Stands for High Altitude Low Opening. This is a freefall parachuting technique developed by the US Army as a means of clandestine insertion of an Special Forces 12 man A-team onto a target with a high degree of accuracy allowing them to complete their mission undetected. This is accomplished by flying an aircraft in a commercial air lane at a high altitude, to appear as an airliner on radar. At the proper time the team exits the aircraft, groups together in freefall, and using highly steerable parachutes, allows them to land with great accuracy on a given target.

United States Army Southern Command parachute demonstration team.(Panama Canal Zone) Now known as the "Jumping Ambassadors" This team preforms parachute demonstration jumps at, local schools, civic functions, and special events.

With AFF training, the first jump is made with two Jumpmasters who provide direct assistance during the exit and the freefall portions of the jump. Once the parachute is deployed, the Jumpmasters deploy their own parachutes, and the student makes a solo canopy descent.

This method also requires the completion of extensive ground school before the jump. The advantage of this method is that the student receives assistance during the actual jump, and the learning curve tends to be steeper as a result.

AFF jumps are usually made from at least 12,500 feet, which allows for freefalls of 45 seconds or longer. Upon reaching the ripcord pull altitude of 4,000 feet, the student pulls his own ripcord. He then steers the parachute into the designated landing area. As with the static line method, the student is required to exercise emergency procedures if necessary.