Redispatch

Hi SimBrief,

I know that this has been mentioned once or twice, please add Redispatch as a specific Topic in Feature Requests.

Redispatch is an ESSENTIAL feature of real world long haul flying. The increased payload and/or increase range possible makes the difference profitability and loss, especially in freight flying.

Also Redispatch is just smart for fuel and route planning. It gives a pre-planned diversion option in event of unexpected changes in fuel burn (due weather deviations, lower flight levels than planned, etc.). And it keeps the pilots’ brains active on long routine flights, because you have to be sure to meet the criteria at the redispatch point to continue to intended destination and not be forced to divert.

The simple thing to recall/retain is that for the flight segment to the redispatch point you carry reserve only to the “diversion” airport (not to intended destination). Then you start from scratch, requiring reserve only for redispatch point to intended destination (“recycling” that previous reserve). And even smarter, because you carry less reserve fuel, burn is reduce for the same route because less reserve means less weight carried.

Just rule of thumb, napkin calculations, picture this:

  1. 8 hour flight on a 744 with an AVERAGE burn of 10,000KG/hr = 80,000 KG fuel burn
  2. Standard Dispatch, 5% reserve required = 4,000 KG fuel reserve
  3. Redispatch at 5 hours into the flight:
    3.1 Initial dispatch 5% reserve required = 2,500 KG fuel reserve
    3.2 Redispatch 5% reserve required = 1,500 KG BUT it’s onboard already in the above 2,500 KG

This is a simple example, but here you see nearly 2,000 KG less fuel (the fuel saved plus the fuel not burned to carry that fuel) on every flight, or more payload, or getting the same payload off a smaller runway, etc.

Redispatch rules! Up vote redispatch! Viva SimBrief and Navigraph!

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Good Evening @LaneTOGA,

I think it would be essential a) to make sure about which rulesets you are talking and b) providing sources for it. I do assume, based on “re-dispatch” or “re-clearance” you are talking about FAA regulations, aren’t you?

Reading your “rule of thumb” makes that pretty clear, as no EASA OFP calculates 5% Contingency Fuel (CONT) for a long haul flight.

I would also consider a Reduced Contingency Fuel Procedure (RCF) (that’s what the name of this EASA procedure is), but I am pretty sure 99% of users wouldn’t use it nor understand.

Just to add a scheme for better understanding:

Hi @Alpolex88

Yes, the terminology used under FAA regs is “Redispatch Flight Plan”, “Redispatch Point”, etc.

Important under FAA, the Captain (or designated crewmember in the cockpit if the skipper is in the bunk) MUST have contact with the Dispatcher, as it is a joint decision between the captain and the dispatcher to actually cross the Redispatch Point and continue to the Planned Destination. I don’t believe this is a requirement under EASA.

I used 5% as an example for easy calculation.

My post/topic was to “encourage” the addition of redispatch option in SimBrief flight planning.
I’m not sure from your post if you agree or disagree.

Most of the more progressive ultra-long-haul 121s don’t do Redispatch anymore if they have Performance-Based Contingency Fuel under OpSpecs B343. The ATL-based major doesnt have B343 yet so they’ll do RDSP, but neither AA nor UA, they’ll both B343 everything to/from the US.

If your fuel performance shows that this flight only requires 10 minutes of contingency fuel, on top of a 30 minute final reserve and the gas to an alternate, why do a redispatch?

@dougsnow because a Reduced Contingency Fuel Procedure (RCF) saves on a Boeing 747-8 on Trip from FRA to EZE quite a lot once it is a) MTOM limited b) TCAP limited or c) weather is below planning minima at destination and requires 2x Alternate Aerodromes and you are required to take more fuel.

Based on a Trip Fuel (TF) of 133.978 kg (13:35h) it makes a Contingency Fuel of a) 3.288kg (00:20h) based on 20MIN ruleset and b) 4.020kg (00:24) based on 3% + ERA.

You can further reduce this applying the RCF which will save not only Contingency but as well as Trip Fuel - see relation between Trip and Cont (-> e.g. proteced/unproteced cont fuel). Such a procedure saves easily 5.000 kg for a Boeing 747-8 on such trip.

Besides not saying it’s quite jeopardizing the operations because it’s not safe to determine whether the aircraft will arrive at the commercial destination until it has passed the Decision Point (DP).

But only if you operate under EU-OPS. His question was describing US 121 ops, which doesn’t have the RCF procedure.

The operator can conduct Redispatch under FAR 121, but only if the operator holds OpSpec B044, for the concept of redispatch doesn’t exist in a plain reading of FAR 121.

For the US 121 operator, here is your menu of flag fuel planning options:

  1. Straight flag fuel of 121.645, the best of 1964 fuel planning.
  2. OpSpecs B043 (Special Fuel Reserves in Int’l Operations), a 45 minute final reserve on top of a 10% reserve if you are in oceanic airspace for more than 2 hours)
  3. OpSpecs B044 (Redispatch)
  4. OpSpecs B343 (Performance-Based Contingency Fuel for Flag and Supplemental Operations)

The OpSpecs are special authorizations granted by the FAA, if your operation doesn’t hold them, you are stuck with the 1964 fuel standard of a full 10% enroute reserve. The 10% reserve made sense when the 707 was in operation - but it doesn’t make sense today.

But I would agree, whether its 121 B044 redispatch or RCF, few people outside those operators who do it regularly would understand all the permutations.

But I would agree, whether its 121 B044 redispatch or RCF, few people outside those operators who do it regularly would understand all the permutations.

Agreed! Based on our interesting discussion I would assume that there are also quite a lot of differences between FAA and EASA rulesets which had to be implemented for 1% of realistic usage opportunities.
I have rarely calculated it in real-life as well - so I think other options would be way more appreciated like a proper NO ALTN or Isolated Aerodrome planning.

For example, under 121, if I am dispatching to an isolated airport (think Hawaii when all the other alternates are closed) all I am required to carry is the 2 hour final reserve; whereas under EASA I believe, the EASA operator is required to carry the %age based contingency fuel to get to the isolated airport, then the 2 HR reserve.

While 121 doesn’t require it, since we as an airline are subject to IOSA, we are required to put a Point of No Return airport on the flight plan when I am dispatching with 2 hour reserve, so if I am going to Hawaii with 2 HR reserves as all the other alternates would be closed when I’d get there, we have to identify a PNR airport, and the OFP will put a PNR point in the navlog where I could turn back around and get to the mainland airport (say KLAX) and land there with the 30 minute final reserve. In that case its great circle back direct to the airport reference point. Now granted I don’t have to put an alternate on any flight shorter than 6 hours ETE under any 121 flag rule unless WX would require it, and a flight from KSFO to PHNL is always less than 6 hours. I could get out there with all the other airports closed, alternate none as its less than 6 hours, but with all the ETOPS fuel I’d add, I might as well do it 2HR for the islands with a PNR; few crews will go out there alternate none, without the 2HR and the mainland PNR airport.

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Here are 4 OFPs that should help explain the differences for the 121 operator, using the 787-900 on a leg from PHNL to KEWR.

For the first option is full 10% flag reserves with the redispatch. The redispatch destination on this flight is KIND, using KCVG as the alternate for KIND. In this example the STL VOR is the redispatch fix. For this, I’d have to have 18474 lbs FOB overhead the STL VOR to make it work. Note that I can not be planned to land overweight at my initial destination (KIND). One nice thing is RDSP allows me to dispatch alternate none for the final destination (even though its a long flight) however, if overhead STL VOR I’d have to add an alternate for KEWR, and I don’t have the gas onboard, I’m kinda screwed. One thing most DX will do is add 15 minutes or so of DX ADD fuel as insurance gas.

XXX123 PHNL-KEWR (ETD 14Nov 23.45UTC) #1 (Generated 14Nov 20.59UTC).pdf (148.3 KB)

The next is using B343. This OpSpec allows the operator based on their actual fuel burn performance in the city pair to carry that fuel which provides either a 90% coverage, or a 99% coverage (in the case of convective WX at the destination at ETA). In this example, the ACF90 value is a 2.5% enroute reserve, on top of the 30 minute final reserve, and the gas to an alternate. What this means is that for the advanced operator, their overburns over the past 2 years for this flight, ETA, and equipment type, would never exceed a 2.5% overburn in this example. These are recalculated monthly, and if it’s a brand new city pair, you carry a 5%. Regardless of the percentage carried, the minimum time value is 5 minutes. Also, the route to the alternate must be based on a realistic routing, altitude, and airspeed.

XXX123 PHNL-KEWR (ETD 14Nov 23.45UTC) #2 (Generated 14Nov 21.01UTC).pdf (64.3 KB)

B043 is next. On B043, we carry a 45 minute domestic reserve, ontop of an enroute reserve of 10% the time the flight is in Class II (Oceanic) Airspace for more than 2 hours - in this example, that is 8 minutes of gas. That 8 minutes is handled like the 10% flag reserve, and just has to be on board at takeoff, its there to be burned, and doesn’t have to be protected in the FMS as FMS Reserves.

XXX123 PHNL-KEWR (ETD 14Nov 23.45UTC) #4 (Generated 14Nov 21.16UTC).pdf (64.3 KB)

And for comparison an OFP using the full 10% reserves without the redispatch.

XXX123 PHNL-KEWR (ETD 14Nov 23.45UTC) #3 (Generated 14Nov 21.05UTC).pdf (64.3 KB)

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One thing I forgot to mention on the redispatch plan, is that in the ATC FPL the redispatch plan is identified to ATC with the RIF/, tag, so on this plan it would be identified as:

RIF/STL DCT WIDAM SMUKE2 KIND

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Atlas Air still does redisptach because is saves fuel and/or allows bigger payload.
Not sure I’d doubt Atlas to know how to make money.