Anthony
Contingencies of "as little as 1% or 2%" of Trip fuel are not unheard of.
Here's an example:
Take, say, a 747 flying from Singapore to London where the trip fuel could be perhaps 140 tonnes.
Under the old percentage system the 5% contingency fuel figure would be 7 tonnes. Even using 3% the contingency fuel would be just over 4 tonnes. Now in reality the flight may use some extra fuel enroute due to unforecast headwinds and altitude constraints but arriving at, say, 0500 UTC into London in good weather there's normally nil or minimal delay so having an extra 7 tonnes contingency fuel is probably in most cases just a little excessive.
On the other hand the modern statistical system will have analysied the actual fuel burn on dozens if not hundreds of these flights. It will quite conceivably come up with an answer that 1.8 tonnes of contingency fuel will give 99% coverage or 1.4 tonnes will give 95% coverage....which equates to a contingency fuel of around 1% or 2 % of a trip fuel of 140 tonnes.
So no, it's not impossible or odd to see contingency fuels of 1 or 2 % of trip fuel - often it simply depends on the time of day of arrival!
Last edited by wiggy; 11th Mar 2009 at 18:43.
Reason: remove clumsiness!