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A KC-10A Extender from Travis Air Force Base, California sits on the tarmac Thursday, May 11, 2017 at Ted Stevens Anchorage International Airport. The KC-10A Extender, participating in the Northern Edge exercises, can carry 350,000 pounds of fuel and can refuel aircraft from any U.S. and coalition force. (Loren Holmes / Alaska Dispatch News)

ABOARD AN AIR FORCE KC-10A EXTENDER FLYING OVER INTERIOR ALASKA — Nearly 200 military aircraft are participating in this year's Northern Edge training exercise, and in order to maximize the training opportunities, many of them won't have to land to refuel.

The Air Force has two main types of aerial refueling tankers, the KC-135 and its larger counterpart, the KC-10A Extender. The newer Extender is much more capable than the Vietnam War-era KC-135. The Extender is capable of carrying nearly twice as much fuel, can deliver it farther from home, and can refuel any U.S. or coalition aircraft.

Northern Edge is the largest military exercise Alaska will see this year. The operating area in the Interior and the Gulf of Alaska is about the size of Florida.

The combat exercises pit two teams against each other, running various daily scenarios, including having one team try to penetrate the air defenses of the other.

[Thousands of military personnel converge on Alaska for Northern Edge exercise]

High-performance military jets like the F-15, F-35 and F-22 are fairly small, which increases their performance and maneuverability, but limits their range. Each time they take off and land there are usually many hours of mission briefing and debriefing that have to happen. So to maximize the training opportunities, they are refueled in flight.

When a group of fighter jets needs fuel, they will approach the KC-10 tanker, flying in formation off the left wing. One by one, the fighters will drop back to 30 feet behind the tanker, where a boom operator will make contact with the jet and transfer fuel.

"I could never be a boom operator," said Capt. Nathan Reineke, the pilot of the KC-10. "The control that they have in the back is very impressive."

Once contact is made, the two aircraft have to maintain close formation flying for the duration of the fuel transfer. For a smaller jet like the F-22, that can take 10 minutes. For a large aircraft like the E-3 Sentry, it could take an hour.

Once the fuel has been transferred, the boom operator will break contact and the jet will move into formation to the right of the tanker. After all the jets in the group have been refueled, they will leave the area, making room for other planes that need fuel.

During Thursday's five-hour flight, the tanker transferred $138,000 worth of jet fuel, according to 1st Lt. Byron Barfuss. He estimates that the KC-10 mission that day cost around $175,000 in total.