More than one million passengers have flown from Heathrow in the past 10 days – the busiest period for departures at the airport since Christmas 2019.
The hub said it was “fully operational” with all terminals welcoming passengers and both runways open.
It estimates 13 million people will travel in and out of the airport between July and September.
Despite Heathrow planning for this summer since last November, passengers experienced disruption in June, prompting airport bosses to set a daily cap of 100,000 on departing passenger numbers for the remainder of the summer.
Around 1,300 additional recruits have been employed by Heathrow to ease congestion in the airport.
“Most of the new joiners work in security, which now has the same capacity as summer 2019,” a Heathrow spokesperson said.
“Currently, 80% of Heathrow passengers will clear security within 20 minutes or less, although queues can be longer at our busiest times.”
The airport stressed new security recruits would become “more efficient” each week as they gained “valuable experience”.
Heathrow chief operating officer Emma Gilthorpe said: “My colleagues and I are thrilled to welcome so many passengers back to Heathrow again after two years of Covid cancellations and empty terminal buildings.
“The pandemic has been rough on the travel sector, but as we emerge and ramp-up operations, everyone at Heathrow is working hard to get you on your journeys.
“We’re focused on getting back to giving you the excellent service you expect every time you travel.”