More than 500 Ryanair passengers were diverted to other airports nearly 100 miles away while trying to land in London this week as Air Force One was late taking off.

President Donald Trump was in London for the NATO summit and was flying back to the U.S. on Wednesday night, but his flight was delayed, according to the Independent. The reason for the delay was not reported.

The presidential jet was scheduled to leave London Stansted Airport, which is northeast of the city and tends to be less congested than Heathrow or Gatwick. But the airport also happens to be Ryanair’s busiest base, The Points Guy pointed out.

And while it is less crowded, the Independent explained that there were no arrivals for more than an hour from 4:36 p.m. to 5:45 p.m. because traffic has to stay clear while Air Force One is moving.

Air Force One in Europe
Credit: Leon Neal/Getty Images

So when three Ryanair flights from Limoges, France; Lodz, Poland; and Lisbon, Portugal flew into the city after Air Force One was scheduled to take off, they couldn’t land, according to the Independent. The planes from Limoges and Lodz, both Boeing 737s, were forced to circle with no clear end in sight. They finally decided to divert to the Birmingham airport and East Midlands, respectively.

The flight from Lisbon decided to avoid circling near the city completely and diverted straight to East Midlands.

All three planes refueled at their new airports before finally flying to Stansted about two hours later than originally planned.

"We worked closely with Essex Police and the U.S. Secret Service in advance to develop a well-rehearsed plan for the arrival and departure of POTUS,” a representative for Stansted airport told the Independent. “However, the additional delay to the departure did unfortunately affect our schedule as we were going into the evening peak period. As always, we will work with all the relevant parties involved to review the process for accommodating Air Force One to ensure we minimize any disruption to our passengers in the future."

The paper reported the Ryanair flights weren’t the only affected planes: An easyJet plane from Amsterdam was delayed from taking off to keep the air clear for Air Force One, and another easyJet plane was forced to circle over London before being allowed to land more than 30 minutes late.