What happened
On September 4, 2023, at approximately 16:50 local time, a Waco Classic Aircraft YMF, registration N901DP, was performing a local flight in the Medellín area. The aircraft, an ultralight, was operated by a pilot and one passenger. After a 35-minute flight, the pilot attempted to land at Olaya Herrera Airport (SKMD) on runway 20.
As the aircraft's main gear made contact with the runway, the pilot began the transition to lower the tailwheel. During this phase, the aircraft encountered a crosswind gust. Due to P-factor and the loss of rudder effectiveness during the transition, the aircraft drifted to the right. At a speed of approximately 15 knots, the pilot attempted to correct the deviation by applying the brakes on both main wheels simultaneously. Because the tailwheel was not yet in contact with the pavement, this sudden braking caused the aircraft to pitch forward in a nose-over maneuver, resulting in the aircraft landing upside down on the runway.
Both occupants were able to exit the aircraft on their own and were found to be uninjured following medical evaluation.
The investigation
The GRIAA investigation focused on the sequence of events during the landing roll and the pilot's corrective actions. Investigators examined the aircraft's maintenance records, which showed the Waco Classic Aircraft YMF was airworthy and up to date with all required inspections. The investigation also reviewed meteorological reports, confirming the presence of wind gusts during the landing.
Technical analysis of the aircraft revealed substantial damage to the propeller blades and the empennage due to the impact. The investigation also evaluated the pilot's proficiency and operational procedures, noting that while the pilot was highly experienced with over 20,000 total flight hours, the specific technique used to manage the crosswind and braking was inappropriate for the aircraft's configuration at that moment.
Findings
- The pilot failed to maintain directional control during a crosswind landing.
- The pilot applied simultaneous braking on both main wheels while the tailwheel was still airborne.
- A crosswind gust, combined with P-factor, caused the aircraft to deviate from the runway centerline.
- The pilot's attempt to correct the deviation was erratic, involving a sudden reduction in power and heavy braking, which triggered the nose-over.
- The aircraft was operating within its approved weight and balance limits.