Heathrow Airport has recorded its busiest January since the start of the pandemic, with 5.4million passengers travelling through it last month.
The latest figures are still below the six million people that passed through in January 2020, but Heathrow boss John Holland-Kaye said it showed the airport was "back to its best".
But the BBC says it comes as more than 3,000 workers are to be balloted over strike action.
Unite says security guards, engineers and firefighters at Heathrow would begin voting on Friday on whether to walk out over pay, after its members rejected a 10% wage increase.
The union said that, if workers did strike, it would "inevitably cause severe disruption" at Easter.
A Heathrow spokesperson said the airport was "extremely disappointed" by Unite's move and warned that, if the strike action commenced, the "pay offer will be withdrawn".
Making losses
The spokesperson added that the 10% salary increase offer came at a time the business was making losses.
Some 17,458 flights are scheduled to depart UK airports during half-term, but departures remain 19% down compared to the same period in 2019.
The Association of British Travel Agents said many tour operators were "expecting a busy half-term as demand for travel continues to return to pre-pandemic levels".
Mr Holland-Kaye added Heathrow's services in advance of the school half-term holidays had been "going very well".
Heathrow said its overall passenger satisfaction was now "at or above pre-pandemic levels", with 98% of passengers waiting less than 10 minutes for security last month, which is typically a quieter time of year for UK passengers.
The airport said Border Force was trialling using e-gates for children aged 10 and 11 in Terminal 5 over the half-term holiday, as it was also doing at Gatwick and Stansted.
Biometric passports
Currently, travellers aged 12 and above with biometric passports can use e-gates to bypass manual inspections when they cross border control.
Last year, thousands of air passengers suffered delays and cancellations across the UK after airports and airlines struggled to recruit enough staff to cope with the surge in demand for international travel following the removal of Covid restrictions.
Airports and airlines cut thousands of jobs at the height of the pandemic, and many workers did not return to the industry due to finding other jobs.