhat befuddled by the PPRuNe technical details.
|
Originally Posted by Temps
(Post 30872864)
I'm flying to Livingstone tomorrow on comair, thankfully it's a 737-800 from 2007. Really don't fancy getting on a Max 8.
|
My understanding is that MCAS is only enabled when a) the autopilot is not engaged and b) the flaps are retracted. Whilst it does command a nose down attitude and that will not be affected by yoke inputs, it should be overridden by either a) disabling the system or b) manual trim input. The idea behind the system is eminently sensible to counteract unexpected changes in the pitch of the aircraft. However, the main issue (based solely on Lion Air) is that it is reliant on the AoA sensors and there are only 2 of them. If one of he sensors provides erroneous information you would expect that the system would deactivate. It appears this is not the case and requires manual deactivation. The sensible fix would be to amend the system such that disagreement between the 2 sets of data provided automatically deactivates MCAS. This would, I believe, be similar to Airbus whereby if 1 (of 3) systems is in disagreement it is ignored and if 2 (out of 3) fail then “Normal Law” is deactivated and it is for the pilots to manually control the aircraft. There’s a bit more on MCAS here |
Originally Posted by T8191
(Post 30874237)
Oh, dammit, I've posted that on PPRuNe. I wonder how long that will last!
https://www.pprune.org/10414149-post460.html Please let us know what reaction you get over there. |
Originally Posted by cauchy
(Post 30872892)
It might be subbed at a later date. If you definitely don't want to travel on a MAX 8 then you are best off booking another airline now.
|
Originally Posted by KARFA
(Post 30870962)
Do we even know what went wrong on the Ethiopian flight? if not how can one conclude the aircraft isn’t safe? |
Originally Posted by KARFA
(Post 30874344)
Out of interest what specifically makes you uncomfortable on a 737 with MCAS and not uncomfortable on an Airbus which has equivalent stall protection systems? The Airbus is far more complicated and has far more layers of automation and protections than the 737. It's rather like software. You can add patches, new code and whatever else over an old system, or you can write something completely new from scratch. Both will achieve the same result but (assuming you write it properly) one will be far simpler, easier to troubleshoot and less likely to go wrong every time you add something new to it. |
Originally Posted by 1010101
(Post 30874782)
Well the fact the 737 system has caused one, possibly two fatal crashes in its 2 years of existence would be pretty specific.
If so, which was the second crash to which MCAS is known to have contributed? |
Deleted. |
Originally Posted by djbenedict
(Post 30874777)
As you will see if you read my post, I have already acknowledged the possibility of a type substitution on this sector. Given the relative numbers in the Comair fleet, I think your advice (given you have zero knowledge of the overall itinerary, purpose of travel, number of travellers etc.) is, let me put this politely, ill-founded, extreme and unlooked-for. |
News just in: MEXICO'S AEROMEXICO SAYS HAS DECIDED TO SUSPEND THE OPERATION OF ITS SIX BOEING 737 MAX 8 PLANES UNTIL IT HAS CLEAR INFORMATION ABOUT ETHIOPIA INVESTIGATION
|
More: Communique from argentine pilots association announcing decision to not permit members to fly 737 max planes
|
For me, the question is can we at this point say, for sure, it’s not caused or contributed to by aircraft malfunction? If not, I’d personally rather wait until that point arrives before flying on one. |
The disturbing part of this from the pprune thread is that with runaway trim during takeoff, both pilots need to pull back with considerable force (60kg I think) AND find and follow a checklist AND flick a switch, while heading groundwards fast. it seems a difficult situation to manage to put it mildly. If this crash turns out to be similar to Lionair (which itself hasn't been proved to be MCAS yet) then it's a serious design defect. I imagine the FDR and CVR will be looked at very expeditiously and we'll be told soon. Personally I'd be very wary of getting onto a 737 max until this has been done. |
| All times are GMT -6. The time now is 2:12 pm. |
This site is owned, operated, and maintained by MH Sub I, LLC dba Internet Brands. Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Designated trademarks are the property of their respective owners.