Piper PA-28A-161 OK-AKA Radio Communication Incident

Incident Overview and Aircraft Details On 18 June 2004, a Piper PA-28A-161 with registration OK-AKA, operated by F AIR, spol.s r.o., was conducting an instructional flight from Karlovy Vary (LKKV) to Prague (LKPR). The aircraft, manufactured by New Piper Aircraft in Vero Beach, Florida, USA, had a serial number of 2842004 and a total time of 2,397 hours and 29 minutes at the time of the incident. The flight was planned at flight level 50 under the control of Prague Area Control Center (ACC LKPR). ## Sequence of Events During the flight, the aircraft lost two-way radio communication with air traffic control. Approximately 10 minutes before reaching the RAK VOR, the pilot-instructor failed to respond to further calls on the assigned frequency of 120.520 MHz. Subsequent attempts to establish contact on the emergency frequency of 121.5 MHz were unsuccessful. After passing the RAK VOR, the aircraft's SSR transponder also stopped responding. The pilot-instructor identified that the aircraft's radio transmitter was frequently switching on and off automatically, which blocked communications for other users on the frequency. Efforts to control the communication from the left control of the student pilot resulted in weak transmission and unintelligible reception. The pilot attempted to switch from COM2 to COM1 and retune the radio, but these actions were unsuccessful. ## Resolution and Landing To alert air traffic control to the loss of two-way communication, the pilot set the SSR transponder to code A7600. Communication was subsequently established via the ICOM22A on frequency 119.00 MHz. The pilot received instructions from Prague Approach (APP LKPR) to cancel the A7500 code, which had been set incorrectly. The pilot then cancelled the IFR flight plan and continued with radar vectors to a position downwind of runway 31 at LKPR, where a successful approach and landing were completed. The loss of communication resulted in the suspension of all departures from LKPR, with an average delay of 20 minutes. ## Investigation Findings The investigation determined that the loss of two-way communication was caused by a technical fault in the Push-To-Talk (PTT) button, specifically a blockage of the right control's radio station operating button. The damaged button was replaced, and the radio station was checked in an authorized service center with no further faults found. ## Personnel and Conditions The pilot-instructor was 59 years old, held a valid ATPL and medical certificate, and had approximately 200 hours on the PA-28 type. The student pilot was 42 years old, held a valid PPL(A) and medical certificate, and had 25 hours on the PA-28 type. Both were qualified and medically fit for the flight. The weather conditions were CAVOK and had no influence on the incident. The aircraft was fully airworthy before the flight, and the engine and fuel type were not factors in the incident. The last radio navigation equipment check for IFR flights was performed on 22 January 2004. ## Safety Recommendations No further safety recommendations were required as a result of the investigation.