Incident Overview
On February 27, 2016, a Cessna 152 departed from EPBC (Bielsko-Biała Airport) and planned a low pass over the runway at EPWA (Warsaw Chopin Airport). The pilot was in communication with FIS EPWA and was identified on radar. While flying from VFR Z to VFR N at approximately 18:44 at an altitude of 1,400 feet, the pilot contacted TWR EPWA. The controller instructed the aircraft to proceed to VFR E, maintaining 1,000 feet upon arrival.
Transponder Issues
At around 18:47, while inbound to point N, the aircraft's radar track disappeared from the radar display. The crew confirmed that the transponder was set to ON and that the altitude was 1,000 feet. The TWR controller repeatedly instructed the crew to fly right parallel to Runway 15 and then continue toward the city. At approximately 18:54, the radar showed the aircraft's track with squawk code 7406 at about 3 nautical miles northwest of point E, at 1,000 feet, heading towards EPBC. The track appeared and disappeared multiple times.
Continued Flight and Communication
Around 18:59, the aircraft reported VFR O, and TWR instructed it to proceed to VFR N. The crew acknowledged a climb to 1,500 feet. After passing 1,100 feet, the track reappeared. Later, the crew requested to fly to VFR J and perform a low pass at AD EPMO (Mazowiecki Airport). While in CTR EPMO below 1,000 feet, the track again disappeared. After exiting CTR EPMO, FIS EPWA asked the crew to descend from 1,400 feet to below 100 feet. At approximately 900 feet, the track vanished once more. The crew then confirmed a problem with the transponder.
Cause and Outcome
The investigation identified the cause as a transponder failure. The incident was discussed with other flying personnel. The transponder was removed from the airframe and replaced with a new unit. No safety recommendations were formulated.