Aircraft Performance

Effect of Wind on Airspeed and Groundspeed

Airspeed is the speed of the aircraft relative to the surrounding air.

Groundspeed is the speed of the aircraft relative to the ground.

In nil wind:

• Airspeed = Groundspeed

With a tailwind:

• airspeed remains the same;
• groundspeed increases.

With a headwind:

• airspeed remains the same;
• groundspeed decreases.

Remember:

Tailwind = same airspeed, higher groundspeed

Headwind = same airspeed, lower groundspeed

Effect of Wind on Gliding Distance

Every aircraft has a recommended best glide speed which gives its best glide performance through the air.

Wind does not change the aircraft's basic glide performance through the airmass, but it does change the distance travelled over the ground.

Headwind

Into a headwind:

• groundspeed is reduced;
• the aircraft covers less distance over the ground;
• therefore the gliding distance is reduced.

Tailwind

With a tailwind:

• groundspeed is increased;
• the aircraft covers more distance over the ground;
• therefore the gliding distance is increased.

Remember:

Headwind = shorter glide over the ground

Tailwind = longer glide over the ground

Effect of Wind on Track

A crosswind will cause an aircraft to drift away from its intended ground track.