Bonjour,I know it is the way it works on a real plane but I would like to understand why when we select FLCH the AFDS target airspeed is set to the current airspeed.Suppose on approach ATC ask us to reduce the speed we then modify the AFDS target airspeed, and just after that the control request a lower flight Level , we then select FLCH with the new altitude but unfortunately the AFDS target airspeed is reset to the current airspeed, we have then to modify it again.I think there is a logic behind that but I cannot see it.RegardsClaude

Hi thereFL CH, (Flight Level change) , This is a speed on Elevator-autothrottle mode, that meens the airspeed is controled by pitch chages (vertical speed), to slow down, V/S increases to accelerate v/s decreases, vice versa for decent. And thNow the reason you cannot pre select an airspeed b4 engageing FLCH is so as to avoid rapid pitch changes where the Autopilot would try to alter the speed by moving the elevator. This is why FLCH speed is synchronised.Hope this helps, Any other Q's just ask.StuartAvionic Engineer

Hi Claude,A more elgant technique is to switch to VS when you get a change in flight level following a speed reduction. Change the altitude, Hit VS to about -300 ft /min while you set the lower speed. As the speed reduces increase Vs to about 1500 ft/min then hit FLCH again. VS is often used to minimize g levels for the passengers. Pedro

It depends on whatever mode you have selected before selecting FL CH. There shouldn't be any problem.If you were in VNAV and you have to reduce, press the speed selector switch and select your new speed. You're now in IDLE | VNAV SPD and later on THR HLD | VNAV SPD mode, while the plane reduces by controlling speed by pitch attitude, reducing at about 1 knot per second.Should you, during deceleration press FL CH, the selected airspeed in the airspeed window should remain at what you selected before, so no problem there! I don't know if this is the same way in 767PIC, but it is in the real thing.If you were in VNAV ALT or VNAV PTH and you have to reduce, same procedure. If you were in ALT HLD, the airspeed window would be open already and changing to FL CH will keep the selected airspeed in the window, even if it's not your actual airspeed.If starting FL CH out of a normal VNAV PTH situation, no reduction required, pressing FL CH will show the VNAV FMC speed in the airspeed window.Hope this helps.

Hi Iz,Thank you for your answer,>Should you, during deceleration press FL CH, the selected >airspeed in the airspeed window should remain at what you >selected before, so no problem there! I don't know if this >is the same way in 767PIC, but it is in the real thing. It is not working like this in PIC ,for that matter it is written in the manual that if FL CH is selected the airspeed window is reset to the current indicated airspeed, that's why I thought it was working like that in the real life.regards Claude

HiNow there ya are! Thanks for that IZ, i didnt know thats the way it worked. Dont work on the 767 so i was doing a bit of guessing.Thanks for that:)