Reduced Contingency Fuel Planning

[SandBob]

Good Day,

Can any of the boffins perhaps advice me to why it is 6 hrs or where it comes from?

I am referring to to EU OPS Appendix 1 to OPS1.255 Fuel Policy paragraph 2.1.d "alternate fuel or no alternate fuel if decision point is at less than 6 hours from the Destination 1 aerodrome . . ."

Thanks,

Bob

[Hunter58]

Just guessing, but would hat not cover Finnland-Canaries?

[Canuckbirdstrike]

Original concept based on wether forecast time periods and reliability decreasing as time from forecast issue is longer. At 6 hours in all likelihood the worst case scenario is in the 6-12 hour period for the TAF.

[Microburst2002]

Sandbob

For dispatch fuel planning you normally have to include alternate fuel. But sometimes you can plan without it, if it is less than 6 hours away, and weather is good, and they have two runways, etc, etc...

For inflight determination of fuel required at the decision point of a re-dispatch, you can also "benefit" from that. I mean, at departure you were at 11 hours from destination, but now, from the decision point, you are at only 2, so if the conditions are met (weather, independent runways, etc...) then alternate fuel is not required.

However, when alternate fuel is not required, an additional fuel reserve of 15 minutes is required.

hope it helps

[SandBob]

Thanks, I have gathered from further research it was a TAF validity factor. I have, however, been unable to find a valid source explaining as to how the 6 hours were calculated.

Any Met Man out there with a reason why TAF validity is questionable after 6 hours?

Regards,

Bob

[Canuckbirdstrike]

There is a direct relationship between the length of time from forecast issue and the ability to predict accurately. TAF's are issued every 6 hours and constructed around the principle of 6 hour windows. This was the primary driver for the 6 hour planning rule.