a380900
Posts: 801
Joined: Fri Dec 05, 2003 11:26 pm

How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 2:26 am

What would be the characteristic of a fly without pressurization for a jetliner?

What altitude should it be? What speed? Is it specified in the operating handbook for all aircraft?

How often are such flights performed?

[Edited 2005-02-04 18:26:39]
 
AirWillie6475
Posts: 2372
Joined: Thu Jan 27, 2005 1:45 pm

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 6:04 am

The highest that a human can legally fly without oxygen aid is 15k feet and only about 30 minutes at that altitude. Also I think at night the altitude limit is lower.
 
PhilSquares
Posts: 3371
Joined: Sun Mar 28, 2004 6:06 pm

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 6:22 am

Normally, if you lose cabin pressure you're going to descend to atleast 14,000 feet, 10,000 feet if possilbe. Most likely you would divert to the closest airport at that point.

If it were an explosive decompression, you would have some people who experienced some minor injuries and you'd want to get them on the grouned.

There is no speed restriction, assuming you haven't had structural damage. And these flights aren't all that common. An aircraft can't be dispatched with the cabin pressure system in op. However, I have ferried several aircraft that have sustained damage from jetways, catering trucks, fuel trucks, etc. In these situations the flights were with no pax and unpressurized. In most cases, there was no speed restrictions. Sometimes, in the case of an aircraft that has damage to say a cargo door, the mfg will put an airspeed restriction as part of the ferry permit.
Fly fast, live slow
 
SlamClick
Posts: 9576
Joined: Sun Nov 23, 2003 7:09 am

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 7:18 am

As loss of pressurization is a symptom rather than a fault in and of itself, I'd say it depends.

There are two major possibilities; with or without structural damage.

If you have nothing more than the inability to control cabin pressure (outflow valve stuck open for example) you must get down to an altitude that permits passengers to remove their little yellow nosebags, and then you must find a suitable place to land and fix it.

If a door blows off or a bulkhead ruptures you want to do these things in such a way as to not add any stress to the airframe.

In any event you are not going to be overflying a suitable airport to proceed.

You probably don't have enough fuel.
You might have other problems.
etc.
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
Bobster2
Posts: 1523
Joined: Mon Jan 17, 2005 3:04 am

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 7:50 am

This is a pretty good article on the subject. It includes the story of the BAC-111 captain who got partially blown out of the plane when a window popped out and the crew members had to hold on to his feet until they landed.

http://www.casa.gov.au/avreg/fsa/download/00mar/page42-44.pdf
"I tell you this, no eternal reward will forgive us now for wasting the dawn." Jim Morrison
 
LeanOfPeak
Posts: 496
Joined: Thu Oct 21, 2004 2:18 am

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 7:55 am

I believe the question was about unpressurized ferry flights.

They tend to be done when there is an uncertainty about either the structural soundness of the pressure vessel, the capabilities of the pressurization system, or both and the aircraft needs to be repositioned where there is equipment better suited for the diagnosis and/or repair of the situation.

As long as the flight crew and any passengers aboard (Generally engineers or mx workers, not paying passengers) are willing to wear oxygen masks, I would anticipate the flight envelope to be affected more by the underyling reason for the flight being undertaken unpressurized than by the fact that the flight was being undertaken unpressurized. The one significant point is that the cabin pressure is no longer a reliable means of keeping plug doors secure, and all must be properly latched.

If for some reason supplemental oxygen is not to be used, then the altitude restrictions above would come into play.
 
Bobster2
Posts: 1523
Joined: Mon Jan 17, 2005 3:04 am

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 8:16 am

If the ferry flight is at normal altitude, wouldn't it be very cold inside? Is there heated air without pressurization?

And the article I cited above says there is a risk of decompression illness after exposure to altitudes above 18000 ft.

[Edited 2005-02-05 00:18:51]
"I tell you this, no eternal reward will forgive us now for wasting the dawn." Jim Morrison
 
Woodreau
Posts: 1243
Joined: Mon Sep 24, 2001 6:44 am

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 8:33 am

I was wondering about the temp as well...

Any of the pax wouldn't be using the oxygen that comes from the overhead since it only provides oxygen for a very limited time. I think just enough to get the aircraft down to an altitude below 12,500ft.

Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
 
SlamClick
Posts: 9576
Joined: Sun Nov 23, 2003 7:09 am

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 8:45 am

You will not be carrying paying passengers on an upressurized flight.

Just because we cannot control the cabin altitude does not mean we don't have temperature control. We may be able to use the packs.

Once, out of curiosity I ferried a plane with the temperature controller set at full cold, then backed off just off the stop. (I don't like to operate machines against the stops.)

Took off out of an 85 or so degree airport. After an hour and ten minutes of flight and a landing at a 70 degree airport, the cabin temp was only down in the mid 50s.

On the other hand I once saw an ONA DC-9 freighter bring in a load of live penguins for SeaWorld. That cabin was cold. The pilots were wearing some kind of warm suits.


Happiness is not seeing another trite Ste. Maarten photo all week long.
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 8:55 am

We have flown unpressurized revenue flights before (cargo). We don't like to do it, but if you don't have a spare aircraft, you do what you can. The flight is slower, lower and costs a whole in fuel. Also requires quite a bit of coordination with enroute ATC.
 
PhilSquares
Posts: 3371
Joined: Sun Mar 28, 2004 6:06 pm

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 10:31 am

On 747, I have done several flights unpressurized. I remember the last one from MAN-LUX to have the aft cargo door fixed after the ground handling agent tried to close the door on the loader. Didn't quite make it.

The flight was planned at 110 and 320 kias. No packs and the cockpit was actually quite stuffy.

There was no speed restriction, no revenue payload (people or cargo). Nice way to sightsee along the way.
Fly fast, live slow
 
Inbound
Posts: 614
Joined: Sat Sep 15, 2001 7:59 am

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 12:35 pm

On the Dash8, engage autopilot if it isn't already on, don oxygen masks and initiate an emergency descent.

simultaneously, turn 45degrees off course for 1 minute,then turn back to original heading to parallel the airway.

declare and emergency and descend to 14,000' or 10,000' if available.
Maintain own separation with terrain!
 
SlamClick
Posts: 9576
Joined: Sun Nov 23, 2003 7:09 am

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 12:43 pm

For a long time here in the US we practiced emergency descents in the simulator by making a turn off course before starting down. The idea was to get off the airway.

It took the training departments a lot longer than it took line pilots to realize that you were as likely to turn into traffic as you were away from it. Not all traffic is on YOUR airway. Once they finally got it, you get a clearance for any turn or descent.
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
User avatar
HAWK21M
Posts: 29917
Joined: Fri Jan 05, 2001 10:05 pm

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 4:22 pm

The flight was planned at 110 and 320 kias. No packs and the cockpit was actually quite stuffy
What is the Altitude flown normally.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
PhilSquares
Posts: 3371
Joined: Sun Mar 28, 2004 6:06 pm

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 5:57 pm

Hawk21M,

The normal altitude would have in the upper 30's. So there was quite a big difference.

Fly fast, live slow
 
Silver1SWA
Crew
Posts: 4458
Joined: Wed Mar 10, 2004 6:11 pm

RE: How To Fly An Airliner If Pressurization Fails?

Sat Feb 05, 2005 7:06 pm

This is interesting to me. I do know of one flight about 4 months ago that did fly a revenue flight from SJC-LAX at 10000 feet because of pressurization problems on the flight before. Just took a bit more fuel that's all...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
mandala499
Posts: 6460
Joined: Wed Aug 29, 2001 8:47 pm

RE: How To Fly An Airliner If Pressurization Fails?

Sun Feb 06, 2005 3:18 am

What's annoying is when you have to fly a plane with a problematic outflow valve that won't keep the pressure in... when you descend, u gotto keep the thrust above flight idle... can give an intesting ASI figure sometimes... like 330KIAS (a 732)! LOL, well somewhere near the barberpole! Gotta do it otherwise the pax might start passing out!

Mandala499
When losing situational awareness, pray Cumulus Granitus isn't nearby !
 
airplay
Posts: 3369
Joined: Sat Oct 25, 2003 1:58 am

RE: How To Fly An Airliner If Pressurization Fails?

Sun Feb 06, 2005 4:38 am

There was an incident years ago with a Crossair SAAB 340 that had the outflow valve freeze up. It's failure caused the cabin to dump. Unfortunatly, the airplane was over the Alps in an area where they couldn't descend immediatly. Since there is no pax oxygen in the SAAB 340 (not required for airplanes who's ceilings are 25,000 feet or less) the passengers suffered some oxygen starvation.

Nobody was killed or seriously injured but it did cause an AD and subsequent re-design. The outflow valves were moved from the tail cont to the rear cabin bulkhead. A tube was added between the outflow valve and the tailcone.

Many modern aircfraft (including the SAAB 340) have a limited amount of cabin pressure available from a ram-air source. Of course it doesn't help if the outflow valve is open or there is a hole in the side of the fuselage.

A great many modern airliners are built to very stringent standards with respect to depressurization. Any airliner with a max certified ceiling above 410 has been required to meet additional "high altitude" airworthiness standards where the calculated probability of a depressurization due to system malfunction or structural failure is extremely remote. These newer "high altitude" fuselages have very miniscule leak rates under normal conditions.

 
Inbound
Posts: 614
Joined: Sat Sep 15, 2001 7:59 am

RE: How To Fly An Airliner If Pressurization Fails?

Sun Feb 06, 2005 1:01 pm

SlamClick,
Seeing as we still follow some older british based regulations during our training in the caribbean, even at the sim in toronto, I wouldn't doubt that a new regulation exists that allows you to descend through your own airway.

but with the new RVSM regs in effect, it might be twice as possible to collide with traffic on your airway now as compared to those who may be off of it.

perhaps?
Maintain own separation with terrain!
 
User avatar
HAWK21M
Posts: 29917
Joined: Fri Jan 05, 2001 10:05 pm

RE: How To Fly An Airliner If Pressurization Fails?

Sun Feb 06, 2005 4:37 pm

What would the Max Altitude be in a Commercial Aircraft [eg B737] if it has to Ferry fly from A to B with U/s Pressurisation & Oxygen system.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
User avatar
longhauler
Posts: 5038
Joined: Sat Mar 06, 2004 12:00 am

RE: How To Fly An Airliner If Pressurization Fails?

Mon Feb 07, 2005 12:06 am

HAWK21M, for extended periods, without oxygen, the maximum altitude would be 10,000 feet. I did it once in the DC-9 from YQB to YYZ.

No passengers, and not all that cold, it was July, but as mentioned above, it was very stuffy and humid.
Just because I stopped arguing, doesn't mean I think you are right. It just means I gave up!
 
OPNLguy
Posts: 11191
Joined: Tue Jun 15, 1999 11:29 am

RE: How To Fly An Airliner If Pressurization Fails?

Mon Feb 07, 2005 1:25 am

>>>What would the Max Altitude be in a Commercial Aircraft [eg B737] if it has to Ferry fly from A to B with U/s Pressurisation & Oxygen system.

It also depends upon what you're authorized for....

For unpressurized ferries, we usually stay at 9,000 or 10,000 depending upon direction of flight, but if MEAs/terrain are an issue, we have the option of operating up to 17,000 (with the flightcrew on oxygen) not to exceed one hour's time between 10,000 and 17,000.

Unpressurized revenue flights at/below 10,000 are rare, but still possible in some cases, as long as pax count is low (for cabin temp considerations) and that MEAs can be complied with. The flight that Silver1SWA mentioned in post #15 is a good example, and SJC-LAX is one leg where it's possible to be done. You wouldn't have the same luck coming out of RNO...  Big grin
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
L-188
Posts: 29881
Joined: Wed Jul 07, 1999 11:27 am

RE: How To Fly An Airliner If Pressurization Fails?

Tue Feb 08, 2005 9:58 am

Assuming that nothing else in the equasion changes. It will fly just the same, except maybe lower and slower, or under the mask.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.

Who is online

Users browsing this forum: No registered users and 14 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos