NTSB Factual Report

On July 14, 2011, about 1933 eastern daylight time, Delta Air Lines flight 266, a Boeing 767-300ER, N185DN, was taxiing for departure when its left winglet struck the horizontal stabilizer of Atlantic Southeast Airlines flight 4904, a Bombardier CL-600-2D24 (CRJ900), N132EV, which was on taxiway M holding for departure on runway 09 at Boston Logan International Airport (BOS), Boston, Massachusetts. The CRJ900 sustained substantial damage and the 767 sustained minor damage. There were no injuries to any of the passengers and crew aboard either airplane.

Flight 4904, the CRJ900, was stopped behind two other airplanes on the south side of taxiway M awaiting takeoff clearance for runway 9. Flight 266, the B767, was taxiing for departure on runway 4R and was instructed by the ground controller to hold short of runway 4L on taxiway B. After holding short of runway 4L for a few minutes, the ground controller instructed them to "taxi to runway 4R, good rate around the corner." The captain recalled the ground controller had said the landing traffic was four miles out on final approach. The flight crew stated that they looked for the landing traffic and saw a "heavy" airplane approaching the airport with its landing gear extended were not sure if the landing traffic was going to runway 4L, runway 4R or runway 9. The captain indicated he expedited the taxi to cross the runway 4L approach path and estimated a taxi speed of more than 20 knots when they crossed the 4L approach path.

After the B767 crossed the runway 4L approach path, ATC said "nice job, monitor tower on 132.22, should get you right outta here at this next arrival." The B767 first officer (FO) stated he then was changing to the tower frequency when he looked up and saw that they were closing the distance to the CRJ900 faster than he had expected and said "watch this guy". The captain stated that after turning on to taxiway B, he noticed the CRJ900 that was stopped on taxiway M and thought that it looked clear of taxiway B. The captain stated that it looked like they would be clear of the CRJ900 but the distance was going to be close so he steered the B767 slightly to the right (about three feet) of the taxiway centerline and applied light braking when the collision occurred. According to the accident captain and a Delta check airman, the B767 wingtips are not visible from the cockpit unless the windows are opened. The CRJ900 sustained substantial damage to the horizontal tail and vertical tail and fluid was lost in all three hydraulic systems.

NTSB Probable Cause

the B767 flight crew's failure to maintain a safe clearance with the CRJ900 that was stopped on a taxiway.