A hold, or holding pattern, is a predetermined maneuver that keeps aircraft within specific airspace while awaiting further clearance.
Flying a hold, or "holding" is usually required during times of high traffic and weather. However, other reasons to hold may occur, such as a pilot needing more time to set up for an approach.
A hold begins with a fix. A fix is a point that can be many types of navaids such as a VOR, Airway Intersection, NDB, GPS Waypoint, or radial with a DME distance.
While traveling to the fix, an aircraft is said to be on the inbound course on the non-holding side. The inbound course is the radial/holding course the aircraft is traveling on and ends once the aircraft has crossed the fix. Once across the fix, an aircraft will begin a turn to the outbound course. While turning away from the fix, an aircraft is said to be on the "fix end" leg.
While traveling away from the fix, an aircraft is said to be on the outbound course on the holding side. The outbound side begins once an aircraft crosses abeam the fix. The outbound side ends after a set amount of time has passed, or the aircraft has traveled a certain distance from the fix. When an aircraft begins its turn back towards the holding course, it is said to be on the "outbound end" leg.
Two types of holds exist. Standard and Non-Standard.
Standard Holds consist of right turns with legs 1 minute in length. Non-Standard holds consist of left turns with legs 1 minute in length.
All holds should be flown as a "standard hold" unless otherwise published or requested by ATC.
All turns during the entry into a hold and while holding are performed with whichever requires the lowest bank angle:
In most situations, a 3 degree per second, or standard rate, will be used.
In a no-wind condition, flying a standard hold has an aircraft follow a course inbound to a holding fix, turn 180 degrees to the right, fly outbound parallel to the inbound course for 1 minute, make another 180 degree turn to the right, and then fly the inbound course to the fix.
With standard rate turns, a standard hold should take 4 minutes to complete, with each leg of the hold consisting of 1 minute.
In conditions with wind, a standard holding pattern cannot be flown. With wind, a pilot is expected to:
To compensate for wind, a pilot will adjust to the wind with drift corrections and changing the amount of time flown on the outbound leg.
To apply a drift correction, a pilot should fly the inbound course and note what heading is required to maintain a ground track that follows the holding course. This heading should then be subtracted from the holding course, and the result is the wind correction angle. This wind correction should then be multiplied by three and applied into the wind during the outbound leg.
For example, an inbound course has an aircraft follow the 090 radial to a fix. The pilot corrects for wind by applying an 8-degree wind correction into the wind to the left. The pilot should use a 24 degree (8 x 3 = 24) wind correction into the wind or to the right on the outbound leg.
To adjust for headwinds and tailwinds, a pilot will add or subtract from the amount of time flown during the outbound leg to achieve an inbound leg of 1 minute or 1.5 minutes above 14,000ft.
For example, a pilot flies an inbound leg that took 1 minute 15 seconds to complete. To reduce the inbound legs' total time to 1 minute, the pilot will remove 15 seconds from the outbound leg. This gives the outbound legs total time to be 45 seconds and an inbound leg of 1 minute.
If the pilot's inbound leg took 50 seconds to complete, the pilot would then add 10 seconds to the outbound leg to compensate.
Since most winds are not a perfect headwind, tailwind, or crosswind, pilots need to adjust the outbound leg's timing and drift correction simultaneously.
When ATC issues a hold that is not published, ATC will issue a clearance that includes: