Piper PA-44-180 Serious Incident at Prague Airport (OK-MLR)

Incident Overview and Flight Details On January 20, 2003, a Piper PA-44-180, registration OK-MLR, operated by F-AIR, spol. s r.o. from Benešov, experienced a serious incident at Prague Airport. The flight, which took off between 09:45 and 10:05 UTC, was intended for IFR qualification testing. Following takeoff, the aircraft's course system failed, a fault detected when the pilot deviated from the direction of Runway 31. The pilot immediately notified Ruzyně Radar on 119.00 MHz and requested radar vectoring to the ILS for Runway 31, where Visual Meteorological Conditions (VMC) prevailed. During the approach, both NAV 1 and NAV 2 systems displayed unreliable glide slope (GS) indications while the aircraft was 7 nautical miles from the runway threshold. Consequently, the pilot requested and was granted a visual approach, landing the aircraft without incident or damage. ## Crew, Aircraft, and Environmental Factors The flight crew consisted of a 56-year-old pilot-in-command holding a Commercial Pilot License (CPL) with 10,892.20 total flight hours, and a 28-year-old pilot with 250 total flight hours. The 1980-manufactured aircraft, serial number 44-8095018, had 2,384.10 flight hours at the time of the incident. Its last 50-hour inspection was completed on August 26, 2002, and a radio navigation check on September 9, 2002, confirmed the equipment was suitable for IFR flights. A repair to the NAV 1 (HSI) connector was performed on January 16, 2003, by LD Aviation Prague. Weather conditions at Prague between 08:00 and 10:00 UTC included visibility of 6–8 km, winds from 140–180° at 1–4 m/s, cloud bases at 390–450 m AGL, and temperatures between -1°C and +2°C. ## Investigation Findings and Safety Recommendations The investigation, conducted by the Institute for Professional Technical Investigation of Causes of Aviation Accidents (ÚZPLN), concluded that the serious incident was caused by the failure of the course system and the unreliable function of the NAV 1 and NAV 2 systems during glide slope indication. No injuries, aircraft damage, or other losses occurred. Following the event, the aircraft was transported to LD Aviation Prague at Prague-Kbely Airport for repairs. The ÚZPLN recommended that the operator conduct a check flight focused on the course and navigation systems after the fault was rectified, and report the results to the Civil Aviation Authority (ÚCL). The decision on further operational measures was left to the ÚCL.