Unite, the union representing British Airways cabin crew, says thousands of cabin crew working for BA have voted “overwhelmingly in favour of strike action over poverty pay and broken promises”. The union has warned travellers that “2,500 Unite members who crew long and short-haul routes to dozens of destinations could go on strike after the 21st December”.

Simon Calder assesses the possible impact — and the background to the dispute.

Could a Christmas strike ground BA flights?

Industrial action might affect some flights to and from Heathrow, but not services at Gatwick, London City or Stansted airports.

At present all British Airways flights are operating normally. But Unite has indicated it may call a strike to begin before Christmas. The union must give the airline a week’s notice of industrial action, which is why the announcement today talks of possible action after 21 December. A Unite spokesperson told me: “Our reps are meeting over the coming days to discuss the next steps.”

Could there be another “12 days of Christmas” strike call?

Some travellers will recall that, just before Christmas 2009, Unite called a 12-day strike by BA cabin crew. The aim was to shred the schedules over the festive season. That proposed stoppage, which was overturned in the High Court, was part of a long-running battle over working practice changes that cabin crew perceived as threats to their pay and conditions.

Over the months that followed, BA cabin crew went on strike repeatedly, grounding hundreds of flights on each occasion.

The numbers then and now are very different. In 2009, around 10,000 cabin crew voted in the strike ballot, with a majority in favour of 92 per cent.

But this dispute involves far fewer workers. It concerns only the “Mixed Fleet” group, who number 4,500 — about 28 per cent of the total cabin crew working for BA. Of this group, around 2,500 are Unite members. Six out of 10 of them voted, with a 79:21 majority in favour of striking.

That amounts to around 1,200 staff — about 7.5 per cent of cabin crew.

Who are “Mixed Fleet”, and why are they unhappy?

Until 2010, all British Airways Heathrow-based cabin crew belonged either to Eurofleet, serving short-haul routes, or Worldwide Fleet, working on intercontinental services.

But since the dispute was settled, all cabin crew recruited by British Airways have joined Mixed Fleet, operating on both long- and short-haul routes.

They were recruited on less-favourable terms than existing cabin crew, with lower pay and less generous working conditions. Mixed Fleet staff never work on the same flights as longer-serving staff, and instead routes are shared out. Across the Atlantic, for example, Mixed Fleet work flights from Heathrow to San Diego but not to New York; in Europe, Mixed Fleet work to Paris Orly but not to Charles de Gaulle airport.

Over time, the number of routes Mixed Fleet work on will gradually rise in line with the ratio of Mixed Fleet to longer-serving staff.

The union says that recruits to Mixed Fleet were promised they would earn a salary of at least £21,000, but in reality they start at just over £12,000 plus £3 an hour in flying pay — wages earned only when they are on duty. Unite says cabin crew have rejected a 2 per cent pay rise, while customer service managers — the senior member of cabin crew on each flight — have had a “six-year pay freeze”.

BA says: “We are extremely disappointed that the union is creating uncertainty for our customers.

“We remain focused on resolving this issue as quickly as possible without any disruption to customers.

“We have proposed a fair and reasonable pay increase to Mixed Fleet cabin crew which is in line with that accepted by other British Airways colleagues and which will ensure their reward levels remain in line with cabin crew at our airline competitors.”

But Unite’s regional officer, Matt Smith, calls BA’s pay rates “indefensible”, says that “the crew are at breaking point” and insists “low pay is a safety issue”.

Should passengers be concerned about safety?

British Airways has an outstanding safety record, which is the envy of many other airlines.

But Unite has issued details of a survey of its members working for BA’s Mixed Fleet that could concern some travellers, given the critical safety role of cabin crew.

The union says over two-thirds of cabin crew surveyed admit to reporting for duty when they were actually unfit to fly because they could not afford to be off sick and lose the allowances involved. Eighty-four per cent of cabin crew report that their financial circumstances since joining BA have caused “stress and depression”. And Unite says that some members have been “sleeping in cars between flights because they could not afford the petrol to get home”.

Fatigue and depression among pilots, not cabin crew, have been blamed for two aviation tragedies.

In 2009, 50 people died when a Colgan Air flight from New York stalled on the approach to Buffalo airport. The National Transportation Safety Board concluded that pilot fatigue contributed to the crash. Its final report revealed that one of the pilots, Rebecca Shaw, had earlier said that one of the couches in the crew room at Newark airport “had her name on it.”

Last year, First Officer Andreas Lubitz committed suicide and killed the other 149 people on board his Germanwings flight from Barcelona to Dusseldorf when he deliberately crashed the plane into the French Alps. He had been suffering from depression.