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Helios 522 And The B737 Pressure Warning  
User currently offlinerolfen From Germany, joined Jan 2006, 1807 posts, RR: 2
Posted (3 years 8 months 2 weeks 2 hours ago) and read 7791 times:

Hi, I just watched the helios 522 documentary (again) and something boggles me ... Isn't there a "cabin pressure" warning light somewhere in a visible place in the cockpit?


rolf
40 replies: All unread, showing first 25:
 
User currently offlineFly2HMO From , joined Dec 1969, posts, RR:
Reply 1, posted (3 years 8 months 2 weeks 2 hours ago) and read 7792 times:

Quoting rolfen (Thread starter):
Hi, I just watched the helios 522 documentary (again) and something boggles me ... Isn't there a "cabin pressure" warning light somewhere in a visible place in the cockpit?

IIRC, a master warning annunciation will go off directing attention to the pressurization panel, which will have yet another warning displayed. It will go off when the cabin pressure goes above 14000ft. Been a while since my 737 training though so take that with a grain of salt.

Also, while I haven't seen that documentary, I seem to recall reading that the warning system was defective.


User currently offlineKELPkid From United States of America, joined Nov 2005, 6372 posts, RR: 3
Reply 2, posted (3 years 8 months 2 weeks ago) and read 7761 times:

Quoting Fly2HMO (Reply 1):
Also, while I haven't seen that documentary, I seem to recall reading that the warning system was defective.

As I recall (from reading up on the accident), in the 737 Classic, the cabin altitude warning uses the same warning horn as the takeoff misconfiguration warning. The flight crew (poorly trained, and who could barely communicate with each other due to language issues-the captain was German and the F/O was a Cypriot, and apparently the two did not have enough command of the English language to effectively communicate with each other in English) disregarded the warning as a spurious nuissance, since it did not seem likely that a takeoff misconfiguration warning would be issued while climbing well after takeoff. The warning horn sounded just like it should have, however the crew did not properly recognize the warning as a cabin altitude warning. All communications following this warning showed that the flight crew was suffering the effects of hypoxia.



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 3, posted (3 years 8 months 2 weeks ago) and read 7755 times:

Quoting rolfen (Thread starter):
Isn't there a "cabin pressure" warning light somewhere in a visible place in the cockpit?

Yes. There can be a "CABIN ALTITUDE" light right next to the TAKEOFF CONFIG light (center console) but I'm not sure if the Helios flight had that, there's always a warning horn, and (assuming you were in auto mode when the failure happened), you'll get an AUTO FAIL light on the pressurization panel.

Quoting Fly2HMO (Reply 1):
IIRC, a master warning annunciation will go off directing attention to the pressurization panel, which will have yet another warning displayed. It will go off when the cabin pressure goes above 14000ft. Been a while since my 737 training though so take that with a grain of salt.

You should get a master warning and illumination of the AIR COND six-pack light, which directs the flight crew to look up at the air conditioning panel where you would see the actual cabin altitude, the AUTO FAIL light, etc.

Quoting Fly2HMO (Reply 1):
Also, while I haven't seen that documentary, I seem to recall reading that the warning system was defective.

The maintenance crew didn't put the pressurization system back in the mode the flight crew expected. The warning system worked just fine, and correctly annunciated to the crew that the cabin altitude was becoming too high. However, the cabin altitude warning and the takeoff config warning use the same horn...apparently, the crew mistook one for the other. This is somewhat baffling, as you only get takeoff warning on the ground, and only get cabin altitude warning in flight (excepting very high altitude airports, which wasn't the case here).

Basically, the plane correctly told the flight crew exactly what was wrong. They misinterpreted the warning, for reasons unknown, and didn't take the appropriate corrective action.

Tom.


User currently offlinerolfen From Germany, joined Jan 2006, 1807 posts, RR: 2
Reply 4, posted (3 years 8 months 2 weeks ago) and read 7743 times:

Quoting tdscanuck (Reply 3):
Yes. There can be a "CABIN ALTITUDE" light right next to the TAKEOFF CONFIG light (center console) but I'm not sure if the Helios flight had that,

You are right, here it is:
http://www.b737.org.uk/pressurisation.htm

But followed by the note:

Quote:
Following the Helios accident where the crew did not correctly identify the cabin altitude warning horn, new red "CABIN ALTITUDE" and "TAKEOFF CONFIG" warning lights were fitted to the P1 & P3 panels to supplement the existing aural warning system.

So apparently they did not have it...

The second question I was asking myself is: even if there is no warning light, don't they have a reference at hand for understanding different warning sounds...?

Anyway I'm no pilot I was just under the impression that the 737 cockpit had a clear visible cabin altitude warning, and it does, but unfortunately was only added after the Helios accident.



rolf
User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 5, posted (3 years 8 months 1 week 6 days 20 hours ago) and read 7699 times:

Quoting rolfen (Reply 4):
Anyway I'm no pilot I was just under the impression that the 737 cockpit had a clear visible cabin altitude warning, and it does, but unfortunately was only added after the Helios accident.

The Aural warning was always present.The additional lights on the front panel were added.
http://www.b737.org.uk/helios.htm

regds
MEL.



Think of the brighter side!
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 6, posted (3 years 8 months 1 week 6 days 16 hours ago) and read 7659 times:

Quoting rolfen (Reply 4):
The second question I was asking myself is: even if there is no warning light, don't they have a reference at hand for understanding different warning sounds...?

Sort of, in this case. The FCOM is very specific that the takeoff config warning and cabin altitude warning use the same horn (same sound). The argument that this was an acceptable thing to do is that the two modes are mutually exclusive (except very high altitude airports, which is a corner case with special planning anyway). If you get the horn in air, it's the cabin altitude. If you get the horn on the ground, it's takeoff config.

The crew had all the information necessary (including the great big cabin pressure readout on the overhead panel) to understand what was happening. However, they got task focussed and misinterpreted the warning. There's obviously a human factors issues there, but it's an open question as to exactly how much misinterpretation can you assume on the behalf of the flight crew.

This isn't a new problem from the Helios accident...pilots have flown aircraft into the ground while fixated on troubleshooting a different problem, or on torubleshooting what they think is the problem instead of what's actually the problem. This was just a particularly egregious example.

Tom.


User currently offlinemandala499 From Indonesia, joined Aug 2001, 6844 posts, RR: 75
Reply 7, posted (3 years 8 months 1 week 6 days 16 hours ago) and read 7625 times:

Quoting tdscanuck (Reply 6):
This isn't a new problem from the Helios accident

Definitely isn't!

Quoting tdscanuck (Reply 3):
However, the cabin altitude warning and the takeoff config warning use the same horn...apparently, the crew mistook one for the other. This is somewhat baffling, as you only get takeoff warning on the ground, and only get cabin altitude warning in flight (excepting very high altitude airports, which wasn't the case here).

And one would be amazed at how many crew made the mistake (although all but Helios) and only eventually realizing that it was the cabin pressure. A lot of training is on take offs and landings (which is of no surprise) and one tends to immediately realize what the noise is telling you!

Instead of trying to figure out what the noise is (since it can't be take off config if you're already airborne... unless some wiring is screwed up (to which I am told has happened but probably very rarely)), the Captain simply wanted to know "how to switch the damn thing off" by calling Ops...

But am glad that the "CABIN ALTITUDE" and "TAKEOFF CONFIG" lights are now in place.

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineFly2HMO From , joined Dec 1969, posts, RR:
Reply 8, posted (3 years 8 months 1 week 6 days 14 hours ago) and read 7561 times:

Quoting KELPkid (Reply 2):
The warning horn sounded just like it should have, however the crew did not properly recognize the warning as a cabin altitude warning.
Quoting tdscanuck (Reply 3):

You should get a master warning and illumination of the AIR COND six-pack light, which directs the flight crew to look up at the air conditioning panel where you would see the actual cabin altitude, the AUTO FAIL light, etc.
Quoting tdscanuck (Reply 3):

Basically, the plane correctly told the flight crew exactly what was wrong. They misinterpreted the warning, for reasons unknown, and didn't take the appropriate corrective action.

Ah yes I remember now. My memory was very fuzzy.   


User currently offlineBarney Captain From United States of America, joined Nov 2001, 940 posts, RR: 13
Reply 9, posted (3 years 8 months 1 week 6 days 11 hours ago) and read 7481 times:

Quoting rolfen (Reply 4):
You should get a master warning and illumination of the AIR COND six-pack light, which directs the flight crew to look up at the air conditioning panel where you would see the actual cabin altitude, the AUTO FAIL light, etc.

That is only true if there was a pressurization malfunction - which was not the case with Helios. The crew had inadvertently left the pressurization selector in manual, which left the outflow valve open. The aircraft never pressurized, and the only indication is the intermittent warning horn - no master caution and no AIR COND annunciation. This would also happen if the bleeds were left off for take-off for increased performance and not reset. Since there is not any malfunction of the pressurization controller - no master caution.

New NG's have the additional TAKE OFF CONFIG/ CABIN ALT warning lights on the forward panel in front of both pilots - but only the very newest.



...from the Banana Republic....
User currently offlineMender From United Kingdom, joined Feb 2004, 240 posts, RR: 0
Reply 10, posted (3 years 8 months 1 week 5 days 12 hours ago) and read 7325 times:

Quoting Barney Captain (Reply 9):
That is only true if there was a pressurization malfunction - which was not the case with Helios. The crew had inadvertently left the pressurization selector in manual,

IIRC maintenance had left the pressurization selector in manual having carried out a ground pressurization check to rectify a leaking door, however the crew should have corrected this during their pre-flight checks.


User currently offlineetherealsky From United States of America, joined Apr 2010, 328 posts, RR: 0
Reply 11, posted (3 years 8 months 1 week 5 days 12 hours ago) and read 7312 times:

Since Helios 522 was a 737 classic, can we assume that if the same thing happened to a newer aircraft, EICAS / ECAM would have saved the day?


"And that's why you always leave a note..."
User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 12, posted (3 years 8 months 1 week 5 days 11 hours ago) and read 7292 times:

Quoting Barney Captain (Reply 9):

That is only true if there was a pressurization malfunction - which was not the case with Helios. The crew had inadvertently left the pressurization selector in manual,

Isn't more than one Automatic pressurisation function INOP a NO GO.
regds
MEL.



Think of the brighter side!
User currently offline777236ER From , joined Dec 1969, posts, RR:
Reply 13, posted (3 years 8 months 1 week 5 days 11 hours ago) and read 7277 times:

Quoting tdscanuck (Reply 6):
The argument that this was an acceptable thing to do is that the two modes are mutually exclusive (except very high altitude airports, which is a corner case with special planning anyway). If you get the horn in air, it's the cabin altitude. If you get the horn on the ground, it's takeoff config.

The crew had all the information necessary (including the great big cabin pressure readout on the overhead panel) to understand what was happening. However, they got task focussed and misinterpreted the warning. There's obviously a human factors issues there, but it's an open question as to exactly how much misinterpretation can you assume on the behalf of the flight crew.

This isn't a new problem from the Helios accident...pilots have flown aircraft into the ground while fixated on troubleshooting a different problem, or on torubleshooting what they think is the problem instead of what's actually the problem. This was just a particularly egregious example

This is a ridiculous argument. The fact that the two modes are mututally exclusive is nonsense - a t/o config warning is significantly more likely to occur than a cabin altitude warning, hence more likely for the crew to interpret the warning as a t/o config. In a hypoxic state it's clear that flight crew will jump to the cognitively easy solution: it's a t/o warning. The next cognitively easy jump is that it's a spurious warning.

The crew didn't have all the information necessary in the physiological state they were in - a state brought about by a problem with the aircraft.

This isn't the first example of that 737's poor human-machine interface causing deaths (BMA92 and TK1951 spring to mind). It's shocking that this out-moded 60s flight deck design is still being produced and sold as one of the most popular large commercial aircraft. In the days of dark cockpits, EICAS/ECAM, clear warning hierarchy and system synopses it's a travesty that the 737 can still be produced.

This isn't just my conjecture, to quote one of the causes from the final report:

"Ineffectiveness and inadequacy of measures taken by the manufacturer in
response to previous pressurization incidents in the particular type of aircraft,
both with regard to modifications to aircraft systems as well as to guidance to
the crews."


User currently offlinerolfen From Germany, joined Jan 2006, 1807 posts, RR: 2
Reply 14, posted (3 years 8 months 1 week 5 days 9 hours ago) and read 7242 times:

Quoting 777236ER (Reply 13):
This is a ridiculous argument.

Well, it makes more sense if you call this warning the "misconfiguration warning". It would alert the crew about the aircraft being misconfigured for the current phase of flight. In any case the manufacturer assumes that the pilots are fully trained. Yes it is poor design. A spoken warning would be much better, but I guess the 737 inherited this from the 1st generation. Still I don't think this is an excuse... dont they do cabin depressurization training drills? Simulations?



rolf
User currently offline413X3 From United States of America, joined Jul 2008, 1983 posts, RR: 0
Reply 15, posted (3 years 8 months 1 week 5 days 9 hours ago) and read 7239 times:

Quoting 777236ER (Reply 13):
In a hypoxic state it's clear that flight crew will jump to the cognitively easy solution: it's a t/o warning.

But you wouldn't start suffering until above 12k feet, correct? So they had how many minutes to listen to this horn while doing nothing before the airplane climbed to an altitude where the effects could be seen?


User currently offlineKELPkid From United States of America, joined Nov 2005, 6372 posts, RR: 3
Reply 16, posted (3 years 8 months 1 week 5 days 9 hours ago) and read 7228 times:

Quoting 413X3 (Reply 16):
But you wouldn't start suffering until above 12k feet, correct? So they had how many minutes to listen to this horn while doing nothing before the airplane climbed to an altitude where the effects could be seen?

IIRC, 14,000' is the magic cabin altitude at which the warning begins to sound...I would imagine a fairly typical climb in a 737 would be around 1500'/minute or so.



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineautothrust From Switzerland, joined Jun 2006, 1595 posts, RR: 9
Reply 17, posted (3 years 8 months 1 week 4 days 18 hours ago) and read 7121 times:

Quoting 777236ER (Reply 13):
This isn't the first example of that 737's poor human-machine interface causing deaths (BMA92 and TK1951 spring to mind). It's shocking that this out-moded 60s flight deck design is still being produced and sold as one of the most popular large commercial aircraft. In the days of dark cockpits, EICAS/ECAM, clear warning hierarchy and system synopses it's a travesty that the 737 can still be produced.

Very well said. Not only is the flight deck poorly designed also the E&E bay is misplaced

Quote:
On 22 October 1995, G-BGJI, a 737-200Adv experienced undemanded yaw & roll oscillations during an air test. This was put down to fluid from the cabin leaking into the E & E bay and onto the yaw damper coupler. The report stated:

"The location of the Electronic and Equipment (E&E) Bay, beneath the cabin floor in the area of the aircraft doors, galleys and toilets made it vulnerable to fluid ingress from a variety of sources



“Faliure is not an option.”
User currently offline777236ER From , joined Dec 1969, posts, RR:
Reply 18, posted (3 years 8 months 1 week 4 days 13 hours ago) and read 7061 times:

Quoting 413X3 (Reply 16):
But you wouldn't start suffering until above 12k feet, correct? So they had how many minutes to listen to this horn while doing nothing before the airplane climbed to an altitude where the effects could be seen?

The crew silenced the horn at 14kft, a altitude where they would already feel the effects of hypoxia. The effects of hypoxia were apparent when they ignored the request from maintenance on the ground to check the status of the pressurisation panel.

The fact that the 737 can take off, with no warnings, with the pressurisation system in 'manual' is another simply dangerous feature.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 19, posted (3 years 8 months 1 week 3 days 23 hours ago) and read 6976 times:

Quoting 777236ER (Reply 13):
This is a ridiculous argument. The fact that the two modes are mututally exclusive is nonsense - a t/o config warning is significantly more likely to occur than a cabin altitude warning, hence more likely for the crew to interpret the warning as a t/o config.

The system could be better (and now is better on new aircraft), but to say that something that's fully accepted by the FAA, EASA, and the vast majority of airlines is "ridiculous" and "nonsense" is stretching it a little far. If the flight crew is so unfamiliar with the aircraft as to think they've got a takeoff config warning *after* takeoff, there is more at work than just bad flight deck design.

Quoting 777236ER (Reply 13):
The crew didn't have all the information necessary in the physiological state they were in

The warning horn goes off at 10,000' cabin altitude. The whole point of having it there is that you *haven't* started changing physiological state at that point and you're supposed to respond properly.

Quoting 777236ER (Reply 13):
In the days of dark cockpits, EICAS/ECAM, clear warning hierarchy and system synopses it's a travesty that the 737 can still be produced.

The 737 is essentially a dark cockpit, it does have a clear warning hierarchy, and it does have system synoptics. It just uses master caution/warning, rather than CAS/CAM (the EI/E function is already there).

Quoting KELPkid (Reply 16):
IIRC, 14,000' is the magic cabin altitude at which the warning begins to sound...I would imagine a fairly typical climb in a 737 would be around 1500'/minute or so.

Horn goes off at 10,000'. The 14,000' (actually 13,875') trigger is the AUTO FAIL annunciation for auto pressurization.

Quoting autothrust (Reply 17):
Very well said. Not only is the flight deck poorly designed also the E&E bay is misplaced

Then it's misplaced on every modern jet. It's always under the flight deck and aft of the nose gear well, which is always where you have a pair of doors, at least one galley, and at least one lav.

Quoting 777236ER (Reply 18):
The fact that the 737 can take off, with no warnings, with the pressurisation system in 'manual' is another simply dangerous feature.

Why? You're supposed to set it during preflight, and if you forget to set it you get a warning before it becomes dangerous. It's only dangerous if you forget to set it *and* ignore the warning horn. Takeoff warnings are supposed to warn you of things that threaten *the takeoff*. Even EICAS/ECAM airplanes inhibit non-takeoff-critical warnings during the takeoff period.

Tom.


User currently offlineLTC8K6 From United States of America, joined Jun 2009, 1209 posts, RR: 0
Reply 20, posted (3 years 8 months 1 week 3 days 18 hours ago) and read 6923 times:

Clearly, the 737 should set itself up preflight, and then fly itself, auto correcting any errors those pesky humans make...how dare Boeing produce a plane that doesn't...

User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 21, posted (3 years 8 months 1 week 3 days 16 hours ago) and read 6912 times:

Quoting LTC8K6 (Reply 20):
Clearly, the 737 should set itself up preflight, and then fly itself, auto correcting any errors those pesky humans make...how dare Boeing produce a plane that doesn't...

Actually, this is almost what the Helios aircraft did...with the crew incapacitated, the aircraft flew its flight plan properly and, absent further instructions, continued to fly safety until it exhausted its fuel.

Tom.


User currently offlineKELPkid From United States of America, joined Nov 2005, 6372 posts, RR: 3
Reply 22, posted (3 years 8 months 1 week 3 days 12 hours ago) and read 6862 times:

Quoting tdscanuck (Reply 21):
Actually, this is almost what the Helios aircraft did...with the crew incapacitated, the aircraft flew its flight plan properly and, absent further instructions, continued to fly safety until it exhausted its fuel.

Tom.

Didn't a PPL-rated flight attendant, wearing a portable oxygen mask, attempt to gain access to the cockpit, as I recall? (too late to do any good...)



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offline777236ER From , joined Dec 1969, posts, RR:
Reply 23, posted (3 years 8 months 1 week 3 days 12 hours ago) and read 6859 times:

Quoting tdscanuck (Reply 19):
The system could be better (and now is better on new aircraft), but to say that something that's fully accepted by the FAA, EASA, and the vast majority of airlines is "ridiculous" and "nonsense" is stretching it a little far. If the flight crew is so unfamiliar with the aircraft as to think they've got a takeoff config warning *after* takeoff, there is more at work than just bad flight deck design.

It's not stretching anything. The 737 has the most archaic systems of any large commercial aircraft being produced in the West. It doesn't get anywhere near the certification standards of today. The classics didn't even get near the certification standarsd of the 80s.

Quoting tdscanuck (Reply 19):
The whole point of having it there is that you *haven't* started changing physiological state at that point and you're supposed to respond properly

The reality proves you wrong.

Quoting tdscanuck (Reply 19):
The 737 is essentially a dark cockpit, i

Demonstrably incorrect! The dark cockpit means that when everything is normal, it's dark. A simple glance upwards at a A320, A330/A340, A380, 777 or 787 flight deck will tell you if everything is normal. With the 737? No. The mistake the pilots made resulted in no abnormal lights, and regardless of that normal operation lights glare away on every 737 cockpit (window heat lights being a good example). It's archaic design, completely superceded by even Boeing. Yet these aircraft still roll out of the factory every day.

Quoting tdscanuck (Reply 19):
and it does have system synoptics

No, it doesn't. It has a bunch of warning lights that correspond to problems, like the 707 did. There are no system synoptics.

Quoting tdscanuck (Reply 19):
Why? You're supposed to set it during preflight, and if you forget to set it you get a warning before it becomes dangerous. It's only dangerous if you forget to set it *and* ignore the warning horn. Takeoff warnings are supposed to warn you of things that threaten *the takeoff*

And yet Boeing, Airbus and modern regulators disagree with you. It's crazy to allow an aircraft to depart, with no warnings of an unsafe condition, then expect the flight crew to understand the details of a system they hardly ever touch in flight, whilst hypoxic, with a warning they assosicate exclusively with another flight phase.

Quoting LTC8K6 (Reply 20):
Clearly, the 737 should set itself up preflight, and then fly itself, auto correcting any errors those pesky humans make...how dare Boeing produce a plane that doesn't...

This is meant pejoratively, but an aircraft that did that would have saved the lives of the innocent people on the 737. A modern aircraft will provide a warning for the unsafe state of any system before take off. The 737 still doesn't.

Quoting tdscanuck (Reply 21):
Actually, this is almost what the Helios aircraft did...with the crew incapacitated, the aircraft flew its flight plan properly and, absent further instructions, continued to fly safety until it exhausted its fuel

This is a slightly sleazy attempt at suggesting that the Helios 737 actually displayed good system design in what it did. The 737 did NOT auto-correct any of the flight crew errors. The actions of the 737 did nothing to save the passengers - are you suggesting this 'marvel' of actually following the flight plan is a somehow remarkable design? It's a bit like saying that despite the pressurisation failures, the oxygen masks in the cabin deployed...how clever of the 737! Nonsense - the 737's poor design caused this crash, as you have admitted yourself.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 24, posted (3 years 8 months 1 week 3 days 9 hours ago) and read 6821 times:

Quoting KELPkid (Reply 22):
Didn't a PPL-rated flight attendant, wearing a portable oxygen mask, attempt to gain access to the cockpit, as I recall? (too late to do any good...)

I'm not sure if they were PPL-rated, but the F-16's sent to intercept saw a cabin crew member enter the flight deck, attempted to communicated with them via handsignals, and heard them make repeated Mayday calls on the radio.

Quoting 777236ER (Reply 23):
It doesn't get anywhere near the certification standards of today. The classics didn't even get near the certification standarsd of the 80s.

I love it when this red herring comes up. The classics were certified to Amendment 25-15 (1967), the original basis, *but* included specific supercessions up to and including 25-51 (1980). The FAA never lets you grandfather superceded safety regulations, so you'll always be within 5 years of whenever you applied for the amended TC.

Quoting 777236ER (Reply 23):
Quoting tdscanuck (Reply 19):
The whole point of having it there is that you *haven't* started changing physiological state at that point and you're supposed to respond properly

The reality proves you wrong.

You know something to suggest they were going hypoxic at 10,000'? That suggests a medical issue with the crew that wasn't mentioned, *at all*, in the accident report.

Quoting 777236ER (Reply 23):
The dark cockpit means that when everything is normal, it's dark.

No exactly. All the panel lights still run just fine, all the way up through the A380/787. It does mean the *indication* lights are dark in normal configuration...the 737classics follow this on some, but not all, systems.

Quoting 777236ER (Reply 23):
A simple glance upwards at a A320, A330/A340, A380, 777 or 787 flight deck will tell you if everything is normal.

Yes, but not because it's literally dark. Specially, you're looking for absence of color, not absence of light.

Quoting 777236ER (Reply 23):
With the 737? No. The mistake the pilots made resulted in no abnormal lights, and regardless of that normal operation lights glare away on every 737 cockpit (window heat lights being a good example).

It did not result in an abnormal light. It did result in an abnormal dial. The information was all there. Could it have been presented in a clearer way? Certainly, and improvements have been made to the 737 specifically, and more modern flight decks in general, to mitigate that. But that does not excuse the flight crew from 1) incorrectly doing their preflight, 2) incorrectly responding to a clear warning, 3) allowing the warning to continue to the point that hypoxia did start to take hold.

Quoting 777236ER (Reply 23):
No, it doesn't. It has a bunch of warning lights that correspond to problems, like the 707 did. There are no system synoptics.

Absolutely right, I was thinking 737NG. Sorry for the confusion.

Quoting 777236ER (Reply 23):
And yet Boeing, Airbus and modern regulators disagree with you.

Which regulators disagree? If it were a safety issue, by definition, there would be an AD. The fact that there isn't means that the regulators don't think it's a safety issue. Boeing certainly doesn't consider it a safety issue or they'd have said so as well (determination of safety/non-safety is part of every modification disposition).

Quoting 777236ER (Reply 23):
It's crazy to allow an aircraft to depart, with no warnings of an unsafe condition, then expect the flight crew to understand the details of a system they hardly ever touch in flight, whilst hypoxic, with a warning they assosicate exclusively with another flight phase.

"This horn means your cabin altitude is too high" is hardly "understand the details", it's a fundamental part of the aircraft's warning system. One that is explicitely trained to the flight crews. You experience high cabin altitude *way* more often than some other failures, like inflight fire, but you can bet that crews have no problem responding appropriately to that.

And, unless you've got evidence that never showed up in the investigation report, they weren't hypoxic when the warning started.

Quoting 777236ER (Reply 23):
A modern aircraft will provide a warning for the unsafe state of any system before take off. The 737 still doesn't.

No modern aircraft will provide a warning for *all* unsafe systems prior to takeoff. It will provide a warning for *some* unsafe systems.

Quoting 777236ER (Reply 23):
This is a slightly sleazy attempt at suggesting that the Helios 737 actually displayed good system design in what it did. The 737 did NOT auto-correct any of the flight crew errors. The actions of the 737 did nothing to save the passengers - are you suggesting this 'marvel' of actually following the flight plan is a somehow remarkable design? It's a bit like saying that despite the pressurisation failures, the oxygen masks in the cabin deployed...how clever of the 737! Nonsense - the 737's poor design caused this crash, as you have admitted yourself.

1) I stated the facts. If you want to call that sleazy, that's certainly your call.
2) The 737 did not auto-correct any of the flight crew errors. The 737, of any generation, has never had that capability and every flight crew knows it. The fundamental design of the airplane is to tell the flight crew there is a problem and allow the flight crew to respond. If you think this is truly a safety issue, then you've got no alternative than to argue for grounding of the entire 737 fleet.
3) I did not, nor would I, state that "the 737's poor design caused this crash." I will state, flat out, that the 737's design (poor or not) did *not* cause this crash. This crash was caused by improper flight crew actions during the preflight and after takeoff. Contributing factors were, certainly, prior maintenance actions and the warning system, but it's ludicrous to suggest that the design *caused* the crash when the flight crew took off in the wrong configuration and then did not restore the configuration when the problem was brought to their attention by the airplane.

Tom.


25 mandala499 : Really? How does one ferry flight a defective aircraft from an outbase with "limited/conditional" release? Again... checklists are there for a reason
26 777236ER : And yet newly created 737-800s (certified to 25-77 from 1992) are certified to hold 189 passengers with only 4x Type C doors and 4x Type IIIs, despit
27 Post contains links mandala499 : The 737NG exits are upward hinging swing type and not the "manually remove and manually dispose/stow prior to use" type. This reduces the time requir
28 tdscanuck : Mandala499 already covered most of my comments more eloquently than I would have. Just a couple of add ons: The service bulletin for that has been out
29 LTC8K6 : And a modern pilot will ignore or misinterpret that modern warning... Maybe the plane should slap them?
30 Post contains images MarkHKG : I've always wondered why most flight decks designs rely on a non-vocal alert for the cabin altitude alarm. Instead of an actual voice prompt stating,
31 Post contains images HAWK21M : Would this Dog have special qualification requirements . Isn't Multiple snags on the Pressurisation system with Two systems INOP a nogo. regds MEL.
32 777236ER : Yes, but they're still Type IIIs. The regulations are clear. Not yet it doesn't. There is a proposed EASA rule, but if Boeing or Airbus applied for c
33 mandala499 : A type III exit is a type III exit... But... just because a type can only have 180 seats with 2 type I and 2 type III a side does not mean that others
34 tdscanuck : It appears you're using "modern" = "EICAS/ECAM"...so yes, by your definition, all "modern" aircraft have EICAS/ECAM. But that's not the definition th
35 Post contains images Revelation : The report breaks down the causes into two categories, direct and latent, and the one you cite is one of the latent causes. The direct causes are giv
36 Post contains images nycbjr : Tom I would never try and correct you, so I'm going to ask a question instead, are you referring to 990? If so then it was a 767. my bad if it was an
37 tdscanuck : Arrgghhh!! Too much eggnog, my sincere appologies. I was trying to think up good examples, was thinking about both Egyptair (pilot intentionally cras
38 Post contains images KELPkid : Just eggnog, or eggnog and rum? 'Tis the season...
39 rheinwaldner : Beside the otehr mishap there is another problem with this: IIRC the envelope protection does not prevent a flight into terrain. As long as the aircr
40 tdscanuck : Exactly. That was my point. 777236ER appears to be taking the stance that any unsafe situation that resulted in a crash demonstrates inadequate desig
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