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Block fuel- Help wanted

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Block fuel- Help wanted

Old 26th Sep 2018, 07:48
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Block fuel- Help wanted

Good morning all,

Was wondering if turbo prop/jet pilots could help with their block fuel?
As part of a university project I am undertaking research into how the pilots make sure a company offered fuel load is acceptable: What gross error checks are used?
  • Fokker F27
  • DHC8 (all types)
  • ATR 42 and 72
  • CRJ200
  • B717
  • DC9 ( all types)
  • A320- A321
  • A330 200 and 300
  • A330 NEO (800-900)
  • A340 300 and 600
  • A350
  • B757 200 and 300
  • B767 200ER and 300 ER
  • B777 all series
  • B787 900
All replies and all turbo prop and jet aircraft types, not just those listed are appreciated!
Thanks in advance
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Old 26th Sep 2018, 12:36
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6 tonnes per hour works well for the 330-200 and 330-300. It's a tad on the conservative side, but not far off.
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Old 26th Sep 2018, 13:13
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SW1
 
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2400 per hour for the a320. Quick determination of flight planning tables give a good ball park figure to check for gross error.
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Old 26th Sep 2018, 13:29
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PGA
 
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A380 - 12 tons per hour is a good ballpark figure for the trip fuel.
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Old 26th Sep 2018, 20:51
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Hi Aumonier,

In 99.99%% of cases, the fuel the company (or more specifically, the Flight Operations department) gives us sufficient to perform the flight safely and arrive with above legal minimums (30 mins holding fuel). Sure we can use an average fuel flow to perform a quick gross check but these days more commonly we need to take other matters into consideration. In order to produce a BLOCK fuel figure, the route the company thinks we are going to fly needs to be accurate. It used to be that they all used to plan fuel for the 'longest' departure procedure and the 'longest' arrival procedure. Nowadays, they don't. They use what they think we will get based on weather or past patterns they have observed. If they insert a shorter route into the flight planning system (Jeppesen or LIDO are the two most popular ones), then they will get a smaller amount of BLOCK fuel. We therefore need to sometimes uplift more fuel to match what we think we will need on the day. Secondly, we need to observe the weather and bear in mind traffic at the destination. These may require us to hold, more fuel needs to be taken for this.
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Old 26th Sep 2018, 21:13
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My gross error check is that I copy the OPF into the FMS and before departure, we do a triple check that the fuel displayed by the on-board SW (with full route and correct weight) matches to OFP and to what is in the tanks. It is also the manufacturer's procedure.
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Old 27th Sep 2018, 01:20
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For the A320 as per FlightDetent.

For the Dash 8 we did our planning ourselves but it was around 1000 lbs / hour plus 200 lbs for a climb.

BAe146 is around 2000 kg / hour and 600 kg for climb.
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Old 27th Sep 2018, 04:28
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Fuel requirements vary depending upon whether you are at the planning stage or in actual flight. Different airlines will have their own planning mothods but typically it's:

A fixed reserve - 30mins
Approach fuel - to get from 1,500' to end of the landing roll
Flight fuel - from the start of take off roll to 1,500' at destination.
Taxi fuel - from the gate to the end of the runway.
Variable reserve - 10% of the flight fuel
Holding fuel - for nominated ATC holding.
WX holding fuel - to cover any TEMPO or INTER where the weather is below the nominated holding criteria.
Diversion fuel - if the WX holding periods exceed the ability to hold.

When in flight things change and all you need is:

1) Fuel to go somewhere (anywhere)
2) 10% of (1)
3) Approach fuel
4) Minimum reserve
5) WX holding AND but not always, ATC holding
6) Alternate fuel, but only if you can't manage (5)
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Old 27th Sep 2018, 06:15
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CFM56-5A1: 0.596
IAE V2500A1: 0.581

...then, take the typical cruise thrust...

CFM: 5000 lbs
IAE: 5070 lbs

...and finally, multiply the SFCs for each engine by their typical cruise thrust to get raw ruel consumption...

CFM: 0.596 X 5000 = 2980 lbs fuel per hour
IAE: 0.581 X 5070 = 2945.67 lbs fuel per hour

Hope this helps!

A_pollo
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Old 27th Sep 2018, 07:44
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Atlas, thanks, that's very interesting. Two questions, if I may:

(a) Why 1,500'? Is that height significant, or is it an arbitrary point?

(b) Why "alternate fuel, but only if you can't manage (5)"? Surely you must always provide for diversion to alternate from anywhere, down to GA after touchdown since many things beside WX or ATC holding can prevent you from landing at the last moment?
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Old 27th Sep 2018, 08:02
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Originally Posted by PGA View Post
A380 - 12 tons per hour is a good ballpark figure for the trip fuel.
Thanks to all for the replies. I appreciate all of them!

My gross error check is that I copy the OPF into the FMS and before departure, we do a triple check that the fuel displayed by the on-board SW (with full route and correct weight) matches to OFP and to what is in the tanks. It is also the manufacturer's procedure.
Thanks FlightDetent, I assume the OPF is the onboard performance equipment for calculating V speeds?

I was wondering when handed the flight plan, do you check the fuel offered and check for their 'reasonableness' in what the company offered?
If it is ok, can you let me know which type you fly and what block fuel you would use?

Keep them coming folks!

Thanks to all
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Old 27th Sep 2018, 08:10
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Atlas, you need to add what type of operation and which regulatory framework the above applies to!

@OldLurker: and why no APU and de-icing fuel, why landing roll fuel, why 3 types of extra fuel...., why 10% contingency (last week I had 59 kgs on top of of 11.112 trip)

​​​​​
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Old 27th Sep 2018, 11:54
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OldLurker, it depends on the rules you operate under. Most of the sectors I fly do not have fuel for an alternate.

FlightDetent, he did say "typically" .
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Old 27th Sep 2018, 12:35
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Then I claim the above is not typical for an airline - until a scope is attached to it. It might be common or even the rule in some place, and I am genuinely curious where that is. Not disputing a word of what is written.

I recently took a look on what the CAAC requirements are (FAA-like?) and it was a nice educative experience.

Last edited by FlightDetent; 27th Sep 2018 at 15:44.
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Old 28th Sep 2018, 05:35
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Your operations may well be different.

To answer three of the questions fro OL, 1500' neither significant nor arbitrary and varies from aircraft to aircraft

There is no requirement whatsoever to habitually carry an alternate. Legally, all that is needed is to have 30 minutes of fuel remaining at the end of the landing roll. It may vary slightly, but generally not very much.

In some places there might be perfectly acceptable airports within only a few miles and the alternate is almost in the circuit - Heathrow/Gatwick/Stansted for example. In such cases you can have an alternate, basically without carrying any extra fuel although these are not 'real' alternates as they are almost certain to have exactly the same weather conditions. In contrast, on a Pacific crossing for example, if you take somewhere like Tahiti, which is the only decent runway within a very long way, you cannot reasonably carry an alternate so generally there's some form of remote fuel allowance which might be something like 90 minutes of holding on top of anything else that might be required.

On arriving at destination you could have enough fuel to fly to an alternate 200 miles away, but if held for any length of time that alternate option will disappear. You may still be able to carry a closer airport, but eventually, you'll be left with only one choice. Managing when to hold and when to divert and more importantly if you'll let options disappear, is what we are supposed to to, is it not......?

It's not impossible that you might not be able to consider one place, and so another may be of interest. The option to go to somewhere may exist right to the gate or it could disappear whilst airborne. What's the weather at all of these places. What requirement do they have. There is NO fixed answer and if we play the 'what if' game, then it's easy to come up with ones that are difficult to comply with.
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Old 28th Sep 2018, 10:05
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Atlas, thanks!
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Old 28th Sep 2018, 10:45
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Thanks too, I learned what was requested. As an ex LGW pilot.
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Old 28th Sep 2018, 11:06
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Originally Posted by FlightDetent View Post
My gross error check is that I copy the OPF into the FMS and before departure, we do a triple check that the fuel displayed by the on-board SW (with full route and correct weight) matches to OFP and to what is in the tanks. It is also the manufacturer's procedure.
Good technique! At the outfit where I work (Airbus Fleet) nobody knows the FUEL PLANNING function on the init-B page...
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Old 1st Oct 2018, 08:27
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Thanks for the replies!
Very much appreciated!

Am still having trouble with a few types.

Are there any:
  • A340 300 to 600
  • B717
  • B757 200 and 300

Thanks to all
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Old 1st Oct 2018, 22:02
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Check your PMs
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