Keep speed adjustments to the minimum necessary to achieve or maintain required or desired spacing. Avoid adjustments requiring alternate decreases and increases. Terminate speed adjustments when no longer needed.
NOTE: It is the pilot's responsibility and prerogative to refuse speed adjustment that he/she considers excessive or contrary to the aircraft's operating specifications.
- Consider the following when applying speed control:
- Determine the interval required and the point at which the interval is to be accomplished.
- Implement speed adjustment based on the following principles.
- (a) Priority of speed adjustment instructions is determined by the relative speed and position of the aircraft involved and the spacing requirement.
- (b) Speed adjustments are not achieved instantaneously. Aircraft configuration, altitudes, and speed determine the time and distance required to accomplish the adjustment.
- Use the following techniques in speed control situations:
- (a) Compensate for compression when assigning air speed adjustment in an in-trail situation by using one of the following techniques:
- (1) Reduce the trailing aircraft first.
- (2) Increase the leading aircraft first.
- (b) Assign a specific airspeed if required to maintain spacing.
- (c) Allow increased time and distance to achieve speed adjustments in the following situations:
- (1) Higher altitudes.
- (2) Greater speed.
- (3) Clean configurations.
- (d) Ensure that aircraft are allowed to operate in a clean configuration as long as circumstances permit.
- (e) Keep the number of speed adjustments per aircraft to the minimum required to achieve and maintain spacing.
- Do not assign speed adjustment to aircraft:
- At or above FL 390 without pilot consent.
- Executing a published high altitude instrument approach procedure.
- In a holding pattern.
- Inside the final approach fix on final or a point 5 miles from the runway, whichever is closer to the runway.
- At the time approach clearance or a climb via/descend via clearance is issued, previously assigned speeds must be restated if required.
- Approach clearances or climb via/descend via clearances cancel any previously assigned speeds. Pilots are expected to make their own speed adjustments to fly the approach, SID, or STAR unless assigned speeds are restated.
NOTE: Pilots are required to comply with published speed restrictions.
- A speed restriction published as part of a SID/STAR is canceled when an aircraft is vectored off, or a deviation from the SID/STAR is approved. If necessary, assign a speed in conjunction with the vector or approval to deviate.
NOTE: The last published speed on a STAR will be maintained by the aircraft until ATC deletes it, assigns a new speed, issues a vector, assigns a direct route or issues an approach clearance.
- When issuing speed adjustments to aircraft cleared along a route or procedure that has published speed restrictions, if feasible, advise the pilot where you intend on allowing the aircraft to resume the published speed.
NOTE: If it is anticipated that an aircraft will be allowed to resume the published speeds on a procedure, advising the pilot where that may occur avoids flight crews from unnecessarily deleting speeds from the Flight Management System.
- Express speed adjustments in terms of knots based on indicated airspeed (IAS) in 5-knot increments. At or above FL 240, speeds may be expressed in terms of Mach numbers in 0.01 increments for turbojet aircraft with Mach meters (i.e., Mach 0.69, 0.70, 0.71, etc.).
- 1. Pilots complying with speed adjustment instructions (published or assigned) should maintain a speed within plus or minus 10 knots or 0.02 Mach number of the specified speed.
- 2. When assigning speeds to achieve spacing between aircraft at different altitudes, consider that ground speed may vary with altitude. Further speed adjustment may be necessary to attain the desired spacing.
- 3. Controllers should anticipate pilots will begin adjusting speed at the minimum distance necessary prior to a published speed restriction so as to cross the waypoint/fix at the published speed. Once at the published speed, controllers should expect pilots will maintain the published speed until additional adjustment is required to comply with further published restrictions or ATC assigned speed restrictions.