BOAC, how is KLM's 90 cont or 99 cont similar to BA's?
The 16 minutes is not a percentage of the flightplan fuel.
It is the average (90 % or 99%) of the delays in the previous months.
So in a month with lots of delays due to wx for instance, the cont fuel will reflect those delays and can even be 30 min.
In slow months, with no delays, it goes down to the minimum of 5 minutes.
In my day, BA went completely 'statistical' on contingency and were often around 3% - with plogs worked on destination and arrival time. I do not recall them ever exceeding 5%.
Clearly KLM takes more then 5% based on statistics, they add this delay fuel on top of the minimum contingency of 5 minutes or 5% of trip fuel. In accordance with normal EUops rules.
Regarding BA taking less then 5% of trip fuel... my ops manual states this about reduced contingency
Reduction of Contingency Fuel by the Use of 3% ERA
Not less than 3% or 5 minutes, which ever is greater, of the planned Trip Fuel or in the event of in flight replanning, 3% of the Trip Fuel for the remainder of the flight, provided that an en-route alternate is available in accordance with the diagram below. The en-route alternate should be located within a circle having a radius equal to 20% of the total flight plan distance, the centre of which lies on the planned route at a distance from the destination of 25% of the total flight plan distance, or at 20% of the total flight plan distance plus 50 NM, whichever is the greater; as illustrated below.
Does BA do this on a regular basis? And how does taking less then the minimum 5minutes /5% of trip involve statistics?
Contingency fuel:
Fuel to cover deviations from the planned operating conditions such as unfavourable variations in cruise altitude or track, deviations from the forecast wind values or any other unforeseen adverse circumstances.
Contingency Fuel shall be the higher of (1) or (2) below:
5% of the planned Trip Fuel or in the event of in-flight replanning, 5% of the Trip Fuel for the remainder of the flight.
an amount of fuel to fly for 5 minutes at holding speed at 1500 ft above the destination aerodrome in standard conditions.
How can anybody statistically determine unforseen conditions I wonder? Or statistically determine deviations from planned operating conditions?