It was 11.30pm, and hour two of struggling with American Airlines’ third-party app, when I started to give up hope. It hadn’t been this bad on the way over. Before flying from New York to London, I had downloaded the Covid security app, uploaded my vaccine and passenger locator forms, and waited for authorisation to fly. It was onerous but straightforward and the following day, at JFK, I sailed past lines of people still waving their paperwork. “Should’ve downloaded the app,” I thought smugly. That was on Friday, three days before the US reopened its borders to British passport-holders. The following morning, after a two-thirds empty flight, as per most international travel during Covid, I landed at Heathrow. It was empty, but apart from that still very much Heathrow. There was something reassuring about the Covid test authorities sending me to the wrong test centre at Terminal 5, and when queried, informing me – with the sadness of those conveying an immutable reality – “Our systems need updating.” Ah, good to be home. Americans have been able to enter the UK since July, but it has been almost two years since British and European travellers have been permitted reciprocal entry into the US. It is, along with so many other consequences of the pandemic, an extraordinary breach in life as we knew it that over time has faded to normal. Newborn babies unseen; birthdays and holidays celebrated remotely; grandparents barely able to recognise children who, toddlers before the pandemic, are now twice the size and practically running their own businesses. When the White House confirmed last month that the rules would change, and Brits and Europeans would be allowed in, it was the best news many of us had had in a long time. On Monday morning, British Airways and Virgin Atlantic arranged synchronised departures from Heathrow – a sort of lumbering civilian version of the Red Arrows – and we would, once again, be off. Or rather, those of us who could figure out the pre-flight paperwork would be off. The first sign of trouble for my return flight to JFK was when an email arrived from the airline’s customer service department offering passengers flying on AA flight 101 on Monday morning a $600 voucher to change their flights. Prior to the pandemic, about 3.8 million British people visited the United States annually and now the travel ban was over, they all seemed to be booked on my 9.30am flight. Words long unheard surfaced from the past, to send chills down the spine of every traveller: “This is a very full flight, please check large carry-on bags as there is limited space in the overhead luggage bins.” But I had downloaded the app! The app would save me. OK, the American Airlines check-in page was totally confusing, but I’m competent, I could definitely do this. I opened VeriFly, the pre-check app, and spent 45 minutes trying to find my flight, before erasing and redownloading the app. I found the flight. I clicked on the dropdown menu to upload my negative Covid test. Hmmm. The date of my test, taken two days earlier, wasn’t offered as an option. Panicking, I double checked the US state department website, to ensure I hadn’t misunderstood the requirements. I was comfortably inside the three-day deadline. Oh, well. I’ll just put the wrong date on it, I thought. They probably won’t check – United States border control is, after all, famously relaxed – and what could possibly go wrong? The app crashed; then it crashed again. Like something from a seance, there was an almost physical sense of the hundreds of people all invisibly swearing while trying to check in. If you are flying from Britain to the US, a boarding pass won’t be generated until evidence of your vaccination and pre-flight Covid test have been authorised. For 20 minutes, I sat refreshing my phone. “Pending,” it said. At 4am, I woke up and checked the app. “Error,” read the notice. The date of my Covid test did not match the date I had clicked on the app. Oh, now suddenly everyone’s systems are working. I felt like John Cleese in the manic final moments of Clockwise. I considered whether the phrase, “it’s not my fault,” might work at the airport. I wondered if there was some special lane for people whose kids were in tenuous care in their absence and had to get back to retrieve them. Finally, I clicked on the dropdown menu, found new test dates, resubmitted the info and went to sleep. Two hours later, I had a green tick. The scene at Heathrow was chaotic. British people wandered about clutching fistfuls of printouts, in search of someone to take them. “I pre-screened on the app,” I told a check-in clerk, preening, and he gave me a look of pure sympathy. “We don’t have the staff for an extra desk for pre-checks,” he said and indicated the conga-line of paper-waving Brits. “I’m afraid you’ll have to wait.” And there it was, pre-Covid life, fully up and running and ready to receive us. Emma Brockes is a Guardian columnist