Maintenance and ground support staff at LATAM Airlines’ LAN Express unit went on strike on Thursday after contract talks failed.

The 881-member union at LAN Express, which mostly covers routes within Chile and also has some flights to other South American destinations, rejected LATAM’s contract offer last week and asked for government mediation in contract talks.

After those mediated talks fell through earlier this week, the union representing maintenance and ground support staff said it would strike.

“The strike has started in all of the country,” Eric Arce, a senior official of the union said.

LATAM, which was formed in mid-2012 when Chile’s LAN took over Brazil’s TAM, said on Wednesday that its contingency plan would allow for normal operations despite the strike.

According to LATAM the strike affects 5 percent of its Chile staff.

“The company is going to be able to resist the first few days, but on the weekend (their contingency plan) is going to fall apart because the areas they have covered don’t work on Saturday and Sunday,” said Arce.

He added that by Monday some planes may need to be grounded because of a lack of adequate maintenance.

The union is seeking a 15 percent salary increase for its workers, in addition to improved benefits, as annual inflation has remained above 4 percent in Chile for the last year.

LATAM has domestic operations in Argentina, Brazil, Chile, Colombia, Ecuador, Paraguay and Peru