CAIRO — In an eerie coincidence, the EgyptAir jetliner that plunged into the Mediterranean on Thursday was once the target of political vandals who wrote in Arabic on its underside, “We will bring this plane down.’’
Three EgyptAir security officials said the threatening graffiti, which appeared about two years ago, had been the work of aviation workers at Cairo Airport. Playing on the phonetic similarity between the last two letters in the plane’s registration, SU-GCC, and the surname of Egypt’s president, Abdel-Fattah el-Sissi, some workers also wrote “traitor’’ and “murderer.’’
The officials, who were interviewed separately and who spoke on condition of anonymity to describe the airline’s security procedures because they were not authorized to speak publicly, said the graffiti had been linked to the domestic Egyptian political situation at the time rather than to a militant threat. Similar graffiti against Sissi, a former general, was scrawled across Cairo after the military ousted the elected president, Mohammed Morsi, in 2013.
Since then, the airline has put into effect a variety of new security measures in response to Egypt’s political turmoil, jihadi violence, and other aviation disasters like the crash of a Russian plane that killed 224 people in October. EgyptAir has fired employees for their political leanings, stepped up crew searches, and added extra unarmed in-flight security guards. Three such guards died in Thursday’s crash that killed 66 people on Thursday’s flight from Charles de Gaulle Airport in Paris, one more than the normal team of two for reasons that were not entirely clear.
Whether those moves were sufficient remained an open question Saturday as experts pored over data emitted by the plane in its final minutes for clues as to what had brought it down. The French air accident investigation authority confirmed that the data showed that several smoke alarms had been activated while the plane plunged toward the sea.
But they cautioned that the signals, sent by a monitoring system on board the Airbus A320 jetliner, did not offer enough information to conclude what had caused the crash.
“These are not messages that enable us to interpret anything,’’ said Sébastien Barthe, a spokesman for France’s Bureau of Investigations and Analysis. “If there is smoke, it means that there is potentially a fire somewhere, but it doesn’t tell us where the fire is, and it doesn’t help us establish whether it is something malevolent or something technical.’’
EgyptAir’s security procedures last came under scrutiny in March when a passenger on a domestic flight pretended to be wearing an explosive vest and forced the plane to land in Cyprus. The crisis was resolved within hours when the man, later determined to be psychologically troubled, surrendered. Egyptian authorities were quick to post surveillance videos that they said showed he had been searched before boarding the flight.
EgyptAir security guards differ in several respects from the undercover air marshals who travel on US airlines. The Egyptian guards are unarmed and wear an understated uniform consisting of a dark blazer and a white shirt. When called on, they help crew members deal with unruly passengers. They come from a wide variety of backgrounds and earn a moderate wage of about $400 a month.
Normally, one security officer sits in the first economy row, behind business class, and the other is at the rear of the aircraft, two members of an EgyptAir crew said. During stopovers at foreign airports, the security officers are usually responsible for searching the workers who clean the plane and checking the credentials of all crew members or employees who board. They do not monitor the baggage handlers who load the plane’s hold.
Security officials said those procedures would have applied to the EgyptAir plane during short layovers it made at two African airports — in Tunis and the Eritrean capital, Asmara — in the days before the crash. But the procedure is different in Paris because European airports do not permit EgyptAir security officials to search local cleaning workers, a source of disgruntlement among Egyptian officials who feel they are being discriminated against.
Colleagues described the security guards who died in Thursday’s crash — Walid Ouda, Mohammed Farag, and Mahmoud el Sayed — as professionals who had exhibited no signs of unusual behavior.
Friends and relatives also presented a uniformly untroubled picture of the pilot, Captain Mohamed Shoukair, 36, and his co-pilot, Mohamed Mamdouh Assem, 24. An EgyptAir pilot, who spoke on condition of anonymity because he was not authorized to speak to the news media, said he had worked with both and described them as professional aviators who had not exhibited any mental or social problems. At 24 years old, Assem was the average age of many co-pilots at the airline, he said.
EgyptAir crew members have been subjected to much stricter security measures since the crash of the Russian jetliner in October, said the pilot, who described the procedures before that crash as lax. The new procedures include personal searches that have prevented crew members from smuggling cigarettes or currency, he said.
The graffiti about Sissi occurred several times for about two years after Morsi, of the Muslim Brotherhood, was removed as president in July 2013. At the time, it was taken as a sign of the country’s bitter political divide rather than a directed threat against the plane.
Nonetheless, over that period, EgyptAir fired a number of employees, mostly members of the ground staff, who were presumed to be sympathizers of the Muslim Brotherhood, security officials said. Similar purges took place in other companies in Egypt at the time.
More recently, fears of terrorism have tightened security at regional airports, including Tunis, where the Airbus A320 had traveled just before its trip to Paris, the pilot said. Foreign flight crews face new restrictions on their movement and are now prevented, for example, from leaving the plane to buy items in the duty-free shop, he said.
