Holding can be a long, tedious process. Understanding the reason for your holding is important for a few big reasons.

If you know the reason why you're holding, you can estimate how much longer the holding will last before fuel becomes a concern. Let's look at 6 reasons for holding and get a little more in-depth...

1) 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 a lot of the time, your hold won't last long.

2) 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 awhile 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 line.

3) Low Visibility/Ceiling

Low IFR conditions can back up traffic flow easily. There's no way to clear aircraft to visually follow each other, so the IFR separation minimums are increased.

4) Medevac Aircraft

If a medevac flight is inbound or outbound, ATC can give them priority. The good news is, the holding probably won't last long. It's usually just enough to get that one aircraft in, and then the sequence resumes.

5) 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 awhile...

6) 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 awhile. Getting information from ATC will help you determine how serious the incident was, and how soon to begin your diversion planning.

What other reasons might you hold during an arrival procedure? Tell us in the comments below.