OKLAHOMA CITY — During spring break many students used airplanes to reach a destination, but what they may not have known is that someone else was up in the air watching their plane and its flight pattern.

The E-3 Sentry jet has been part of homeland security to ensure the safety of American citizens when flying. The jets have been monitoring the skies since Sept. 11 to make sure planes are going where they should be. Now they have teamed up with the E-3 planes of the North Atlantic Treaty Organization.

For the first time since NATO was formed, countries in the organization have sent people and planes to help protect the United States on U.S. soil in accordance with article five.

Article five of the alliance’s treaty says that an attack on one NATO partner is an attack on all in the alliance. This is the first time the article has been activated.

Its activation means it is the first time NATO has been forced to uphold its part of the agreement, said Selika Ducksworth-Lawton, associate professor of history.

Now NATO forces are in Oklahoma City at Tinker Air Force Base. Once the alliance decided to support the war on terrorism, it sent 200 people and five jets by Oct. 15 to Tinker, said Capt. Steven Rolenc, the chief of public affairs for the 552nd Air Control Wing.

Tinker Air Force Base is home to 552nd Air Control Wing, which oversees the operation of 28 E-3 Sentry jets. The E-3 is an airborne warning and control system aircraft, hence its common name — AWACS. The aircraft can provide all-weather surveillance, command, control and communications needed by commanders of U.S. and NATO air defense forces.

NATO has sent its AWACS and crews to help lessen the strain on the people at Tinker, Rolenc said. He said this strain comes from four missions the wing is involved with. The NATO crews are helping with Operation Noble Eagle, which has AWACS flying missions over the United States.

The United States has its AWACS defending the country by flying combat air patrol over the United States around the clock, Rolenc said. In fact, on Sept. 11 there was an AWACS flying a training mission on the East Coast. After the first plane hit the World Trade Center, the plane was diverted and the 552nd Wing has been there ever since, Rolenc said.

“Twenty-four hours a day, seven days a week, we’ve been up there.”

As of April 4 the AWACS from the United States have flown 528 flights, a total of 6,341 hours, Rolenc said. The AWACS of NATO have flown 331 flights, at a total of 3,705 hours, since joining the operation.

Planes from Tinker Air Force Base are also involved in Enduring Freedom in Afghanistan, as well as the Northern and Southern Watches, which are operating in the Middle East. The base is also the main training facility for men and women of AWACS. Rolenc said this is Operation Sustain Century, which must have the right amount of trainees and proper training for them.