A group from Black Lives Matter chose the approaches to the airports as two of several points of protest across major cities.
Protestors chained themselves together under the Welcome to Heathrow sign and unfurled a banner saying "This is a Crisis".
Long tailbacks of traffic developed during the morning rush hour and diversions were put in place.
A number of arrests were made and police at Heathrow were able to reopen one lane for traffic just before 10am.