On Fuel Saving

First published in “The Log” Autumn 2012

Over 20 years ago in a very Big Airline it was decided to improve the on time departure statistics and encourage people to take it more seriously. A very clever man asked a very precise question. How much does it cost to delay the Narita flight by one hour. The answer was £60,000 as it involved missing the night jet ban, delaying till the morning, re-crewing and putting all the passengers at Heathrow and Narita in an hotel. He then divided the £60,000 by 60 to get the cost per minute and somewhere in the subsequent “spin” the word Narita was dropped and it was decided that one minute’s delay to a jumbo was costing £1000. Sometime later even the reference to a 747 was being dropped. I’m sure you can see the error.

Sometime before that someone else had calculated that putting extra twenty tonnes of fuel on a long haul aeroplane meant that it could not make as high a level for the Atlantic crossing and under these circumstances it could burn “….up to 4% of the extra fuel per hour of cruise”. By quoting this often enough and forgetting some of the conditions it is now applied to an extra 300 kg of fuel on an A319 going to Amsterdam at FL230.

This, of course, makes no sense at all; if you cast your mind back to your principles of flight studies you will remember that at low IAS (high altitude, near the performance limit) induced drag is dominant, at low/medium levels (high IAS) form drag is dominant. Form drag does not change with weight. In any case on short haul flights a far greater percentage of the flight is spent at inefficient speeds (even 250 knots IAS is considerably above the most efficient speed for most short haul aeroplanes)

The extra fuel that the navlog requires in a little note at the bottom if there is an increase in weight is often quoted as proof of the increased burn. You should remember that this increase is just a fudge factor to get the aeroplane away without a re-calculation. If you ask for the re-calculation you will see the real (very small) increase, if there is any increase at all.

You may ask why would any pilot want to prove that extra fuel costs a lot to carry. The answer is, of course that every few years, pressure is put on managers to “reduce costs”. The Board believe they are in charge and therefore they don’t have to bear the pain themselves. The senior managers reduce a few of their numbers and also the number of secretaries (the managers who leave become consultants with, if anything, more pay, the secretaries are replaced at the next management re-shuffle or change of office building).

The marketing section get rid of two colour photocopiers and a cold drinks machine (again, later replaced) and the IT section say they have made many cost savings, but no-one else understands IT enough to realise they haven’t actually done anything.

Engineering suffer most with a reduction of spares on the shelf, reduced numbers of licensed engineers and stopping what little training they were doing. The rapid increase in sick aeroplanes needing spares/engineers when the upturn comes is corrected by reversing the above, admittedly after the problem has led to a large number of cancelled flights. By this time the engineering manager that was in charge of the cuts (and is an engineer first and doesn’t really understand the management game) has either retired of been sacked.

Operations spend a lot of money on a new flight planning system that attempts to prove that the same aeroplanes flying the same routes will burn less fuel and also on a rostering system that either fails completely or makes the pilots so tired that they leave in droves at the next upturn in business when other companies are recruiting.

This leaves pilot management with a problem. Since Orville Wright aeroplanes have been operated as efficiently as possible, if only because they don’t really work at all unless you do so. Almost everything that could be done has been done decades ago and unlike most other sections, the pilots cannot have a re-shuffle or a new building to cover up the backsliding between recessions that happens everywhere else. As Robert Ayling discovered, you can’t reduce numbers to use only 1.98 pilots per aeroplane, there has to be two.

All they can do is try to find some things that might produce an apparent improvement in costs. The first one is to look the excess fuel saving above and conveniently forget about some (most) of the conditions that originally applied (if indeed they ever knew them). If you can establish to your own satisfaction (and senior management/the board) that there is a saving in fuel per extra kilo carried (whether there is really a saving or not), then the computer can calculate the huge (but mythical) savings across the fleet.

Every 100 kg less extra fuel that is loaded is now, on paper, a saving of 4kg per hour (note how “per hour of cruise” has disappeared) for flight ops, or more correctly for flight ops management. It is also 3 minutes less holding fuel, but in flying nothing unexpected ever happens.

Similar disingenuous statements are made about most of the other fuel saving measures which either don’t work, or create some increased risk of distraction. To mention them all here would sound like a rant, but at least one aircraft recently has found itself crossing a runway in a “No Engine” taxy situation whilst trying to start a second engine. An interesting bit of number crunching is that in the airline concerned the amount of money saved by single engine taxi per year is almost the same as the CEO’s reported issue of free shares.

And the clever man in the first paragraph? He also fudged the way delays were recorded and took the credit for saving £1000 for every one of the many minutes less delays that were recorded. I don’t know what his bonus was, but……………….