What happens to airspeed during a departure with a sudden decrease in headwind?

During a departure, if there is a sudden decrease in headwind, the effect on airspeed can be better understood through the relationship between airspeed and groundspeed. When an aircraft is taking off, its airspeed is the speed of the aircraft relative to the surrounding air. A headwind contributes positively to this airspeed, meaning it effectively increases the airspeed required to achieve liftoff.

If the headwind suddenly decreases, the aircraft experiences less wind resistance against its forward movement. This loss of headwind leads to a corresponding loss in the effective airspeed. Therefore, the airspeed will decrease by an amount that correlates to the reduction in wind velocity. This is crucial for maintaining the necessary lift at takeoff. Hence, the correct understanding is that the loss in headwind directly results in a loss in airspeed equal to the decrease in wind velocity.

Groundspeed, which is the speed of the aircraft over the ground, does not play a role in affecting the airspeed understandings in this scenario. Thus, those alternative responses that touch upon groundspeed or imply that airspeed remains unchanged miss the key dynamic of how wind affects lift and aircraft performance during departure.