More travel disruption has been threatened following a bank holiday weekend which saw the failure of airport e-gates and dozens of British Airways flights axed due to an IT glitch.
A pay dispute at Heathrow is set to escalate as around 600 more security officers voted to join strike action over the summer.
Security staff members of the Unite union at Terminal 3 have recorded an 85% vote for strike action.
They will join 1,400 colleagues at Terminal 5 and airport campus security, who are taking industrial action.
The latest round of walkouts took place on Saturday – coinciding with problems with electronic passport gates for arriving passengers at airport across the UK.
The 24-hour outage forced travellers to wait for manual passport checks from Friday night – the busiest day for UK air travel since 2019. There are more than 270 e-gates at the UK border.
The Home Office said the issue had been resolved in a statement at around 6pm on Saturday.
A spokesperson said: “Following a technical border system fault which affected e-gate arrivals into the UK, we can confirm all e-gates are now operating as normal.
“We thank those travellers who were impacted for their patience and staff for their work in resolving the issue.”
Heathrow deployed extra staff to manage queues while the e-gates were down.
“Our teams are working closely with Border Force to help resolve the problem as quickly as possible, and we have additional colleagues on hand to manage queues and provide passenger welfare,” it said earlier on Saturday. “We apologise for any impact this is having to passenger journeys.”
The issue arose as BA sought to recover from a systems failure on Thursday which led to dozens of flight cancellations and hundreds of delays overflowing into the bank holiday weekend.
Which? Travel editor Rory Boland said: “It’s completely unacceptable that chaotic scenes at UK airports and ports have become such a common occurrence at peak travel times.
“It’s especially concerning this year, when travellers have been asked to pay extortionate amounts for flights.
“Whether it’s issues with the airline, the airport or Border Force, passengers should receive the service they paid for. If they don’t, companies and organisations must face consequences for their lack of service.”
Meanwhile, Unite general secretary Sharon Graham, referring to the security staff dispute, said: “Escalating strike action will inevitably cause disruption, delays and cancellations across Heathrow.
“Strike action is now set to escalate throughout the summer and Unite will leave no stone unturned in support for our members involved in the dispute.”
Heathrow has vowed to keep the airport running smoothly despite the strike action.