One of the engers on the flight said he saw people “hitting the roof” and food and drink going everywhere.

The airline said a small number of its flights have been cancelled due to the strikes, and apologised to customers for the “unavoidable cancellations and any delays”.

A friend went to the airport in Kansas City to look for her missing luggage, and another to the airport at Newark, to no avail.

They will undergo training to help alleviate some of the pressure on staff until the end of the summer.