Logan crash leaves a trail of questions

The inquiry will look at whether pilot error, mistakes by ground controllers, or the impending emergency landing of another aircraft could have played a role.

Board spokesman Peter Knudson said yesterday that the agency has already sent the flight data and cockpit voice recorders from Delta Flight 266 and Atlantic Southeast Flight 4904 to its labs in Washington.

It will take 10 business days before the agency issues a preliminary report, but it will take much longer before investigators identify the cause of the crash, Knudson said. Investigators will review recordings from the airport’s new ground radar system, interview crews from both aircraft and the air traffic controllers directing them, and inspect the planes to document what happened.

“We’ll be looking at any number of things, but we’re not going to get into speculating about the cause,’’ Knudson said.

The crash occurred about 7:33 p.m., moments after the Atlantic Southeast flight, a comparatively small Canadair Regional Jet 900 heading to Raleigh-Durham with 74 passengers aboard, made a left turn from Logan’s Taxiway B onto Taxiway M and stopped suddenly. The Delta flight, a much larger Boeing 767 bound for Amsterdam with 204 passengers, followed right behind on Taxiway B.

Knudson said the left wingtip of the larger plane, as it proceeded on Taxiway B, clipped the tail of the smaller plane, slicing it with such force that its winglet remained lodged in the smaller plane’s tail after they separated.

It remains unclear why that happened, but there are several possible reasons. Among them, the pilots in the larger plane may have failed to pay sufficient attention to the smaller plane as it turned. Another possible explanation could be poor instructions from ground and air traffic controllers.

FAA officials said there were no mechanical problems on either aircraft before the crash and weather was not a factor.

“Anything that took place while this accident was occurring could be included in the investigation,’’ Peters said.