Fredairstair,
to start with the final reserve is: For aeroplanes with turbine power units, fuel to fly for 30 minutes at holding speed at 1 500 ft (450 m) above aerodrome elevation in standard conditions, calculated with the estimated mass on arrival at the alternate or the destination, when no alternate is required.
So one can say it's equates to a holding fuel and to determine the amount one can refer to VOL 2 on the BUS.
An operator can prescribe a compulsory min amount of fuel upon touch down being more restrictive than JAR. Usually it's a recommended fuel upon landing.
If one takes flight plan fuel one can use any amount of fuel he/she deems necessary anywhere during the diversion to an en route alternate or at destination or the destination's alternate until the commander reaches the final reserve plus fuel required for the approach. Let's say it'd be 5 tonnes for an A346 Having hat amount of fuel physically on board a PAN call is due with fuel remaining in minutes. Having the final reserve 3.7 t for A346 physically on board a MAY DAY call is due.
In regards to in flight fuel management
In-flight fuel management.
(1) If, as a result of an in-flight fuel check, the expected fuel remaining on arrival at the destination is less than the required alternate fuel plus final reserve fuel, the commander must take into account the traffic and the operational conditions prevailing at the destination aerodrome, along the diversion route to an alternate aerodrome and at the destination alternate aerodrome, when deciding whether to proceed to the destination aerodrome or to divert, so as to land with not less than final reserve fuel.
It must be emphasized once again REGARDLESS of where one lands JAR requires one to have only final reserve upon touch down nothing more or less. One can go below it provided emergency has been declared.
Cheers.:ok:

Popay,
Just to clear things up in my mind.
For operational reasons you have dispatched with minimum flight plan fuel. You arrive at your destinations MAP with Diversion fuel plus Final reserve fuel.
There is a runway incursion that requires you to 'go around'.
Can you come back around for a second appraoch even though you now only have diversion plus final reserve fuel remaining?
Are you only required by JAR to declare a MAYDAY if you are going to land with less than final reserve?
Thanks

FL800, hi there.
Well, it all depends on the incursion. However, as a general rule the commander may decide whatever he/she deems appropriate including a decision to come back and land provided the commander assesses the landing to be completed safely. That includes weather, traffic, ATC, etc.
JAR requires one to declare emergency when ACTUAL fuel on board is equal to final reserve. Check your part A since the company may lay down more restrictive rules.
Once again in order to make the life easier and decision making more convenient JAR basically says do whatever you want but make sure you have final reserve upon touch down. That's all.:ok:
Cheers
P.S. It must be emphasized that the lawmaker expects one to have at least alternate+final reserve at IAF at the destination in regular case unless the commander has made the decision to continue to the destination while en route (as described above after assessing the whole thing) despite the fact that the fuel over IAF is predicted to be less than final+alternate. It's entirely commander's responsibility anyway that's why take some extra and don't get yourself into trouble.:ok:

Can someone clarify this for me. If I think I might use my Final Reserve fuel before touchdown it is a Pan Call, if I am in the air and I AM using the Final reserve fuel it is a mayday? My Ops manual uses the phrase which I hate "Declare an emergency", they should leave that for Hollywood movies.

Are there any hard and fast rules about whether to use a Pan or a Mayday?

Hi Popay,

Thanks for the reply. I think we're getting to the nub of the issue, I do understand how Final Reserve Fuel is calculated - I think 212man said "It's simply a means of defining what fuel consumption you should apply to calculate what 30 minutes fuel actually is!" So I'm afraid I have to take issue with your statement "So one can say it's equates to a holding fuel" I really don't think it is, I won't be using it to hold - I'll be using it to get my sorry @rse out of trouble if I was dim enough to get down to Final Reserve.

Telstar - I think MAYDAY comes from the French - Help Me. Entirely appropriate I think if you're down to 30 min (at best!) before your engines stop.

John T - Ta for the clarification on useable fuel.

So I'm afraid I have to take issue with your statement "So one can say it's equates to a holding fuel" I really don't think it is, I won't be using it to hold - I'll be using it to get my sorry @rse out of trouble if I was dim enough to get down to Final Reserve.

Fredairstair, if you get to a condition where you are down to Final Reserve then, normally, you won't be using it to hold. You should have now declared a MAYDAY and will be vectored straight in to land. Let's not forget that if you departed with flight plan fuel and go around from MDA/DH at destination then proceed to your alternate you should arrive at your alternate with enough fuel for an approach and landing + Final Reserve. If the unexpected happened and a straight in approach and land was unavailable then you now have your Final Reserve to eat into. (Maybe the previous landing burst a tyre??? Not something you can plan on but it happens)

30 mins at holding speed @1500ft AAL = 30 mins in the hold @1500ft AAL
Just because it doesn't state it doesn't make it untrue. You could also not go to a hold and just fly around near the airfield while at holding speed, whats the difference?:ugh:

Obviously this is backs to the wall stuff here, hopefully we'll only see it thrashed out here on these pages:ok:

Certainly in the 737 Jurassics and Classics you need to also take into account the fuel quantity gauge accuracy tolerance which is I believe 2.5% or 3% of the full wing tank reading. With typically a full tank reading of say 4500 kgs that means 135 kgs may not be there. So if you are down to your last 1200 kgs total fuel (30 minutes), at worst case you may have 270 kgs less than you think.

My current work involves a mission management system, which includes fuel calculations.

To keep things simple, the minimum fuel state seen on commencing a go-around is the sum of the fuel required to reach the alternate, 30 min of holding at the alternate and the desired touchdown fuel state. Default values are currently 2000 kg for 30 min holding, 360 kg for the approach and 0 kg on landing - it is assumed that the aircraft will land within those 30 minutes. We also assume that the 5% contingency will have been used before reaching the go-around at destination.

However, the estimation of fuel required to reach the alternate and carry out an IFR approach is far from simple. Aircraft designers will pretend that low values are sufficient, so that their customers can dispatch with the absolute minimum of fuel to maximise payload within RTOW constraints (or whatever JAR calls it).

Currently we propose a linear relationship of fuel vs distance for the diversion trip to the alternate. For the aircraft in question, this is 800 + (12 x great circle distance in nm from dest to altn). However, the end-user will be able to amend the distance as necessary. Thus he will see:

Trip distance (dest to altn): nm (edit if required)
thus Trip fuel (800 + 12d) = kg
+ approach (default 360kg) = kg (edit if required)
+ 30 min hold (default 2000kg) = kg (edit if required)
+ min landing fuel (default 0 kg)= kg (edit if required)
= min fuel at go-around from dest.

So all elements of the diversion process are clearly defined and may be edited by the end-user. On a day-to-day basis, all the user will need to do is to type in the ICAO of the dest and altn and review the results.

This defines the minimum landing fuel weight at the dest, although it is assumed for fuel burn calculations that the contingency is carried right up to the start of the go-around at destination. The system can then calculate the fuel required for the flight given this weight, the ZFW and the route, including taxi allowance.

BEagle, hi there.
Well, I have to disagree on that one, I'm afraid. It's indeed very simple. My company uses LIDO system and it's very accurate. It takes into account the departure from the filed approach RWY at destination, SID, the route, STAR, type of approach, RWY at the alternate. It also take the the appropriate level into account, whereas the FMC doesn't. That's one of the reasons why one is ought to correct the diversion fuel on FMGC INIT B page. The problem with FMGC is the level that FMGC calculates for the diversion.
It's a default level which might significantly diverge from the real one. As an example for a diversion of something like 320 NM the system calculates with the FL 320 way off the reality. In real live one will get FL220 doing the same flight as a normal departure and arrival.
However regardless of whatever FMGC is calculating (mind you it's only advisory) the OFP must reflect an accurate figure representing a legal guide line for the commander.
Cheers.:ok:

Yes, it's slavish reliance on FMGC figures which are the problem! LIDO, like other suppliers, uses knowledge gained from years of experience to develop practical figures - such as the FL you suggest. But if the alternate doesn't have a STAR, or the crew doesn't have access to LIDO at the time? That's why they need an easy 'alternate fuel calculator' which doesn't assume that they'll be able to use optimum levels.

Just one curious question from a SLF - I so hate that phrase - aviation fan.

Been reading with interest the threads on various ways to conduct the descent, approach and so on with the idea of saving fuel. Kinda thinking though, who cares? You guys arnt paying for the fuel. Why be concerned?

Does 300-400kg of fuel really matter depending on whether you use a high speed descent of ecom path descent or whatever?

Or whether you don't quite get it right on the approach and perhaps have added power a little early.


If you had arrived with more fuel then planned for whatever reason, even though you could've saved a little more but didn't, is that an issue?

Don't take any of that the wrong way. Not being picky or arrogant or a smart arse or whatever.


Just wondering if perhaps some one in the company may notice a poor approach or descent as far as saving fuel and question you guys? Or is it just considered slightly poor airmanship? Or both?

Our company tracks fuel usage by Captain. The "fuel savings" program could well get ugly in the future if management decides some individuals use more fuel than others on identical routes. After all, fuel costs LOTS of money, and may dip into the executive bonuses...

737NG Fuel!!! Any Pilot there??? Need Help!!!
 

Hi all!!!

I have two questions for you about 737NG minimum required fuel. First one, Which is currently the contingency fuel? 3% 5% 10%... second one which is the reserve fuel value in lbs. for the 737NG aircrafts?

Taxi = 500 lbs - 10min
Trip = Variable corrected by aloft winds
Cont = ??? 3%, 5%, 10%...
Altn = Variable corrected by aloft winds
Frsv= ???
Add = it depends on multiple factors

Thanks in advance

Regards
------------------
Marciaaa ;)

I guess it varies from Company to Company and Country to Country. In India, DGCA clearly says that for seasonal wind one must carry 10% contigency fuel whereas for actual wind we are allowed to carry 6% contigency fuel.

Ruddman,

If you look at an individual case 300-400 kgs doesn't sound much. But if you have lets say 100 departures a day, that 300 kgs of fuel equates to 30 T of fuel, that is a lot of money. Most of the airlines have more than 100 departures a day. As Intruder said many companies track the fuel usage.

Interesting thread, it appears what should be black and white about important items ie Fuel (!!!) required; without going into cut and paste and the 2 page document on what minimum fuel is required we use Taxi, Trip, Contingency, Alternate , and then enough for a 30 minute hold AND a final reserve.

I know what has been said 30 Minute at 1500ft at holding speed IS Final reserve therefore one and the same however practically we feel (company) that having a bit of fuel between the alternate and physically landing with what is hopefully your reserve in tact a buffer (I loves buffers!) not a bad thing. Howvever re -reading my post Im sure others would say well why you dont effectively call that extra bit 'any additional fuel' as per fuel proforma - yes, I guess, does it matter what I call it - no - so long as it there.