Contaminated Runways

071-02-13Pablo Asensio Martínez2026-04-011 min

Definition

Snow covered runway

A runway is considered contaminated when more than 25% of the surface area is covered by:

  • Surface water > 3mm deep.
  • Slush, loose snow.
  • Compacted snow or ice.

Hazards

  • Braking Action: Reduces friction, increasing Stopping Distance (ASDA/LDA).
  • Aquaplaning: Loss of continuous contact between tire and ground.
    • Dynamic: At high speed on standing water (Formula: $9 \times \sqrt{P_{psi}}$).
    • Viscous: On ice/rubber deposits (low speed).
    • Reverted Rubber: Locked wheel melts tire rubber creating steam seal.
  • Drag: Slush/water spray creates impingement drag on landing gear/airframe, retarding acceleration during take-off.
  • Directional Control: Reduced effectiveness of nosewheel steering.

Reporting

  • GRF (Global Reporting Format): New ICAO standard. Uses Runway Condition Code (RWYCC) from 0 (Nil) to 6 (Dry).
  • SNOWTAM: Special NOTAM notifying presence of hazardous conditions on movement area.
Written and reviewed by

Pablo Asensio · 2026-04-01

Aeronautical engineer. Passed the thirteen EASA ATPL(A) theoretical knowledge exams studying from these very notes. Writes and reviews each topic against the Part-FCL Learning Objectives.

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