DHU,
If we could ignore ATC and other traffic separation constraints, what are the minimum possible flight crew interventions required to carry out a typical flight from the line-up for take-off to the landing roll-out?
For the case of 737 the below scenario would be possible. I see from your profile that you are a PPL, so I'll explain a bit of the 737 technical stuff as well, in simple terms.
After manually taxiing to the runway, arm autopilot mode LNAV and VNAV = Lateral/Vertical Navigation where the autopilot is directed by the pre-programmed Flight Management Computer (FMC) to follow a route and a climb, cruise and descend profile. LNAV is basically GPS guidance as your would find in your car. VNAV controls the aircraft path by commanding the speed and throttles depending on the phase of flight and is thereby able to accelerate the aircraft during the climb and vice verse during descend.
The takeoff is always made manually (but with auto throttle engaged for the most cases), but I have heard that it has been tried in the simulator to engage the autopilot, before initiating the takeoff by activating the autothrottle. If indeed true the autopilot could rotate the aircraft by itself. The pilot would still have to steer the aircraft along the runway with the rudder pedals. Once airborne the autopilot would keep wings level and control pitch to keep the selected takeoff speed. As the engines produce takeoff thrust, the autopilot would have to pitch the nose up to keep the speed from accelerating thus resulting in a climb. Passing 400 feet the armed LNAV will engage, and practically direct the aircraft almost to it's destination. VNAV would engage after the FMC pre-programmed acceleration altitude and with flaps up (in my company we do not arm VNAV on ground so not absolutely sure about the criteria - but the point is that it's possible to for this to happen automatic). Hence for the take off only the flaps and gear would have to be retracted manually.
The climb, cruise and descend would then follow the FMC route and profile. Though for longer flights, were a higher cruising level is required as the fuel is burned, there has to be an intervention as well. The descend would also have to be initiated by someone. VNAV would then descend the aircraft and slow it to the minimum speed before flap extension is required.
For auto landing, someone has switch the autopilot from LNAV/VNAV to approach mode for the autopilot to follow the ILS. The complete radio setup for this could be made prior to departure, as this is not required for takeoff (though in real world it would be set as backup for the departure routing in case of LNAV failure and for crosschecking). Only things that would need to be done is arm the autopilot approach mode, arm the autobrakes, select the landing speed in the FMC and engage the second autopilot (both autopilots required for auto landing). And of course someone to extend the landing gear and flaps. When the approach mode engages you also have to set the autopilot speed manually. The autopilot would land and (if chosen as an options from Boeing) do the roll out on the runway - itself reducing the throttles to idle and braking to a complete stop (no reverse thrust though).
As you see very little intervention from crew needed, hypothetically!
If only it worked as advertised! But the fact that the FMC has the same computing power as a Commodore 64 from 1984 doesn't make it so. The biggest factor in the equation being the weather. See, if there is a bit more tailwind than expected during descend for example, VNAV will not be able to cope and will require that the speedbrakes be extended (manually) and in many cases it will not be sufficient and another mode must be used and another profile be flown with the "less advanced" autopilot modes.
I'm drifting away from you question about minimum crew intervention, but nevertheless it's so hypothetically. Even if like you said we pretend that we are the only aircraft in the air.
About the inevitable question about pilotless aircrafts.
In my opinion weather and general decision making are the biggest factors in flying a modern airliner. Yes with very few means, it would be possible to upgrade the automatics to retract the gear and flaps itself and the other smaller tasks. And with some descent programming and modern computing power probably also very easy to make the VNAV handle unexpected tailwind etc. Maybe even make is so reliable that it no longer would be necessary for the pilot to have the skills to handfly anymore (absolutely not so today reliability wise, far from). But who is going to decide whether or not to divert if there is a sick or unruly passenger onboard. Who will make the decision to continue to a remote destination in case of minimum fuel. And so on... Pilotless aircrafts in our lifetime? No chance! When you include traffic which we ignored, then even more unlikely. Even if ATC could pass directions to the pilotless aircraft, I would be very reluctant to board such an aircraft in Europe as a passenger. Now try to trust the same ATC passing over a third world country (will not offend anyone by mentioning any countries, but ATC wise even some countries in Europe are also third world like). Aircraft that will be flow on autopilot 100% of the time maybe, but unlikely as this would require massive investment in ground equipment at airports, and if keeping the same amount of traffic, then possibly development of completely different equipment that we have today (auto land requires that there are no other aircraft near the landing runway, not to interfere with the radio signals). And all this for what purpose? If you are going to pay two guys to sit there anyway to take directions from ATC, check and evaluate the weather along the flight, keeping track of fuel, system operability and performance and so on - then why not let them work during the takeoff and landing and save all that money.
Last edited by cosmo kramer; 7th May 2010 at 21:13.
Reason: clarity / spelling