This still video image shows the moment before collision between a helicopter and a small aircraft on August 8, 2009 over New York's Hudson River.
The pilot of a plane involved in a mid-air collision over the Hudson River read back the wrong radio frequency to an air traffic controller but wasn't corrected, a federal safety official says.
Nine people were killed in the Aug. 8 crash between the single-engine Piper and an air tour helicopter.
National Transportation Safety Board Chairman Deborah Hersman told a congressional committee Wednesday that an air traffic controller gave the plane's pilot the radio frequency for Newark Liberty International Airport in New Jersey, but the pilot read back the wrong frequency. She said there is no indication the pilot was corrected and he never contacted Newark. Later attempts to contact the pilot were unsuccessful.
Two air traffic controllers at Teterboro Airport were placed on administrative leave after the deadly crash. One of them wasn't in the tower when the collision happened. The other was apparently chatting on the phone with someone about a dead cat until the accident occurred.
The Federal Aviation Administration opted to modify air traffic rules over the Hudson in the wake of the tragedy. The new rules include requiring pilots to tune their radios to specific frequencies and restricting speeds to 140 knots or less, the FAA said.