The Big Question: Why has another Airbus crashed, and is flying becoming more risky?

Why are we asking this now?

A little over a month after an Airbus 330 crashed into the sea off the coast of Brazil, killing all 228 people on board, another of the manufacturer's aircraft has been involved in a disaster. This time, there were 153 people on the A310 in question, a Yemenia Air flight which dove into the sea as it tried to land on the Comoros islands, an archipelago of volcanic islands off the south-east coat of Africa in the Indian Ocean. The plane was heading from Yemen to the Comoros, but many on board had begun their journey in France.

So what exactly happened?

So far, we don't know much. While at least three bodies have been recovered and a 14-year-old girl, Bahia Bariki, has survived, the rest of the passengers are unaccounted for. The circumstances of the crash will become clearer once investigators find the plane's black box, but initially they have pointed to atrocious weather and the late-night landing time as possible contributing factors. More worryingly, the condition of the aircraft itself has been called into question. The families of many of those on the flight, who were Comorans returning to the French overseas territory from holiday from France, have bitterly blamed the state of the Yemenia Air fleet. "They put us aboard wrecks, they put us aboard coffins, that's where they put us," one relative told French television. "It's slaughter. It's slaughter." The Comoros' honorary consul in Marseille, Stephane Salord, called the Yemenia aircraft "flying cattle trucks". "This A310 is a plane that has posed problems for a long time," he said. "It is absolutely inadmissible that this airline, Yemenia, played with the lives of its passengers this way."

The French Transport minister, Dominique Bussereau, told parliament yesterday that the Yemenia Airbus 310 which crashed was not permitted to fly into France, and raised concerns about the transfer of passengers from a plane classed as safe to one that crashed into the sea. Most had flown on a different Yemenia aircraft from Paris or Marseille before boarding flight IY626 in Sanaa, the capital of Yemen.

So is it likely that the plane itself is to blame?

Yemenia's fleet has certainly come in for considerable criticism in the past. Most damningly, French inspectors who looked at the plane at Charles de Gaulle airport in Paris in 2007 noticed a number of faults. The aircraft was banned from flying in French airspace and, under the EC's safety directives, they instructed Yemenia to carry out stricter checks on the place in future. But Yemen's Transport minister, Khaled Ibrahim al-Wazeer, insisted it had since been rigorously checked under the supervision of Airbus experts.

Why was the plane still allowed to fly if French officials had flagged it up?

For one thing, even though the EU was due to investigate Yemenia's safety record following the 2007 inspection, the airline was not added to the "blacklist" of airlines banned within the EU. Even if it had been, there would have been nothing to prevent the flight from Yemen to the Comoros; that would be the responsibility of the Yemeni and Comoran governments.

Is there another viable explanation besides a technical failure?

David Learmount, safety editor at Flight International magazine, thinks human error is most likely the cause of the crash, pointing out that a tired pilot would have been coming in at 1.30am into a strong wind. The polit would have had to make a "non- precision" approach without radar, using his eyes rather than instruments – a method which is three to five times more likely to result in an accident. If it was indeed such an incident, Mr Learmount says it is hard to avoid, adding: "Accidents like this happen. They always have."

Is this crash anything to do with the recent Air France disaster?

It seems not. That aircraft, an A330, was a different model entirely. Whereas yesterday's crash happened on the final descent to the airport, Flight AF447 went down in ordinary flight, making it more likely to have been a technical failure than a human error. But two crashes so close together are a public relations disaster for Airbus. The share price of its parent company, EADS, fell by 3.6 per cent yesterday.

What does Airbus do after selling an aeroplane to ensure its safety?

Once an aircraft is sold, a manufacturer is no longer responsible for its safety. They do sometimes work for airlines in an safety advisory role, but they do not offer maintenance services. Legally, the responsibility lies with the operator.

So should I worry about flying by A310 in future?

You should certainly think carefully about travelling with Yemenia. The EU transport commissioner Antonio Tajani has announced a new investigation into the airline's practices, and that may well result in the company being added to the next airline blacklist, which is published in two weeks. Other airlines flying the same model are as trustworthy as ever. Nevertheless, those of a nervous disposition may think twice on any carrier. The A310 is an older model designed in 1986 – the one that crashed yesterday was built in 1990 – and older aircraft are statistically more likely to crash than newer ones. The A310 has also been in more accidents than its main competitor, the Boeing 767.

And what about flying on an Airbus in general?

Airlines would not buy Airbus jets if they had serious doubts about their safety record, which is respectable and comparable to its rival, Boeing. Some pilots have expressed reservations about the Airbus "Fly-By-Wire" approach, which automates more processes than Boeing's system does – but Airbus firmly believes its method is safer and eliminates opportunities for pilot error. There may have been a string of recent Airbus accidents – last year, the Fly-By-Wire system led to a Qantas A330 plunging 650ft in seconds – but it is probably only a matter of bad luck. "That's the throw of the dice," says Mr Learmount. "There are only two major aircraft manufacturers in the world. Any crash is bound to be one or the other."

What can be done to improve air safety?

One practical step already proposed by Mr Tajani is to extend the EU blacklist system to a global version. That would not have stopped this crash but it might give travellers peace of mind to know that dozens of airlines banned in Europe will not be operating elsewhere either. It would also ensure that, if Yemenia was added to that group, it could not continue to operate regardless.

Should I continue to fly in the meantime?

Flying disasters are often horrifying, and the concentration of deaths in a single incident can make air travel seem uniquely risky. In fact, while it is never risk-free, it is certainly not the most dangerous way to travel. In the US in 2006, for instance, there 42,642 deaths were caused by car accidents and only 1,500 involved aircraft. While there are 117 fatalities per billion air journeys, there are 170 deaths per billion bicycle journeys. So, unless you are also planning to travel on only foot in future, your routine should probably not change.

Are there good reasons for concern about travelling on an Airbus?

Yes...

* Airbus aircraft have been involved in a string of accidents, and no firm explanation has yet been found for the crash of Air France AF447

* Some pilots worry about relying on the company's automated "Fly-By-Wire" navigation system

* No manufacturer or airline can entirely legislate for human error

No...

* There is no reason to think the the two recent disasters are linked; they involved different models of Airbus in different circumstances

* With only two plane-makers, accidents are bound to be with one or the other

* The risks of flying are no worse than those of many other activities