It is not a flat fee for every F ticket to Europe. The amount of the taxes, fees, and fuel surcharge will vary, based on the length of your itinerary and your destination city. Also, the Heathrow departure tax will vary, based on whether Heathrow is your final destination, you are merely passing through, or making a stopover. I have not taken the time to figure out the exact formula, but I am sure that some FTer has calculated it to the penny.