Caution, wake turbulence: What do you do?
Most general aviation pilots know
they need to maintain a safe distance from larger aircraft during approach and
landing. The question that arises is "how much distance?" On July 2,
2003, the pilot of a Beechcraft Baron and one of his passengers were killed
during an encounter with wake turbulence while on approach to Runway 36R at
Memphis International Airport. Two passengers also were seriously injured in the
The pilot of the Baron was in
contact with Memphis Approach and was told to expect the ILS to Runway 36R. The
Baron was then asked to slow down to 170 knots and was cautioned about wake
turbulence from an Embraer 145 Regional Jet on approach to Runway 36C about
four miles ahead. The Baron was then vectored and cleared for the ILS Runway
A pilot taxiing between Runways
36R and 36C saw the Baron on final approach and stated that it was about 10 to
15 feet above the runway and "had it made." The Baron then yawed and
rolled to the left, appearing to try a sidestep maneuver to the other runway.
The plane then pitched up about 15 degrees, abruptly rolled to the left, and
hit the ground inverted.
The investigation revealed that
the Baron was about 3.5 miles behind the ERJ and that the "wake vortex of
the ERJ 145, in particular the right wing tip vortex (downwind counterclockwise
rotating), could have migrated toward the Baron's flight path. An airplane's
typical response to a counterclockwise rotating wake vortex would be to roll to
The Air Traffic Controller's
Handbook (FAA Order 7110-65P) states that runways that are less than 2,500
feet apart should be treated as a single runway because of the possible effects
of wake turbulence, and that for a small aircraft landing behind a large
aircraft, the separation should be four miles.
The NTSB determined the cause of
this accident was the encounter with wake turbulence on approach, which
resulted in the pilot's inability to maintain control.
According to the Aeronautical
Information Manual (AIM), when landing behind a larger aircraft (including
one on a parallel runway within 2,500 feet), stay at or above the larger
aircraft's final approach flight path, note its touchdown point, and then land
To learn more about wake turbulence and how to avoid it, take the AOPA Air Safety Foundation's Wake Turbulence Sporty's Safety Quiz, and read Bruce Landsberg's "Wake Turbulence: Should You Worry?" from the October 1998 issue of AOPA Pilot magazine