GM1 to AMC2 ATS.TR.210(a)(3) Operation of air traffic control service

HORIZONTAL SPEED CONTROL INSTRUCTIONS — DESCENDING AND ARRIVING AIRCRAFT

(a)The air traffic controller should, when practicable, authorise an aircraft to absorb a period of notified terminal delay by cruising at a reduced speed for the latter portion of its flight.

(b)The air traffic controller may instruct an aircraft to maintain its ‘maximum speed’, ‘minimum clean speed’, ‘minimum speed’, a specified speed or a speed equal to or less/more than a specified speed. ‘Minimum clean speed’ signifies the minimum speed at which an aircraft can be flown in a clean configuration, i.e. without deployment of lift-augmentation devices, speed brakes or landing gear.

(c)The air traffic controller should avoid issuing instructions for an aircraft to simultaneously maintain a high rate of descent and reduce its speed, as such manoeuvres are normally not compatible. Any significant speed reduction during descent may require the aircraft to temporarily level off to reduce speed before continuing descent.

(d)The air traffic controller should permit arriving aircraft to operate in a clean configuration for as long as possible. Below 4 550 m (FL 150), speed reductions for turbojet aircraft to not less than 410 km/h (220 kt) IAS, which will normally be very close to the minimum speed of turbojet aircraft in a clean configuration, may be used.