Aviation report 2013/14
A private pilot flying with a passenger were about to look at a house in Kåfjorddalen in Troms County, Norway when the airplane hit a cable car wire. Parts of the tail and the right wing were torn off the airplane and the plane was close to becoming uncontrollable. However, the commander regained control and landed later at Tromsø Airport Langnes (ENTC). The cable car was equipped with an Obstacle Collision Avoidance System (OCAS) warning system, but neither the flashlight nor the aural warning via the VHF-radio was detected by the pilot. The investigation has revealed that the warning lights were ineffective. Furthermore, the system has a fundamental weakness because the aural warning is only allowed to be transmitted at 6 frequencies. These frequencies does not necessarily correlate with the frequencies used for radio communication in the area, and have to be intentionally set manually for the warning to be received. The AIBN believes that the Norwegian CAA has not given these issues sufficient focus during the system's operational approval.
Safety recommendation
Safety recommendation SL nr. 2013/02T
A large number of OCAS installations are currently out of service.
The Norwegian Accident Investigation Board therefore recommends that the Norwegian Civil Aviation Authority immediately find compensatory measures to ensure that obstacles to aircraft in flight equipped with OCAS installations get a satisfactory warning system.
Safety recommendation SL nr. 2013/03T
The Norwegian Accident Investigation Board is of the opinion that difficult and partly misleading information about OCAS installations degrades the warning system efficiency.
The Norwegian Accident Investigation Board recommends that information about the system's functionality, active frequencies and individual installation locations must be substantially improved in order to reach important user groups.
Safety recommendation SL no. 2013/04T
The Norwegian Accident Investigation Board is of the opinion that future systems for obstacle warning to aircraft in flight should be based on readily available equipment/methods such as the use of GPS and electronic maps. A database of obstacles already exists at NRL.
The Norwegian Accident Investigation Board therefore recommends that the Norwegian Civil Aviation Authority in collaboration with a map provider find a solution so that this information can be made conveniently available to actual user groups.
Facts
| Location | Kåfjorddalen in Troms County, Norway |
| Occurrence date | 07.04.2010 |
| ICAO Location indicator | ENTC |
| Aircraft | Piper PA-28 Cherokee/Arrow/Archer m.fl. |
| Operator | Tromsø Flyklubb |
| Registration | LN-TOS |
| Meteorological conditions | VMC |
| County | Troms |
| Type of occurrence | Accident |
| Type of operation | Private (club) |
| Category of operation | Light, aeroplane (< 5 700kg) |
| Aircraft category | Landplane, Single-engine, Piston engine |
| FIR/AOR | ENBD (Bodø ATCC) |