Definition 1 of 2
Definition
A controlled flight condition in which the airplane's longitudinal axis is not aligned with the flight path, produced by deliberately crossing the controls — applying bank in one direction while applying opposite rudder. The result is a sideways, descending flight path that increases drag without increasing airspeed, allowing the pilot to lose altitude rapidly or to compensate for a crosswind during landing.
Plain English
A slip is when the pilot intentionally banks the airplane one way and pushes the rudder the other way, so the airplane flies slightly sideways through the air. It's used to come down faster without speeding up, or to stay lined up with the runway in a crosswind.
Context Anchor
Seen during level turns when checking whether the turn is coordinated, especially by looking at the slip-skid indicator or noticing whether the airplane feels like it is sliding inward in the turn.
Derivation
From the Old English 'slipan,' meaning to slide or move sideways. The aviation use keeps that everyday sense — the airplane is sliding sideways through the air rather than flying cleanly forward along its nose.
Why Pilots Care
Uncorrected slips reduce turn efficiency and can cause unexpected altitude loss; pilots learn to recognize and correct them for smooth, coordinated flight.
Grounding Statement
In a slipping turn, the airplane feels as if it is sliding toward the inside of the turn instead of carving a clean path through it.
Intuition Check
A slip does not mean the airplane is falling out of the sky or losing all control. In this context, it means the airplane is flying slightly sideways because the bank and rudder are not properly matched.
Example Sentence 1
The pilot used a forward slip on final approach to lose extra altitude without picking up speed.
Example Sentence 2
A slight slip developed when the pilot steepened the bank without increasing rudder pressure.