B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 200; Flight Crew Total 22000
Aircraft Equipment Problem Less Severe; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Provided Assistance; Aircraft Automation Overrode Flight Crew; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification
Aircraft; Environment - Non Weather Related
At FL400; ATC issued hold instructions at intersection. As FO entered holding instructions into FMC and pushed enter; airspeed bug rolled back to 206 knots. Engines came to flight idle. Disconnected autothrottles and advanced power. Airspeed was at about 240 knots; or about .76 Mach. As the throttles came to idle airspeed began to deteriorate. I advanced the throttles to max power. N1 predictive indicator showed max power (to the chevron.) Speed continued to decrease and N1 stayed between 40 and 50%. I told ATC that we needed to descend 'NOW.' I disconnected the autopilot and started descent. Engines stayed between 40 and 50% until passing through FL370-FL380 and then began to rise; but not to the N1 I wanted via throttle setting or as the predictive N1 indications were calling for. As we regained airspeed I pulled the throttles back and the engines operated normally.
Boeing 737-700 crew; level at FL400; entered holding instructions into FMC and when 'ENTER' was activated the airspeed bug decreased to 206 knots and the engines rolled back to flight idle. Engines were slow to respond to the pilot's manual throttle movement; and did not fully recover to 'normal' operation until FL380-370.