Any Unknown or Unlisted Aircraft Manufacturer
Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Workload; Distraction; Confusion
ATC Issue All Types; Aircraft Equipment Problem Less Severe; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance
Flight Crew Returned To Clearance
Human Factors; Procedure; Airspace Structure; Aircraft
Took off Runway 24; RUUDY 6 WHITE transition. Altitude select set at 1500 feet. Noise abatement procedure. Engaged FLC (Flight Level Change) and AP (Auto Pilot). NAV was in standby so was engaged shortly after takeoff. We were level at 1500 feet 1 mile from WENTZ; and NY Departure gave us 'climb to 6000'. Engaged FLC. We were at 210-220kts. Set 6000 began pushing power up. Then NY gave us turn left HDG 160. Engaged HDG mode. Turned HDG bug to 160. Before I could finish setting HDG bug he gave us HDG 180. Began setting 180. Saw we were passing 4500 feet. Altitude select started flashing 'altitude capturing'. Pulled power back to keep turn radius shorter. Was watching speed and pulling back power to make sure we didn't accelerate too much after level off. Speed was about 210-220. Then Second in Command said; 'It isn't capturing.' I pulled power to idle. Disengaged AP. We were still in left turn. We touched 6400-6500 feet and were back to 6000 feet in a few seconds. I'm unsure why the AP didn't capture 6000 feet. It was a very busy time of radio calls; changing NAV modes; managing speed and altitude and obviously I spent more time on speed management and didn't circle back to altitude until we had gone through our assigned altitude. When I saw it flashing I thought it was capturing. I have used FLC for years and not had this issue. Frankly; I don't know if it was a failure of the AP or why it didn't capture. No RA issued. I don't remember seeing any targets close to us at the time. ATC said; 'I hope you're headed back down'. We said yes. We were almost level at 6000 when he made this call. I will most likely not use FLC in altitudes less than 10;000 feet or when climbing less than 8-10000 feet from present altitude. I am unclear why the AP did not capture the altitude when it was flashing like it was capturing.
Captain reported exceeding assigned altitude during initial climb while complying with multiple heading clearances.