Section 1, Chapter 12 - Speed Control

Question 1

What guidelines do controllers follow regarding speed control of aircraft?

Answer 1

Controllers may request pilots to adjust speeds to facilitate a safe and orderly flow of traffic, specifically to establish or maintain separation/deconfliction minima or spacing. Adjustments should stay within the speed ranges specified in MATS Part 2. Pilots must be informed when a speed control restriction is no longer required.

Question 2

When should speed control not be applied by controllers?

Answer 2

Speed control should not be applied:

• In holding patterns, except where published on approach charts.
• In areas of thunderstorms or known turbulence.

Question 3

What are the specific guidelines for applying speed control at different flight levels and phases of flight?

Answer 3

The guidelines for speed control are:

• At or above FL280: Speed adjustments should be in multiples of 0.01 Mach.
• Below FL280: Speed adjustments should be in multiples of 10 knots based on indicated airspeed (IAS).
• Phase of Flight: Speed control should be appropriate for the phase of flight, avoiding long periods to prevent affecting fuel reserves and operating profiles. Frequent changes should be avoided.
• Pilot Adherence: Pilots must adhere to the speed approved or assigned by ATC and request approval before making changes. If unable to maintain the assigned speed, pilots must inform ATC promptly, and controllers will use alternative methods to maintain desired separation or spacing.

Question 4

What are the speed control guidelines for arriving and descending aircraft?

Answer 4

The guidelines for speed control for arriving and descending aircraft are:

• At or above FL280: Speed adjustments may be based on IAS when descending below FL280. Pilots might not immediately change to IAS due to aircraft system factors.
• High rate of descent and speed reduction: Avoid instructing simultaneous high descent rates and speed reductions. Allow aircraft to descend at preferred speeds, typically 250-280 knots, with 270 knots being a good compromise.
• Transfer between sectors: Avoid significant speed changes during sector transfers. Transfer aircraft from en-route to Approach control within 250-300 knots IAS, coordinating speeds outside this range.
• Clean configuration: Permit aircraft to operate in a clean configuration as long as possible. For arriving aircraft below FL150, do not allocate speeds less than 210 knots (200 knots for propeller aircraft) unless within 20 nautical miles of the runway threshold. Then, reduce speed to 150-180 knots or to ‘minimum approach speed’ in exceptional circumstances.
• Final approach: Do not apply speed control after the aircraft is within 4 nautical miles from the threshold. Ensure a Stabilised Approach, where the aircraft is in landing configuration and final approach speed by at least 1,000 feet above the threshold elevation (or 500 feet if agreed by the operator).

Question 5

What are the minimum speed allocations for departing aircraft?

Answer 5

The minimum speeds allocated for departing aircraft are:

• Jet aircraft: 230 knots
• Turboprop and piston-prop aircraft: 150 knots
• Helicopters and tilt-rotor aircraft: 60 knots