Hi!
Over the last few days I’ve dispatched quite a few flights and something in two of them caught my eye. A minute ago, a friend just reported me the same apparent bug in one of his.
Flying an E190 from Marseille to Lisbon, using EASA fuel contingency rules. The route overflies the city of Madrid and LEMD is selected as an enroute alternate, thus being obviously within 60 minutes and the defined number of miles for enroute alternate, yet the system dispatches the flight with 5% contingency (6 mins in this case) instead of the supposed 3% contingency or 5 mins. According to EASA legislation operators with an appropriate fuel-consumption monitoring system under AMC6/AMC7 CAT.OP.MPA.181 can use a variation involving 3% (or 5 mins) , provided a qualifying fuel ERA (in this case LEMD) is available. Is there any explanation I might be missing here or is this genuinely a bug that support could have a look at? Below is a link to the OFP in question.
Thanks in advance
Hi, this is intentional. There is a long history of discussions with real-world dispatchers regarding this interpretation, though most of them were on the old forum many years ago and are not viewable anymore.
In summary, apparently if 3% results in less than 5 minutes and 5% results in more, you cannot use the 3% reduction at all. So you end up needing to use the greater of 5% or 5 minutes, which ends up being 5% (6 minutes) in your case.
I think the regulation can be interpreted either way, but apparently this is how it’s done in the real world.
Related topic with a similar question: EASA Contingency Rule - 3% Not Being Applied? - #2 by Rodeo314
And a screenshot of a post from the old forum:
Best regards,
Hi! Thanks for your input
After pulling up my OM-A, here’s the current text:
“The contingency fuel at departure should be the fuel described in points A or B, whichever is higher:
A - an amount of fuel that should be either:
• 5 % of the planned trip fuel or, in the event of in-flight re-planning, 5 % of the trip fuel for the remainder of the flight; or
• not less than 3 % of the planned trip fuel, or in the event of in-flight re-planning, 3 % of the trip fuel for the remainder of the flight provided that a fuel en route alternate (fuel ERA) aerodrome is available (); or
• an amount of fuel sufficient for 20-minute flying time based upon the planned trip fuel consumption;
() Location of the Fuel En-route alternate aerodrome to reduce contingency fuel to 3%
Or
B - an amount of fuel to fly for 5 minutes at holding speed at 1500 ft above the destination aerodrome in standard conditions.
The fuel en route alternate (fuel ERA) aerodrome should be located within a circle with a radius equal to 20 % of the total flight plan distance; the centre of this circle lies on the planned route at a distance from the destination aerodrome equal to 25 % of the total flight plan distance, or at least 20 % of the total flight plan distance plus 50 NM, whichever is greater. All distances should be calculated in still-air conditions. The fuel ERA aerodrome should be nominated in the operational flight plan.”
Summary:
A - 5% of trip (or 5% of trip remainder if re-dispatching);
A - 3% of trip when using an applicable ERA (or 3% of trip remainder if using ERA when re-dispatching);
A - 20 mins based on trip consumption;
OR
B - 5 mins holding at 1500ft above destination in ISA
With the condition that B is the minimum you can carry a.k.a whichever is higher.
In this case I still believe that for this flight plan, 3% or 5 mins (whichever is higher) would be the adequate contingency.
If you end up reaching the same conclusion, I guess that’s worth a fine tune in your algorithm. I must add I’ve never seen “your” version in several years on the line. I’ll be happy to provide you with an OFP screenshot whenever this case applies so we can compare it.
Thanks
