Federal and USAir officials are investigating why a Boeing 737 lost one of its wheels shortly after taking off from Baltimore-Washington International Airport Tuesday evening.
No one was injured when Flight 1660, en route to Chicago's O'Hare International Airport, landed at 5:32 p.m., minutes after taking off, officials said.
"It's very, very rare," Mary Jo Capizzi, a USAir spokeswoman, said of the incident. "The plane did land smoothly."
She said the pilot and a maintenance crew checked the aircraft just before take-off and all the wheels appeared to be in working order.
"We don't know yet exactly what happened," Ms. Capizzi said.
The Federal Aviation Administration is conducting a separate inquiry. Spokeswoman Marcia Adams said the investigation began today and she could not comment.
Ms. Capizzi said the incident was also reported to the National Transportation Safety Board. Alan Pollock, a spokesman for the NTSB, said the agency is not investigating because there was no accident and no injuries.
Emergency equipment was on standby near the runway for the landing in case any of the 42 passengers needed help, officials said.
The flight was ordered to return to BWI after several witnesses in the terminal told airport authorities they saw something fall off the plane and a wheel was found at the airport. As the plane passed the tower, air traffic controllers saw that a wheel was missing.
The passengers were put on another plane to Chicago.