A long hot summer of flight delays faces Chicago's O'Hare International Airport if federal aviation officials and pilots cannot work out a plan governing takeoffs and landings at intersecting runways.

The Federal Aviation Administration has set a May 27 deadline for its new rules to take effect. But pilots unions say they have not had enough time to study the changes and make sure they are safe.

If the deadline passes without an agreement, the pilots will have to stop "land and hold short" operations that have allowed for faster takeoffs and landings at the airport.

"It's going to be a huge headache," said Craig Burzych, an O'Hare representative for the National Air Traffic Controllers Association. "It's going to cause delays- a lot of upset pax, a lot of late pax."