Narrative:

We took off normally; it was a cold; clear morning. We were assigned 3;000 feet and heading 060 after takeoff. At 2;000 feet in the turn; the PF turned on the autopilot. Upon reaching 3;000 feet; the autopilot decreased pitch and the autothrottles came back to maintain 200 knots and 3;000 feet. At the same time; we received further climb to 5;000 feet. During the radio exchange; the aircraft continued to decrease pitch without increasing power and started to descend. Around 2;950 feet; the PF disconnected both autopilot and autothrottles to prevent the autopilot from descending further. By the time the PF was able to return the aircraft to a pitch and power setting that would allow the aircraft to climb; we were down to approximately 2;700 feet. Around 3;500 feet; we reengaged the autopilot and autothrottles and both functioned as intended. We continued our climb to 5;000 as instructed with no remark from ATC.on the subsequent flight; we departed runway heading; with a turn to 230. After takeoff; I set the heading to 230 and turned on the autopilot; and the aircraft immediately started rolling to the right. The PF disconnected the autopilot and turned the aircraft in the correct direction. After reengaging the autopilot; it functioned as intended again.on both flights; the autopilot was programmed correctly beyond a shadow of a doubt.

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Original NASA ASRS Text

Title: G280 flight crew reported autopilot anomalies on two flights. Reporters mentioned the autopilot was set correctly in both situations; but the aircraft did not react appropriately.

Narrative: We took off normally; it was a cold; clear morning. We were assigned 3;000 feet and heading 060 after takeoff. At 2;000 feet in the turn; the PF turned on the autopilot. Upon reaching 3;000 feet; the autopilot decreased pitch and the autothrottles came back to maintain 200 knots and 3;000 feet. At the same time; we received further climb to 5;000 feet. During the radio exchange; the aircraft continued to decrease pitch without increasing power and started to descend. Around 2;950 feet; the PF disconnected both autopilot and autothrottles to prevent the autopilot from descending further. By the time the PF was able to return the aircraft to a pitch and power setting that would allow the aircraft to climb; we were down to approximately 2;700 feet. Around 3;500 feet; we reengaged the autopilot and autothrottles and both functioned as intended. We continued our climb to 5;000 as instructed with no remark from ATC.On the subsequent flight; we departed runway heading; with a turn to 230. After takeoff; I set the heading to 230 and turned on the autopilot; and the aircraft immediately started rolling to the right. The PF disconnected the autopilot and turned the aircraft in the correct direction. After reengaging the autopilot; it functioned as intended again.On both flights; the autopilot was programmed correctly beyond a shadow of a doubt.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.