Question: Sometimes when you're driving northbound on the New Jersey Turnpike, you see a seemingly endless line of planes emerging to land at Newark Liberty. How far back does that queue go? All the way to Boston?

Answer: It depends on the amount of traffic. In an airport such as Newark where the airspace is congested, the queue can get pretty long, well over 30 miles. One airport that always amazed me was LAX, where you would follow the traffic from over 100 miles out to landing. They literally would be sequencing the landings while the airplane was over different states.

Editor's note: After receiving Captain Cox's response, we asked Dale Wright of the National Air Traffic Controllers' Association, who writes the Ask Air Traffic Control column on this site, to describe this situation from the control tower's perspective.

Q: What is this like for the air traffic controllers at those airports?

A: Controllers who sequence traffic to airports are often at locations other than the airport. An example would be for Newark Liberty, New York TRACON, located on Long Island. For traffic being sequenced into Los Angeles, Southern California TRACON is located in San Diego. However, the sequence for these airports begins many miles from the airports of intended landing. Often, controllers as far away as 500 miles will begin sequencing traffic.

To show the complexities of this situation, here's an example of how traffic may be sequenced into the world's busiest airport, Atlanta Hartsfield-Jackson International Airport:

Delta Airlines is the main carrier in Atlanta. When they have an arrival bank inbound from the Northeast, traffic as far away as Boston may be held for a period of time on the ground. The FAA's Command Center, located in Vint Hill, Va., monitors the air traffic and through traffic management programs determines if an aircraft needs to held on the ground to make the flow of traffic more orderly.

Once the aircraft from Boston is airborne, controllers may have the pilot adjust the aircraft's speed, or give it turns to follow other aircraft. The numerous controllers that will work the aircraft between Boston and Atlanta can give these instructions.

Q: How many facilities will work the aircraft?

A:Approximately eight, including, Boston Tower, Boston TRACON (departure), Boston Center, New York Center, Washington Center, Atlanta Center, Atlanta TRACON (approach), and Atlanta Tower.

Q: How many planes is each controller in contact with in a situation like this?

A: The number of aircraft each controller is in contact with depends on several factors, including sector size, the type of traffic and weather. During busy periods controllers may work 15 – 20 aircraft at the same time in an Enroute or Center sector, but in a TRACON or approach control they may only work from 10 – 15 due to the size of their airspace being smaller. Controllers working aircraft in very large sectors such as Oceanic Sectors can work up to 50 or 60 aircraft. Examples of Oceanic traffic include flights from the West Coast of the U.S. to Hawaii, from North America to Asia and from the Northeastern U.S. to Europe.

Q: If there's a disruption, like a flight failing to clear the runway in time for the next landing, do you have to communicate with every flight in the queue?

A: The controller instructs the next arrival aircraft to go around and provides missed approach instructions. There is no advisory to the aircraft that are not required to go around. The supervisor or the controller in charge of the tower will coordinate with the radar room and the aircraft will be re-sequenced.

Read or Share this story: http://usat.ly/1eFRfF3