This is a sad story and I was amazed thinking about how long-and how
far - the turbulance from a jet could affect a smaller aircraft (Though
not confirmed at this time). Just like dirty wind on a race course but
on a much larger scale. And like the Tsunami, waves are built up by
significant pressures and travel until they are attenuated.
I'm sure some of you aeronautical types can appreciate the effects of
air turbulence better than me.
(I pasted the story below if the link does not work for you. I think
you need to register with the WP to view this article)
Jet's Presence Noted in Copter Crash
Survivor's Account Raises Wake Turbulence Issue, Report Says
By Michelle Boorstein
Washington Post Staff Writer
Saturday, January 22, 2005; Page B01
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
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
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."