Loss of cabin pressure and far from land

[llondel]

Given some recent incidents with loss of cabin pressure, I was wondering what would happen if it occurred out over the Pacific. Having to come down to a lower altitude is going to increase fuel burn, so if you're inbound to Hawaii three hours away, is there enough spare fuel on board to cope? Or is it time to rehearse the lifejacket drill? There's a need for a 180min ETOPS rating, so obviously it could happen. (Isn't that where the 777 that set the ETOPS record ended up?)

[SNS3Guppy]

Hence the purpose for calculating ETP's: Equal Time Points.

We have them for all engines (expedite for medical or other expediency), loss of engines, and loss of pressurization...and fuel reserves are planned not only for the destination but the alternates, too.

[con-pilot]

Along with what SNS3Guppy posted many corporate aircraft have larger than standard oxygen tanks install or carry extra oxygen tanks in the cabin to assure a dry footprint in case of pressurization during extended over water operations.

[Rainboe]

ETOPs fuel reserves are calculated for a failure at the worst possible time and a diversion following descent to 10,000'. Funnily enough, it's better to divert on one engine than two engines with a pressurisation failure (which is the worst case).

Don't worry, someone has been there before and considered all this!

[llondel]

I was wondering how many levels got considered for failure analysis, so it's nice to know others share my "what if?" paranoia. Even nuclear power stations have the concept of the minimum probability of failure they'll design to prevent.

Not that I've done any significant flying over the Pacific, it's always been in sight of the US West Coast.

[SNS3Guppy]

You appear to be saying "how many possibilities" when you say "levels." When it comes to flying, the correct answer is "all of them."

Clearly it's conceivable for something to happen for which there is no procedure...one can imagine all kinds of exotic possibilities. We have no procedure, for example, for an aileron falling off the airplane. We do have procedures for jammed ailerons, jammed elevators, jammed rudders, etc...or landing with some, but not all ailerons, etc.

We have procedures available, and plan accordingly, for failures or malfunctions of any given aircraft system. All flights are planned with the worse-case "what if" in mind.

I'll be leaving in a few hours for a flight from LAX to Honolulu. You can bet I wouldn't be comfortable doing it unless I knew in advance that all the possibilities were covered for dealing with engine failures, pressurization failures, communication failures, etc...we've planned for these failures before the flight ever gets dispatched, starting with the takeoff roll and ending up with parking at the gate...and we've planned for them given real-world conditions, such as weather, winds, etc.

Rest assured that when you're riding somewhere as a passenger, the crew lives in a constant world of "what if" as we address each contingency. What if the engine fails here? What if we have a report of smoke in the cabin? What if we lose communications? What if we lose all generators? What if we encounter volcanic ash? What if...? We have a procedure and a plan for each of those...and hundreds of pages of many others, too.

Remember...if something goes wrong, we're the first ones to the scene of the crash...so you can bet we're keenly interested in ensuring it's a safe departure and a safe arrival, with a pleasant, safe flight in between. It's in your interest, and ours, too.

[con-pilot]

To give an example to back up what SNS3Guppy posted.

Many years ago I operated a Westwind II to Hawaii from San Francisco. The Westwind had a marginal dry footprint for the crossing, there would be times we would have to wait for a day or two for favorable winds to make the crossing to assure a dry footprint. Then during recurrency school a pilot I knew related an incident that happened to him about an hour out of Guam heading for Wake Island to refuel on a flight to Hawaii. A little over an hour out of Guam the hydraulic up-lock line on the right main gear blew and the right main gear came down. With a main gear hanging down you are in very serious trouble on a long over-water flight. You cannot maintain speed, altitude and the fuel burn goes through the roof. If he had been another two hours into the trip he would have had to ditch, with the gear down. The odds of survival are very slim.

After hearing this I informed the owner that I would no longer operate the Westwind on Hawaii flights until the manufacture developed a fix for this problem, if in fact they ever would fix the problem. He informed me that he did not think that it could happen to us and I had problems with that I could quit.

So I quit.

Sure enough about six months later the same thing happened to his aircraft, fortunately on a flight over land. He sold the Westwind II and bought a Jetstar II.

Point of this story is, a good competent crew takes any and all possibilities under consideration, even the type of aircraft that will be operated on long over-water flights.

Just to assure some of the people here reading this, most all aircraft have mechanical gear up-lock on the landing gear. If the up side of the landing gear hydraulic system should have a leak or lose a hydraulic line the gear will remain up and locked. I know all Boeing aircraft do.

[MarcJF]

what's a dry footprint?

[K.Whyjelly]

what's a dry footprint?

Having enough fuel to complete a maritime crossing without dropping into the 'oggin.

Been a while since I've said the words (and not sure if they are still in use), but whenever we used to coast out and drop down low level over the water we would transmit a "feet wet" call to advise the controllers we were out over water and likewise on recovery over land a "feet dry" call would be made.