DRT is an acceptable power setting for takeoff when which condition is met?

The correct answer indicates that DRT, or "Derated Thrust," is an acceptable power setting for takeoff when the critical field length is less than the runway available. This condition suggests that the aircraft has more than enough runway to take off safely, even with a reduced thrust setting.

Using derated thrust for takeoff can be advantageous in certain situations, such as when the aircraft is operating in hotter temperatures or at higher elevations where full thrust may not be necessary or optimal. It also promotes engine longevity and fuel efficiency.

When the critical field length is less than the available runway, it offers a comfortable safety margin, meaning the aircraft can accelerate to the required takeoff speed before reaching the end of the runway using the reduced thrust setting. This gives pilots confidence that they can safely conduct the takeoff without the risk of running out of runway, allowing for a more controlled and efficient climb-out after takeoff.