Hmm, actually - the FCOM says the cabin altitude warning is the same intermittent aural tone as the takeoff config warning.

And this is why Helios went in. . . The Cabin Alt horn is the same as the T/O Config horn. Landing Config is steady horn. T/O Config and Cabin Alt are an intermittent horn. Whoever came up with this system should be kicked in the Jimmy.

Whoever came up with this system should be kicked in the Jimmy.

The Helios screw did screw up pretty badly, but having the same warning sound with no annunciations is a pretty big fail on Boeing's part.

Hmm, actually - the FCOM says the cabin altitude warning is the same intermittent aural tone as the takeoff config warning.

And this is why Helios went in. . . The Cabin Alt horn is the same as the T/O Config horn. Landing Config is steady horn. T/O Config and Cabin Alt are an intermittent horn. Whoever came up with this system should be kicked in the Jimmy.

Oops. You guys are correct! Sorry. I didn't verify my info because I was posting from my phone.

I'm guessing the logic behind that decision was to use a warning that's recognizable enough (that you don't need a manual to decipher) and can not be mistaken. The flow of action:1. Intermittent horn alarm occurs2. Can it be a takeoff warning? Gear is up, flaps is up, airplane is in a climb above 10.000ft, probably not a takeoff warning.3. Is it a cabin altitude alert? Look at cabin altitude gauge? It's indicating higher than normal.4. Problem diagnosed. Obviously, like any other warning system - knowledge of the airplanes systems is necessary. :)

And this is also why we have to follow AD2008-23-07 when we fly the plane. It even talks about the intermittent warning, just so you get it straight.

The Helios screw did screw up pretty badly, but having the same warning sound with no annunciations is a pretty big fail on Boeing's part.

The new planes have lights on the main panel for cabin altitude and takeoff warning. That came about after the Helios crash. Also we are now required to brief what we will do in the event of hearing that horn in the different situations if we are flying one of the older planes that doesn't have the new lights. I remember hearing that the old planes were going to get the new lights but so far I haven't seen any that have been converted. I could have heard wrong though.

I don't know wich sound you exactly mean. But you can try the alt warning button up in the upper panel. Try that maybe it works!

The problem is that if cabin altitude sounds for packs off, the pilots are breathing the same air from take off some of thhhh this air will go out and the pressure will decrease slowly. At 10000ft of cabin altitude in this condition, probably the pilots are already suffering for the low oxygen in the air.

I just want to be clear about the systems stuff. The AUTO FAIL light won't necessarily accompany the cabin altitude warning. It is possible to get the warning sound with no lights. It has happened where the only warning the crew received was the cabin altitude warning when they failed to turn the pack on.

Thanks for the heads up. Curious why the auto fail light wouldn't illuminate if the pack was off/couldn't pressure while switched in auto position. *EDIT*

As I wrote the 2 annunciations have different logic.If panel is left in AUTO position, and packs are off, the outflow valve will be commanded fully closed trying to maintain pressure. Controller will then not recognize more than 2000ft/min that triggers the AUTO FAIL, but, the cabin pressure will decrease untill reaching 10000 feets, at this moment the pressurization warning sound will play. If packs are restored the alarm will cease, if not, reaching 15800ft of cabin pressure, the AUTOFAIL will come on.

Ah thanks for the clarification.