SWISS airline pilot Guido Keel was assaulted following a dispute about whether a baby carriage could be transported in the plane's cabin, rather than in the hold, a spokeswoman for the airline told CNN.
The alleged incident took place after the flight had landed.
Henrietta Mitaiare, 23, and Mary Roberts, 53, both from London, are accused of scratching and kicking the pilot after the flight landed at London's Heathrow Airport on May 2 last year, the UK's PA Media agency reports.
The women deny charges of failing to obey the lawful commands of the aircraft's captain and assault by beating on board.
Prosecutors say the pilot also had a bite mark on his upper arm.
Uxbridge Magistrates' Court heard that the pair were traveling with Mitaiare's young daughter and had asked flight attendant Ali Chkerdaa to store the stroller in the cabin before takeoff.
Chkerdaa told the court that he refused and an argument broke out between Mitaiare and two airport workers, but the flight took off for London.
Upon landing, Mitaiare approached Chkerdaa and asked to note down the airport workers' names in order to make a complaint, according to prosecutor Arlene De Silva.