Speed restriction during descent

[Checks]

Ok, another dummy question.

At 9,000ft you get issued a decent to 3,000ft. During your decent, at 8,000ft, you get a speed restriction "Maintain 210kts". So the question becomes: Do you stop your descent, slow to 210kts, then continue descent? or do you continue to 3,000ft then slow to 210kts?

I had a discussion in the cockpit about this the other day and the "official" answer doesn't seem to be readily available via the AIM/other rules.

Thanks in advance

 

[kf4amu]

What are you flying? In a Dash you just pull it back to flight idle and continue your descent.

 

[firstthird]

is it a problem getting down if you slow? as in, you won't make a restriction if you slow first? then I'd ask what ATC wants the speed or the descent.

if it isn't a problem, I'd probably go to a 500 fpm descent while I slowed, then resume either my idle descent or a 1000 fpm descent. I wouldn't go all the way to 3000 at 250 then slow, but that is just me. would be interested in hearing other opinions.

 

[avbug]

As always, if you're unclear on the clearance, you're required to seek clarification.

If you're unable to comply, you're unable to accept.

If you're in a descent and given a speed restriction, you're expected to abide the speed restriction.

If you're unable to comply with the speed restriction, then refuse the clearance (eg, unable to meet that and still meet the crossing clearance), clarify (eg which would you prefer sir, the descent or the speed restriction), or comply.

If you're in a descent and given a speed restriction, you're expected to slow when given the speed restriction. Meeting an altitude is a space restriction, and meeting a speed limitation is a time restriction.

AIM 5-5-9:

5-5-9. Speed Adjustments ​

a. Pilot.
1. Advises ATC any time cruising airspeed varies plus or minus 5 percent or 10 knots, whichever is greater, from that given in the flight plan.
2. Complies with speed adjustments from ATC unless:
(a) The minimum or maximum safe airspeed for any particular operation is greater or less than the requested airspeed. In such cases, advises ATC.
NOTE-
It is the pilot's responsibility and prerogative to refuse speed adjustments considered excessive or contrary to the aircraft's operating specifications.
(b) Operating at or above 10,000 feet MSL on an ATC assigned SPEED ADJUSTMENT of more than 250 knots IAS and subsequent clearance is received for descent below 10,000 feet MSL. In such cases, pilots are expected to comply with 14 CFR Section 91.117(a).
3. When complying with speed adjustment assignments, maintains an indicated airspeed within plus or minus 10 knots or 0.02 Mach number of the specified speed.
b. Controller.
1. Assigns speed adjustments to aircraft when necessary but not as a substitute for good vectoring technique.
2. Adheres to the restrictions published in the FAAO JO 7110.65, Air Traffic Control, as to when speed adjustment procedures may be applied.
3. Avoids speed adjustments requiring alternate decreases and increases.
4. Assigns speed adjustments to a specified IAS (KNOTS)/Mach number or to increase or decrease speed using increments of 10 knots or multiples thereof.
5. Advises pilots to resume normal speed when speed adjustments are no longer required.
6. Gives due consideration to aircraft capabilities to reduce speed while descending.
7. Does not assign speed adjustments to aircraft at or above FL 390 without pilot consent.

From FAA Order 7110.65 (ATC Handbook):

c. 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[SIZE=-2]. [/SIZE]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


TO MACH (Mach number),

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. ​

d. Specify combined speed/altitude fix crossing restrictions. ​

PHRASEOLOGY-
CROSS (fix) AT AND MAINTAIN (altitude) AT (specified speed) KNOTS. ​

EXAMPLE-
"Cross Robinsville at and maintain six thousand at two three zero knots." ​

 

[rondo]

I'd slow my rate of descent and pull the power back.

If you can just ask ATC for clarification.

 

[Checks]

Guys,

I also just try and do both at the same time. Just curious what everyone else was doing.

Thanks

 

[Singlecoil]

If you can comply, then fine. If you can't then see avbug's post above.

 

[Booker]

Where I work the "standard technique" is similar to the above above: reduce rate to 500 until you achieve the requested speed.

 

[Cobra17]

Ok, another dummy question.

At 9,000ft you get issued a decent to 3,000ft. During your decent, at 8,000ft, you get a speed restriction "Maintain 210kts". So the question becomes: Do you stop your descent, slow to 210kts, then continue descent? or do you continue to 3,000ft then slow to 210kts?

I had a discussion in the cockpit about this the other day and the "official" answer doesn't seem to be readily available via the AIM/other rules.

Thanks in advance

Just ask ATC: "You need that now or when we get to 3?"

Forget about the FAR/AIM...it's about the sequence.

 

[avbug]

The aeronautical information manual and the regulations should not be forgotten, as these contain the procedures and rules by which this decision must be made.

Chief among them is the regulatory requirement to query ATC for clarification regarding a clearance for which there is any doubt.