ICAO Doc 4444 Air Traffic Management: Separation, Clearances, and Contingency Procedures

010-07-02Pablo Asensio Martínez2026-03-272 min

Detailed operational procedures for air traffic management.

Separation

Longitudinal Separation

Maintenance of an interval between aircraft on the same, converging, or reciprocal tracks.

  • Time-based:
    • 15 min: General standard.
    • 10 min: If navigation aids are frequent.
    • 5 min: If the preceding aircraft is 20 kt faster.
    • 3 min: If the preceding aircraft is 40 kt faster.

Vertical Separation (RVSM vs Non-RVSM)

  • RVSM (Reduced Vertical Separation Minima): 1000 ft separation between FL290 and FL410.
    • Two aircraft flying in the same direction (and odd/even level) will be separated by 2000 ft.
  • Non-RVSM: Above FL290 standard separation is 2000 ft (Same direction = 4000 ft).

Wake Turbulence

  • ATC must apply wake turbulence separation minima on approach and departure (e.g., Light behind Heavy).
  • Exception: Not applied to VFR arrivals or IFR arrivals executing a visual approach if the pilot reports having the preceding aircraft in sight. In this case, ATC issues a warning ("Caution Wake Turbulence") and responsibility for separation rests with the pilot.
  • Note: Heavy behind Light does not require wake turbulence separation.

Clearances and Aerodrome Control

  • Landing Clearance: Only issued when there is reasonable assurance that separation will exist when crossing the runway threshold. It should not be given if the preceding aircraft has not crossed the threshold (runway occupied).
  • Runway in Use: Normally the one aligned into the wind. The pilot can refuse it for safety or performance reasons (e.g., tailwind > 5 kt) and request another, even if it implies delay.
  • Landing Priority: Emergencies, Hospital, SAR.

Emergencies and Contingencies

  • Emergency Descent:
    • If an emergency descent broadcast is received from another aircraft: Continue with current clearance, maintain listening watch, and visual/TCAS vigilance. Do not maneuver unless necessary due to immediate danger.
  • Fuel Dumping:
    • Advise ATC.
    • Perform preferably over water, away from cities/storms, at not less than 6000 ft.
  • Air Reports (AIREP Special):
    • Must be made for: Severe turbulence, Severe icing, Severe mountain waves, Thunderstorms without hail (obscured/embedded), Volcanic ash.
  • Change from IFR to VFR:
    • Must be initiated by the pilot: "CANCELLING MY IFR FLIGHT". ATC should not suggest it.

Speed Procedures

  • On final approach (after 4 NM from threshold) speed control should not be applied.
  • Minor adjustments (± 20 kt) permitted on intermediate/final.