The National Transportation Safety Board expects to hear from about 30 witnesses when it opens a public hearing Tuesday into the Aug. 31 crash of Delta flight 1141 at Dallas-Fort Worth International Airport.

The three flight officers of Delta flight 1141 are among those scheduled to testify about the crash that killed 14 of the 108 people aboard.Safety board officials say no conclusions about the crash will be offered in the four-day hearing.

Investigators are baffled by certain contradictions that have turned up as they tried to learn why the Boeing 727 failed to get more than 50 feet off the ground as it took off for Salt Lake City.

The focus of the probe has centered on whether the jet's wing flaps were in the proper position for takeoff.

After the crash, the flaps that provide lift during take-off were found in the incorrect position. But the cockpit records include a notation from first officer Carey Kirkland that the flaps were set.

Representatives of the Air Line Pilots Association say the board is leaning toward blaming the crash partly on the crew.

The pilot's union, which believes stall alarms on the jetliner malfunctioned, was to lay out its version of the reason for the crash at a news conference Monday.