Coordination and communication are the keys to landing each plane without incident

Ever wonder how planes are sequenced for landing when so many arrive at the same time? Airports have only a few runways to accommodate the numerous airplanes coming in for a landing at once, and there has to be a system to get them in order.

Air Traffic Control (ATC) dictates the sequence to aircraft inbound for landing, but it’s pretty much first come, first serve. ATC can adjust the sequence of planes if necessary, or even, when it’s really busy. change the arrival route for some aircraft to ensure the orderly flow of traffic.

In a broad sense, our sequence starts as early as taxiing for takeoff at the departure airport, especially if another airplane ahead of us is headed to the same destination. There may be a few irritated sighs emanating from the cockpit when the pilot discovers that a plane on the taxiway ahead is headed to the same destination, whether we’re flying across the state, the country or the ocean. In other cases, approach control works us in with other arriving traffic when the en-route controllers hand us off. The distance from the airport varies for this handoff at different locations. It’s the job of the approach controller to take all the planes converging from many directions on an airport, and line them up for landing.

Here’s how Chicago approach controller Dave Cushwa describes arrival sequencing:

"We start talking to arrivals about 40 miles out. The length of the final [or “turn-on point”], however, is partly decided by the approach controller on duty at that specific time. Typically, a controller might try to keep his final at somewhere between 15 and 20 nautical miles. On final, the aircraft are three miles apart at the marker, then 2.5 miles apart inside the marker.” [Note: By “marker,” Dave means the “outer marker,” acomponent of the Instrument Landing System, or ILS, typically around five to eight miles off the end of the runway.]

"If the tower has them in sight, we can squeeze them tighter; they just have to turn off the runway before the next guy crosses the threshold.

"Frequently, the controller is taking arrivals from at least two inbound directions, and the planes might be 10 to 12 miles apart at 11,000 feet, with 300 knots of airspeed. Our job is to turn, descend and slow the airplanes in such a way that we’ll always have someone in the right position to turn on at our turn-on point.

"I prefer to turn planes on about 15 miles out, with the airplanes at 4,000 feet and 180 knots. At 180 knots and each arrival three miles apart, one should observe an arrival passing overhead about every 60 seconds. There are always exceptions, and sometimes the final is extended out 25 miles or more."

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captain meryl getline (fromthecockpit.com) is a retired B777 pilot. She is the author of The World at My Feet. Email Captain Meryl at editor@executivetravelmag.com.