ARLINGTON, Va. — Retired Air Force Col. Rolando Aguilar, a former Texas Air National Guard F-16 Fighting Falcon pilot, remembers the morning of Sept. 11, 2001 — a day off that turned into a scramble to intercept an inbound aircraft he didn’t yet know was Air Force One.

Awakened by his unit’s crew chiefs with news that a plane had hit the World Trade Center, the young Airman quickly got ready as the alarm sounded for battle stations.

He ran to his jet and was strapped in when his wing commander ordered him to intercept an aircraft with “one of our former members” aboard.

Aguilar didn’t understand what that meant until he was airborne and caught his first glimpse of Air Force One’s unmistakable blue-and-white color scheme.

With the Federal Aviation Administration grounding civilian air traffic nationwide, Aguilar and his fellow Houston-based Guardsmen — flying with the same squadron in which a young George W. Bush had once served — escorted the president’s aircraft toward Barksdale Air Force Base, Louisiana, carrying authorization to fire on any aircraft that failed to respond.

The mission, Aguilar said, was executed flawlessly.

Twenty-five years later, he calls it a legacy his unit can be proud of.

“The National Guard stepped up,” Aguilar said. “We had a role in a real important day in history.”