Spanish airline Iberia workers have begun a five-day strike in protest at planned cuts to jobs and salaries.
Iberia has cancelled more than 400 flights out of 1,000 scheduled for this week, with cabin crew and baggage handlers staging the walk-out.
A lack of services at Spanish airports are expected to affect more than 1,000 flights from various airlines.
Iberia has announced plans to cut 3,807 jobs after it reported mounting losses last year.
In the first nine month of 2012 it lost 262 million euros ($349 million).
Unions are planning three separate five-day strikes in February and March.
Iberia workers have begun a five-day strike in protest at planned cuts to jobs and salaries
Iberia said 70,000 passengers would be affected by the first strike, though in a statement the company said 60,000 had been found seats on alternative flights.
It said 90% of long-haul flights would be operating, but domestic flights would be the worst affected, with more than half of flights grounded.
Analysts suggest 15 days of strikes could cost Iberia up to 100 million euros.
Iberia merged with British Airways in 2011 to create International Airlines Group, and the new management has been trying to cut costs.
Iberia has been hit by increased competition from low-cost carriers and a prolonged recession in its home market.
British Airways-owner IAG has announced 4,500 job cuts at Iberia as part of a widely anticipated restructuring of the Spanish carrier.
Iberia is cutting its 156-strong fleet by 25 aircraft, and reducing 15% of its network capacity, with the airline focusing on the most profitable routes.
The plan aims to stem Iberia’s cash losses by mid-2013, and raise profits by at least 600 million euros ($766 million).
IAG also revealed a 30% drop in pre-tax quarterly profits to 221 million euros.
The drop was due to the poor performance at Iberia and at the recently-purchased UK regional airline BMI, as well as rising fuel, operating and engineering costs.
“The group performance is coming back to the levels seen in 2011 and this is particularly true if you strip out the BMI losses of 31 million euros in the quarter,” said IAG chief executive Willie Walsh.
“However, there remains a strong difference between the performances of British Airways and Iberia.”
IAG has announced 4,500 job cuts at Iberia as part of a widely anticipated restructuring of the Spanish carrier
The parent company said it now expected to make an overall operating loss of 120 million euros for the year – excluding any costs associated with the Iberia restructuring – with further losses likely in the remaining three months due to the impact of storm Sandy in the US.
Its pre-tax losses for the first nine months of the year have now reached 169 million euros, compared with a 355 million-euro profit in the same period last year.
Iberia has been suffering record losses, and IAG flagged up three months ago that job cuts were likely to come.
“Iberia is in a fight for survival,” said the Spanish subsidiary’s chief executive, Rafael Sanchez-Lozano.
“It is unprofitable in all its markets.
“Unless we take radical action to introduce permanent structural change, the future for the airline is bleak.”
The 4,500 job losses are not as steep as the 7,000 figure that reportedly had been expected by the airline’s unions.
IAG said the restructuring would safeguard 15,500 posts at the airline.
However, the restructuring plan also includes “permanent salary adjustments to achieve a competitive and flexible cost base”.
The airline has set a deadline of 31 January next year to reach agreement with unions over the cuts.
“Time is not on our side,” said Rafael Sanchez-Lozano.
“The company is burning 1.7 million euros every day,” he added.
“If we do not reach consensus, we will have to take more radical action, which will lead to greater reductions in capacity and jobs.”
The restructuring plan comes a day after IAG announced that it would pay 113 million euros to buy up the remaining 54% stake in Spanish budget airline Vueling that it did not already own.
Willie Walsh had said that the acquisition of Vueling would be “good for Spain” and “create new Spanish jobs”.
On Wednesday, IAG released its latest passenger figures for October, which showed that traffic rose by 6.2% at British Airways from a year earlier, while at Iberia traffic was down 3.7%.
The airline’s woes in part stem from the weakness of the eurozone economy, including a sharp downturn in its Spanish home market. However, according to Rafael Sanchez-Lozano, the airline’s problems are also “systemic and pre-date the country’s problems”.