Some federal safety officials who have investigated two fatal airliner accidents are concerned that pilots may not always be focusing on the business at hand in the critical moments before takeoff.

Federal investigators at the National Transportation Safety Board are closely examining the tape covering nearly 30 minutes in the cockpit of Delta Air Lines Flight 1141 last August before the Boeing 727 crashed seconds after takeoff, killing 14 of the 108 people aboard.More than half of the tape, covering a lengthy taxi period at the huge Dallas-Forth Worth International Airport, involves idle chatter among the pilots and two flight attendants on subjects ranging from the recent purchase of a house to birds nesting near airports.

Nearly 11 minutes of the tape were omitted from the transcript because they were considered irrelevant, including a reference, according to sources, to news reports a few days before the crash of chatter aboard a Continental Airlines that crashed in Denver 10 months earlier.

If there were an accident, one participant in the Delta cockpit reportedly reminded his colleagues, their words might end up in the newspapers, too.

Later, the Delta plane's captain told investigators he did not care for the lengthy presence of the flight attendants in the cockpit, but that it was not his nature to order them from the cockpit during the long takeoff delay.

Investigators emphasized that so far there has been no clear evidence linking these conversations - some of which were technically legal because the plane was not moving - with the possible cause of the crash.

But investigators are trying to determine whether the flight crew forgot to properly set the jetliner's wing flaps, which help it gain lift, and if the conversations distracted them from preparing the plane for flight.