British Airways carried out its threat Wednesday and stripped striking cabin crew members of their travel perks.
Staff who joined the strike last weekend will now lose benefits including free and heavily discounted travel, BA said.
"Letters are going out to staff who took industrial action concerning staff travel," a statement from the airline said. "Our cabin crew knew that if they took part in the strike they would lose their staff travel permanently.
"Staff travel offers heavily discounted travel to airline employees. This is a non-contractual perk that the company can withdraw at its discretion."
BA Chief Executive Willie Walsh had threatened last week to take away the travel perks, which may have been one reason why some union staff agreed to work despite the strike last weekend.
The airline said Wednesday it is expanding its flight schedules this weekend ahead of a second round of strikes because more staff are willing to cross the picket lines.
The planned four-day walkout follows the one last weekend by crews dissatisfied with pay, benefits and staffing levels.