Two key things. First the AIM is advisory in nature and second the operative word 'should' was used in this statement; "Speed adjustments should not be assigned inside the final approach fix on final or a point 5 miles from the runway"
Coming into STL last Jan I was given an approach clearance that had a speed restriction to maintain best speed until the threshold. Given the length of the runway, the fact my max speed was like 120kts and the 757 behind me was doing at least 140 to 180 kts I figured it was best to head that clearance as it was reasonable.
So it can happen.
When it happens, the controller has erred.
Order JO 7110.65S Air Traffic Control
Section 7. Speed Adjustment
5-7-1. APPLICATION
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.
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.
a. Consider the following when applying speed
control:
1. Determine the interval required and the point
at which the interval is to be accomplished.
2. 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.
3. 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.
b. Do not assign speed adjustment to aircraft:
1. At or above FL 390 without pilot consent.
2. Executing a published high altitude instrument
approach procedure.
3. In a holding pattern.
REFERENCE-
FAAO JO 7110.65, Para 4-6-4, Holding Instructions.
4. Inside the final approach fix on final or a point
5 miles from the runway, whichever is closer to the
runway.
c. At the time approach clearance is issued,
previously issued speed adjustments shall be restated
if required.
d. 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.
e. Express speed adjustments in terms of knots
based on indicated airspeed (IAS) in 10-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.).
NOTE-
1. Pilots complying with speed adjustment instructions
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.
REFERENCE-
FAAO JO 7110.65, Para 5-7-2, Methods.
