Strike action will take place from 31 August to 3 September – followed by a period of “work-to-rule”.
Hundreds of Border Force officers at Heathrow Airport will go on strike from the end of the month.
The 650 members of the Public and Commercial Services (PCS) union will be on strike for 23 days.
Strike action will take place from 31 August to 3 September, at which point a period of work- to-rule – where no overtime is undertaken and no extra work beyond what is contractually required is done – will begin and continue until 22 September.
The long-running dispute centres on enforced changes to terms and conditions – including the introduction of inflexible rosters.
Part-time workers and partially retired staff are being forced to change their working hours and practices, the PCS added, while new staff members are having their flexible work applications refused.
Many strikes have been threatened in recent years, but few have materialised as management has acceded to demands.
“We know our strike action is likely to cause serious disruption to travellers using Heathrow at the end of the summer, but the strike can be avoided if the employer listens to the concerns of our members,” said the PCS general secretary Fran Heathcote.
The union said 160 staff have left the Border Force due to the lack of flexibility.
“Our hard-working members at Heathrow take great pride in keeping our country’s border safe, but many are being forced out of the job they love,” Ms Heathcote added.
“They’re being told by managers to choose between caring responsibilities and their job, which is no choice at all. The only reason they’re being forced to choose is because their managers are forcing them.”
Heathrow is not just the UK’s busiest airport but the largest in Europe too.
Heathrow bosses insist they will work closely with Border Force to support contingency measures during strike periods.
The Home Office, which runs the Border Force, have been contacted for comment.