Egyptian authorities began examining the flight data recorder from a Russian jetliner that went down in the Sinai Peninsula, searching for clues about a crash that killed all 224 people on board and prompted several international airlines to divert their planes from the area.

The recorder, or black box, aboard the Airbus 321 operated by Russia’s Metrojet was sent to Cairo for analysis by the Civil Aviation Ministry, ministry spokesman Mohammed Rahma said Sunday by e-mail. Russian officials were also in Egypt to investigate what brought down the jet 23 minutes after it left the Red Sea resort of Sharm El-Sheik.

Prime Minister Sherif Ismail said in a televised news conference on Saturday that it would be premature to speculate on the cause of the crash before the data on recorders were analyzed. The second pilot’s former wife told Russia’s NTV channel that her husband was worried about the aircraft’s technical condition.

Conflicting reports have emerged about whether the pilot, who was flying at an altitude of 31,000 feet, indicated a technical problem. While Civil Aviation Minister Hossam Kamal said the pilot hadn’t radioed an SOS call, the Dubai-based Al- Arabiya satellite channel reported he had sought permission to land at a nearby airport. 

Adding to the uncertainty, Islamic State’s affiliate in Sinai claimed responsibility for the crash, though officials and experts questioned whether it has weapons capable of downing aircraft flying so high.

“It is technically difficult to target a plane at that level,” Ismail said. “We have no evidence that anything unusual was happening on the plane before it crashed.”

Sinai Campaign

Islamic State’s statement doesn’t specify how the plane was downed and the local affiliate may have jumped the gun to take credit, Mokhtar Awad, an analyst at the Center for American Progress, a research institute in Washington, said by e-mail. Russian Transportation Minister Maxim Sokolov said on state television that reports of a terrorist missile aren’t credible.

Former Israeli national security adviser Yaakov Amidror, an army reserves general, concurred that it was unlikely an Islamist group shot down the aircraft. But “other scenarios also have to be considered, especially the possibility that the plane was sabotaged at the airport before taking off,” Amidror said.

Preliminary investigations indicate the plane went down due to a technical problem, the state-run Ahram Gate website said, citing Egyptian security officials. The plane had reached cruising altitude before crashing in the remote Al Hassana area of central Sinai, about 50 kilometers (30 miles) south of Al- Arish. Egyptian security forces have been waging a fierce campaign in the area against militants who have pledged allegiance to Islamic State.

Flight Paths

The crash, which may be Russia’s deadliest airline disaster, could signal even more troubles for Egypt’s important tourism industry, which has yet to fully recover from the beating it took after the 2011 ouster of President Hosni Mubarak. About a fifth of all tourists visiting Egypt come from Russia, making it the largest source of vacationers to the North African country.

Russian officials began the process of repatriating bodies to St. Petersburg, the Interfax news agency reported, citing Vladimir Stepanov, deputy head of the Emergency Situation Ministry. Egypt’s state-run Al Akhbar newspaper said 173 bodies had been recovered as of 1 a.m. local time.

Air France, the French unit of Air France-KLM Group, Deutsche Lufthansa AG, Emirates Airlines and FlyDubai said they would avoid flying over the Sinai area until the cause of the crash is known.

Flight paths came under public scrutiny following the downing of Malaysia Airlines Flight 17 in July 2014 over eastern Ukraine, an area some airlines skirted because of fighting between government troops and pro-Russian separatists. Investigators said the crash, which killed 298 people, was caused by a missile.

In its final seconds Saturday, the Metrojet plane was bucking wildly, abruptly climbing and descending before communication was lost, according to FlightRadar24.com, which tracks flight routes. At times it dropped as fast as 6,000 feet per minute, only to reverse and climb even faster, repeating that pattern several times. At other times, it slowed dangerously. About 24 seconds before losing contact, it dropped to 71 miles per hour from 470 miles, according to the data. Jetliners such as the Airbus 321 can’t stay aloft at such a speed.

If the FlightRadar24 data are correct, “it probably rules out sabotage,” said Paul Hayes, director of air safety and insurance at Ascend Worldwide. “It’s probably some sort of control problem.”

Speed Loss

Most worrisome is data showing a loss of speed, according to John Cox, a safety consultant and former airline pilot. “That bothers me,” he said. “I wonder, did they manage to get the airplane stalled?”

Two recent accidents occurred with Airbus aircraft climbing sharply before losing speed and falling. In June 2009, an A330 operated by Air France went down in the Atlantic Ocean and in December 2014, an A320 operated by AirAsia Bhd. crashed in the Java Sea.

The A320 family is Airbus’s most popular plane, a single- aisle, twin-engine type that allowed it to create a global duopoly with Boeing Co. for large passenger aircraft. The A321 is the longest variant.

The plane, operated by Metrojet since 2012 and produced in 1997, had logged about 56,000 flight hours over the course of nearly 21,000 flights, according to a statement from Blagnac, France-based Airbus.

Metrojet isn’t attributing the crash to human error, Interfax reported, citing Oksana Golovina from Tourism Holding & Consulting, which owns Kogalymavia, as the carrier is known in Russia.

Deadly Crashes

Russian President Vladimir Putin declared Sunday a day of mourning. Since the Soviet Union collapsed in 1991, there have been at least 100 deadly passenger plane crashes involving aircraft operated by Russian airlines that have killed more than 2,000 people, according to Aviation Safety Network data.

BEA, France’s air safety authority, is sending two officials to the crash site and six Airbus investigators will go as well, according to an e-mailed statement. Russia and Germany are also sending people, BEA said.