Flight Planning Philosophy

[roadrabbit]

Could someone refresh my fast-disappearing knowledge?

When flight planning, how is the route constructed? I recall (from long haul experience with Big Airways) it was something like:

1. SID from the most used runway
2. Route from end of SID to start of STAR
3. Longest STAR to the furthest suitable runway (eg approaching from north, then land to the north)
4. Diversion fuel from wave-off to diversion (calculated again as er steps 1,2 and 3)
5. 30 mins holding fuel
6. Contingency fuel (min of 5% of the above)

Not sure where taxy out and taxy in fuel appeared in the figures.

Any information much appreciated.

roadrabbit

[AerocatS2A]

Surely that depends on where you work? The rule is that you have to have enough fuel for the flight, how that's calculated would be variable.

[roadrabbit]

Surely that depends on where you work? The rule is that you have to have enough fuel for the flight, how that's calculated would be variable.

Actually,there is more to it than that. If you are flying a commercial flight you will come under the FAA, CAA, or whatever legislative body controls aviation in the countries in which you fly, all in accordance with the minimum rules as laid down by ICAO. [ICAO Annex 6 part 1, para 4.3.6.3] They determine in law the minimum fuel to be loaded onto an aircraft. They typically use the parameters I stated in my opening question. What I am trying to find out is the content of those legal parameters. It appears that now the SID and runway used at departure, destination and alternate airfields can be that which would be used in line with the weather and the forecast for the expected time of departure and arrival.

What airlines actually do is work to those minimum parameters, even if they phrase them slightly differently. They may also choose to carry more fuel then that specified in the legal criteria. They cannot legally carry less.

[Bergerie1]

roadrabbit, I have sent you a PM

[AerocatS2A]

Actually,there is more to it than that. If you are flying a commercial flight you will come under the FAA, CAA, or whatever legislative body controls aviation in the countries in which you fly, all in accordance with the minimum rules as laid down by ICAO. [ICAO Annex 6 part 1, para 4.3.6.3] They determine in law the minimum fuel to be loaded onto an aircraft. They typically use the parameters I stated in my opening question. What I am trying to find out is the content of those legal parameters. It appears that now the SID and runway used at departure, destination and alternate airfields can be that which would be used in line with the weather and the forecast for the expected time of departure and arrival.

What airlines actually do is work to those minimum parameters, even if they phrase them slightly differently. They may also choose to carry more fuel then that specified in the legal criteria. They cannot legally carry less.

Ok. But just as a quick example, you say 5% contingency, my company uses 2%, previous company used 10%. Current company and previous company flight planning software didn't allow for a STAR or SID so departure and arrival allowances were added. The question can't be answered without getting into specifics of who and where.

[roadrabbit]

I accept what you say, but do not see how your company can reduce contingency below that required by ICAO. If your country is signatory to ICAO, then ICAO rules apply. In which country were you flying? Was it a commercial jet operation (which is what I am concerned with here)?
What your described company software does or doesn't do is irrelevant, provided you add the fuel to cover the departure and arrival, which you say is what happens. The software used by the company I worked for certainly covered all these items.
Basically you are correct in saying that you need to get into specifics - that is precisely what I am trying to do here.

[AerocatS2A]

I don't know what current ICAO says because it seems you have to pay for it. Older versions make no mention of SIDs and STARs, only that you had to have enough to get from here to there. Taxi out fuel is included as a separate line in the ICAO Annex and there's no talk of taxi in, presumably because it doesn't matter once you've landed.

From 2018 regarding trip fuel:

"Trip fuel, which shall be the amount of fuel required to enable the aeroplane to fly from take-off, or the point of in-flight re-planning, until landing at the destination aerodrome taking into account the operating conditions of 4.3.6.2 b);"

[roadrabbit]

It may not actually say SID or STAR, but it does say "from point of take-off". You could then ask just what does that mean? Is it from the start of the take-off roll, or the point of getting airborne (obviously written by lawyers for lawyers!). My company software also assumed that to include SIDs and STARs. The software also includes an amount of taxi fuel. Another potential anomaly is that contingency fuel can be used during taxi to initial departure take-off, to cover departure delays (routine, for example, at KJFK in the 1970s and 1980s).

For reference here is an extract from ICAO Annex 6 (ninth edition - see StackExchange):4.3.6.3 The pre-flight calculation of usable fuel required shall include:

a) taxi fuel, which shall be the amount of fuel expected to be consumed before take-off;

b) trip fuel, which shall be the amount of fuel required to enable the aeroplane to fly from take-off, or the point of in-flight re-planning, until landing at the destination aerodrome taking into account the operating conditions of 4.3.6.2 b);

c) contingency fuel, which shall be the amount of fuel required to compensate for unforeseen factors. It shall be five per cent of the planned trip fuel or of the fuel required from the point of in-flight re-planning based on the consumption rate used to plan the trip fuel but, in any case, shall not be lower than the amount required to fly for five minutes at holding speed at 450 m (1 500 ft) above the destination aerodrome in standard conditions;
Note.— Unforeseen factors are those which could have an influence on the fuel consumption to the destination aerodrome, such as deviations of an individual aeroplane from the expected fuel consumption data, deviations from forecast meteorological conditions, extended taxi times before take-off, and deviations from planned routings and/or cruising levels.
d) destination alternate fuel, which shall be:


where a destination alternate aerodrome is required, the amount of fuel required to enable the aeroplane to:
i) perform a missed approach at the destination aerodrome;
ii) climb to the expected cruising altitude; iii) fly the expected routing;
iv) descend to the point where the expected approach is initiated; and
v) conduct the approach and landing at the destination alternate aerodrome; or

where two destination alternate aerodromes are required, the amount of fuel, as calculated in 4.3.6.3 d) 1), required to enable the aeroplane to proceed to the destination alternate aerodrome which requires the greater amount of alternate fuel; or

where a flight is operated without a destination alternate aerodrome, the amount of fuel required to enable the aeroplane to fly for 15 minutes at holding speed at 450 m (1 500 ft) above destination aerodrome elevation in standard conditions; or

where the aerodrome of intended landing is an isolated aerodrome:
i) for a reciprocating engine aeroplane, the amount of fuel required to fly for 45 minutes plus 15 per cent of the flight time planned to be spent at cruising level, including final reserve fuel, or two hours, whichever is less; or
ii) for a turbine-engined aeroplane, the amount of fuel required to fly for two hours at normal cruise consumption above the destination aerodrome, including final reserve fuel;


e) final reserve fuel, which shall be the amount of fuel calculated using the estimated mass on arrival at the destination alternate aerodrome, or the destination aerodrome when no destination alternate aerodrome is required:


for a reciprocating engine aeroplane, the amount of fuel required to fly for 45 minutes, under speed and altitude conditions specified by the State of the Operator; or

for a turbine-engined aeroplane, the amount of fuel required to fly for 30 minutes at holding speed at 450 m (1 500 ft) above aerodrome elevation in standard conditions;


f) additional fuel, which shall be the supplementary amount of fuel required if the minimum fuel calculated in accordance with 4.3.6.3 b), c), d) and e) is not sufficient to:


allow the aeroplane to descend as necessary and proceed to an alternate aerodrome in the event of engine failure or loss of pressurization, whichever requires the greater amount of fuel based on the assumption that such a failure occurs at the most critical point along the route;
i) fly for 15 minutes at holding speed at 450 m (1 500 ft) above aerodrome elevation in standard conditions; and
ii) make an approach and landing;

allow an aeroplane engaged in EDTO to comply with the EDTO critical fuel scenario as established by the State of the Operator;

meet additional requirements not covered above;


Note 1.— Fuel planning for a failure that occurs at the most critical point along a route (4.3.6.3 f) 1)) may place the aeroplane in a fuel emergency situation based on 4.3.7.2.

Note 2.— Guidance on EDTO critical fuel scenarios is contained in Attachment D;
g) discretionary fuel, which shall be the extra amount of fuel to be carried at the discretion of the pilot-in-command.