On September 23, 2018, at about 2145 EDT, United flight 138, Boeing B757-224, N13113, was in the process of boarding at Newark International Airport (EWR), Newark, New Jersey when a flight attendant was struck by a catering cart. Of the 177 passengers and crew who were scheduled to be onboard, one flight attendant was seriously injured. The flight was scheduled as a 14 Code of Federal Regulations Part 121 international passenger flight from EWR to Reykjavik-Keflavak International Airport (KEF), Keflavak, Iceland.

During the initial boarding process, the resupplying of the catering was still ongoing. As the caterer personnel was quickly pushing a catering cart throught the aisle the flight attendant's foot was struck by the cart as it passed by. The flight attendant was injured, but thought his foot was only bruised, so he remained onboard to work the flight. During the flight, the flight attendant's foot became more painful, which required him to elevate his foot for short periods of time. After arrival at KEF, the injured flight attendant went to a local hospital and was diagnosed with a fractured heel.