PhilSquares From , joined Dec 1969, posts, RR: Reply 2, posted (8 years 10 months 1 week 6 days 15 hours ago) and read 4548 times:
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.
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 69 Reply 3, posted (8 years 10 months 1 week 6 days 14 hours ago) and read 4516 times:
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.
Happiness is not seeing another trite Ste. Maarten photo all week long.
Bobster2 From , joined Dec 1969, posts, RR: Reply 4, posted (8 years 10 months 1 week 6 days 14 hours ago) and read 4491 times:
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.
LeanOfPeak From United States of America, joined Oct 2004, 509 posts, RR: 1 Reply 5, posted (8 years 10 months 1 week 6 days 14 hours ago) and read 4488 times:
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.
Woodreau From United States of America, joined Sep 2001, 936 posts, RR: 7 Reply 7, posted (8 years 10 months 1 week 6 days 13 hours ago) and read 4462 times:
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.
Good judgement comes from experience. Experience comes from surviving bad judgement.
Air2gxs From , joined Dec 1969, posts, RR: Reply 9, posted (8 years 10 months 1 week 6 days 13 hours ago) and read 4446 times:
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 From , joined Dec 1969, posts, RR: Reply 10, posted (8 years 10 months 1 week 6 days 11 hours ago) and read 4424 times:
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.
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 69 Reply 12, posted (8 years 10 months 1 week 6 days 9 hours ago) and read 4392 times:
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.
Silver1SWA From United States of America, joined Mar 2004, 4655 posts, RR: 27 Reply 15, posted (8 years 10 months 1 week 6 days 2 hours ago) and read 4313 times:
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 From Indonesia, joined Aug 2001, 6417 posts, RR: 74 Reply 16, posted (8 years 10 months 1 week 5 days 18 hours ago) and read 4231 times:
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!
When losing situational awareness, pray Cumulus Granitus isn't nearby !
Airplay From , joined Dec 1969, posts, RR: Reply 17, posted (8 years 10 months 1 week 5 days 17 hours ago) and read 4214 times:
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 From Trinidad and Tobago, joined Sep 2001, 846 posts, RR: 2 Reply 18, posted (8 years 10 months 1 week 5 days 8 hours ago) and read 4128 times:
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.
OPNLguy From , joined Dec 1969, posts, RR: Reply 21, posted (8 years 10 months 1 week 4 days 20 hours ago) and read 4051 times:
>>>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...