Whether you’re a seasoned instrument pilot or you’re just getting started, here’s what you should know about holding…
Reasons For Holding
Holding patterns are assigned to aircraft by ATC for a variety of reasons. Holds are flown in protected airspace, away from obstacles, and may be published tracks off of individual fixes or “random” holding assigned by ATC off of a nearby NAVAID. Here are a few of the most common reasons you’ll find yourself holding…
- Thunderstorms: If there’s severe weather around your destination, arrival routes, instrument procedures, or the airport itself might be affected. Based on where the storms are, and how fast they’re moving, you can begin to estimate how long you’ll spend in holding. Fortunately, thunderstorms change and move quickly. That means most of the time, your hold won’t last long.
- Flow Control: Some airports operate continuously at maximum capacity *cough* New York *cough*. You might be holding simply because the airspace is so congested that it’s taking a while to get everyone spaced out along a limited number of approaches. In this case, ATC will usually have a projected timeframe for when you’ll fit into the arrival line.
- Low Visibility/Ceilings: Low IFR conditions can back up traffic flow easily. There’s no way aircraft to visually follow each other, so the separation minimums (distance between aircraft) are increased.
- Snow Plowing: If recent snowfall or blowing snow requires runway plowing, holding depends on airport personnel. If you’re flying into an airport that gets snow frequently, it will take a lot shorter time to clear the runway. If you run into a snowy day in Texas, you may be waiting a while…
- Problem At The Airport: This is a worst-case scenario for holding. If there’s an emergency or an aircraft is stuck on the runway, especially a single runway airport (we’re looking at you San Diego), you might be out of luck for quite a while. Getting information from ATC will help you determine how serious the incident was, and how soon to begin your diversion planning.
The easiest of all holding instructions is a “hold as published” clearance, which is for charted holds that you’ll find on your IFR charts. You can find charted holds on approach charts, STARs, or en-route charts. Your clearance will sound something like this:
“Boldmethod 123 hold south of the Cedar Lake VOR as published. Expect further clearance at 12:30 Zulu.”
Note the light gray holding pattern next to the VOR on the chart below…
“Random” holding is a little more tricky. This happens when ATC issues you a non-charted hold. To do this, they’ll have to read off a full series of holding instructions. You’ll want to write these down to start planning your hold, and your clearance will sound something like this:
“Boldmethod 123 hold west of the East Texas VOR, 290 radial, 20 DME, left turns, 5-mile legs. Expect further clearance at 12:30 Zulu.”
Keep in mind, holding can be done almost anywhere en-route. Here’s what the FAA has to say in Chapter 2 of the Instrument Procedures Handbook: “Unplanned holding at enroute fixes may be expected on airway or route radials, bearings, or courses. If the fix is a facility, unplanned holding could be on any radial or bearing and there may be holding limitations required if standard holding cannot be accomplished at the MEA or MRA.”
Holding is conducted in protected airspace that’s determined by FAA TERPS Criteria. Holding patterns are established with a primary area (used for holding) and a secondary area (2NM wide perimeter around the primary area). TERPS uses a series of complex tables to determine how wide a holding area must be. These calculations are determined by distance from the fix to the NAVAID, slant range distance, altitude, nearby holds, and aircraft speed.
In most cases, you won’t know the exact dimensions of the protected airspace. But what is important to understand is that there’s plenty of buffer room to ensure that wind correction, varying groundspeeds, etc. will not affect safety of flight, even at the max holding speeds..
As for height above nearby terrain, the FAA says that “for level holding, a minimum of 1,000 feet obstacle clearance is provided throughout the primary area. In the secondary area, 500 feet of obstacle clearance is provided at the inner edge, tapering to zero feet at the outer edge. Allowance for precipitous terrain is considered, and the altitudes selected for obstacle clearance may be rounded to the nearest 100 feet.”
Maximum Holding Speeds
The size of the holding pattern is directly proportional to aircraft speed. In order to limit the amount of airspace that must be protected by ATC, maximum holding speeds KIAS (Knots Indicated Airspeed) have been designated for specific altitude ranges.
If a holding pattern has a nonstandard speed restriction, it is depicted by an icon with the limiting airspeed.
There are three types of standard holding entries: direct, parallel, and teardrop. They’re simple procedures to help you establish your aircraft in the hold. Check out our Boldmethod Live session below for a great explanation on all three holding entries.
What else do you want to learn about holding? Tell us in the comments below.