A preliminary report on the Jan. 10 medevac helicopter crash near the Woodrow Wilson Bridge says that a 70-passenger jet passed the area less than two minutes before the helicopter went down and notes that the only survivor, a flight nurse, wondered whether it might have left a wake of dangerous air turbulence.
The nurse, Jonathan Godfrey, 36, of Chesapeake Beach told investigators for the National Transportation Safety Board soon after the crash that "we must have hit something," leading to initial speculation that the helicopter hit one of the construction cranes being used to build a new bridge.
But the transportation board's report says a traffic surveillance video shows an aircraft flying over the bridge about the time of the crash and descending after it had passed above and beyond the cranes being used to build a new bridge.
The nurse said he called the pilot's attention to the lights on the cranes, according to the report, "and the pilot acknowledged him." The report said Godfrey "remembered being over the outer loop of the span of the bridge, and then being submerged in the water with his seatbelt on, and his helmet off.
"He stated, 'I don't remember striking something, but my initial reaction was that we must have hit something.' "
The report does not conclude whether the LifeEvac helicopter -- which the report described as properly maintained -- encountered wake turbulence, an invisible whirlwind that comes off a plane's wings, then sinks and dissipates. The crash killed the other two crew members, pilot Joseph E. Schaefer III, 56, of Sterling and Nichole Kielar, 29, of Henrico County.
Wake turbulences can be very powerful and stretch for miles, so much so that planes are required to travel at certain distances from one another to avoid them. An Airbus A30-600 that crashed into a Queens, N.Y., neighborhood in 2001 encountered wake turbulence seconds before it went down. Airbus said the pilot's use of the rudder after the wake turbulence caused the tail of the aircraft to come off.
Phone calls to the transportation safety board were not immediately returned last night.
One air-safety expert said the report did not point to obvious wake turbulence from the jet, which passed over the bridge 105 seconds before the helicopter did and which was 900 feet directly overhead.
"Without further study, I would not consider that to be an obvious danger," said Peter Goelz, former managing director of the transportation board.
But Todd Curtis, a former Boeing safety official who runs a Web site about air safety, noted that wake turbulence is more likely to cause problems when two aircraft are of different sizes. He said it is also significant that wake turbulence sinks.
"The risk factors are lining up. The question is, how much wake turbulence was generated by the jet?" he said. "These are the kinds of conditions that are associated with wake turbulence."