What happened
On December 2, 2010, at 17:20 UTC, a Dornier Do 228-202, registration CS-TGG, was performing a commercial passenger flight from Vila Real Airport (LPVR) to Bragança Airport (LPBG). The flight, operated by Aero Vip, carried two crew members and four passengers.
During the approach to runway 02, the aircraft encountered adverse weather conditions, including heavy snow and reduced visibility of approximately 600 meters. As the aircraft reached the end of the touchdown point, approximately 1.3 nautical miles from the threshold, the landing gear struck three medium voltage power line cables. The impact severed the lines, resulting in electrical power outages for nearby villages and the airport. The crew initially reported the event as a possible bird strike. Despite the collision, the aircraft sustained no damage and was able to complete a normal landing.
The investigation
The GPIAAF investigation established that the flight crew was properly certified, trained, and medically fit for the operation. The aircraft was found to be airworthy, with all maintenance and weight and balance requirements within limits. The investigation focused on the atmospheric conditions and the accuracy of the aircraft's instruments during the approach.
Findings
- The approach was conducted under visual flight rules (VFR) despite significantly reduced visibility due to heavy snow.
- There was a failure to correct the altimeter error caused by low temperatures and the terrain's altitude.
- Due to this uncorrected error, the aircraft's true altitude was 135 feet lower than the altitude indicated on the altimeters.
- The medium voltage power lines lacked visible marking or signaling.
- There was no published RNAV approach available for runway 02 at Bragança Airport at the time of the incident.
Safety action
Following the investigation, the following safety actions were identified:
- Safety Recommendation 34/2016: Directed to ANAC to validate the Aero Vip operator's procedure for an RNAV approach to runway 02 at Bragança Airport.
- Safety Recommendation 35/2016: Directed to EDP Distribuição to install light signaling on power line supports number 4 and 5 of the line serving PTD 0227-BGC.
As a result of the incident, Aero Vip implemented an operational standard involving an altimeter correction table based on temperature and airfield altitude, which was placed on the flight deck. Additionally, EDP Distribuição installed signaling balls on the affected power line span.