St. Louis Downtown Parks Airport
Aircraft Accident/Incident Report

Cahokia, Illinois 62206
Thursday, March 18, 1999 15:18 CST

The dual student reported that during final approach to runway 30R, the airplane encountered, 'somewhat severe turbulence'. The dual student stated that, '...the turbulence was severe enough to require the assistance of his instructor...to recover from the turbulence encounter.' The dual student reported that upon completion of the landing and subsequent takeoff, '...they again encountered turbulence on takeoff and the airplane began a rolling maneuver until impact.' Reported winds taken immediately after the accident were wind from 320 degrees at 11 knots gusting to 18 knots. Prior to and during the time of the accident a United States Army Chinook helicopter was operating upwind and parallel to the active runway. A transcript of the voice communications between aircraft and Federal Aviation Administration (FAA) Air Traffic Control (ATC) did not disclose any wake turbulence cautionary advisory or hazardous condition advisory transmissions given by the local controller to any aircraft. Research revealed that rotor wake turbulence, generated by the Army helicopter, had the potential to drift across the runway and the final approach course. A 1996 FAA study, entitled 'Flight Test Investigation of Rotorcraft Wake Vortices in Forward Flight', recommended that ATC separation standards should exist between heavy helicopters and small fixed-wing aircraft to prevent rotor wake turbulence encounters.

the in-flight loss of control by the student pilot due to wind turbulence. Additional causes were the flight instructor's inadequate supervision of the flight and the flight instructor's decision to continue the touch and go after encountering turbulence on the vfr final approach that had required the flight instructor's intervention to correct.