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  • #16
    Evan, I just read the Spiegel article (talk about disaster porn!) It reasons from debris that the least-experienced pilot was in the captain's seat when they lost the autopilot. Maybe if the captain had not been resting (assuming he was), he would have chosen to divert. Maybe the junior pilot felt uncomfortable with a decision like that and hoped to be relieved before it became impossible. I still am scratching my head why none of the ATC's radioed about the decision of the other captains with regard to the weather.

    I'm also wondering if any flight plan across the ITCZ wouldn't plan for diversion to avoid violent storms. It has been said repeatedly that "there was nothing unusual in the weather that day". So if flying a zigzag path is to be expected, fuel loads should comfortably cover that. If luck is with them and they get to fly straight, then they land with fuel to spare.

    The Spiegel article said there was some sort of 300,000 euro/plane upgrade that Air France hasn't chosen to add. OK, maybe I can understand that, but to also trust to luck that diversion is unnecessary is something only an executive who hates passengers would do.

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    • #17
      Originally posted by Evan View Post
      Secondly, I'm not following his math. By the above reasoning, climbing out of FL35 for FL37 at SALPU, there would be 2.4t of route reserve providing 20 minutes of diversion available without a fuel stopover (with seems adequate to me). That works out to an average burn rate at cruise of 120kg/min: 2,400/20=120. Then he states that if the flight maintained FL35 after SALPU instead of climbing as planned, the route reserve would only allow for an 8 minute diversion after SALPU. The average burn rate at cruise is now 112.5kg/min: 900/8=112.5. That doesn't add up in my head. Why is the burn rate lower at the lower FL, when it should be higher?
      Urks, I'm guilty on this one. the 8 minutes were calculated by me, not by Huettig.... In Hüttig's mail, he makes the remark that 2.4t is good for "over 20 minutes of flight at most", and I used this number to turn the 900 remaining kilograms into *roughly* 8 minutes... so nothing really wrong here with the professor's math.


      Maybe I'll with him a second time, or better point him to the forum directly, but to me the last remark in his mail - that a B747 or A340 wouldn't have had the problem - seems to point out that the A320 on this route will always be tight on fuel. Can anyone post the full fuel capacity of the A320 - maybe compared to the other types mentioned? How much more than the rather close numbers in the three flight plans can the aircraft actually take?

      m.

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      • #18
        Originally posted by mfeldt View Post
        Urks, I'm guilty on this one. the 8 minutes were calculated by me, not by Huettig.... In Hüttig's mail, he makes the remark that 2.4t is good for "over 20 minutes of flight at most", and I used this number to turn the 900 remaining kilograms into *roughly* 8 minutes... so nothing really wrong here with the professor's math.


        Maybe I'll with him a second time, or better point him to the forum directly, but to me the last remark in his mail - that a B747 or A340 wouldn't have had the problem - seems to point out that the A320 on this route will always be tight on fuel. Can anyone post the full fuel capacity of the A320 - maybe compared to the other types mentioned? How much more than the rather close numbers in the three flight plans can the aircraft actually take?

        m.
        The A330 (not A320) is advertised by Airbus as having the effective range to service the Paris to Buenos Aires route nonstop in a typical configuration. I assume that means taking a full passenger load + luggage and then fueled to MTOW. I assume this claim excludes non-passenger related cargo. I'm almost certain the A330 used by AF447 was at or below the typical configuration, and if it was not carrying freight, it would have been able to take on more fuel. Therefore, it is not the limitations of the aircraft, it is the limitations of the aircraft combined with the load. What Huettig is saying is that, given the load they chose to carry, a longer range aircraft would have more margin in the MTOW for additional fuel. The alternative to using longer range aircraft is to file a Reclearance-in-Flight (RIF) option with the flight plan, as they did here. The RIF allows them to legally fly more load with less fuel reserve. Obviously, this option is more appealing to the operator, since the A330 is capable of making the flight without a stopover in most cases.

        If you contact Prof. Huettig again, ask him to expand on how he calculates the route fuel requirement for the two different flight levels. I'm curious to know how that is done.

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        • #19
          Originally posted by Evan View Post
          The fact is, they flew directly into this weather system, and from the very beginning I've been wondering if this was because they saw no threat, because they had no choice, or because their choice was weighted by external pressures. Heuttig's findings do support the possibility of the third motivation, and I don't think we can rule it out unless we can rule it out by the numbers.
          Well, Evan, I don't think you will ever be able to rule that out by the numbers. I might be coming at you all with hpyerbole again, but if you think the "maximum fuel" thing through you might end up at asigning a fully fueled 747-400 for a CRJ flight because if they discovered one of their wheel lights was inop they would have a maximum flight time to sort out the problem. (Hyperbole off)

          For me the AF447 issue still doesn't seem so difficult. The flight carried 0.9t more fuel than was legally required. Pilots have a natural instinct of self-preservation. All pilots were fully qualified (nicluding the most junior pilot on the flight deck) to operate an A330. The weather in the path of AF447 was not unsual for this area or route. Bearing all this in mind I don't see anything dangerous looming for AF447 from these aspects of the flight.

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          • #20
            Originally posted by Peter Kesternich View Post
            Well, Evan, I don't think you will ever be able to rule that out by the numbers. I might be coming at you all with hpyerbole again, but if you think the "maximum fuel" thing through you might end up at asigning a fully fueled 747-400 for a CRJ flight because if they discovered one of their wheel lights was inop they would have a maximum flight time to sort out the problem. (Hyperbole off)
            You know Peter, with all due respect, admitting that you are using hyperbole does not make it any more relevant or any less useless here. I'm not sure why you keep doing it.

            Originally posted by Peter Kesternich View Post
            Pilots have a natural instinct of self-preservation.
            I realize this. They also have a natural instinct for completing tasks as assigned, and for calm practicality in the face of danger. The mind of the pilot is influenced by complex instincts. The less clearly situations are defined, the more these instincts can contradict one another, and this complexity makes their grey-area decisions harder to predict.

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            • #21
              Switching gears a bit, I have question about the last comm sequence of AF447.

              01:35:43 “ AFR 447 -AIR FRANCE FOUR FOUR SEVEN, thank you.
              01:35:46 “ ACC-AO -Welcome, maintaing flight level three five zero,
              say your estimate TASIL?
              01:35:53 “ ACC-AO -Say your estimate TASIL?
              01:35:59 “ ACC-AO -AIR FRANCE FOUR FOUR SEVEN estimate TASIL?
              01:36:14 “ ACC-AO -AIR FRANCE FOUR FOUR SEVEN say your estimate
              TASIL?


              In that very last transmission to AF447 from the ATLANTICO controller asking them for an estimate to TASIL, are they instructing them to maintain FL350 until TASIL? AF447 never reads back, so we never know if they received the transmission, but we know they received another transmission just three seconds earlier.

              When we covered this way back in the thread, the consensus was that AF447 dropped out of VHF range at that moment and therefore the ATLANTICO controller simply repeated the request several times and then gave up. This was considered acceptable because the instruction was simply to maintain current flight level and there was no vital information in the transmission.

              Now that I have read the flight plan, I realize that it included an FL change at SALPU to FL370. Therefore, if ATLANTICO was instructing AF447 to maintain FL350 until contacting DAKAR, he was effectively instructing a FL deviation from the flight plan. Since there was never any readback, how could ATC know what flight level they were at after SALPU?

              Is it possible to SELCAL them with HF or SATCOM? Is it acceptable to have a flight on a mid-Atlantic lane at an indeterminate flight level? Are flights required to contact ATC if they deviate from their flight plan altitude? Or does the lack of traffic at that point allow them to rely on TCAS alone?

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              • #22
                I will present this "exhibit" that I prepared with no other comment by now but that something looks odd.

                (Sorry for the crappy quality. I prepared a pdf that barely weights 1/5 of this jpg and has much better quality, but the forum would only accpet 19 KB of pdf while several MB of jpg. If someone wants the pdf please PM your e-mail)

                --- 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 ---

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                • #23
                  Originally posted by Evan View Post
                  Switching gears a bit, I have question about the last comm sequence of AF447.

                  01:35:43 “ AFR 447 -AIR FRANCE FOUR FOUR SEVEN, thank you.
                  01:35:46 “ ACC-AO -Welcome, maintaing flight level three five zero,
                  say your estimate TASIL?
                  01:35:53 “ ACC-AO -Say your estimate TASIL?
                  01:35:59 “ ACC-AO -AIR FRANCE FOUR FOUR SEVEN estimate TASIL?
                  01:36:14 “ ACC-AO -AIR FRANCE FOUR FOUR SEVEN say your estimate
                  TASIL?
                  I am so glad this thread is back on topic. I really hope they get the searches going again soon so we will have some new things to discuss.

                  Are flights required to contact ATC if they deviate from their flight plan altitude? Or does the lack of traffic at that point allow them to rely on TCAS alone?
                  I am certainly not a pilot, but I thought you had to have clearance for the altitude unless they gave you a block? I also thought that it is ultimately the ATC reponsibility to keep adequate space between planes, and TCAS is there as a protection measure. (Please correct me if I am wrong.)

                  These are definitely some interesting points that you brought up.
                  I do work for a domestic US airline, and it should be noted that I do not represent such airline, or any airline. My opinions are mine alone, and aren't reflective of anything but my own knowledge, or what I am trying to learn. At no time will I discuss my specific airline, internal policies, or any such info.

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                  • #24
                    Originally posted by Gabriel View Post
                    I will present this "exhibit" that I prepared with no other comment by now but that something looks odd.

                    (Sorry for the crappy quality. I prepared a pdf that barely weights 1/5 of this jpg and has much better quality, but the forum would only accpet 19 KB of pdf while several MB of jpg. If someone wants the pdf please PM your e-mail)
                    Nicely done. It illustrates how little of the MTOW is available for payload, how mostly you're flying fuel and airplane around. It also shows how the route reserve in any case is dwarfed by the fuel to alternate and the final reserve, and is nowhere near 10% of the route fuel. I'm seeing that, as this is not a long flight over open stretches of water (like the LAX-Sydney route for instance), the route reserve is not provided as a safeguard against fuel starvation, but is basically just there to prevent an undesirable technical stopover, which is always available on the latter part of this route. In all cases the route reserve isn't providing much (or in the case of the RIF, any) time for diversions on top of other burn-rate factors. But the additional extra fuel seems to make a short diversion possible (about 1/2 as much as what the fuel to alternate provides for).

                    One thing I would like to see is a chart comparing the route reserve (and extra fuel) to the cargo load (after deducting pax and luggage). These seem to be the two variables that trade off each other. I also think 25 kg/passenger luggage might be a low estimate on a transcontinental flight.

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                    • #25
                      G'day Evan.

                      The Flightplan is just that... a plan.

                      It is based on forecast winds, as well as forecast weight at a given waypoint.

                      So, the indication that the aircraft was planned at FL370 at SALPU is like a "heads up" to ATC that the crew will likely be looking for a climb at that point - but it is not something that the pilots directly follow. The actual time they request that climb will depend on actual winds, actual weight etc... and is far more efficient.

                      Also, in this day and age, being stuck at an altitude that is not your optimum (say not being able to climb to FL370 when they want to, but an hour later) usually has a negligable effect on fuel due to the way we fly on a cost index.

                      Its important to remember that the aircraft would maintain its LAST CLEARED LEVEL. You do not climb based on your flightplan, only based on an ATC clearance to do so.

                      They would not be at an "indeterminate" level, because they would be maintaining their cleared level.

                      They could be SELCAL'd if they had tuned the correct HF frequency. I don't know the HF/VHF mix in that part of the world.

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                      • #26
                        So the conclusion is they DID maintain FL350 - either because the understood what the controler said but for some reason did not acknowledge, or because they didn't hear him and thus had no clearance.

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                        • #27
                          They maintain FL350 because that is their existing clearance. The new controller is just confirming that existing clearance... if the controller said nothing, they would maintain 350.

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                          • #28
                            Originally posted by MCM View Post
                            They maintain FL350 because that is their existing clearance. The new controller is just confirming that existing clearance... if the controller said nothing, they would maintain 350.
                            The flight plan (and the route fuel) called for a flight level change at SALPU. If they planned this FL change, how do they go about getting clearance for it? Do they request it in advance before they lose VHF with ATLANTICO or do they have to try to contact ATLANTICO on HF once they reach SALPU? (I always thought the flight plan was a pre-approval, and only deviations had to be cleared). Because they didn't request FL370 at any point, can we then assume they opted to stay at FL350 due to turbulence?

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                            • #29
                              Originally posted by Evan View Post
                              The flight plan (and the route fuel) called for a flight level change at SALPU. If they planned this FL change, how do they go about getting clearance for it? Do they request it in advance before they lose VHF with ATLANTICO or do they have to try to contact ATLANTICO on HF once they reach SALPU? (I always thought the flight plan was a pre-approval, and only deviations had to be cleared). Because they didn't request FL370 at any point, can we then assume they opted to stay at FL350 due to turbulence?
                              To change the FL they need to be cleared by ATC - and by the control sector they are in, and it doesn't matter whether they use HF, VHF or satellite communications to obtain the clearance.

                              If the guys on AF447 didn't request a clearance from FL350 to FL370 at any time during the flight, we only know that they didn't request clearance and we can assume nothing, because there are so many reasons why they didn't request a clearance. We can speculate that turbulence may have been a reason for not requesting a climb to FL370, but then taking the aircraft higher can also be a course of action to get OUT of the turbulence and into calmer air. I think there is no direct relation between staying at FL350 and turbulence.

                              Comment


                              • #30
                                Originally posted by Peter Kesternich View Post
                                I think there is no direct relation between staying at FL350 and turbulence.
                                What other reason would cause them to maintain FL350 at a higher burn rate?

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