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  • Originally posted by mfeldt View Post
    A legal landing at CDG would have required 4.1t of reserve fuel. If it had appeared en route that this amount could not be maintained, a technical stop would have become unavoidable
    • Thus the additional reserve to circumvent weather while keeping the 4.1t, was only 2.4t, around 20 minutes of flight time according to Huettig.
    On the other hand:

    The aircraft left the gate with a calculated weight of 233,257 kg. The estimated
    takeoff weight was 232,757 kg(11), for a maximum authorised takeoff weight of
    233 t. This takeoff weight broke down as follows:

     empty weight in operating condition: 126,010 kg,
     passenger weight: 17,615 kg (126 men, 82 women, 7 children and one baby(12)),
     weight in cargo compartment (freight and luggage): 18,732 kg,
     fuel weight: 70,400 kg.

    The on-board fuel weight corresponded to forecast trip fuel of 63,900 kg,
    route factor fuel of 1,460 kg, final reserve of 2,200 kg, fuel to alternate airport
    reserve of 1,900 kg and 940 kg additional fuel.

     Regulatory fuel:
    The regulatory fuel necessary to perform a flight is determined at brake release before
    takeoff, thus 69.5 t in this case.
    Note that 63,900+1460+2200+1900=69,460 are the 69.5 t is the regulatory fuel, that matches that of plan 2 that was DTC (not RIF).

    The required fuel when landing at CDG is the 2200kg of final reserve plus the 1900kg to fly to the alternate. That's the 4.1t mentioned as needed for a legal landing.

    If the flight went exactly as planned, the trip fuel would have gone, leaving the route reserve of 1450 kg and added to the 940 kg of additional fuel that makes 2390 t of fuel that would be in the tanks, in addition to what's the regulatory minimum, when landing at CDG (again, if the flight went as planned and the route reserves are not used). That's the 2.4 t mentioned as available as "additional reserve to circumvent weather while keeping the 4.1t" required for a legal landing at CDG.

    And those 2.4 t reportedly equals to about 20 minutes of curise flight (or some 157 NM no wind, ISA, FL350, M0.82)

    If that's correct, the "regulatory" route reserves of 1460 kg would have been good for:
    20 min * 1.46/2.39 = 12 min
    157 NM * 1.46/2.39 = 96 NM

    And that would be legal route reserves for a DTC such a long flight from Rio to CDG???? It looks so, because that's basically the nmbers of flight plan 2 that was DTC.

    I tend to agree with Evan here. To my untrained eyes, that looks ridicously low for a route reserve, unless you are willing to try to land at CGD with less than alternate + 30 minutes (and maybe havinng to miss the approach and go for the alternate, landing there with less than the famous 30 minutes)

    That brings another question. How can Orly be a useful alternate to CDG??? (unless CDG gets closed for something other than weather)

    So Huettig's commentary was not that there was an actual shortage of fuel, but simply that due to the usage of the re-clearance procedure the crew was forced to balance their decisions with fuel consumption in mind in order not to jeopardize a punctual landing at CDG already at that stage of the flight.
    Here Huettig's seems to be wrong. As Evan said, with the fuel they had on board they had more than enough to legally file a DTC flight plan (more than needed for plan 2). So the fact that they filled an RIF fight plan doesn't seem to be of any significance. Had they filed a DTC flight plan in the same conditions, all the same concerns about the fuel reserves and the chances to need a mandatory fuel diversion would still apply exactly in the same way.

    Now I admit I'm puzzled.

    Once again the RIF strategy is NOT the issue here. If the crew was under pressure to avoid a fuel stop in this RIF flight, the pressure would have been exactly the same with a DTC flight on the same fuel at TO.

    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
    --- Defend what you say with arguments, not by imposing your credentials ---

    Comment


    • Originally posted by Gabriel View Post
      That brings another question. How can Orly be a useful alternate to CDG??? (unless CDG gets closed for something other than weather)
      Orly and CDG are at opposite sides of the Paris metro area and the weather can differ significantly between two places that are separated by 25-30kms.

      Comment


      • Originally posted by Gabriel View Post
        [/list]
        On the other hand:


        Note that 63,900+1460+2200+1900=69,460 are the 69.5 t is the regulatory fuel, that matches that of plan 2 that was DTC (not RIF).

        The required fuel when landing at CDG is the 2200kg of final reserve plus the 1900kg to fly to the alternate. That's the 4.1t mentioned as needed for a legal landing.

        If the flight went exactly as planned, the trip fuel would have gone, leaving the route reserve of 1450 kg and added to the 940 kg of additional fuel that makes 2390 t of fuel that would be in the tanks, in addition to what's the regulatory minimum, when landing at CDG (again, if the flight went as planned and the route reserves are not used). That's the 2.4 t mentioned as available as "additional reserve to circumvent weather while keeping the 4.1t" required for a legal landing at CDG.

        And those 2.4 t reportedly equals to about 20 minutes of curise flight (or some 157 NM no wind, ISA, FL350, M0.82)

        If that's correct, the "regulatory" route reserves of 1460 kg would have been good for:
        20 min * 1.46/2.39 = 12 min
        157 NM * 1.46/2.39 = 96 NM

        And that would be legal route reserves for a DTC such a long flight from Rio to CDG???? It looks so, because that's basically the nmbers of flight plan 2 that was DTC.

        I tend to agree with Evan here. To my untrained eyes, that looks ridicously low for a route reserve, unless you are willing to try to land at CGD with less than alternate + 30 minutes (and maybe havinng to miss the approach and go for the alternate, landing there with less than the famous 30 minutes)

        That brings another question. How can Orly be a useful alternate to CDG??? (unless CDG gets closed for something other than weather)



        Here Huettig's seems to be wrong. As Evan said, with the fuel they had on board they had more than enough to legally file a DTC flight plan (more than needed for plan 2). So the fact that they filled an RIF fight plan doesn't seem to be of any significance. Had they filed a DTC flight plan in the same conditions, all the same concerns about the fuel reserves and the chances to need a mandatory fuel diversion would still apply exactly in the same way.

        Now I admit I'm puzzled.

        Once again the RIF strategy is NOT the issue here. If the crew was under pressure to avoid a fuel stop in this RIF flight, the pressure would have been exactly the same with a DTC flight on the same fuel at TO.

        Admittedly I'm not an expert at all in this, but can someone maybe explain to me what the RIF procedure is good for when it makes no difference at all here? What I understand is that, since there was a decision point along the route, and since circumventing the weather would have meant that at decision point legally required reserves would (possibly) not have been there any more, a stop.over would have become mandatory. Correct? Now what if you file a DCT plan without decision point, and you still realize along the way that you maybe able to reach the destination, but not with the full legal reserve required? Are you still obliged to do a stop-over? Or have you simply been spending your reserve?

        Originally posted by Peter Kesternich View Post
        Orly and CDG are at opposite sides of the Paris metro area and the weather can differ significantly between two places that are separated by 25-30kms.
        Moreover, coming from Rio, Orly is closer than CDG...

        Comment


        • Remember that under the DCT plan, a fuel stopover would have required a fuel emergency declaration
          As Gabriel says, this is not correct.

          You only need to declare a fuel emergency when you are going to land with less than the minimum reserve fuel, and you need priority handling. ATC couldn't give a rats derierre if you land at your destination or for a tech stop.

          Reserves are a funny beast, especially when you consider how many airports are available for them to use along the route. At all times, they had fuel to go to a good airport, along with variable reserve to get there, and would land with fixed fuel reserve in tanks.

          What you are now talking about is commercial consistency - the fact that you might not make destination on a number of occasions. That is part of the aviation risk management system, and it is very much necessary to keep operations going. If you don't like the idea that you might not be able to make your destination, then don't fly longhaul.

          Comment


          • Originally posted by MCM View Post

            What you are now talking about is commercial consistency - the fact that you might not make destination on a number of occasions. That is part of the aviation risk management system, and it is very much necessary to keep operations going. If you don't like the idea that you might not be able to make your destination, then don't fly longhaul.
            I have very little against the idea of occasionally not making my destination if the "not making" means finding myself at an airport I didn't intend to go. If that's for a good reason, where good reason includes economic risk management that keeps the industry going, that's fine.

            What I'm prepared to find myself in is an airplane wreck at the bottom of the Atlantic, even more so if the reason has to do with economic risk management that failed.

            Comment


            • Originally posted by mfeldt View Post
              What I'm prepared to find myself in is an airplane wreck at the bottom of the Atlantic, even more so if the reason has to do with economic risk management that failed.
              I think this concern needs to be fully vetted, and the go-with-the-flow attitude I've been getting from pilots here is alarming. If it is a red herring, than we need to reach that conclusion by proving it as such. Eight minutes of route reserve less than halfway through an overfueled, underweight flight?

              Comment

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