BOS-LHR is about 7 hour flight which equates to 20,000 gallons of fuel on 777. At $3/gallon, fuel is about $60,000. If there are 250 people, round trip fuel p

BOS-LHR is about 7 hour flight which equates to 20,000 gallons of fuel on 777. At $3/gallon, fuel is about $60,000. If there are 250 people, round trip fuel price per passenger is $480. Considering fuel is about 1/3rd of airline's operating expense, charging anything less than $1,000 for BOS-LHR roundtrip ticket is a money losing proposition, unless they can pack 350 people.