Definition
The presence of water, snow, slush, ice, frost, rubber deposits, or other foreign material on a runway surface that reduces the friction between the tires and the pavement, lengthening the takeoff or landing roll and degrading directional control.
Plain English
Anything on the runway — water, snow, slush, ice, or other deposits — that makes the surface slippery and reduces braking and steering effectiveness.
Context Anchor
You will see this term in landing, takeoff, and rollout discussions, especially when runway condition, stopping distance, or braking effectiveness is being considered.
Derivation
From Latin contaminare, 'to make impure by contact.' In aviation it keeps that sense — the runway is no longer in its clean, dry state, and that change matters for stopping and steering.
Why Pilots Care
It increases the runway length needed to stop and raises the chance of skidding or leaving the runway if performance calculations ignore the reduced traction.
Grounding Statement
A clean, dry runway gives the tires a firm surface to grip; water, ice, snow, or slush can take away some of that grip.
Intuition Check
Runway contamination does not mean the runway is chemically dirty or unsafe only because of pollution. It means there is material on the runway surface that can affect airplane control or stopping.
Example Sentence 1
After the heavy rain, the tower reported runway contamination, so the crew recalculated their landing distance before continuing the approach.
Example Sentence 2
Melting snow created patches of slush that counted as runway contamination and reduced braking effectiveness.