EasyJet pilots are about to begin the first of a set of three day strikes this August.
Pilots working for the budget airline in Spain will walk out tomorrow, Saturday and Sunday due to an argument over pay.
They plan to do so again on August 19, 20 and 21, as well as 27, 28 and 29 if negotiations are not successful.
The strikes are contained to Spain but are likely to impact customers flying into and out of the country on the chosen days.
Airports in Barcelona, Malaga and Palma de Mallorca are expected to be particularly affected.
Union Sepla says that they've been trying to come to an agreement with easyJet for more than six months, but that the company has rejected three of their proposals.
A union representative issued an apology to passengers who they said would bare the brunt of the industrial action.
"During the worst months of the pandemic, we agreed to lower our salaries to guarantee not only jobs, but the survival of the company itself in Spain," they said.
"However, having achieved the objective of reducing the pilots' working conditions, easyJet announced an increase in the number of planes and pilots at its bases in Barcelona and Palma, and opened a completely new base in Malaga.
"We are not asking for anything that we did not have two years ago.
"Companies are within their rights to regain muscle, but not at the expense of workers; if the situation has returned to 2019 levels, it is time to recover the conditions lost as a matter of justice."
The UK government travel advice for those going to Spain states: "Possible strike action may cause some disruption to flights to and from Spain.
"You should consult your airline for updates prior to travel."
EasyJet said they were planning on running a full schedule despite the strikes, but admitted that disruption was expected.
The airline is not the only airline to have had to deal with strikes in Spain this summer, with Ryanair flight attendants starting five more months of strike action on Monday.
This week members of security at Leeds Bradford Airport voted to go on strike over pay.
If negotiations are not successful, then they will walk out at the end of August.
An easyJet spokesperson said: “easyJet has been formally advised of strike action by its Spain-based pilots union Sepla between 12-14, 19-21 and 27-29 August at its Spanish bases.
"We advise customers travelling to and from Barcelona, Malaga and Palma to check the status of their flights on our Flight Tracker page or manage their bookings using our disruption portal on our mobile app or website.
"Although this is outside of our control we would like to apologise to all our customers for any inconvenience caused and would like to reassure them we are doing all possible to minimise any disruption as a result of the strike action.”
