I don't have access to "my" MD-11 for some days, so I ask here if this equation is correct:UFOB = BLOCK - TAXI - BLST == TRIP + RTE RSV + EXTRA + FINALI'm somehow unsure about TAXI...

Afraid not. UFOB doesn't need a formula, it is simply how much you have. Or, in the case of the progress page, how much you are expected to have.

UFOB means Usable Fuel On Board. Hopefully that de-mystifies it a little.Just as Paul said, UFOB is exactly how much fuel you have. Basically, the only formula for UFOB is FOB - UNUSABLE. Every aircraft will have unusable fuel, by the way.FOB - UNUSABLE = UFOBUFOB should take into account the following:Taxi, ballast, trip, alternate (if required), holding and final (landing with fuel still in the tanks is always advisable if you want to avoid the embarrassment of a tow back to the gate).UFOB - TAXI = TAKEOFF FUELTAKEOFF - TRIP = ESTIMATED LANDING (BALLAST + ALTERNATE + HOLD + FINAL)Since everything is plus or minus, it's simple to work the whole mess out to show you whatever combination you'd like in the end.