What happened
On 6 July 2016, a Klemm Kl35D, registration HB-UBK, was conducting a private flight from Southend to Old Warden. While descending through 1,500 to 2,000 feet near Luton, the pilot noted an audible change in the engine's performance. This prompted an immediate declaration of an emergency. Following guidance from Elstree ATC, the pilot turned toward a nearby airfield, but the Hirth Motoren KG HM 504 A2 engine lost all power approximately five minutes later.
Seeking a suitable site for an emergency descent, the pilot identified a field near Earls Lane, South Mimms. While maneuvering on the downwind leg of the forced landing, the pilot encountered a line of trees obstructing the path. To avoid the obstacle, a 180-degree turn was executed at minimum airspeed, resulting in a significant loss of altitude. As the turn was completed, the pilot pulled back on the controls to prevent a nose-first impact. At an altitude of roughly 10 feet, this maneuver induced a stall, causing the aircraft to strike the ground on its right wing.
The investigation
The investigation established that the impact was severe enough to cause the wings and the undercarriage to detach from the fuselage, with the engine sustaining significant damage. Although the pilot and passenger were able to exit the open cockpit unassisted, the pilot required hospitalization for serious injuries.
Findings
- The engine failure necessitated an unplanned forced landing.
- The pilot attempted to avoid a tree line by performing a 180-degree turn at the aircraft's minimum flying speed.
- The loss of altitude during the turn, followed by an attempt to raise the nose at a very low height, led to the aerodynamic stall.