i_hate_toms
New Member
I am flying a Boeing-777 from heathrow to san francisco international.
This problem occurs when I'm configuring my aircraft for landing/ touchdown..
This is what i do:-
Remember, the Auto Pilot, and the Auto throttle are in control of the aircraft at this point.
I start reducing speed. Say i dial in 200kts in IAS mode. Next I start reducing altitude -- I dial in, say FL100, set vertical speed to say -800, and press the "VS/FPA" button.
The green light for "altitude hold" turns off, another green indicator under VS/FPA lights up, and the aircraft begins a slow descent.
When I reach 200kts IAS, i start applying FLAPS and dial a lower speed, say 180 kts. I next get the ILS Frequency and Heading of the runway i am to land on, and dial them in for NAV1.
I apply some more flaps and dial in say 170kts for IAS.
The A/P and A/T are still in control of my aircraft and everything appears to be going nice and easy.
When I reach FL100, I apply some more FLAPS and dial in an even lower speed, say 160kts. When I'm in range of the ILS, I disengage the LNAV and dial in a HDG that will take me on a flight path in which i can intercept "Glide Slope" of the runway. The aircraft banks a little and starts changing course towards the glide slope. I now apply some more flaps, say flaps are now at 15. The A/T and A/P are still in control of the aircraft.
This goes on for like 30 seconds and then a "Master Caution" indicator lights up, a loud audio alarm fills the cockpit, and one of the cockpit displays show "Auto Pilot Disengaged".
It's not catastrophic, i don't crash, I take manual control of the aircraft and proceed to land visually. But why does the autopilot disengage on its own? That too, in an awkward situation-- I am close to the ground, the airspeed is pretty low, the flaps are set, and the aircraft is banked (remember, we started changing course to intercept the glide slope). The room for error is very low, one single miscalculation will stall the aircraft and make me lose control, with altitude so low, a loss of control will most likely result in a crash -- i would definitely not want the autopilot to kick out in such a critical stage of the flight. Surely the auto pilot should be able to auto-land the aircraft, switch to retard flare mode and control it even after touchdown-- all i would do is set autobrakes to say 2 or 3, arm the speedbrakes, arm thrust reversers, and apply throttle to slow down the aircraft after touchdown, everything else should be handled by the AutoPilot. Ideally i would take manual controls at about altitude 500 ft, but i am forced to take manual control from about 3,000 ft. Pretty scary. What am I doing wrong? I have tried every little thing i can think of. I even turned on the "Seat-belt" sign for the passenger cabin thinking that might be the problem. but no matter what i do, the A/P would still disengage. (FGFS/ Boeing-777). Any idea??
This problem occurs when I'm configuring my aircraft for landing/ touchdown..
This is what i do:-
Remember, the Auto Pilot, and the Auto throttle are in control of the aircraft at this point.
I start reducing speed. Say i dial in 200kts in IAS mode. Next I start reducing altitude -- I dial in, say FL100, set vertical speed to say -800, and press the "VS/FPA" button.
The green light for "altitude hold" turns off, another green indicator under VS/FPA lights up, and the aircraft begins a slow descent.
When I reach 200kts IAS, i start applying FLAPS and dial a lower speed, say 180 kts. I next get the ILS Frequency and Heading of the runway i am to land on, and dial them in for NAV1.
I apply some more flaps and dial in say 170kts for IAS.
The A/P and A/T are still in control of my aircraft and everything appears to be going nice and easy.
When I reach FL100, I apply some more FLAPS and dial in an even lower speed, say 160kts. When I'm in range of the ILS, I disengage the LNAV and dial in a HDG that will take me on a flight path in which i can intercept "Glide Slope" of the runway. The aircraft banks a little and starts changing course towards the glide slope. I now apply some more flaps, say flaps are now at 15. The A/T and A/P are still in control of the aircraft.
This goes on for like 30 seconds and then a "Master Caution" indicator lights up, a loud audio alarm fills the cockpit, and one of the cockpit displays show "Auto Pilot Disengaged".
It's not catastrophic, i don't crash, I take manual control of the aircraft and proceed to land visually. But why does the autopilot disengage on its own? That too, in an awkward situation-- I am close to the ground, the airspeed is pretty low, the flaps are set, and the aircraft is banked (remember, we started changing course to intercept the glide slope). The room for error is very low, one single miscalculation will stall the aircraft and make me lose control, with altitude so low, a loss of control will most likely result in a crash -- i would definitely not want the autopilot to kick out in such a critical stage of the flight. Surely the auto pilot should be able to auto-land the aircraft, switch to retard flare mode and control it even after touchdown-- all i would do is set autobrakes to say 2 or 3, arm the speedbrakes, arm thrust reversers, and apply throttle to slow down the aircraft after touchdown, everything else should be handled by the AutoPilot. Ideally i would take manual controls at about altitude 500 ft, but i am forced to take manual control from about 3,000 ft. Pretty scary. What am I doing wrong? I have tried every little thing i can think of. I even turned on the "Seat-belt" sign for the passenger cabin thinking that might be the problem. but no matter what i do, the A/P would still disengage. (FGFS/ Boeing-777). Any idea??