passed out in the cockpit?

Factual Questions
1

Yes, I apologize for another missing jet type question.
If the pilots passed out because they weren’t able to get their oxygen on fast enough during decompression; would someone be able to enter the locked cockpit to assist?

I’m imagining a hypothetical where decompression occurs, but the pilots don’t move fast enough to get the masks on before they pass out. I expect the rest of the crew (and passengers) would wonder why there hasn’t been any announcements from the cockpit. Could the crew outside the cockpit, somehow realize there is a problem, and break into it before they themselves run out of oxygen? Can they contact ground control outside the cockpit to let people know of difficulty?

2

AFAIK, once the cockpit is locked by the captain it’s very difficult to get inside from the outside. I doubt that the flight attendants have a key to get them in since a hijacker could certainly take advantage of that, and I doubt there is a radio outside the cockpit that could be used to contact the ground, but I could be wrong about that.

I don’t think it would happen quite as fast as you imagine, so the pilot and co-pilot should have time to put on their masks, but I suppose if a cockpit window blew out at cruising altitude they wouldn’t have all that much time to react…

3

Airliners have to carry quick-donning oxygen masks for the crew. Quick as in, they can be put in place as fast as 5 seconds. I used them when I flew private jets and they’re very nifty.

The reason for them is that in a fast decompression you’d have 30 seconds or less of useful conciousness. Nobody except the crew has those quick masks, so it’s doubtful anyone else could help them, even with access to the cockpit.

4

On some pilot board, there is a post that speculates that an incident similar to the Quantas failure of the oxygen bottle under the cockpit could have happened. that would cause the electronics to either be mashed and shorted by the bottle (before it rockets through the hull causing decompression) or the sudden flood of oxygen and a spark would cause a significant fire taking out all the electrical supply.

So everything fails, the crw dons their masks only to realize too late they have no oxygen. Given 30 seconds to a minute to realize you have no oxygen, how much longer would they stay conscious? Whatever emergency action they take points the aircraft in a random direction.

Then one of several scenarios takes over -
-the autopilot or good trim keeps the aircraft flying for a long distance.
-the engines fail but good trim means the aircraft glides inact to the water, lands relatively intact and sinks with minimal debris.
-the aircraft engines stop, it eventually goes into a dive and impacts - but then there should be a moderate amount of debris.

SO the questions:
-how long can you stay conscious / stay alive at 30,000ft without oxygen? How long to recover as you pass through 10,000 feet?
-How many minutes supply do those passenger masks have?
-How mobile are the cabin crew when on oxygen?
-Will the aircraft engines keep running with major control electronics/ power failure in the cockpit?

I assume that a failure that kils the radios also kills power and control for the autopilot. How reliable is the trim after that? What are the odds of the trim causing them to keep climbing higher and higher until the upper limit is reached (45.000 feet?), then what does that do to the viability of the crew?

5

so it is at least conceivable, that my sceneario is possible. I’m not saying it is likely at all, but its interesting to me that if something happens in the cockpit, nobody in the cabin can render assistance

6

The case of Helios Airways Flight 522 is probably pertinent here. Departing from Nicosia, the entire aircraft depressurized and flew on autopilot to Athens, where it automatically went into a holding pattern. Fighter jets were scrambled to intercept it, and reported seeing the captain’s seat empty. Shortly before the engines flamed out, a flight attendant entered the cockpit and tried to regain control of the aircraft, but was unsuccessful.

It’s not clear where the captain was at the time of the crash. He might have unlocked the door from the inside before losing consciousness, or it might have been that the flight attendant broke down the door. We’ll probably never know.

7

Something else: Even though the post-9/11 cockpit doors are secured against forced entry, I doubt they are air tight. There wouldn’t be any reason for them to be. In fact there would be a lot of reasons for them not to be. If there was a puncture in the cockpit part of the airframe and it depressurized rapidly you’d most likely hear air rushing (very loudly) from the passenger cabin into the cockpit thru the door. And as someone else mentioned, pilots are trained to don their masks very quickly.

8

The intent of the design of the cockpit door was to make it impervious to anything known to be in the cabin, or possibly carried aboard.
It is my understanding that they succeeded.

Unless it was either never locked or unlocked from within, nobody else got onto the flight deck with permission.

9

You would probably not be able to get into the cockpit and there is no way to contact ground from outside the cockpit.

It is Qantas, not Quantas, Queensland And Northern Territory Air Services.

  1. About 1 to 3 minutes is the time of useful consciousness at 30,000’. A rapid depressurisation will shorten this time as the air is forced out of your lungs.

  2. Long enough to descend to 10,000’ from cruising altitude. We carry enough for 10 minutes.

  3. The cabin crew may have drop down masks in which case they are not mobile, or they may be able to use first aid oxygen in a portable bottle in which case they are fully mobile.

  4. Yes the engines will keep running with a major power failure.

As a fly by wire aeroplane generalisations about how trim works might not apply. You can’t really come up with realistic scenarios without a deep understanding of how the B777 systems work.

10

On US flights, the pilot is never alone in the cockpit. IF the co-pilot leaves, another member of the crew must be with the pilot.

I found that out on the news when the Italian flight was hijacked by the copilot.

11

The other obvious questions -
The current news says the transponder and the AFARS(?) were deliberately turned off at different times, thus indicating a hijack scenario. Can they really tell that the radio was manually powered off? Or are they simply going by time of last transmission?
The other interesting fact in the news is that the radio that transmitted the engine data was still alive for 7 hours after. (8 hours fuel for a 6 hour flight? I assume that’s normal?)
Plus suggestions the plane varied up and down to 45,000 feet and 20,000 feet.

The suggestion to me is progressive electrical failures in the cockpit equipment, coupled with depressurization and loss of crew oxygen. Once the crew realized they had serious problems, they attempted a return 180-degree turn but don’t quite complete the turn. If they did not realize their oxygen was compromised, they would waste their last minute fiddling with wearing masks that were not delivering anything.

If at this point they pass out from lack of oxygen, the plane flies on, out over Aceh and into the Indian ocean, meandering higher and lower, until it runs out of fuel far southwest of Perth.

The first 10 minutes, the passengers assume the crew is taking care of things. Then they pass out. These 10 minutes, they are still over water, never near enough to cell towers for passengers to text any messages about the situation.

Two more things - if some power goes out, presumably the pumps compressing the cabin start to fail too. Also, what provides heat at 35,000 feet? Within a few minutes, the plane will start to cool to outside temperature and I assume most passengers and crew were not dressed for it. If the hypoxia did not do them in, hypothermia would.

12

It occurs to me a simple check (which I hope they thought of)

If the plane did indeed turn around and re-cross the Malay peninsula, then there must have been at least one passenger out of 280 that did not turn his cell phone off; the towers in proximity to the flight path would have picked up these cell pings.

Ditto for Burma, Thailand, Bangladesh, Indonesia and India.

I assume someone has thought of this and the cell system keeps these records for a while?

13

It seems that the primary radar paint that they believe was MH370 made a number of turns followed by straight flight that is more consistent with someone flying the aeroplane rather than it meandering around. I think also that they’d be lucky to get anything off cell towers. I’ve been unable to get my cell phone to work much higher than 10,000’. At this point, considering they are leaning heavily towards it being a hijacking, I doubt they’re making all of their information public. It’s frustrating but we don’t have any right to immediate information.

14

The published radar information says they think the aircraft turned north (NNW) after crossing the Malay peninsula, but the published satellite data shows the craft going either north or south. If they are so sure it turned north, why also show the southerly possibility.

That almost suggests to me a disoriented crew member realized they had crossed the peninsula, thought he had made a 180 when he only did about 120 turn, assumed he was south of Kuala Lumpur based on the coast below and headed north.

(A more likely scenario for incapacitated crew is that it did not turn, but kept going straight into the Indian ocean)

I’m not suggesting the plan meandered in heading, but rather kept a heading and from what the reports say, changed (meandered?) up and down between 45,000 and 20,000 feet. This might be consistent with a slight upward trim, which would keep the plane heading up until that trim did not work any more when the air was too thin, and it nosed down to pick up speed. Rinse and repeat.

Of course, if it stalled at 45,000 feet and recovered without intervention, it may have come out of the fall pointed in another random direction and continued on that heading, and so on - explaining too the turn after the peninsula crossing - and also suggesting if it kept doing this, it could be basically anywhere.
SO are ALL the satellite transmissions consistent with a straight line course? I’m understanding they had hourly pings but the indicated position forms a circle, not a line (and not, it looks like, a great circle).

I’m not buying the hijack hypothesis because of psychology. This would have taken serious planning, somewhere. Even if the hijackers did nothing or crashed, some organization would be crowing about how they had fooled the world’s superpowers. Plus, the aircraft would have to cross into India and China based on its course, and that border is not unmonitored. Ditto heading for Pakistan or Afghanistan, or over Kashmir. A lot of watching on both sides.

If a crew wanted to commit suicide, there would be wreckage in the area. I can’t imagine a crew in that area thinking they would fly undetected by military radar in a place with a lot of military tensions. Why commit suicide the hard way? Why wait? Push the nose into a steep dive and at a certain point it’s unrecoverable.

15

The Malaysian officials are stating that the aeroplane made several course changes. They believe the course changes are deliberate. They have the data in front of them while all we have is second hand information from news reports that have come from what little the Malaysians have been willing to release. I’m inclined to believe the course changes were deliberate based on that.

They only satellite data we seem to have available is the final ping which doesn’t suggest any kind of course, only an arc of possible position. The indicated position forms a circle because there is not enough data to narrow the circle down to a point. As I understand it the satellite pings were able to give them distance from the satellite and the general orientation of the satellite antenna lets them narrow the position down slightly. But it does not give a course unless you match up the data from the other satellite pings and then, given the broad nature of the position information we do have, any further information is going to give us a very broad corridor that will not be able to confirm any manoeuvring.

16

What about handhelds?

(Low power aviation-band transceivers, seen around airports and often carried as back-up radios in small planes. And used as sole radio in some very small planes).

What would their range be at 30,000 over the Indian Ocean?

Would seem like a handy thing to have, say on the food carts - not usually in the cabin, but readliy accessible by the cabin crew.

And never mentioned.

17

What about them? They’re not carried as equipment on an airliner if that’s what you mean. It is always possible that a passenger or crew member would have one but unlikely.

18

Are they powerful enough to be used at altitude over the middle of nowhere, and why not spent a few hundred dollars per plane (if it a food cart item, it gets swapped out every time the cart does) and have com ability that is NOT locked from the inside of the flight deck? If something bad happens behind the locked door, communication could be maintained.

19

I don’t know the range of a typical hand-held, but even if it is useful at those altitudes and areas, they could also be used to disrupt communications. Only one person at a time can transmit on aviation frequencies, so a hand-held could be used to effectively jam an aircraft’s radios to some degree. I’m actually surprised they’re allowed on commercial flights, or even for sale to those without a need for them.

20

Looking at these backup aviation transceivers, they don’t advertise range, but they all seem to have 5 watts of max power. With handheld ham radios which operate just above the air band, the range is usually about 5 miles max using the highest power setting of 5 watts. The military’s most widely used handheld radio, the AN/PRC-119, supposedly gets 5-6 miles on it’s highest power setting of 5 watts too. So basically, if it were possible to get more than 5 miles from a 5W transceiver, ham nerds or the military would be doing it. The metal fuselage may screw up the little antenna and cut the range too, and airliners fly 5-6 miles high so it may not work even directly above an airport.