A300
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew FLC Overrode Automation
Aircraft
On takeoff at about 500 ft. AGL; the number one engine began rolling back. We initially thought we had an engine failure and about the same time Tower contacted us to switch to departure at which time we notified Tower we thought we had an engine failure and [advised ATC]. We were instructed to fly runway heading and we continued our climb to 5;000 ft. I got the autopilot on and looked down and saw the number one throttle was back at or near idle; and saw the ECAM message of asymmetrical throttles. We saw the #1 engine was still operating within normal parameters; just at a low N1. I then advanced the throttle to match the number 2 throttle and saw the engine was fine; just that the number one throttle went back to idle for no apparent reason. After we brought the power back up; checked all engine parameters; and went through the QRH procedure; we concluded nothing was wrong with the engine and told ATC we did not need to [request priority handling] after all and we continued on to destination where we wrote up the incident and deferred the auto throttles. We concluded the auto throttle reduced the number one engine to at or near idle for no obvious reason.
A300 Captain reported that an autothottle malfunction resulted in a thrust imbalance on takeoff; and was initially mistaken for an engine failure.