The runway at Amsterdam's Schiphol Airport had been closed to all air traffic since Wednesday's crash, which also injured dozens of passengers.

Planes heading to the airport's Polder runway will now fly low over the wreckage of flight TK1951, which slammed into a muddy field one mile (1.5 kilometers) short of the runway and broke into three pieces.

Haarlemmermeer municipality spokesman Remco Asselbergs said flights would resume at 11 p.m. (2200 GMT). The runway is one of five at the airport.

Dutch Safety Authority spokesman Fred Sanders said investigators were still examining the wreckage for clues to the cause of the crash.

Possible causes under investigation include turbulence caused by another plane that landed shortly before the crash, weather-related factors, insufficient fuel, loss of fuel, navigational errors, pilot fatigue or bird strikes.

The wreckage is not expected to be removed from the field until Tuesday. Investigators hope to give a preliminary report on the cause of the crash later in the week after completing their analysis of voice and data recordings from the plane's black boxes.

Five Turks and four Americans died in the crash, including three Boeing employees from Washington state.

Boeing received confirmation on Friday that a third employee was identified as among the fatalities in Wednesday's plane crash in Amsterdam.

The dead have been identified as Ronald A. Richey of Duvall, John Salman of Kent, and Ricky E. Wilson of Clinton. Photos Of Boeing Employees Killed In Crash

A fourth employee, Michael T. Hemmer of Federal Way, was badly injured and remains hospitalized.

Mike Hemmer Michael T. Hemmer Michael T. Hemmer, of Federal Way, survived but was injured in the crash of a Boeing 737 in Amsterdam. Michael T. Hemmer

The employees on Turkish Air flight 1951 were on company business flying from Istanbul to Amsterdam when the Boeing 737-800 crashed just short of the runway at Amsterdam's Schiphol Airport.

All work for the company's defense division working on the Turkish "Peace Eagle" program, a Boeing-built military jet with an airborne early warning and control system.

VIDEO: Third Boeing Employee Confirmed Dead

A total of 135 people were on the flight. Dutch officials said a total of nine people were killed. The other five victims are Turks.

Investigators are trying to learn more about why the plane fell from the sky and broke into pieces. Dutch Investigators have said the engines may have quit, or lost most of their power in the moments before impact, but they're careful to say that's just one of dozens of possible causes for the accident.

They're also working with data from the plane's black boxes, and are pursuing a number of other lines of inquiry.

Meanwhile, a pilots group said so-called wake turbulence likely caused the crash. According to the Web site of the Hurriyet Daily News, the Turkey Airline Pilots' Association said turbulence left by the wake of a Boeing 757 that landed minutes earlier could have caused the crash of the Turkish Airlines 737.

The Turkish pilots group said the 737 descended very rapidly, which doesn't happen when the engines have stopped.

"We are asking, was the required distance placed between the two planes or not? Did the (air controller) inform the pilots of our plane that there was an aircraft ahead in the category of wake turbulence? Those questions should be answered," the Turkey Airline Pilots' Association General Secretary Savas Sen said Friday at a press conference, the Hurriyet Daily News reported.

Previous Stories: February 27, 2009: Pilots Group Blames Wake Turbulence For Crash February 26, 2009: 2 Boeing Workers Dead, 1 Injured In Plane Crash February 25, 2009: 4 Boeing Employees On Plane In Amsterdam Crash