Passengers aboard a Flydubai flight from Dubai to Tel Aviv have described how they subdued a man who stabbed one of the pilots and appeared to be attempting to disable the aircraft, in an incident that has drawn international attention and praise from Israeli and American leaders.

The plane plummeted 17,000 feet, or approximately 5,200 metres, in less than two minutes before passengers intervened and the aircraft was diverted to Tabuk airport in northwestern Saudi Arabia.

Yaniv Hayun, appearing in a bloodstained shirt, recounted the ordeal in a video posted by Israeli Prime Minister Benjamin Netanyahu on social media. Hayun said he realised something was wrong when the aircraft suddenly dropped.

"Someone screamed... the light went out," Hayun said.

He and others attempted to push open the cockpit door, but the stabbed pilot had fallen close to it, making entry difficult. Before losing consciousness, the injured pilot managed to open the door.

Upon entering the cockpit, Hayun said he found one pilot down and the attacker positioned between the two seats, on top of the instruments.

"I grabbed the attacker, put him in a chokehold, and pulled him - first and foremost - outside," Hayun said. "We pulled him out; it was a matter of seconds. I called out to the Israeli guys with us on the plane - I called them, and two other guys came over to me... we pinned [the attacker] down to keep him secure."

Passenger Haim Lazarovich told journalists: "Thank God I'm alive," adding that "the most terrifying moment in this flight was when the pilot loses control."

Oran Choen, an 18-year-old passenger, described the incident as "a very tough moment." "Maybe it was five minutes, but it feels like hell - I heard my brother behind me scream that we was going to die," he said.

A paramedic from Israel's ambulance service said a number of passengers were "very emotional and crying as they came off the plane."

The stabbed pilot, Indian national Captain Smit Machchhar, was taken to hospital and is reported to be in stable condition, according to the Indian embassy in Saudi Arabia.

Netanyahu praised Machchhar as a "true hero" of "extraordinary bravery." He also met the passenger who helped subdue the attacker when the replacement Flydubai aircraft landed at Ben Gurion Airport in Tel Aviv, where crowds gathered playing music, singing, dancing, and waving Israeli flags.

The attacker was arrested and is being questioned by Saudi authorities. No official motive has been provided.

Israeli Defence Minister Israel Katz described the incident as an "attempted jihadist terror attack."

US President Donald Trump said he had spoken with Netanyahu following the incident, stating it appeared the attacker was "perhaps a terrorist" or that there were other reasons behind the attack.