One of the more interesting elements on the resumé of Capt. Chesley ‘Sully’ Sullenberger — the pilot at the helm of US Airways flight 1549 — is his training flying gliders. It stands to reason that familiarity flying such engine-less aircraft could come in handy since he reportedly lost both engines on the Airbus A320 Thursday afternoon, possibly after striking birds.

Sullenberger may not speak to the press until he has been debriefed by the the NTSB, which is investigating the accident. But Dr. Frank Ayers, chairman of the flight department at Embry-Riddle Aeronautical University in Daytona Beach, Fla. says of Sully’s glider experience: “It certainly would help, because in a glider, every landing is an engine-out landing.”

To safely land Flight 1549 onto the frigid Hudson River — as with other water landings — Sullenberger had to fly “as slow as you can without stalling,” Ayers said, adding that the process is similar to landing a glider.

Besides landing, being a glider pilot might have helped Sullenberger decide against shooting for a landing at tantalizingly close Teeterboro airport in nearby New Jersey. A spokesman for the National Air Traffic Controllers Association says air traffic controllers told the Sullenberger to divert to Teterboro. “It was not clear why the pilot, identified as Chesley B. “Sully” Sullenberger III of Danville, Calif., did not land there and headed for the Hudson instead,” according to an AP report. It’s possible that Sullenberger’s glider pilot experience at judging how far aircraft can coast without engines played a part in the call he made to land in the river, Ayers said.

How far a plane can glide without power is a relatively simple math calculation, best mixed with seasoned judgment and flying skill. Knowing the plane’s speed, altitude and rate of descent will tell you how far the plane can glide. In this case, Capt. Sullenberger may have known that he didn’t have enough altitude to make it to Teterboro, or may have simply judged that he might not make it and the river was a far better landing spot than New Jersey, where the penalty for crashing short of the airport would be severe.