Description

ICAO defines an Alternate aerodrome as "an aerodrome to which an aircraft may proceed when it becomes either impossible or inadvisable to proceed to or to land at the aerodrome of intended landing where the necessary services and facilities are available, where aircraft performance requirements can be met and which is operational at the expected time of use".

Alternate aerodromes may be designated as Take-off , En-route or Destination alternates. ICAO defines each of these as follows: