Inspired by current events obviously.
Barring flight control freaking out (I’m imagining some sort of Ferris Bueller-esqe tape recorder contraption), how long could a flight crew sleep before things go bad? Is auto-pilot good enough that you could take off from New York, fall asleep when you hit altitude and then wake up just before it’s time to land in LA? Or do pilots still need to keep making adjustments even with auto-pilot on?
All the way until you run out of fuel.
Until the fuel run out is likely. Also, if this is a very long-haul flight, this will likely occur short of the intended destination without any pilot intervention. Basically, what happens is that the higher you fly, the more efficient the aircraft becomes. On the other hand, the weight of the aircraft also places a limit of how high it can get. On a long-haul flight, due to the amount of fuel the aircraft is carrying, the initial portion of the flight is conducted at a relatively low altitude. Normally, as fuel is burned off, the pilot will gradually climb higher (called step climbs). This is obviously not going to happen if the pilots are asleep.
Depending on the aircraft, the pilots may also need to change the configuration of the fuel system to ensure that the engines can get to all of the fuel carried amongst the many fuel tanks of the aircraft.
The newest airliner autopilots are very sophisticated and can technically fly departure runway centerline and autoland the plane at the destination airport. If you really insisted on doing it, you could make almost an entire flight on autopilot. However, those features aren’t built so that the pilots can sleep through the flight. The takeoff and landing functions of the autopilot are intended to be used during bad weather and are tools to lighten the pilot’s job during difficult conditions in the interest of safety. Autopilots are good at precision flying but there is lots of other work to be done like radio communications and general decision making.
You can put an airliner on autopilot at altitude and have it fly itself across the Atlantic while you sleep as a stunt I believe but that would be against lots of procedures. One of our airliner pilot Dopers will have to chime in to say whether there are any manual steps left that absolutely have to be done outside of the autopilot to keep the plane in the air but I can’t think of any. I am not sure how far you could push this experiment if you really wanted to lose your pilot’s license. Some autopilots can handle all phases of flight other than taxiing but I don’t think they will allow you to set up your personal 747 to take off in Sydney by itself and land in Los Angeles while you party it up in your flying dance club the whole way. The technology exists to allow things like that but there are pesky little things like other planes around and air traffic controllers that make something like that a really bad idea.
You’d normally have to do something to initiate a descent such as set a lower altitude in the altitude selector. Most vertical navigation (VNAV) systems won’t start a descent unless you’ve set a lower altitude in the selector, this prevents descents prior to getting a clearance or descents with pilots asleep etc.
If you fell asleep shortly after take off the autopilot and autothrottle should take care of everything until you get to overhead your destination at which point the autopilot will default to a certain mode (varies amongst manufacturers.) I believe the Airbus defaults to a heading hold mode, so it will maintain the aircraft heading at the final waypoint.
Yup. One flight I was on way back around 2000, after we landed, the captain announced that the autopilot had performed the final approach, landing, and rollout. Said they had to do that every so often to maintain the plane’s certification. I knew this was possible, but didn’t know it had to be done on a fairly regular basis.
I was also impressed that he had the guts to actually TELL us they’d done that, even after the fact!
BTW, I noticed absolutely nothing different in the landing. Smooth as could be.
Way back in the 60’s I heard of a business guy who took off from TUL or OKC to the North in a C-310 about 1AM , put it on auto-pilot and started doing paper work. He nodded off and as he had not climbed much he slid into the ground in a big field in northern Nebraska or South Dakota some place . It did not wake him up. When the sun came up and he woke up and could not figure what was wrong for a while.
About that same time, a guy did a similar thing leaving Kansas west bound in a Beech Baron but he hit the front range just north of Boulder, CO. Killed him.
Now, why in the world would the pilot feel the need to announce that? Was it required? I can see where this might freak a few people out.
Don’t see why it would freak anyone out. After all, they were safely on the ground at that point.
My one and only Concorde flight landed in very poor visibility in New York. As we taxied to the terminal the pilot told us that the aircraft had landed itself. I thought that was really cool. I was certainly glad to be told.
No, this is not fully accurate. If the plane is set to climb it is possible to get into a lot of trouble if the plane flies above it’s rated ceiling. If the autopilot is set at cruise altitude then it would continue as set.
The problem with the recent NWA flight is that the pilots never changed frequencies as directed. They were distracted (for whatever reason) and didn’t react to the request. This is easy to happen when instructions aren’t read back. It seems minor not to acknowledge a frequency change but if pilots don’t do this then the radar centers have no way of knowing if the instructions were received. When it’s a busy day it’s not unusual for pilots to simply change frequencies and pick up the next center without acknowledging the instructions.
According to one report, the center looking for them finally called them on the previous center’s frequency and that’s how they re-established contact. If it were only a 5 minute distraction they could have bluffed their way through it but it was 20+ minutes and situational awareness was lost. At 450 mph that’s a 150 mile detour. With today’s GPS systems pilots have a visual representation of exactly where they are in relation to the planned flight.
I think the assumption is that the pilot would have never dialled in an altitude that is too high before falling asleep. Also, if the plane is climbing on VNAV SPD, the autothrottle will set climb thrust, and the autopilot will pitch for the computed climb speed. The plane will never reach the selected altitude, but it should be ok.
On the other hand, if for some unknown reason the pilot decides to climb on V/S (like what happened in the Pinnacle accident), and an altitude that is too high is dialled in, and then falls asleep, this can get ugly…
Are you guys saying that the newer autopilot would be able to know that it had been cleared for landing? I’d always assumed the pilot would get that information by radio, and would have to tell the autopilot it was okay.
The autopilot wouldn’t know that it was cleared for landing. It would just do it as long as the right information had been entered into the autopilot in the first place and the destination airport has a Category III instrument landing system in place and the plane has the right equipment as well. That is obviously a huge procedures violation if there isn’t any pilot to air traffic controller contact during the approach and landing so that is why I said it could probably be done as a stunt but it isn’t safe, practical, or legal either.
What I am getting at is that you could probably fly a 747 to a city several thousand miles away acting as a programmer to the autopilot rather than an actual pilot once the plane is lined up on the takeoff runway and make it there safely if you had a good understanding of the autopilot system as long as you didn’t care about being thrown in jail or something afterwards. If you had a good checklist for it, it wouldn’t be that much work. Microsoft Flight Simulator X models autopilots at a very detailed level and I have simulated versions of this and it worked. This is mostly just a curiosity of course but setting a course across the open ocean and going to sleep is feasible and I have read stories from military cargo pilots that said they did it before during periods of exhaustion.
Auto pilots don’t know anything. They follow input from the pilot. Approaches flown blindly to the runway (Category IIIC) requires special equipment in the aircraft, at the airport, and a certified pilot.
It’s not unusual for one or both pilots to go into a kind of twilight state.
Ever arrive somewhere and not remember driving? Imagine staring out at nothing for 3 hrs.
Even our lowly Dash 8 will climb and capture the set altitude. I could, if I wanted, set 25000 feet in the altitude selector, and NAV and IAS 130 kts on the flight director shortly after take off and then go back and read a magazine (or have a snooze.) The aeroplane will climb at 130 knots indicated, level off at 25000 feet and follow the flight plan to the destination. The power setting wouldn’t be quite right at altitude, but it’d be near enough. More modern aircraft have auto-throttles that take care of speed and power settings.
As far as I know it’s the other way round. Pilots have to do a number of manual landings and take-offs during a specific time to keep their licenses. On the other hand I think they do it anyway, if not for anything else, just for the fun of it.
NPR had an interesting and somewhat related segment a few days ago. Link here. Apparently it’s not uncommon for pilots to take little cat naps (one at a time, of course) during cruise, when there’s not much else to do. And there’s also a fine line between pilots being distracted with too much to pay attention to, and pilots being bored by nothing to do. Both lead to bad situational awareness.
I had no idea autopilots were so sophisticated nowadays. If both pilots died or were incapacitated, in some sort of Airport dramatic situation, and the cockpit door was locked, could ATC remotely control and land any large passenger-carrying jet today?
Whenever I bounce a landing, I always blame it on a faulty “auto-land” system.