View Full Version : how do you measure fuel efficiency?

13th Nov 2005, 21:00
many fuel conservation measures are being implemented these days but I wonder how the (positive) effects can be measured.

Since fuel consumption depends on many different factors (e.g. payload, wind, speed regime etc.) how can one say that one specific fuel conservation measure lead to a specific saving? Which (combined) factor is useful in this respect?

Is making a statement - before and after the implementation of a fuel conservation measure - about fuel burned per nautical mile and revenue payload ton a possible solution?

I appreciate your opinion on this, thank you.

15th Nov 2005, 13:13
Basically manipulate (Speed/tsfc)*(Lift/Drag) which rules fuel related costs. [Breguet's Rule]. Substitute Mach No for Speed where appropriate.

Collate with fixed costs and time-related costs. Express this as the number of kg of fuel that the total cost of one flight minute
would buy.

Sometimes a longer path in climb helps if you can get a better cruise level and avoid being stuck low down for a longer period than you'd like.

Sometimes an extra 100nm of route avoids more expensive route charges.

Two good handouts to download from Airbus Flight Ops are "Getting to Grips with Performance" and "Getting to Grips with Cost Index".