A pilot on an Israel-bound flight has been stabbed by his co-pilot who was allegedly trying to “crash the plane”, with passengers fearing for their lives as the aircraft went into freefall.

The terror unfolded on Flydubai flight FZ1073 from the United Arab Emirates to Tel Aviv, with more than 170 Israeli passengers on board.

A group of hero passengers broke into the cockpit after the aircraft “entered a tailspin and began to dive”, said Israeli Prime Minister Benjamin Netanyahu.

Netanyahu said the passengers found the co-pilot “trying to sabotage the plane’s systems”.

“They saved many lives. ‌They prevented a heavy disaster,” he said.

A ⁠Netanyahu spokesman said the wounded pilot, covered with blood and lying on the floor, had clicked open the release on the cockpit door.

A second ​set of pilots on board, who were due to replace the first pair, landed the plane.

A photo of the pilot who was stabbed. Photo: Supplied

One of the bloodied passengers spoke with Netanyahu after landing and told him he grabbed the co-pilot in a chokehold and dragged him out of the cockpit.

“I called out to a bunch of Israelis on board, and two other guys came over. We pinned him down,” Yaniv Hayoun said.

“I jumped back, grabbed the controls, and started pulling back the handles.”

The aircraft’s flight data showed it suddenly and rapidly descended by nearly 14,000 feet in less than 30 seconds before a first emergency signal was sent on Wednesday morning (local time), according to flight-tracking website Flightradar24.

Israeli officials say the co-pilot tried to crash the ‌plane after stabbing the pilot but passengers subdued him while other pilots landed the plane safely in Saudi Arabia.

Yasmin Abukasis said her daughter Miriam, who was among the passengers on the flight, told her that she had heard screaming and that a man holding a knife had forced one of the pilots onto the floor, and that there was blood everywhere.

Describing the event as “a highly severe security incident,” Netanyahu said Saudi authorities would interrogate the ‌co-pilot.

The airline said in a statement that the underlying reasons for the event remained unknown and warned against “premature speculation”.

The cause of the altercation ‌between the pilots was not clear.

The co-pilot, who an Israeli official identified as an Omani citizen, was arrested after the plane landed, Netanyahu said.

Israel’s transport ministry said there would be a joint investigation of the incident with the defence establishment.

“All passengers are out of harm’s way,” Netanyahu said in a video statement released by his office.

He also ordered tighter security on both Israeli and non-Israeli carriers flying into Israel.

The passengers departed Saudi Arabia for Israel aboard a Flydubai replacement aircraft after eight hours on the ground.

The FlyDubai replacement plane later landed in Israel.

Israeli media published a photo purportedly taken from inside the plane, which appeared to show a passenger’s blood-soaked shirt.

Flydubai operates daily return flights between Dubai and Tel Aviv, a route that is popular among Israelis.

Saudi Arabia’s Tabuk airport, where the plane landed, said both pilots had been hospitalised after sustaining injuries.

-with AAP