Pakistan's Civil Aviation Authority said in a post on X that search-and-rescue operations were under way in the Arabian Sea for the aircraft, which was carrying five passengers.

The Boeing 737 was being operated by Karachi-based K2 Airways on a cargo flight from Sharjah in the United Arab Emirates to Karachi when it reported a navigation system problem at 9.18pm local time, the Civil Aviation Authority said.

The Civil Aviation Authority added that radar data showed the aircraft rapidly descending and making a sharp change in heading at about 9.21pm, before radar and radio contact were lost about 155 nautical miles west of Karachi.

Data from flight tracking site Flightradar24 showed the aircraft first lost altitude and then briefly climbed, before another dramatic drop.

The last transmitted data point placed the aircraft at 1,100 feet above sea level, with a vertical rate of minus 22,400 feet per minute, Reuters news agency reported.

This is an extremely steep and abnormal rate of descent.

The plane is believed to have dropped approximately 35,000 feet in less than two minutes, according to tracking data.

Pakistan's Geo News added that the aircraft went missing while flying over the Arabian Sea near Ormara in Balochistan.

The aircraft is one of Boeing's decades-old 737. The 737-400 was first delivered as a passenger plane to Russia's Aeroflot in 1999, but in 2012 it was converted ​to a freighter.

It is K2 Airways' only aircraft ​and entered ⁠into service with the carrier in 2024.

K2 Airways is a private Pakistani cargo airline based at Jinnah International Airport in Karachi. Founded in 2017, the airline operated scheduled and charter freighter flights, primarily connecting domestic hubs and regional international destinations.

There is currently no confirmed cause of the disappearance. Officials have only confirmed that the crew reported a navigation system issue shortly before contact was lost.

Investigators will examine flight data, communications and any wreckage recovered before determining what happened.

If casualties are confirmed, the incident would be the first fatal crash in Pakistan since 2020, when a Pakistan International Airlines ⁠Airbus A320 ​came down short of the runway in Karachi.

Ninety-seven lost their lives in the incident.