A question regarding Pressurization

[KriVa 307]

It's not that Boeing doesn't want to do it. The problem is airlines won't pay extra for it.

[serviceceiling 135]

I still remember as I once forgot to turn the PACK's back on after takeoff. At about 5.000ft. I heard the "takeoff warning".

Out of instinct I kicked out the autopilot, and maintained the altitude manually, after that I started to figure out what was wrong. Since I knew what the "takeoff warning" sound sounded like, I payed attention to the flaps and the gear - but there was nothing. After a quick scan of the overhead panel I realized that my cabin altitude was pretty high and that both PACK's were still off. I guess this happens because of the lack of a co-pilot in FS.

 

What I wanted to say is that, hearing the takeoff warning sound during your climb and not knowing that the same sound is used for cabin altitude warnings, causes a lot of confusion and the time for figuring out what it is is too long. As previously said above, an aural "CABIN ALTITUDE" warning would solve the issue within a couple of seconds.

[xxJohnxx 21]

What I wanted to say is that, hearing the takeoff warning sound during your climb and not knowing that the same sound is used for cabin altitude warnings, causes a lot of confusion and the time for figuring out what it is is too long. As previously said above, an aural "CABIN ALTITUDE" warning would solve the issue within a couple of seconds.

 

And that's exactly the reason why a type rating doesn't only take 20 minutes.

A good trained pilot, who probably would have read the manuals more than once, should know what this horn means in this stage of the flight.

It is the same with the EGPWS. You also don't just fly straight into a cloud in a valley until you hear the "PULL UP" sound. Of course it would be "easier" as you don't have to know where you are and you won't have to use charts, but do you think this is gonna work?

[Spin737 102]

It's not that Boeing doesn't want to do it. The problem is airlines won't pay extra for it.

Ding ding ding.

[serviceceiling 135]

I agree. Since this particular situation I know what that warning sound is for and can indicate during the mentioned stage of flight.

[Airbusman330 300]

Is it a gentle reminder as is the stall warning of the A330 ("Stall-Stall, sotto voce!).

 

The Airbus alarm is not a gentile reminder, I've got to experience a stall test in an A330 cockpit on the ground and that warning is very loud and to the point.

[Loren Larsa 9]

The MD-11 when in the same situation will tell you with words "Cabin Altitude" so you know what is wrong, in addition to the Boieng style warnings.

Why this wasn't put on the 737 we will never know, but the Betty in the MD-11 sure works out better than the Boeing alerts of dings and dongs and other weird noises.

[davierosoft 13]

When voices or aurals are played with the same speaker they need a priority, with the 737 aural warning you don't need a priority as TCAS, EGPWS are played with the speakers, the aural ding, dongs, and bells are played by an independent system. Much easy, much cheaper, and with a trained crew it is easy to understand the warning.

Howevwer the light could help, and is one of the things that they added.

[Airbusman330 300]

The light is a direct result from Helios 522 since the 737 never had a visual warning before (as far as I know) and on other aircraft you will get a EICAS or ECAM warning. On the A320 the pressurization page will pop up in addition to the ECAM warning so it differs from aircraft to aircraft.

[vololiberista 205]

Aaaahhhhhhh! I remember when gauges were gauges! :-)

The cabin height gauge was deliberately positioned to be in the way of PO's left knee!

 

[davierosoft 13]

The light is a direct result from Helios 522 since the 737 never had a visual warning before (as far as I know) and on other aircraft you will get a EICAS or ECAM warning. On the A320 the pressurization page will pop up in addition to the ECAM warning so it differs from aircraft to aircraft.

Different aircraft, different design, different way to alert.

the 737 flyes with the same altitude warning from it's -100 release, never changed, so it was found pretty good if trained people use it. However, you can give also 100 warnings, visuals, aural, or also electroshock, but a wrong trained crew will fail to do his job.

It is basically not a problem of the kind of alert, if it was working in the past, it will work in the future, the important thing is that the pilot must know what to do in case of the alert.

[japascoe 98]

The MD-11 when in the same situation will tell you with words "Cabin Altitude" so you know what is wrong, in addition to the Boieng style warnings.

Why this wasn't put on the 737 we will never know, but the Betty in the MD-11 sure works out better than the Boeing alerts of dings and dongs and other weird noises.

 

Actually we will know, and the answer has been given several times already in this thread. The 737 is a design from the early sixties. At that time technology wasn't advanced enough to include the an aural 'cabin altitude' warning. Adding it in when they upgraded the design to the NG would have cost lots of money to recertify the plane, (and possibly mean the classic and NG would no longer have a common type rating). This would make the plane more expensive and airlines weren't willing to pay the extra price.

The MD-11 is based on much newer technology (early 80ies I think).

[Loren Larsa 9]

True that the original 737 design is from the 60s with a low bypass turbofan, but it is quite revamped.

The MD-11 is based on a 60's 70s DC-10, only difference from the bodywork is a revamped tail that is very controversial and a stretched fuselage, which is also true for the 737.

Considering the type rating for an early 60s 737 is different from the NG which was made around the MD-11 days, there is still no excuse for Boeing to not have it modernized as McDonnell Douglas did, they faced the same dilemma, even though it is aimed at a different market.

[KriVa 307]

I think you might be discarding quite some facts here.

The MD-11 and DC-10 are WAY more different than the 737 NG and Classic.

Airlines wanted, needed, the NG to have the same Typerating as the classic, whereas the MD-11 and DC-10 don't. The MD-11 fist flew in 1990, the 737 Classic's first flight was in 1984.

The 737s HAD to have the same typerating from the start, with the design of the MD-11 they could pretty much do whatever they wanted, and whatever was possible with what they had, the DC-10 base structure.

 

Apples and oranges, really.

[Loren Larsa 9]

@KriVa I am comparing MD-11, DC-10, 737 NG and the very first gen 737, not the classic, can't recall what Boeing named the very first generation.

Besides the last time I checked the type rating, it was separate for the Classics and NG which was a few days ago, still pricey though at 17-20k Euros for the rating, plus additional if you need the pilots license, but that is off topic.

You can't get the very first 737 type rating on a NG certificate I think? Not that there are many of those left in the air anyways.