CHICAGO (CBS) — National Transportation Safety Board investigators now have a good idea how far apart the planes were in Monday’s near collision at O’Hare International Airport.

It wasn’t far.

LISTEN: Newsradio 780’s Bob Roberts Reports

Preliminary Federal Aviation Administration radar information indicates that the SkyWest Canadair CRJ-200 crossed runway 32L at O’Hare approximately 225 feet above the ExpressJet Embraer ERJ-145, and less than 480 feet apart laterally.

NTSB investigators have scheduled interviews with air traffic control personnel who were on duty in the O’Hare tower at the time.

The investigators also are reviewing radar data, air traffic control audio and statements provided by the pilots of the ExpressJet and SkyWest regional jets.

ExpressJet flight 6075 was cleared for takeoff to Buffalo, N.Y., on runway 32L, even though SkyWest flight 6958, inbound from Muskegon, Mich., had been cleared to land on runway 9R.

Although 9R and 32L do not physically intersect, planes approaching 9R cross 32L at low altitude before landing. NTSB said in a statement that because of the timing of the two operations, the SkyWest flight nearly overflew the departing ExpressJet aircraft.

A warning horn sounded in the tower, and an supervisor directed the SkyWest flight to abort its landing and circle around, which it did safely. The ExpressJet flight continued its takeoff and departed without incident.

The near-collision occurred less than 25 minutes after a plane carrying Vice President Joe Biden and his wife, Jill, arrived at O’Hare for Mayor Rahm Emanuel’s inauguration ceremony. Biden was off the plane and in a motorcade, and Air Force 2 was in a different part of the airport, when the near-collision occurred.

Watch & Listen LIVE