No theory can be ruled out

Image courtesy JetPhotos.net ©Ahmet Akin Diler

At the time of writing, all we can say categorically about what happened to EgyptAir flight MS804 on Wednesday night is that it disappeared from radar. Nothing more. Circumstantial evidence might suggest a "brutal event", to quote the former chief French air accident investigator, but nothing so far has made terrorism a certainty.

And yet it's hard not to speculate. Not just because we want answers - the families of those onboard 804 need to know, the rest of us to satisfy our morbid curiosity - but because aviation is, globally, one of the most common forms of transport. On an average day more than 100,000 commercial flights take off, covering almost 50,000 routes around the world. If 804 was blown out of the sky, it raises serious questions for everyone who gets on a airliner.

The A320 in question is the workhorse of the skies, not just because of its commonality (there are some 7,000 members of the 320 family in use today) but for how much they fly in a given day. We now know that the missing plane had, in the 24 hours prior to leaving Charles De Gaulle airport, flown a number of 'sectors' from its Cairo base, including return trips to Tunis, Asmara in Eritrea and Brussels the day before. Given the association with terrorism these three locations have, one line of enquiry will have to be that a device could have been placed on board the plane at one of these destinations, programmed to detonate at a certain time or position. That might sound far-fetched, given the sectors flown, but it should not be forgotten that in October 2010 terrorists managed to get bombs disguised as printer cartridges on to two cargo planes in Yemen, bound for the United States, but with stopovers in the UK and Dubai. The belief was that the bombs were to be detonated while the planes were eventually in US airspace.

Paris, though, will still be the prime location for suspicion, simply because it was the point of origin of MS804. Questions, too, have been raised about security at Charles De Gaulle and Orly, the two main airports for the French capital. In the wake of last November's terror attacks in Paris, more than 70 people working at the airports had their airside security clearance revoked over suspicions of connections to terrorism or at least radicalisation. When you consider how many people work airside at any major airport, let alone with direct access to a given aircraft, such as baggage handlers and catering staff, safeguards have always been tight. But that doesn't mean watertight.

The cheering thought for those of us who fly frequently is that if MS804's disappearance isn't terror related, what are the other possibilities? The lack of any mayday call from the flight deck, and the 90-degree and then 360-degree turns radar coverage has shown the A320 to have made as it fell into the Mediterranean certainly suggests an abrubt event. A mechanical issue would still have prompted the pilot or co-pilot to issue a distress signal, especially being only 20 minutes out of Cairo, its destination. Last year the world was stunned by the crash of Germanwings flight 9525, another A320, flying from Barcelona to Dusseldorf, which we later learned was flown deliberately into a gulley in the French Alps by co-pilot Andreas Lubitz who, at the time, had been declared "unfit to work" by a doctor because of his mental condition. EgyptAir itself suffered a similar disaster in 1999, when a Boeing 767 crashed into the Atlantic 60 miles off the coast of Massachusetts, killing all 217 people on board. The "probable cause" was given as "deliberate action" by one of the pilots on board.

As we are constantly reminded, flying is still by far one of the safest forms of transport. Last year, according to IATA, the international aviation body, out of 37.6 million flights there were a total of 68 accidents of which just four resulted in 136 fatalities. However, this doesn't include the 150 passengers and crew on the Germanwings crash or the suspected bombing of the Metrojet A321 over the Sinai desert, resulting in 224 deaths. As a result of that - and the latest incident - Egypt's tourist economy is facing ruin.

If MS804's fate was at the hands of terrorism it is unlikely that we will, en masse, be put off flying. But the fact that terrorists continue to hold a fascination with planes as a means of carrying out mass murder on a dramatic scale will and should affect our behaviour. It amazes me even now, 15 years after 9/11, that passengers do not know about or are unprepared for security screening at airports. Removing shoes, belts and laptops may be an inconvenience, especially if you're running late, but it should, in principle, be keeping everyone safe once airborne. The worry is, passengers may only be one part of the problem.