Egypt Sends Submersible in Search for EgyptAir Jet’s Black Boxes

CAIRO — Egypt has deployed a submersible to help find the wreckage of EgyptAir Flight 804 in the deep Mediterranean waters where it crashed, President Abdel Fattah el-Sisi said Sunday, as he warned that it might take a “long time” before the cause of the crash was determined.

An international flotilla of search ships, aided by surveillance planes, was scouring a section of sea 180 miles north of the port city of Alexandria, and retrieved some wreckage, belongings and human remains over the weekend.

But the search crews have yet to find the main body of the plane and its cockpit data and voice recorders, commonly known as the black boxes. They hope the recorders will explain what caused the Airbus A320, carrying 66 people, to plunge from the sky early Thursday as it headed to Cairo from Paris.

A statement from the Islamic State on Saturday failed to mention the EgyptAir crash, confounding speculation that the group, which claimed to have been behind the crash of a Russian airliner in Sinai in October, might have been responsible.

Although Egyptian officials initially pointed to terrorism as the most likely cause of the crash, Mr. Sisi said Sunday that all possibilities were being considered. “All hypotheses are possible,” he said. “Please, let’s not jump to any conclusions.”

So far, the strongest clues have come from signals emitted by the stricken plane indicating that several smoke detectors were activated as it hurtled toward the sea.

The French air aviation authority said that while those transmissions provided evidence of a catastrophic systems failure inside the plane, they did not provide enough information to determine what had caused the crash.

The uncertainty added to the anguish of the relatives of the passengers, most of them Egyptian and French nationals. Emotional funeral services for some crew members and passengers took place in Cairo and other towns over the weekend; other families remained at two hotels near the Cairo airport, waiting for news. Six of the victims came from a single village, about 50 miles north of the Egyptian capital.

On Sunday night at the Abu el Makarim mosque in central Cairo, men in EgyptAir uniforms stood solemnly as prayers were offered for Mohammed Farag, one of three security officers on Flight 804. “He talked with his hands,” said Ahmad Shalash, recalling Mr. Farag. “Wherever he went, laughter followed him.”

Black-clad women sat around Mr. Farag’s mother, her face streaked with tears as mourners whispered condolences and prayers in her ear. Several people expressed frustration with the slow progress in the search for bodies.

EgyptAir, in a statement on Saturday, condemned efforts by unidentified people to capitalize on the tragedy by falsely claiming to be raising money for the victims’ families.

The submersible that Mr. Sisi said was headed for the search zone on Sunday is operated by the country’s Petroleum Ministry and can descend to a depth of 9,800 feet. The vessel was not manned and was normally used for oil and gas exploration, said Hamdy Abdel Aziz, a spokesman for the Petroleum Ministry.

Mr. Sisi said he hoped the submersible would find the flight voice and data recorders, although experts said it was not clear whether it had the necessary equipment to find them.

Both flight recorders are fitted with acoustic beacons, or “pingers,” that can be detected from a distance of up to about three miles. But those pings can be detected only by using specialized underwater microphones attached to lengthy towing cables. Only a few organizations have that kind of equipment and it was not believed that any of them had been enlisted by the Egyptian authorities.

The disappearance of Malaysia Airlines Flight 370 in 2014 renewed the focus on efforts to make black boxes easier to find when a plane crashes at sea or in a remote area. One proposal involves using a satellite Internet system, much like the ones that provide in-flight Wi-Fi for passengers, to transmit flight data back to the airline headquarters in real time.

In Washington on Sunday, government officials debated whether the Islamic State or some other terrorist entity had orchestrated the EgyptAir crash.

Representative Adam Schiff, a California Democrat and the ranking member of the House Intelligence Committee, said that the preponderance of evidence he had seen suggested terrorism might be less likely than initially thought — and that if the crash was an act of terror, it was more likely carried out by a “lone actor.”

“We’ve looked at the signals intelligence. We’ve looked at the manifests,” Mr. Schiff said Sunday on ABC’s “This Week.” “We have not come up with any hard evidence of terrorism as of yet.”