Talk:Maneuvering Characteristics Augmentation System

Major Updates Needed

This article is a mess and a majority of the listed sources are sensational articles from right after the crashes. In 2024 we know for a fact that:

• There were procedural failures on the part of the Lion Air and Ethiopian Airlines pilots.
• Ethiopian Airlines did not properly distribute Boeing notices regarding MCAS.
• The angle of attack sensor on the Lion Air 737 was miscalibrated by Xtra Aerospace, during a repair for Lion Air.
• During recertification testing after the crashes, test pilots flew 737 MAXs with and without MCAS and said they had no issues with stability whatsoever.
• The information regarding the size and location of the engines affecting the stability of the plane is incorrect.

It does a disservice to thousands of readers when articles are editorialized like this. People deserve the facts and most up-to-date information so they can make informed decisions. Injecting emotions and opinions into informational articles is inappropriate. — Preceding unsigned comment added by Special:Contributions/2603:6080:5A07:C24C:EC6B:E4AB:67DD:BA38 15:57, February 14, 2024

As someone who has actually worked on the development of Flight Control Systems (the Boeing 777's PFCS) I think the article does an extremely good job of distilling a complex technical system into a readable article, nor do I find it sensational. The absence of redundancy in the MCAS system as designed is mind-boggling from a safety critical engineering perspective, the PFCS on 777 by comparison has triple redundancy twice over - three redundant lanes each of three redundant channels. Nor were the Max crashes the first loss of a 737 due to inadequate redundancy in the flight control/air data system, Turkish Airlines Flight 1951 was a 737-800 which crashed on approach to Schiphol in 2009 because the aircraft systems didn't recognise the radio altimeter had failed because it wasn't being compared with the working alternate system.

WRT your alleged problems with the article:

• the attempts to blame the Lion Air and Ethiopian pilots has been roundly condemned by the US pilots unions - see reports of Boeing VP Mike Sinnett's meeting with American Airlines pilots. A system that depends on immediate corrective action while in an aircraft pitching uncontrollably and with no time to troubleshoot is not a safe system. If you read the NTSB's System Safety and Certification Specialist's Report it seems to imply MCAS activation should be considered Hazardous and erroneous AoA data Catastrophic under Boeing's own flight qualities criteria as soon as alarms started sounding and the aircraft pitching unpredictably (ie when 'Normal Flight' transitions to 'Operational Flight'), but Boeing's fault tree analysis contained errors that meant the conditions weren't considered. Even if pilots had immediately followed the Boeing advocated procedures for a stabiliser runaway, which MCAS activation isn't, the article points out that Boeing had rewired the buttons involved, meaning the response in a Max wasn't the same as in an NG. On top of which Boeing repeatedly cited stabiliser runaway as a memory item, despite FAA discouraging reliance on memory items. It's difficult to troubleshoot a complex problem in a stable aircraft, the Ethiopian crew in particular were dealing with a complex series of faults that had them fighting to keep the aircraft anywhere near stable. There is a long and tragic history of highly trained aircrew being unable to successfully troubleshoot faults in which they are also presented with misleading air data, famously including Air France Flight 447
• The AoA sensor from the Lion Air flight had indeed been damaged by Xtra (a US company), who lost their certification over it; however an air data system with proper redundancy would have compared the data from multiple AoA sensors, noticed the mismatch and switched out the faulty sensor. This actually worsens any interpretation of MCAS design and performance rather than vindicating it. To make matters worse, as the article notes, Boeing had then removed the AoA Mismatch indication from the cockpit, meaning the pilots couldn't see they had an AoA mismatch (potentially Catastrophic under Boeing's flight qualities as noted above)
• The issue isn't whether a Max can be flown with or without MCAS, that was never the reason for MCAS. MCAS was there to make a Max fly enough like an NG that pilots didn't need retraining.
• WRT engine size and location, I'd call the section incomplete rather than inappropriate. 737 is so old it predates high bypass turbofans with wide fans, to fit a modern engine in the original position, Boeing had either to complete rework the undercarriage, raising the aircraft further off the ground, or move the engine out from under the wing. Doing that changes the axis of the thrust vector and makes the Max naturally trim a little differently to an NG. MCAS was there to make that difference less obvious. I'd lose the line about the 707 stick-shaker, and personally I'd probably de-emphasise stall protection in the 767, but I don't see any major issues given FAA and NTSB seem to be divided on whether MCAS offers stall protection or not.

82.42.42.74 (talk) 00:55, 21 May 2024 (UTC)

DailyBeast not being Aviation

@Marc Lacoste:: If you are rejecting a citation based solely on the domain name and not the content, I hardly find the recent revert convincing.

It's not a WP:cite, it's a WP:EL.--Marc Lacoste (talk) 20:14, 26 July 2021 (UTC)

MCAS INPUT

Current costly aircrafts have MULTIPLE Systems of Sensors to determine their speed, position and attitude. The original MCAS used ONLY ONE AoA sensor input. This FAIL-SURE logic could only be developed and approved by Retards (in rank and file and also in power/top jobs) 123.201.65.73 (talk) 04:09, 2 January 2022 (UTC)

WP:NOTFORUM. Your opinion does not matter here.--Marc Lacoste (talk) 12:45, 2 January 2022 (UTC)

EASA

This article repeatedly uses the acronym EASA without anywhere defining what it means. Similarly, although the Federal Aviation Administration is mentioned by name in the second paragraph, the acronym FAA is used throughout also without definition. 130.246.57.110 (talk) 11:44, 21 February 2022 (UTC)

Done. See my diff 1 and diff 2. Thank you for drawing that to our attention. Dolphin (t) 11:54, 21 February 2022 (UTC)

Needs an updated link 145

Link 145 is sort of broken it no longer points to the referenced document as the FAA document system was revised. I noticed this while looking for info to supplement a documentary on the 737 MAX I was watching.I do not know how to properly add a citation. Here is the link

https://drs.faa.gov/browse/excelExternalWindow/FB91ABC41EF06432862586260051E5DF.0001 Bruce A. WIlliamson (talk) 14:45, 18 May 2023 (UTC)

AoA or AOA?

The abbreviation for "angle of attack" should be consistently either AoA or AOA, but not a mixture. Wassermaus (talk) 09:52, 1 July 2024 (UTC)