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Guest M-Sauce

Autothrottle Care And Feeding

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Great article Robert, I know that even a lot of real world pilots have a hard time fully understanding the AT system and I've seen a lot of "what's it doing now" or "that's not what I wanted" , but I've never said that myself of course... :( The only thing missing is the AT system's behavior in the all important TOGA mode - specifically during the GA phase. I've found that the PMDG 744 does not behave as it should while in the GA mode. The aircraft executes the GA appropriately, as in it goes to the THRUST | TOGA | TOGA | mode, but when reaching the point at which you want to accellerate, it simply will not let you spin the SPD Bug up. When you try to spin it up, the bug reluctantly scrolls back to the speed at which you pressed the TOGA button. This is not so on the real aircraft, in which you accellerate in TOGA to begin the clean up (Airline procedures vary; ours has us select a vertical mode, preferably FLCH, after raising the flaps to 5 and selecting CLB thrust by use of the THR button on the MCP). If you allow the aircraft to stay in this mode, it eventually all goes pear shaped and you start seeing the airspeed decay with a high pitch attitude at low altitude (not where you want to be).I've worked arround this by selecting VS at the point at which the GA pitch attitude is approximately achieved (approx 10 degrees). Then I select my acceleration speed (ref+100 or 250 kts, whichever is highest, or the GA speed limit if applicable), and reduce VS to keep the aircraft accellerating at an acceptable rate. This allows safe go-arrounds, but again, it is not faithful to the real aircraft and Boeing's recommendations. Now I understand, some things just can't be modeled because the software (FS9) might not allow it. It might also be a conflicting situation in which if it was modeled, it would be at the compromise of other functions or modes. But, having said that, is there any chance this might get fixed at some point? As I've said before, the GA mode is such an important mode and so usefull to practice in the sim, where you are not wasting 2-4 tons of gas per turn.Thanks.Mariano :(

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