What is the minimum autopilot engage height after takeoff?

The minimum autopilot engage height after takeoff for the King Air 350 is 400 feet AGL (Above Ground Level). This limitation is set to ensure that the pilots have sufficient altitude and airspeed to manage the aircraft safely before engaging the autopilot system. Engaging the autopilot too early can compromise the crew's ability to respond effectively to any immediate aircraft handling requirements or emergencies during critical phases of flight, such as the initial climb.

At 400 feet AGL, the aircraft should be well established in its climb, allowing the autopilot to take over efficiently while the pilots can still monitor the aircraft’s performance closely. This altitude allows for a buffer during the climb phase, harnessing the benefits of the autopilot while maintaining a safe operational margin.

Other choices, although presented, do not align with the accepted safety protocols and standards for autopilot engagement after takeoff, making 400 feet AGL the appropriate and correct choice for the King Air 350.