Definition
Glides flown at airspeeds either above or below the airplane's published best-glide speed. Because best-glide speed produces the maximum distance per unit of altitude lost, any glide flown faster or slower is less efficient and is considered abnormal. Practicing abnormal glides develops the pilot's ability to recognize and recover from off-speed glides and to judge how airspeed changes affect glide distance and descent rate.
Plain English
A glide flown either too fast or too slow compared to the speed that gives the longest gliding distance. They are flown deliberately during training so pilots learn how the airplane behaves when the glide isn't at the ideal speed.
Context Anchor
Seen in basic flight training when practicing glides, approach planning, and power-off descents.
Derivation
"Abnormal" comes from Latin roots meaning "away from the norm." Here, the "norm" is best-glide speed, so an abnormal glide is simply one flown away from that reference speed.
Why Pilots Care
Recognizing when a glide has become abnormal allows the pilot to adjust heading or speed early so the airplane still reaches a suitable landing spot.
Grounding Statement
In a normal glide, the airplane is descending in a controlled, planned way; in an abnormal glide, something about that descent needs correction.
Intuition Check
Abnormal does not automatically mean an emergency here. It means the glide is outside the desired condition and should be corrected.
Example Sentence 1
The instructor demonstrated abnormal glides at speeds both above and below best-glide so the student could see how each affected the descent rate.
Example Sentence 2
Making a turn during the descent created an abnormal glide because the increased drag caused the airplane to lose altitude faster than expected.