Delta 737-900 returns to SLC after pressurization fault caused ear and nose injuries

[Not_Karl]

Nothing works. Good thing whoever makes this crappy forum software doesn't make airplanes. I hope.

[Evan]

It's all starting to make sense.

[TeeVee]

with evan it is never safe to assume anything especially where no blue font is present.

yes, evan, aeroplanes do begin pressurizing on the ground and well before takeoff. a few years ago, on one of my last CRJ flights, we stopped about 100 yards form the stand because all of ears were being destroyed by over-pressurization. pressurizing was not accidental. a faulty sensor was the issue.

[Gabriel]

Anyway, not sure what you're getting at but I suppose the message would be something like CHECK CAB PR as a level-2 (amber) message.

And where exactly would that message be displayed again? In what screen of the 737 cockpit?

[Evan]

And where exactly would that message be displayed again? In what screen of the 737 cockpit?

Aha. I didn’t realize we were being so type-specific here. I assume we are speaking about new builds and AFAIK the 737-MAX is still required to retrofit EICAS at some point, but if not, then obviously I am talking about an amber glareshield warning light instead. Right next to the ashtray.

If the Max continues to be exempt from the EICAS requirement, then forget about the whole thing… aviation safety… progress… the FAA… Boeing… We’ll just cling to good old thoughts and prayers.

[Evan]

with evan it is never safe to assume anything especially where no blue font is present.

yes, evan, aeroplanes do begin pressurizing on the ground and well before takeoff. a few years ago, on one of my last CRJ flights, we stopped about 100 yards form the stand because all of ears were being destroyed by over-pressurization. pressurizing was not accidental. a faulty sensor was the issue.

This is the usual misunderstanding we get constantly here. I said the ‘the plane wouldn’t be pressurizing much below 10,000ft cabin altitude’, meaning it would not ultimately have a cabin altitude much lower than 8000ft at the 10,000ft actual altitude where the event happened. So the pressurization differential would only be around 2000ft in a non-sudden decompression event. 3WE misread this because he still doesn’t read all the words. Then he claimed that the airplane was ‘pressurized’ before takeoff, not ‘pressurizing’. The airplane cannot have a cabin pressure lower (cabin altitude higher) than the ambient pressure before takeoff. Cabin suction is not an installed option.

[Gabriel]

Aha. I didn’t realize we were being so type-specific here. I assume we are speaking about new builds and AFAIK the 737-MAX is still required to retrofit EICAS at some point, but if not, then obviously I am talking about an amber glareshield warning light instead. Right next to the ashtray.

If the Max continues to be exempt from the EICAS requirement, then forget about the whole thing… aviation safety… progress… the FAA… Boeing… We’ll just cling to good old thoughts and prayers.

We already talked about that. The regulatory requirement for EICAS started in Jan 1, 2023. The whole MAX family was supposed to be fully certified years ahead of that, but then, with the MAX-9 and MAX-8 already certified, MCAS happened, and all the types were re-certified, starting with the -8 and -9 that were already in service. These delays, together with the very well deserved and much needed tighter scrutiny, meant that the MAX-10 and -7 would not be certified by the deadline.

At that point, the only realistic options were to either get a waiver for the -10 and -7 or just cancel the -10 and -7.

Having EICAS in only the -10 and -7 (and maybe the -8 and -9 after a given serial number) would have been very bad since a given 737-MAX pilot would have to fly, possibly even in the same day, a mixed fleet of EICAS and non-EICAS planes which have very different procedures (may look very similar on paper, but the what pilot has to actually do with their hands and eyes is very different) especially during emergencies and abnormal situations. So that would have actually been detrimental for safety.

And retrofitting EICAS (in any airplane) is not really feasible. It is not just a computer, a screen and a code. You need information from a lot of sensors going to places where they are not going now, so you are talking about a major re-wiring and re-certification. Not realistic to do with planes already in service.

On the other hand, the EICAS A320 family and the non-EICAS 737-NG and MAX have demonstrated to have almost identical safety records (in terms of accidental hull losses and fatal hull losses per million flight), so while there is no question that EICAS is good, makes the pilot's life easier, and can help manage some abnormal and emergency situations increasing the safety, that difference is not reflected in the numbers (maybe the 60's rooted design 737 would be quite safer than the A320 if it had EICAS?)

In the end, Boeing was allowed to finish the MAX family without EICAS, in exchange for retrofitting into the -8 and -9 some safety enhancements done in the -10 and -7 (one was the synthetic airspeed, which in fact computes AoA from first principles so it acts as a much-needed 3rd AoA sensor, and I don't remember the other ones).

So I would say it was a win-win. Boing keeps the 737-10 and -7, and the public gains the safety enhancements in already-certified airplanes (-8 and -9) that were not required to have them.

[Evan]

The 737Max is a lose lose and we all know by now why it even exists. So it is what it is. I don’t have a problem flying on it but it should have been replaced by something safer.

A light or a message, what’s the difference. One advantage of EICAS is that new warnings (such as the one you proposed) can be added with software alone. Adding a light requires hardware and room for it and is far less likely to get done.

[3WE]

***yellow CHECK PRESS message on ECAM/EICAS.***

Ooooo, abbreviations and acronyms…pretend I posted something crude about sexual excitement.

FWIW: My eardrum gets quite the workout when the pressurization is working correctly…and it’s sort of “only” on descent. During climb, ears equalize relatively effortlessly. Something to do with biology, but I forget the acronyms.