Translational lift

Translational lift (also known as Effective Translational Lift, or ETL) is a transitional state present after a helicopter has moved from hover to forward flight. This state provides extra lift, most typically, when the airspeed reaches approximately 16-24 knots, but is present with any horizontal flow of air across the rotor, and therefore can be present without any forward motion of the aircraft, given prevailing wind conditions. As a result, the tail rotor also becomes more efficient due to the wind bubble that is formed around the helicopter from progressively less turbulent air.