Boeing 757-232 N693DL incident near Atlanta, Georgia

Probable cause

The air traffic controllers’ failure to adhere to required radar identification procedures, which resulted in loss of separation between the departing Boeing 757 and three other airplanes. Contributing to the incident was the pilots’ inadequate preflight checks, which resulted in the airplane departing with an inoperative transponder.

NTSB analysis

A Boeing 757-200 departed from Atlanta, Georgia, without its transponder activated, and the pilots did not contact air traffic controllers for about 8 minutes after departure. The airplane flew through one controller’s airspace and entered another controller’s airspace without coordination before radar and radio contact was established.

While the incident airplane’s transponder was not activated, the airplane’s radar data tag (which contained identification, altitude, and airspeed information) did not automatically appear on the controllers’ radar displays as it normally would have. Consequently, the airplane was displayed only as an enhanced primary target with no identifying information. Although local procedures require that Atlanta tower controllers verify that departures have a radar data tag before transferring communications to departure controllers, the tower controllers did not do so. Review of primary radar data determined that a loss of lateral separation occurred between the incident airplane and the following three airplanes: 1) a Beechcraft 55 (closest proximity 1.44 miles); 2) a Pilatus PC-12 (closest proximity 0.81 miles), and 3) a Canadair Regional Jet CRJ-100 (closest proximity 2.36 miles).

Text from the NTSB. Open the NTSB docket for OPS11IA410 for the full record.