Factual Information
On June 27, 2008, at 19:00 UTC, a Tecnam P-92 Echo ultralight aircraft, registration CS-UHB, operated by Aero Clube de Pias Longas, was involved in an incident during a training flight at Pias Longas ULM airstrip in Ourém, Portugal. The flight was a pilot instruction session with two occupants: an instructor and a student pilot. The aircraft was in a taxi phase. No injuries were reported, and the only damage was to the propeller tips.
During initial taxi, the instructor noticed the student had difficulty managing engine power and lateral control. After aligning on runway 30, the instructor decided to cancel the flight and instead practice ground coordination and control. While exiting the runway to the parking apron, the student missed the first exit and, on the second attempt, failed to notice a runway marker cone (also used to delineate two taxi paths) and struck it with the propeller. The cone was a metallic marker, and due to the wooden propeller's non-repairable damage, it was replaced, and the engine was tested and found operational.
The airstrip at Pias Longas is at 1070 ft altitude, with a gravel strip 550 m by 20 m, used for ultralight operations. The apron connects to the runway via a single path informally divided into two taxiways separated by a virtual line marked by a metal cone. On that day, the cone was displaced about 5 meters forward from its normal position toward runway 30.
Analysis
The primary mission was flight training, but it was changed to ground taxi exercises due to the student's difficulty in controlling the aircraft to the takeoff position. The student's inability to control the aircraft likely prevented awareness of the obstacle, which was on the right side (opposite the student) and blended with the ground. The instructor should have been more proactive in issuing a warning or corrective action. The low contrast of the cone against the limestone soil and the sun's position (low on the horizon, about 30 degrees left of the runway axis) likely reduced visibility. The instructor's familiarity with the airfield should have made him aware of marker positions. The collision did not damage the engine crankshaft due to low RPM and the reduction gearbox.
Conclusions
The investigation concluded that the flight was authorized and planned, the aircraft was airworthy, and no mechanical defects were found. The incident occurred near the end of the day with the sun low at about 30 degrees relative to the runway. The white marker cones had poor contrast against the light-colored soil. The student pilot was inexperienced and showed difficulty in ground control. The instructor did not perceive the obstacle in time to correct the trajectory. Both occupants were uninjured. The aircraft sustained minor damage.
Probable Cause
The incident was due to lack of awareness of the obstacle caused by excessive concentration on ground control maneuvers, compounded by poor contrast between the obstacle and the surrounding environment and the effect of the sun's position at the time of day.