Windsheer
We've done this before.
Do you think the world 6th largest airline would start a transatlantic service without looking at performance payload issues.
Take it from me they have fully looked into this to ensure direct flights from Bristol - the new wingletted B757's will even allow for additional cargo even when pressure is low , the runway is wet , headwinds are strong and when additional vectoring is required to take it over your house if you want!
S