KARACHI: A Pakistan-registered Boeing 737 cargo aircraft carrying five crew members lost contact with air traffic control over the Arabian Sea on Tuesday night after reporting a navigational system malfunction while en route from Sharjah to Karachi, aviation officials said.

The 27-year-old converted freighter, operated by K2 Airways, reported a technical fault with its navigation system at 9:18pm Pakistan Standard Time while flying over the Arabian Sea.

According to the Pakistan Airports Authority, air traffic controllers attempted to guide the aircraft after receiving the distress report, but communication was lost shortly afterwards.

Authorities said the aircraft’s last known position was approximately 155 nautical miles (287 kilometres) southwest of Karachi.

A coordinated search and rescue operation involving multiple state agencies has been launched to locate the missing aircraft and its five crew members.

Flight-tracking data indicated the aircraft experienced unusual altitude fluctuations in its final minutes before disappearing from radar.

According to preliminary tracking information from Flightradar24, the aircraft descended nearly 5,000 feet in less than a minute before climbing around 6,000 feet within 30 seconds. It then reportedly entered a steep descent from an altitude of 36,550 feet.

The final transmitted data placed the aircraft at approximately 1,100 feet above sea level, with an unusually high descent rate before all communication ceased.

In a statement, K2 Airways said it was fully cooperating with the Pakistan Civil Aviation Authority and other relevant government agencies.

“We continue to pray earnestly for the safety of our colleagues,” the airline said.

Aviation experts cautioned against drawing conclusions before the recovery of the aircraft and completion of a formal investigation, noting that flight-tracking data alone cannot determine the cause of the incident.

The missing Boeing 737-400, powered by CFM International engines, was originally delivered to Russia’s Aeroflot as a passenger aircraft in 1999 before being converted into a cargo aircraft in 2012. It entered service with K2 Airways as the airline’s sole aircraft in 2024.

According to available flight records, the aircraft had not operated a flight since June 28.

Authorities said search and rescue efforts were continuing, while the fate of the crew remained unknown.