How much piloting does a pilot do? How much is really the computer just maintaining a course? Is there a difference between the amount of piloting on commercial jets and military jets? Under what conditions does a pilot override the autopilot and take over himself?
I’m of course only talking about relatively new-ish, not older craft like a DC-10 or P-51.
I thought this was a good question and wish one of the big iron pilots on the Dope had answered it - maybe the guys like pilot141 are on duty. Anyhow, I’ll take a stab at it, in part to bump it, and see what happens.
You say “military jets’” and “commercial jets” but that’s really quite a big range of stuff, with some considerable overlap. I’ll assume you meant the difference between, say, a Boeing 777 or modern Airbus and an F-16 or some such.
Those machines are “fly by wire”. The controls manipulated by the pilot are not directly connected to the items that actually physically steer the airplane, and these days there is some computer intervention between pilot and the end result. The degree of this intervention can range from the computer merely making sure the pilot doesn’t do anything really stupid to break the airplane and evening out the control inputs for smooth motion, all the way to the pilot’s role being to make suggestions and the computer deciding whether or not to act on those suggestions.
Now, all of these planes you’re referring to have autopilots that can maintain course, airspeed, and altitude - heck, even a 40 year old prop-driven Cessna 172 can be equipped with that. This is pretty basic stuff. And such autopilot systems will typically be set to deactivate themselves if the pilot grabs the controls and makes a motion of sufficient magnitude, or if something like turbulence causes drastic changes in attitude, at which point the human is supposed to take over. For instance, if that Boeing or F-16 is humming along on course and our previously mentioned C172 wanders into its path, the pilot will (I hope) see it, take the controls, alter course to avoid a collision, then return to the prior course when the danger is past. You don’t want the autopilot fighting the pilot in such circumstances, hence it deactivates.
There are systems in use today that allow an airplane to take off, fly a course, and land itself all without a human touching the controls. (In which case the pilot monitors the system to make sure it continues to function properly, and is there just in case the triple-redundancy systems fail.) But such systems only work when there is not a need to change the mission en route - at the very least you’d need a way to input a new course and such. But on something like an air attack you just can’t plan a set course, in which case the human being is better suited to the task of guiding the airplane.
However, for an aircraft like an F-16 which is inherently unstable (that’s what gives it such manuverability) and has the power to rip itself apart if mishandled, you will always need that computer in the loop. If the computer fails completely the human alone can’t keep it under control. So it’s really a partnership between man and machine, with one or the other having more say at any given point, but both of them being required.
That’s as of right now. Already, many spyplane functions are being taken over by remote control drones that can do much of the flying themselves. These still require a human in the loop (if not the cockpit) because the drones can’t see things like birds and other aircraft in their way and need a human to take care of such things from time to time. The military is currently trying develop systems that can detect other airborne things and the software for the machines to avoid them on their own. If successful, such systems may filter down to civilian aivation and result in airliners that fly themselves. How far off is that? I don’t know.
And that’s my poor and vague attempt to answer your question. Hopefully, someone who knows more details will be along presently.
Broomstick thanks for the reply and the bump!
KnightNavro on a commercial airliner most of the flying is done by the autopilot. The takeoff and initial departure are hand-flown, and after that it’s usually personal choice as to when people hook up the autopilot. Some people hook it up right at 1,000 ft AGL, but I wait until 18,000 or higher (I still just like to fly!) Usually the entire en-route portion will be flown on autopilot and most of the descent as well. Most airliners in use today are capable of auto-landing, but that is used only in really lousy weather or for certification purposes. The majority of pilots will click off the autopilot about 2,000 ft AGL on approach and hand-fly it to touchdown.
Why the reliance on autopilot? Well, first of all it reduces workload. Anyone who has flown with an autopilot or instructed in airplanes knows that it is much easier to MONITOR performance of the aircraft when it is being flown by someone (or something) else than to CONTROL and MONITOR the airplane yourself. So, let the machine do it and both of us can monitor it for mistakes. The autopilot is also very helpful in busy terminal environments (ie Chicago or New York). When the air is full of airplanes and you get “Airliner 123 slow to 210 knots, upon reaching that descend and maintain 5,000 ft expect runway 22L” with no chance to respond because the controller is already talking to the next airplane, it’s easier to let the plane handle the flying and for us to concentrate on monitoring it and the radios.
In fact, the automation on modern airliners is so advanced that many people complain that getting checked out on a new airplane is a “button check”. The syllabus for the newest airplanes (777, 737-800) includes a “checkride” in front of a computer with an emulator of the FMS and autopilot. The check airman gives the student a profile (ie hold SW over the ABC VOR, 10 mile legs, standard turns) and then watches as the student programs it into the box.
During my training on my current airplane I once told the simulator instructor that I wanted to hand fly the upcoming pattern (which was to include an engine fire - gotta love the sim!) and he said “We already know that you know how to fly airplanes - that’s why we hired you. My job is to teach you how to fly THIS airplane, which means how to use this flight guidance panel, so hook up that autopilot”.
As to when the autopilot gets clicked off (other than on a normal descent), that happens when it’s not doing what you want it to. If you are supposed to turn left but the airplane (for whatever reason) starts to turn right, click off the autopilot, get the airplane turned where it’s supposed to be and then (most likely) hook up the autopilot again.
For military airplanes (I did that for a while too!) it depends on their mission, but their use is very similar to commercial airliners. Any large airplane that flies for a long time (C-17, B-1, C-130, KC-10, etc) will use their autopilot like we do - ie it does most of the flying. As the jets get smaller the autopilots usually get less sophisticated until down at the older trainer level (T-34,T-37, T-38) there are no autopilots at all. Fighters and attack aircraft usually have some sort of basic autopilot (heading or course hold along with altitude hold) for long ferry trips or very long missions. Once again, the use of autopilot is to reduce workload, and trying to maintain FL 350 for 8 hours is VERY tiring without some help.
And the DC-10 has a very capable autopilot system - it’s just not as gee-whiz magic as a 777!