Alternate Aerodromes (ALTN) and related Fuel Calculation

SimBrief Dispatch
1

Dear Derek,

while testing your new features I came across a problem in terms of Alternate Aerodrome (ALTN) planning and the related fuel calculation:

  1. No Alternate Aerodrome

In this case of an EASA calculation, it requires 15 minutes of Additional Fuel (ADDFUEL) on top of the 30 min Final Reserve (FINRES). Calculating FRA-LAS without an Alternate Aerodrome (yeah, knowing it’s illegal, just for testing) it does only reduce the ALTN fuel to zero and not add the required ADDFUEL.

(6) The minimum additional fuel, which should permit:
(ii) holding for 15 minutes at 1 500 ft (450 m) above destination aerodrome elevation in standard conditions, when a flight is operated without a destination alternate aerodrome.

  1. Two Alternate Aerodrome Calculation

Another problem on this side. In terms of two Alternates which are planned if the Destination Aerodrome (DEST) is below landing mima, EASA requires the Alternate Aerodrome to be available which requires the greater amount of fuel (basically, the one which is the most far away one),

(4) Alternate fuel, which should:
(ii) where two destination alternate aerodromes are required, be sufficient to proceed to the alternate aerodrome that requires the greater amount of alternate fuel.

I would appreciate if you could implement those requirements!
Best Regards and sorry for bothering you!

1 Like
2

Hi Alex,

I will look into these for a future update.

For the ADDFUEL, it probably makes the most sense to add this when I eventually rework SimBrief with more fuel options (for example, only EXTRA fuel is supported right now. Eventually I might add other types, such as OPN, WX, ADDFUEL, etc). For now I guess you can add this manually under EXTRA fuel as a workaround.

Best regards,

3

Good Morning Derek,

thank you for four fast response! Regarding the EASA Fuel Policy (Basic Procedure), there are only the following types of fuel required and neccesary:

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AMC1 CAT.OP.MPA.150 (b) Fuel policy
Planning criterica - Aeroplanes
(a) Basic Procedure

(1) Taxi
(2) Trip
(3) Contingency
(4) Alternate
(5) Final Reserve
(6) Additional Fuel
(7) Extra

Additional Fuel (6) is used for the following sub-requirements:

(i) the aeroplane to descend as necessary and proceed to an adequate alternate aerodrome in the event of engine failure or loss of pressurisation, whichever requires the greater amount of fuel based on the assumption that such a failure occurs at the most critical point along the route, and
(A) hold there for 15 minutes at 1 500 ft (450 m) above aerodrome elevation in standard conditions; and
(B) make an approach and landing,
except that additional fuel is only required if the minimum amount of fuel calculated in accordance with (a)(2) to (a)(5) is not sufficient for such an event; and

(ii) holding for 15 minutes at 1 500 ft (450 m) above destination aerodrome elevation in standard conditions, when a flight is operated without a destination alternate aerodrome.

I am not sure whether such hypothetical items like “WX” (or whatever “OPN” is) are useful, but I would stick to the standard. Everything else is basically covered within the decision to take Extra Fuel.

But just my personal opionion. Thank you for having these ideas in mind!
Best Regards, Alex

4

thanks for the awesome information.

1 Like
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“OPN” is, to my knowledge, a very Ryanair-specific term. It is short for ‘operating fuel’ and accounts for any discrepancy in fuel burn that has occurred on a certain route from statistical experience and is usually around 50-100KG, if it is applicable at all.

I think Ryanair include it in the minimum takeoff fuel so crews can not legally depart without it. You could also think of it as an additional sip of contingency fuel.

6

I’ve seen such an abbreviation used across other Lido/Flight customer carriers to assign a specific fuel bucket for the additional fuel.

7

thanks my issue has been fixed.