What happened
On August 15, 2003, a Cirrus SR20, registration N209CD, was participating in the "International Ladies Cup 2003" navigation rally. The flight was approaching Teuge Airport (EHTE) for a precision target landing. During the approach to the traffic pattern, the crew encountered several other aircraft, including a Cessna PH-JMP and a Boeing MD900 Explorer helicopter, registration N920 and 01U.
To maintain separation from the PH-JMP, which had overtaken them, the pilot of the N209CD performed a 360-degree turn on the base leg. This maneuver placed the N209CD behind the helicopter in the landing sequence. As the helicopter slowed its speed near the runway threshold to maintain distance from the preceding aircraft, the N209CD closed the gap significantly.
While on final approach, the N209CD entered the wake vortex produced by the helicopter. The turbulence caused the aircraft to become uncontrollable, resulting in a sharp, uncontrolled left bank. In an attempt to avoid nearby buildings, the pilot applied full power, but the aircraft's low speed and high-drag configuration (with flaps fully extended) led to an aerodynamic stall. The aircraft subsequently struck a cornfield outside the airport perimeter, resulting in two injuries (one serious) and the total destruction of the aircraft.
The investigation
The Dutch Safety Board (OVV) examined the flight sequence, the aircraft's technical condition, and the environmental factors at Teuge Airport. The investigation reconstructed the traffic pattern, noting that the rally had increased the volume of aircraft in the circuit. Investigators also reviewed video footage, which confirmed the aircraft's high nose attitude and the sudden loss of control near the runway threshold.
Findings
- The direct cause of the accident was the loss of control of the N209CD due to the wake vortex from the helicopter, followed by an aerodynamic stall during an evasive maneuver.
- The PH-JMP had performed an unauthorized overtaking maneuver, which disrupted the established order of the traffic pattern.
- The pilot of the N209CD performed a 360-degree turn that further altered the sequence, placing the aircraft directly behind the helicopter.
- The crew failed to consider an alternative method for increasing separation and chose to continue the landing despite the dangerously small distance to the helicopter.
- Low wind conditions allowed the helicopter's wake vortex to remain hovering over the runway threshold.
- The aircraft was in a high-drag, low-speed configuration with full flaps, leaving the pilot with minimal control authority to recover from the turbulence.
Safety action
- The OVV recommended that the management of Teuge Airport and the organizers of the "International Ladies Cup" implement better regulations to separate rally traffic from regular airport operations.