Keep speed adjustments to the minimum necessary to achieve or maintain required or desired spacing. Avoid adjustments requiring alternate decreases and increases. Permit pilots to resume normal speed when previously specified adjustments are no longer needed. Remember, 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.
While working approach control, you may use speed adjustments to obtain required spacing, better descent gradients or when tight turns are required. Remember, at greater speeds, a descent will take up more space and turns will have greater radii. Also, remember the technique of "vector for space, speed to hold space."
On your scope, you will see displayed the aircraft’s ground speed, however, express speed adjustments in terms of knots based on indicated airspeed (IAS) in 10-knot increments. IAS varies with altitude, a plane at 10000ft can be reporting a GS of 280kts but indicating 250kts.
Whenever you issue a speed restriction, don’t expect it to be immediate as it takes time for an aircraft to speed up or slow down. If an aircraft is descending, they will likely also have trouble slowing down with a descent.
A pilot may refuse a speed restriction if he considers that it will prevent correct aircraft operation.
At the time approach clearance is issued, previously issued speed adjustments must be restated if required. Approach clearances cancel any previously assigned speed adjustment. Pilots are expected to make their own speed adjustments to complete the approach unless the adjustments are restated.
You may not issue speed restrictions to:
1.Aircraft flying a holding pattern
2.Inside the final approach fix on final or a point 5 miles from the runway, whichever is closer to the runway.
“{Reference: FAAO 7110.65 5-7-1}”
Methods
a. You can instruct an aircraft to:
1. Maintain present/specific speed.
2. Maintain specified speed or greater/less.
3. Maintain the highest/lowest practical speed.
4. Increase or reduce to a specified speed or by a specified number of knots.
PHRASEOLOGY-
SAY AIRSPEED.
MAINTAIN PRESENT SPEED.
MAINTAIN (specific speed) KNOTS.
MAINTAIN (specific speed) KNOTS OR GREATER.
DO NOT EXCEED (speed) KNOTS.
MAINTAIN MAXIMUM FORWARD SPEED.
MAINTAIN SLOWEST PRACTICAL SPEED.
INCREASE/REDUCE SPEED:
TO (specified speed in knots in individual form),
or
(number of knots) KNOTS.
Example-
LAS_APP: “American 123, maintain present speed”
LAS_APP: “American 123, maintain two three zero knots”
LAS_APP: “American 123, maintain two three zero knots or greater”
LAS_APP: “American 123, do not exceed two three zero knots”
LAS_APP: “American 123, maintain maximum forward speed”
LAS_APP: “American 123, maintain slowest practical speed”
LAS_APP: “American 123, reduce speed to two one zero”
LAS_APP: “American 123, reduce speed ten knots”
NOTE-
A pilot operating at or above 10,000 feet MSL on an assigned speed adjustment greater than 250 knots is expected to comply with 14 CFR Section 91.117(a) when cleared below 10,000 feet MSL, within domestic airspace, without notifying ATC.
b. Simultaneous speed reduction and descent can be extremely difficult, particularly for turbojet aircraft. Specifying which action is to be accomplished first removes any doubt the pilot may have as to controller intent or priority. Specify which action is expected first when combining speed reduction with a descent clearance.
1. Speed reductions prior to descent.
PHRASEOLOGY-
REDUCE SPEED:
TO (specified speed),
or
(number of knots) KNOTS.
THEN, DESCEND AND MAINTAIN (altitude).
2. Speed reduction following descent.
PHRASEOLOGY-
DESCEND AND MAINTAIN (altitude).
THEN, REDUCE SPEED:
TO (specified speed in knots),
or
(number of knots) KNOTS.
NOTE-
When specifying descent prior to speed reduction, consider the maximum speed requirements specified in 14 CFR Section 91.117. It may be necessary for the pilot to level off temporarily and reduce speed prior to descending below 10,000 feet MSL.
c. Specify combined speed/altitude fix crossing restrictions.
PHRASEOLOGY-
CROSS (fix) AT AND MAINTAIN (altitude) AT (specified speed) KNOTS.
Example-
LAS_APP: “Cross Boulder City at and maintain seven thousand at two one zero knots.”
“{Reference: FAAO 7110.65 5-7-2}”
Minima
When assigning airspeeds, use the following recommended minima:
1.To aircraft operating between FL 280 and 10,000 feet, a speed not less than 250 knots
2.When an operational advantage will be realized, speeds lower than the recommended minima may be applied.
3.To arrival aircraft operating below 10,000 feet:
a. Turbojet aircraft. A speed not less than 210 knots; except when the aircraft is within 20 flying miles of the runway threshold of the airport of intended landing, a speed not less than 170 knots.
b. Turboprop aircraft. A speed not less than 200 knots; except when the aircraft is within 20 flying miles of the runway threshold of the airport of intended landing, a speed not less than 150 knots.
4.Departures:
a. Turbojet aircraft. A speed not less than 230 knots.
b.Turboprop aircraft. A speed not less than 150 knots.
5.Helicopters. A speed not less than 60 knots.
“{Reference: FAAO 7110.65 5-7-3}”
Lower speeds may be assigned if operationally advantageous. Good practice in that instance would be to add an "if unable, advise" to the end of the restriction.
Example-
LAS_APP: "American 123, cleared visual approach runway 26L. Reduce speed to 160, if unable, advise."
Termination
Advise aircraft when speed adjustment is no longer needed.
PHRASEOLOGY-
RESUME NORMAL SPEED.
COMPLY WITH SPEED RESTRICTIONS.
RESUME PUBLISHED SPEED.
DELETE SPEED RESTRICTIONS.
“{Reference: FAAO 7110.65 5-7-4}”