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Crash Probe Examines Navigation-System Kinks
By J. LYNN LUNSFORD and ANDY PASZTOR-- WSJ
FEBRUARY 20, 2009

Investigators probing the fatal crash of a Continental Connection commuter plane last week near Buffalo, N.Y., are looking into previous reports of problems with an airport-navigation system and how many hours the pilots worked on the day of the accident.

Preliminary data suggest the captain went on duty around noon before piloting the Bombardier Q400 turboprop on the evening flight from Newark, N.J., to Buffalo. It is too early to tell whether pilot fatigue played any role in the crash, which occurred around 10:20 p.m. EST on Feb.12 and killed all 49 people aboard the plane and one person on the ground. As in every aviation accident, investigators are looking at how long the pilots had been on duty and whether they were able to get adequate sleep during their last rest period.

A spokesman for Pinnacle Airlines Corp., the parent company of Colgan Air Inc., which operated the aircraft, said the captain hadn't worked since the afternoon of the previous day and the co-pilot was returning to work from three days off in a row.

As the National Transportation Safety Board's probe accelerates, government and industry crash experts also are collecting additional information about the operation of the instrument landing system at the Buffalo airport, according to people familiar with the situation.

On Wednesday, the union that represents the pilots at Dallas-based Southwest Airlines Co. issued a bulletin to its members, warning of a "potentially significant hazard" concerning the instrument landing system that helps guide aircraft to Runway 23, the strip the commuter plane was heading toward before it went into a dive and slammed into a house on Feb. 12.

The bulletin warned pilots that a hill of dirt on the right side of the instrument landing system creates a distortion in the radio signal that guides planes to the runway from that direction. It said that the distortion can cause planes to abruptly pitch upward to angles of "as much as 30 degrees" and lose airspeed.

The bulletin is particularly interesting to investigators as they piece together the final seconds of the flight. One of the mysteries they are trying to solve is why Flight 3407 experienced a rapid decrease in airspeed, which caused the auto-pilot to disconnect and on-board stall warnings to go off.

The Federal Aviation Administration said Thursday that it was flight-checking the landing system, commonly referred to as an ILS.

A spokeswoman for the FAA said the problem with the landing system has been shown in the past to affect only planes entering from the north, making a right turn to line up with the runway. The accident aircraft was coming from the opposite direction, she said.

According to the flight-data recorder, the pilot of Flight 3407 reacted to the stall warnings by pulling back abruptly on the controls and holding them there, raising the nose 31 degrees before the plane pitched over into an unrecoverable dive. The proper response to a wing stall is to push forward on the controls to lower the nose and regain airspeed. Investigators are also trying to determine whether a buildup of ice may have affected the controllability of the plane.

The FAA has known about the ILS situation for years and has included warnings in its navigational charts and on a radio frequency that continuously broadcasts information about weather conditions and potential hazards at the airport.

Jeff Martin, Southwest's senior director of flight operations, said the airline originally issued the ILS bulletin Jan. 30 after receiving reports from some pilots about potential problems.

"We didn't see it as a huge threat, but we wanted to make sure our pilots are aware of a potential problem," Mr. Martin said.

Southwest contacted the FAA on Wednesday and specifically requested that all of its flights enter the landing pattern from the left side of the airport, in part because of the heightened attention on the airport as the result of the crash.