Virgin Atlantic is planning to fly to Jersey and Guernsey from Heathrow, once a third runway is open.
The airline says it wants to end British Airways' 'stranglehold' over the West London hub.
Currently the IAG, which owns British Airways, controls more than half of Heathrow slots.
The rules governing the allocating of new slots are currently being reviewed by the UK government.
12 of the 84 new destinations Virgin plan to serve are in the UK or Channel Islands.
- Belfast City
37 are European routes such as Barcelona, Dublin and Madrid - with the rest going global to the likes of Buenos Aires, Jakarta and Kunming.
"Never has the need for effective competition and choice at Heathrow Airport been more evident than during this summer of disruption, which has brought misery for tens of thousands of travellers. Britain, and those who travel to it, deserve better than this. Air passengers need a choice and Virgin Atlantic is ready to deliver when Heathrow expands.
"Heathrow has been dominated by one airline group for far too long. The third runway is a once in a lifetime opportunity to change the status quo and create a second flag carrier. This would lower fares and give real choice to passengers, as well as giving Britain a real opportunity to boost its trade and investment links around the world. Changing the way take-off and landing slots are allocated for this unique and vital increase in capacity at the nation’s hub airport will create the right conditions for competition and innovation to thrive." - Shai Weiss, CEO Virgin Atlantic