Over Iraq and Syria (CNN) This Thanksgiving, while most Americans are at home with their families enjoying their turkey dinners, some are overseas, in harm's way, serving in the fight against ISIS. Some are on the ground in places like Iraq and Syria, but others contribute to the fight from the air.

The US-led coalition against ISIS relies heavily on airpower to help ground forces from the Iraqi military, Kurdish troops and militias and Syrian groups advance on the terror group's strongholds in Iraq and Syria.

We got the rare chance to ride along with the crew of America's largest and most versatile refueling jet, the KC 10 Extender, on a mission supporting Operation Inherent Resolve to oust ISIS from its strongholds like Mosul and Raqqa. The crew, led by Capt. Clark Palicka, has been flying almost nonstop for months.

"It's a dynamic airspace, a challenging environment. But it's also very rewarding flying," Palicka said. He's from New York and, like all the others involved in combat in the Middle East, didn't make it home for Thanksgiving -- spending it in the air instead.

An airborne gas station

The KC 10 crew started off by refueling two F15 Eagle strike aircraft. The boom operator, Staff Sgt. Uriel Escamilla, carefully helped the jets hook up to the tanker so the fuel could flow. Not an easy task at 400 mph over the Iraqi desert.

Refueling while both aircraft are in the air, flying at 400 mph, is no easy feat.

"It is two moving aircraft, but they are moving at around the same speed. So at the end it is about the rate of closure that the aircraft has towards us, when they are in position and we can make contact," Escamilla said after finishing the refueling.

The KC 10 Extenders are the United States' primary aerial refueling planes in the war against ISIS. They can carry more than 300,000 pounds of fuel and easily remain on missions for more than 10 hours, giving fuel to a wide range of aircraft. On our flight we witnessed the KC 10 servicing C-130 Hercules cargo planes and also A 10 Warthogs that are often used to hit ISIS targets right on the front lines.

"It gives us global reach and global power," Palicka said. "It allows us to project power where we normally wouldn't be able to. A good example is when we fly into Iraq. Many of the planes are not based in Iraq, they are based elsewhere. But their ability to take off, come into the airspace for an extended period of time, is only possible because of air refueling."

A crew member walks toward a KC 10 back on the tarmac.

A mission worth missing the holidays for

In the distance we could see Mosul, ISIS' biggest stronghold in Iraq, with thick plumes of smoke billowing overhead. Fighters for the terror group have laid massive oil fires around the city to try to obstruct the operations of the planes the KC 10 was refueling. It's a desperate measure as mostly Iraqi and Kurdish forces are battling to try to retake the city.

"I think we are making a huge difference here," co-pilot 1st Lt. Tyler Johnson said as he was monitoring the altitude, speed and heading of the KC 10 over the battlefield.

KC 10 crews endure missions of eight to 10 hours hovering over this crucial battlefield against ISIS.

For him, like the others, being away from home over Thanksgiving is painful but the difference they are making in the fight against ISIS is also rewarding, he said.

"I love flying, so I wouldn't want to be doing anything else. It is hard being away from family, but I love this job and I enjoy supporting our country."

Staff Sgt. John Loera is the KC 10's flight engineer. He has to make sure the plane is airworthy before takeoff and manages the fuel output during missions. He says his family understands that he's got a job to do.

"I am honored to be here," he said. "Being away from family, they understand it, we enjoy it when I am home. But now is my time to be out here and I am just happy to be serving."

These tankers are a vital support vehicle for planes flying missions against ISIS, allowing them to remain in the area battling the militants for up to seven hours.

The KC 10 Extenders are an important asset in the air war against ISIS. Without them, jets could only stay in the air for about 90 minutes before they'd have to land to refuel. But with KC 10s, the combat jets can loiter around the battlefield for six to seven hours and fly multiple bombing runs.

The high demand for these battle tested flying gas stations means their crews spend Thanksgiving over Iraq and not at home.