What is the minimum allowed climb gradient for a twin-engine performance class A airplane in the third take-off segment?

In a twin-engine performance class A airplane during the third segment of takeoff, level acceleration is crucial for evaluating climb performance. This segment typically occurs after the aircraft has reached a height of 400 feet above takeoff surface and is a phase where the focus shifts from achieving a minimum climb gradient to accelerating to the best climbing speed.

Only level acceleration means that during this segment, the aircraft must not necessarily climb but rather maintain altitude while reaching a flight speed conducive to efficient climb. This transition is fundamental, as it prioritizes the aircraft's ability to gain speed without immediately worrying about maintaining a specific climb gradient.

In contrast, the other choices represent minimum climb gradients or performance figures that are either elevated requirements for a more aggressive climb or specific to different segments or scenarios. While they may be relevant to other phases of flight, they do not reflect the operational requirement during the specific third take-off segment for twin-engine aircraft. Thus, the minimum allowed climb gradient in this context does not exist in terms of a specific percentage but rather the requirement for level acceleration is acknowledged.