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ahinterl

PROF

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Don't have access to the manuals at the moment, and two things that confuse me came to my mind, so I ask here:1.With PROF ARMED on ground, the switchover to CLB thrust usually occurs automatically. On several occasions when I pushed PROF shortly after takeoff (AP off), PROF ARMED in magenta was announced, but the automatic thrust reduction didn't happen.2.Sometimes when hitting PROF, nothing happens (no FMA change, no mode change), just as if the FMS ignores PROF activation. To me, all systems look nominal, magenta line is on the ND, no warnings (maybe the FMS silently switched to NAV2 or so)...

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Don't have access to the manuals at the moment, and two things that confuse me came to my mind, so I ask here:1.With PROF ARMED on ground, the switchover to CLB thrust usually occurs automatically. On several occasions when I pushed PROF shortly after takeoff (AP off), PROF ARMED in magenta was announced, but the automatic thrust reduction didn't happen.2.Sometimes when hitting PROF, nothing happens (no FMA change, no mode change), just as if the FMS ignores PROF activation. To me, all systems look nominal, magenta line is on the ND, no warnings (maybe the FMS silently switched to NAV2 or so)...
1) I know that there is a specific reason for that, because it happens to me also...but i don't remember exactly now, i have to find out in the manuals when i will have time...I know that when engaging PROF mode after TO i had also to engage manually the FMS SPD mode on the FCP to achieve fully automatic FMC control on the plane...When i takeoff i usually leave the FMA blank, then after TO when i reached the 400AGL, i depress FMS SPD and PROF and the plane is fully stable on FMC indications for lateral/vertical navigation. Then, when i want AP i press AUTOFLIGHT and let the respective AFS system to take control of the plane...2) That's strange, never experinced this beheavior...are all the boxes in the PERF INIT page filled in? because it sounds like the FMC haven't all the data needed to calculate the optimal path for vertical navigation...Cheers,

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2.Sometimes when hitting PROF, nothing happens (no FMA change, no mode change), just as if the FMS ignores PROF activation. To me, all systems look nominal, magenta line is on the ND, no warnings (maybe the FMS silently switched to NAV2 or so)...
Is this only happening on climbout? It will ignore the PROF press below 1,000' if I remember correctly.

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Is this only happening on climbout? It will ignore the PROF press below 1,000' if I remember correctly.
I don't think so, you can also arm it before TO, and it will engage itself when airborne above 400 radio altimeter...Cheers,

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I don't think so, you can also arm it before TO, and it will engage itself when airborne above 400 radio altimeter...Cheers,
Click it twice (otherwise AP2 will appear) after 400 ft (once fd is stable). It will do everything it should.Cheers,John

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Click it twice (otherwise AP2 will appear) after 400 ft (once fd is stable). It will do everything it should.Cheers,John
Exactly, but he said he pressed everything...it sounds strange to me, maybe a problem on his system...We will wait for feedback...Cheers,

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I was incorrect earlier:PROF is available (along with the AF, as mentioned) above 400', per the FCOM. If it was pre-selected on the ground, it will automatically kick in at 400. If it was not, it is not available until 400 (and I still believe that it ignores a button push of PROF until that point if not armed on the ground).

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