LONDON, the UK — A Virgin Atlantic flight had to return to Heathrow International after 40 minutes from departure when it was realized that the first officer did not complete a regular flight assessment test.

The Airbus A330 jet was on its way to New York from London Heathrow when the pilots noticed the rostering error.

A spokesperson of the airline said the first officer was replaced by another one and the plane took off again for New York. The airline says the event did not cause a flight safety problem.

The unnamed first officer started his carrier in 2017, and he is fully qualified under UK aviation regulations. The problem, in this case, is that the first officer did not complete an internal pilot assessment test required by the airline. Airlines have their own training departments, and all pilots must attend regular training and be evaluated by instructor pilots periodically.

If the captain of Flight VS3 were an instructor pilot at the same time, the aircraft wouldn't need to return because the flight could be considered a training or assessment flight.

Virgin Atlantic apologized for the inconvenience that caused its passengers to arrive in New York two hours and 40 minutes later than planned.