The first coronavirus-free transatlantic flight is scheduled to land at Heathrow on Tuesday morning amid pressure to reopen the busy business route.
As part of the month-long scheme, the carrier will guarantee that all passengers do not have the COVID-19 virus. Findings will be shared with officials in the UK and US once the four-week trial is up.
The United trial will be free for all passengers over the age of two and rapid testing will take place at New York's Newark airport. UK airlines are working with Heathrow on their own COVID-free pilot.
"We believe the ability to provide fast, same-day COVID-19 testing will play a vital role in safely reopening travel around the world and navigating quarantines and travel restrictions, particularly to key international destinations like London," said Toby Enqvist, chief customer officer for United.
The US is considered a “red country” by the UK government. At the moment, Americans must quarantine for 14 days when traveling to the UK as the US.
Earlier this year at the height of the pandemic, US president Donald Trump closed the borders to UK and EU travellers. UK travellers can only visit America if they have been granted a special exemption.
The hope is that by sharing the results of the trial, governments on both sides of the Atlantic give the travel corridor the green light.
If the trial is successful it could allow the London to New York routes — one of the world’s busiest and most profitable routes for the likes of British Airways and Virgin Atlantic — to reopen.
The routes are heavily used by executives and dealmakers and provide an important business services link.
It is also an important corridor for Heathrow airport, which has been hard hit by the pandemic impact of grounded flights and reduced passenger numbers.
It recently lost its crown as Europe’s busiest airport to France’s Paris Charles de Gaulle airport.
In October, it became entangled in a row with the UK’s aviation watchdog, after the Civil Aviation Authority (CAA) rejected the Heathrow’s request to increase airport charges by £1.7bn ($2.3bn).
Following CAA’s rejection, the airport said it was entitled to claim for losses incurred during COVID-19. This prompted the CAA to express “significant disappointment” in an open letter at remarks made by Heathrow’s finance chief, Javier Echave.
Last week, the UK’s busiest airport was dealt another blow after credit ratings agency, Moody’s downgraded its debt along with Gatwick’s.
Heathrow owes several financial institutions, banks and bondholders more than £17bn
Watch: Heathrow loses title of Europe's busiest airport