Timed Approaches from a Holding Fix — AIM 5-4-10 Explained

AIM Text

TIMED APPROACHES may be conducted when the following conditions are met:
1. A control tower is in operation at the airport where the approaches are conducted.
2. Direct communications are maintained between the pilot and the center or approach controller until the pilot is instructed to contact the tower.
3. If more than one missed approach procedure is available, none require a course reversal.
4. If only one missed approach procedure is available, the following conditions are met:
  1. Course reversal is not required; and,
  2. Reported ceiling and visibility are equal to or greater than the highest prescribed circling minimums for the IAP.
5. When cleared for the approach, pilots must not execute a procedure turn. (14 CFR section 91.175.)
Although the controller will not specifically state that “timed approaches are in use,” the assigning of a time to depart the final approach fix inbound (nonprecision approach) or the outer marker or fix used in lieu of the outer marker inbound (precision approach) is indicative that timed approach procedures are being utilized, or in lieu of holding, the controller may use radar vectors to the Final Approach Course to establish a mileage interval between aircraft that will ensure the appropriate time sequence between the final approach fix/outer marker or fix used in lieu of the outer marker and the airport.
Each pilot in an approach sequence will be given advance notice as to the time they should leave the holding point on approach to the airport. When a time to leave the holding point has been received, the pilot should adjust the flight path to leave the fix as closely as possible to the designated time. (See FIG 5-4-19.)

EXAMPLE-
At 12:03 local time, in the example shown, a pilot holding, receives instructions to leave the fix inbound at 12:07. These instructions are received just as the pilot has completed turn at the outbound end of the holding pattern and is proceeding inbound towards the fix. Arriving back over the fix, the pilot notes that the time is 12:04 and that there are 3 minutes to lose in order to leave the fix at the assigned time. Since the time remaining is more than two minutes, the pilot plans to fly a race track pattern rather than a 360 degree turn, which would use up 2 minutes. The turns at the ends of the race track pattern will consume approximately 2 minutes. Three minutes to go, minus 2 minutes required for the turns, leaves 1 minute for level flight. Since two portions of level flight will be required to get back to the fix inbound, the pilot halves the 1 minute remaining and plans to fly level for 30 seconds outbound before starting the turn back to the fix on final approach. If the winds were negligible at flight altitude, this procedure would bring the pilot inbound across the fix precisely at the specified time of 12:07. However, if expecting headwind on final approach, the pilot should shorten the 30 second outbound course somewhat, knowing that the wind will carry the aircraft away from the fix faster while outbound and decrease the ground speed while returning to the fix. On the other hand, compensating for a tailwind on final approach, the pilot should lengthen the calculated 30 second outbound heading somewhat, knowing that the wind would tend to hold the aircraft closer to the fix while outbound and increase the ground speed while returning to the fix.

FIG 5-4-19 Timed Approaches from a Holding Fix

Source: FAA Aeronautical Information Manual · current edition · paragraph 5-4-10.

The short answer

AIM 5-4-10 is FAA advisory guidance on timed approaches from a holding fix, an ATC technique that sequences aircraft by assigning each a time to leave the final approach fix or outer marker inbound. It applies only under specific conditions — an operating control tower and no required course reversal. When cleared, pilots must not execute a procedure turn, per 14 CFR 91.175.

Research Notes

Common Questions

What conditions must be met for timed approaches from a holding fix?

Per AIM 5-4-10, a control tower must be in operation at the airport, direct communications must be maintained with center or approach until told to contact the tower, and no available missed approach procedure may require a course reversal. If only one missed approach exists, the reported ceiling and visibility must be equal to or greater than the highest prescribed circling minimums for the IAP.

How do I know timed approaches are in use?

AIM 5-4-10 notes the controller will not specifically state “timed approaches are in use.” Instead, being assigned a time to depart the final approach fix inbound (nonprecision) or the outer marker inbound (precision) indicates timed approach procedures are being used. Alternatively, ATC may use radar vectors to establish a mileage interval in lieu of holding.

How do I adjust my holding to leave the fix at the assigned time?

The AIM example: holding at 12:04 with a 12:07 departure leaves 3 minutes to lose. Because more than two minutes remain, the pilot flies a racetrack rather than a 360-degree turn. The end turns use about 2 minutes, leaving 1 minute of level flight; halving it, the pilot flies 30 seconds outbound before turning back inbound, adjusting for head- or tailwind.

5-4-10. Timed Approaches from a Holding Fix