Washington ? An air traffic controller bantering on the phone about a dead cat at the airport initially failed to warn a small plane of other aircraft in its path and then tried unsuccessfully to contact the pilot, officials said Friday. Moments later, the plane collided with a tour helicopter over the Hudson River, killing nine people.

The controller handling the plane and his supervisor at Teterboro Airport in New Jersey at the time of the accident a week ago have been placed on administrative leave pending an investigation by the Federal Aviation Administration.

The phone call, to an airport contractor, was a “silly conversation” concerning a dead cat that had been removed from the airport, a retired union official said, in an account supported by transportation officials also familiar with the contents of the call.