A Pakistan-registered Boeing 737 cargo aircraft carrying five crew members disappeared from radar on Tuesday night after reporting a navigation system problem while approaching Karachi, triggering a major search-and-rescue operation over the Arabian Sea. The aircraft, operated by Karachi-based K2 Airways, was flying from Sharjah in the United Arab Emirates when it informed air traffic control of a navigational system issue at around 9:18 pm Pakistan Standard Time. According to the Pakistan Airports Authority, controllers attempted to guide the aircraft after receiving the distress report. However, within three minutes, radar showed the plane descending rapidly before all communication was lost. The aircraft's last known position was about 155 nautical miles (287 km) west of Karachi. Flight Data Suggests Possible Sea Crash Preliminary flight-tracking data from Flightradar24 indicates the 27-year-old converted Boeing 737-400 freighter may have crashed into the Arabian Sea after its altitude fluctuated dramatically in its final moments. The tracking service showed the aircraft plunging around 5,000 feet in less than a minute, climbing nearly 6,000 feet within 30 seconds, and then entering a catastrophic descent from 36,550 feet. The final transmitted data placed the aircraft at just 1,100 feet above sea level, descending at an extraordinary 22,400 feet per minute—an unusually steep rate that aviation experts say is highly abnormal. Experts Puzzled by Final Moments Aerospace safety consultant Anthony Brickhouse cautioned against drawing conclusions but acknowledged the unusual flight profile. "Anytime you see something extreme like that, it catches your eye, but it is too soon to say what any of it means without more information," he said. Earlier, aviation expert Imran Aslam also questioned the aircraft's rapid descent, noting that even in the event of engine failure, aircraft typically glide rather than plunge sharply.Massive Search Operation Underway Pakistan has launched a coordinated search operation involving multiple civilian and military agencies. The Pakistan Navy dispatched frigate PNS Zulfiqar to the aircraft's last known location, while the Pakistan Air Force deployed aircraft to assist in the search. A Pakistan Navy ATR surveillance aircraft flew from Turbat, and a merchant vessel operated by the Pakistan National Shipping Corporation was also diverted to the search area. K2 Airways said it is fully cooperating with the Pakistan Civil Aviation Authority and other government agencies. "We continue to pray, earnestly, for the safety of our colleagues," the airline said in a statement. About the Aircraft The missing aircraft is a Boeing 737-400, part of Boeing's classic 737 family and two generations older than the 737 MAX. Powered by engines manufactured by CFM International, the aircraft was originally delivered as a passenger jet to Russia's Aeroflot in 1999 before being converted into a freighter in 2012, according to Flightradar24. The aircraft entered service with K2 Airways in 2024 and is the airline's only aircraft. Flight-tracking data shows it had not operated since June 28, before Tuesday's flight.Echoes of Pakistan's 2020 Air Disaster If fatalities are confirmed, the disappearance would mark Pakistan's first fatal aviation accident since the 2020 Pakistan International Airlines crash, when an Airbus A320 crashed near Karachi while attempting to land, killing 97 of the 98 people on board. Investigators are now examining the aircraft's final radar data, reported navigation system malfunction and erratic altitude changes as the search for the missing Boeing 737 and its five crew members continues.