It is extremely unlikely that flight crews would ever experience a failure of the primary flight control computers that could cause the aircraft to be uncontrollable, but the engineers installed a switch in the overhead panel that allows pilots to disable the computers if they malfunction. Bryan then switched off the primary flight control computers so we could fly the aircraft using direct law. This enables the yoke and rudder pedals directly to command the positioning of the flight-control surfaces. The aircraft is completely controllable, but control response is comparatively crude and there are no flight envelope protections available.
The 787 also has protection against pitot/static system failure, such as an icing blockage. Switching to alternate air data enables the aircraft to compute airspeed and altitude from aircraft weight, configuration, AOA and 3-D GPS position. Using alternate air data, Bryan noted only a 8-9-kt. difference in airspeed and a 40-ft. variance in altitude while cruising at 300 KIAS and 16,000 ft.
We then proceeded to Moses Lake-Grant County for pattern work. We deliberately stayed high prior to descending for the instrument landing system (ILS) approach to Runway 32 so Bryan could demonstrate the aircraft's new autodrag function. The aircraft is so clean that it is difficult to descend to and capture glideslope or glidepath from above, even with gear down, flaps set to 25 or 30 deg. and idle thrust. Under these conditions, the autodrag function deflects the ailerons downward and two outermost spoilers on each wing upward to assist in descending without gaining airspeed. The function is phased out gently below 500 ft. above ground level so that normal flare and landing behavior is not affected.
Our first approach was a normal, all-engine, full 30-deg. flap maneuver that was hand-flown using the HUD and auto-throttles. Aircraft weight was 340,300 lb. Bryan bugged the target airspeed at 142 kt., 5 kt. above Vref. The aircraft was very stable, yet responsive to control inputs. It was easy to stay on localizer and glideslope via the HUD's precision guidance. Over the touchdown zone and 30 ft. above the runway, we flared slightly and touched down gently.
Bryan retracted the flaps to 5 deg., adjusted pitch trim and we advanced thrust for the go-around. On the downwind leg, he pulled back the right throttle to idle to simulate an engine failure. The P-Beta function stabilized the aircraft in yaw and roll. The left auto throttle adjusted the thrust as needed.
Based on a landing weight of 339,600 lb. and using Flaps 20 deg., Bryan set 146 KIAS as the target speed. The left auto throttle maintained that speed within 1-2 kt.
At ILS minimums, we executed a go-around. Bryan instructed me to leave my feet on the floor and allow the P-Beta system to counter the thrust asymmetry. The aircraft lost none of its composure during the maneuver, but there was noticeable side slip to the right caused by the left engine's higher thrust output.
We continued the simulated one-engine-inoperative abnormality for our final landing at Moses Lake. Using Flaps 20 deg. and based on a landing weight of 337,600 lb., Vref was 140 KIAS and the target airspeed was 145 KIAS.
Touchdown was smooth, but I floated a little too long in ground effect. I relaxed prematurely. Make a note. You must fly the nosewheel down to the runway, or you can be embarrassed by an audible thump during the derotation.