IN less than half a century, civil air travel has moved from being relative luxury to a commodity. Once it was mostly only governments that could afford to buy new aircraft and the state companies operated them. To be an airline employee, particularly a pilot, was a high-status, high-pay job. But times and the economics of flying have changed. Last year a record 4.1 billion passengers took some sort of commercial flight.

A revolution in aircraft finance whereby airlines can lease rather than buy planes outright, improvements in engine efficiency and aerodynamics, increased aircraft carrying capacity and the rapid expansion of airports around the world underpinned the steep takeoff in passenger numbers. But probably the greatest impact on the sector was the disruptive arrival of the low-cost carriers. Last year they flew 1.2 billion, some 30 percent, of all passengers. They started first on short-haul and quickly expanded to medium-distance flights. Now they are moving into the long haul sector, which until recently had continued to be dominated by established, full-service carriers. Only on certain routes, most obviously the Transatlantic, has competition kept down the cost of a seat.

The business model of the cheaper airlines has been to remove costs at every possible point. If airports will not reduce their landing charges, the low-cost carriers will use smaller airports nearby. Passengers were happy to pay a fraction of rival’s full-price fares for the inconvenience of extra travel to and from the secondary airports. And indeed these airports have flourished from the passenger-flows of low-cost airlines and stolen significant traffic from traditional hubs.

In the light of these challenges the long-standing carriers are being forced to cut their own costs. And inevitably their employees, who are having to bear a major part of these reductions in perks, such as the removal of free flights, relaxed work rosters with long five-star hotel stopovers on long haul flights, are not happy. Some big national carriers have negotiated the radical changes successfully. Others, including Air France-KLM, the amalgamated French and Dutch flag airlines, have not. Its employees are currently on strike demanding higher pay, which the heavily indebted airline is protesting it simply cannot afford.

In one respect this dispute is related to the rolling strikes of France’s no less indebted SNCF railways. They are both in protest at the financial restraints on state spending that President Emmanuel Macron is trying to impose. But there is one major difference. SNCF is a monopoly whereas Air France-KLM is already being challenged with growing effectiveness by privately-owned low-cost carriers. Following the strikers rejection of a “final” pay offer, the chief executive has resigned, warning that the airline is on the brink of bankruptcy. Similar threats have been made by managements during past industrial disputes. But there is a strong sense that Air France-KLM is close to, if not actually at the end of the line. Union leaders who see the strike as a political challenge to Macron’s state spending clampdown need to understand that there is a very real possibility that they are striking their way out of a job. If their airline goes bust there will be plenty of low-cost carriers ready to snap up its routes.