Ground support worker Kulwant Bhara was knocked to the ground by a 70-tonne pushback tug as he was helping to prepare an aircraft ready to leave Terminal 3.
When the vehicle reversed over his right leg, he suffered fractures to his right ankle and left heel, which resulted in Mr Bhara needing to have his right foot amputated just below the hip.
The former employee, who has not been able to work since, said: "The incident has effectively turned my life upside down and has affected both myself and my family drastically in a number of different ways."
Health and Safety Executive inspector John Crookes said his life-changing injuries were due in part to the airline not following internal guidance with regard to the vehicle in question.
American Airlines fly passengers from London Heathrow to seven US cities including New York and Chicago.
By Colette Paxton
