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Alaska Airlines flight 1282 NTSB preliminary report [pdf]

ntsb.gov

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Re: Alaska Airlines flight 1282 NTSB preliminary report [pdf]

#91

Post by rantingdemon »

hencq wrote: post #76
cjbprime wrote: post #17

Earlier quoted context omitted.

The largest US pilots union opposes it on pilot privacy grounds. (To be clear, I think having an expectation of vocal privacy while you are in charge of an airliner is absurd.)

I think there's some validity to the privacy concerns, but it seems those could be addressed with proper access controls and rules. The recordings should only really be listened to in the aftermath of an accident, in which case, as you say, the expectation of privacy should (in my opinion) take a backseat.

Indeed. Pretty much all your communication is recorded at any company you work for anyway.

Re: Alaska Airlines flight 1282 NTSB preliminary report [pdf]

#92

Post by engcoach »

aftbit wrote: post #19

Depressurization happened around 17:12:33 PST but the aircraft continued to climb until 17:13:41 PST, and the autopilot was configured for 10k ft at 17:13:56 PST. Why did it take the pilots a full minute to begin an emergency descent after the failure? I would expect that the nature of the accident would be clear nearly immediately, at least in the need to descend the aircraft.

Fast hands in the cockpit are scary. Pilots take their time in emergencies because rushing will take your birthday away

Re: Alaska Airlines flight 1282 NTSB preliminary report [pdf]

#93

Post by jbverschoor »

jiggawatts wrote: post #54
jbverschoor wrote: post #20

Earlier quoted context omitted.

Just comment out the tests and they pass

I’m trying to convince a group of devs that catching (and ignoring) every exception is not actually a solution to their crash bugs.

Ya know.. you can also just do that and then change the requirements:

> In a revision to the Flight Crew Operations Manual, issued on January 15, 2024, Boeing confirmed that the door functioned as designed.

Problem solved for the current level in the hierarchy.

Re: Alaska Airlines flight 1282 NTSB preliminary report [pdf]

#94

Post by skywhopper »

belltaco wrote: post #29

>The CVR was downloaded successfully; however, it was determined that the audio from the accident flight had been overwritten. The CVR circuit breaker had not been manually deactivated after the airplane landed following the accident in time to preserve the accident flight recording In addition to local storage, why isn't the audio(along with location, altitude and some sensor information) also streamed using somethi…

This is an old system that works well and reliably for pretty much every incident. I’m not aware of another case of this sort of thing (relevant flight recorder data being overwritten) happening in recent years anyway. If you spend time constantly upgrading systems like this you’re asking for a higher failure rate, for very little gain.

That said, there’s a standard and reliable 25-hour flight voice recorder that solves this problem. But it’s only used outside the US. That’s a regulatory inertia situation and I suspect this incident will speed changes in this area.

However, finally, and particularly in relation to your proposal of streaming cockpit voice recordings to some cloud server. There is some resistance to this (and to longer recordings in general) from air crew on privacy grounds. The privacy issue is less about how much personal info is revealed in a crash situation and more about how easy it would be for a bad actor in management —or whatever operations group runs the audio storage—to listen in on conversations. And you can be sure this would happen if something like your system were implemented without the appropriate regulatory controls (and tbh even with them it would probably still happen).

Re: Alaska Airlines flight 1282 NTSB preliminary report [pdf]

#95

Post by SilasX »

cjbprime wrote: post #17
aftbit wrote: post #13

> The accident airplane was required to be equipped with a CVR that retained, at minimum, the last 2 hours of audio information, including flight crew communications and other sounds inside the cockpit. >The CVR was downloaded successfully; however, it was determined that the audio from the accident flight had been overwritten. The CVR circuit breaker had not been manually deactivated after the airplane landed follow…

The largest US pilots union opposes it on pilot privacy grounds. (To be clear, I think having an expectation of vocal privacy while you are in charge of an airliner is absurd.)

Reminds me of an exchange from Stranger Things (S4E3):

School counselor: Max, I'm… I'm sorry, I… I really can't discuss this. You wouldn't want me talking to any other students about you, right?

Max: If I were dead and it would help catch the killer, then yeah, I most definitely would.

https://subslikescript.com/series/Stranger_Things-4574334/se...

Re: Alaska Airlines flight 1282 NTSB preliminary report [pdf]

#96

Post by michaelt »

aftbit wrote: post #19

Depressurization happened around 17:12:33 PST but the aircraft continued to climb until 17:13:41 PST, and the autopilot was configured for 10k ft at 17:13:56 PST. Why did it take the pilots a full minute to begin an emergency descent after the failure? I would expect that the nature of the accident would be clear nearly immediately, at least in the need to descend the aircraft.

According to the plane's "memory items" [1] in response to a cabin altitude warning or rapid depressurization, pilots must:

OXYGEN MASKS - DON

OXYGEN REGULATORS - Set to 100%

CREW COMMUNICATIONS - ESTABLISH

PRESSURIZATION MODE SELECTOR - MAN AC/MAN

OUTFLOW VALVE SWITCH - CLOSE

Hold in CLOSE until outflow Valve indicates fully closed

If Pressurization is Not Controllable

PASSENGER SIGNS - ON

PASSENGER OXYGEN SWITCH - ON

EMERGENCY DESCENT - ANNOUNCE

The pilot flying will advise the cabin crew, on PA system, of impending rapid descent. The pilot monitoring will advise ATC and obtain area altimeter setting.

PASSENGERS SIGN - ON

DESCENT - INITIATE

I do giggle a little at the thought of a door flying off, the air rushing out of the cabin, and the pilots responding by switching the seatbelt light on.

The plane was only at 16,000 feet when it lost its door and according to [2] you've got 20-30 minutes of 'useful consciousness' at such an altitude, even without your oxygen mask on. So there was no need for an abrupt dive.

[1] https://www.theairlinepilots.com/forumarchive/b737/b737memor... [2] https://skybrary.aero/articles/time-useful-consciousness

Re: Alaska Airlines flight 1282 NTSB preliminary report [pdf]

#97

Post by lp4vn »

gtmitchell wrote: post #55

A very thorough preliminary report. I've worked for a long time in quality systems, and this is a perfect example of a systemic failure. They've got work being handed off between Boeing employees and 3rd party contractors with insufficient controls in place to verify that very basic tasks are being performed. I'd be curious to know how many non-conformances they typically see during assembly of a plane and whether ma…

>I'd be curious to know [...] whether management is actually allowing the quality department sufficient independence to investigate these issues and fully resolve them

If management in the aerospace industry works like management in the software industry, then I guess they are pushing for results as agressively as possible without much concern about safety or anything else.

Re: Alaska Airlines flight 1282 NTSB preliminary report [pdf]

#98

Post by dmitrygr »

margalabargala wrote: post #63
dmitrygr wrote: post #22

Earlier quoted context omitted.

> Given how cheap flash is these days How cheap is flash that will survive a sudden stop from 400mph to 0 mph in no seconds flat, will survive a post-crash fire, and/or submersion for years in salt water? Flash data retention at high temps is TERRIBLE (and gets worse for MLC/TLC/etc), see any flash datasheet. It is NOT nearly as simple a problem as you might think. Yes, it is a solvable problem, but please do not dis…

I don't think the problem you're describing is actually a problem. Exposure to super-high temps occurs in a small set of circumstances, all of which overlap with the destruction of the recording device and the cessation of incoming data. So we only need the same 1.2GB (or whatever) of high-temperature-tolerant storage. The 25 hour storage can be on normal flash, as if we're more than 2 hours past the incident and dat…

Multiple investigations in the past have recovered data from FDR and/or CVR after an extensive high-temperature fire. I do not think that FAA will give that requirement up.

Re: Alaska Airlines flight 1282 NTSB preliminary report [pdf]

#99

Post by antisthenes »

dmitrygr wrote: post #22
aftbit wrote: post #13

> The accident airplane was required to be equipped with a CVR that retained, at minimum, the last 2 hours of audio information, including flight crew communications and other sounds inside the cockpit. >The CVR was downloaded successfully; however, it was determined that the audio from the accident flight had been overwritten. The CVR circuit breaker had not been manually deactivated after the airplane landed follow…

> Given how cheap flash is these days How cheap is flash that will survive a sudden stop from 400mph to 0 mph in no seconds flat, will survive a post-crash fire, and/or submersion for years in salt water? Flash data retention at high temps is TERRIBLE (and gets worse for MLC/TLC/etc), see any flash datasheet. It is NOT nearly as simple a problem as you might think. Yes, it is a solvable problem, but please do not dis…

What you described is not a data retention problem at all.

It's a material science problem, and other forms of media are affected by high temperatures and physical deformation just as much as flash if not more.

Re: Alaska Airlines flight 1282 NTSB preliminary report [pdf]

#100

Post by zer00eyz »

hencq wrote: post #76
cjbprime wrote: post #17

Earlier quoted context omitted.

The largest US pilots union opposes it on pilot privacy grounds. (To be clear, I think having an expectation of vocal privacy while you are in charge of an airliner is absurd.)

I think there's some validity to the privacy concerns, but it seems those could be addressed with proper access controls and rules. The recordings should only really be listened to in the aftermath of an accident, in which case, as you say, the expectation of privacy should (in my opinion) take a backseat.

On one hand I agree with you.

On the other hand, if someone recored my whole work day every day I would not be happy. I don't think you would stay at your job of that was a condition of it.

There has to be a better solution to this issue.. extended recordings in an emergency, triggers based on conditions, private keys for pilots... IDFK, cause I try not to get involved in engineering that might KILL someone.

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