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Guest Toke

How to engage managed CLB according to FP?

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Guest Toke

I'm having big problems getting my A330 and A340 to do FMS managed altitude .. that is, follow the altitude constraints and the flight levels entered into the MDCU flightplan. In fact, I haven't had a single flight (out of approx 50) where the altitude has been set according to the alt settings for different waypoint or CRZ ALT set in MDCU. I'm posting here because, I'm sorry to say, the manual is quite confusing on this point and haven't been able to help me solve this issue or to try to understand if I'm doing something wrong.In the vertical guidance section (p38), it says:"The managed vertical modes, CLB, DES and ALT CST, provide automatic vertical control of aircraft, following vertical profile associated with flight plan entered into the FMS. /../ All speed and altitude constraints and speed limits entered in flight plan are obeyed." and"When a flight plan contains altitude constraints, the aircraft will level off at such constraints, and ALT CST mode will engage. As soon as a waypoint with the constraint is passed, the climb or descent will continue automatically. When cruise altitude is reached, the aircraft levels off and ALT CRZ mode engages.".. which makes sense. With A/THR on the aircraft should be able to gain height on it's own while in stable conditions. Now, AP and A/THR has their own "activate" buttons while "NAV" controlled flight can be armed before take-off. So where/how is the "ON" for managed altitude from flight plan? the only close explanation of how to engage flight plan managed altitude CLB is found on p38:"If NAV managed lateral mode is active, the managed CLB mode will automatically engage when aircraft climbs above acceleration altitude, which defaults to 1500 ft AGL."So here's what I do. I program the MCDU using a complete flightplan including speed and alt restraints, fuel predictions and both SID and STAR. I arm FD, NAV and Speed and leave the ALT meter at default setting of 100 with the V/S meter dashed out. I take off using TO/GA (the A/THRL lights up). At 1500 feet I've tried both with AP engaged and off and no altitude management activates at all. I've tried tons of variations but nothing works. Pushing down the ALT setting button, pulling it or just letting it be (either before, at or after 1500 ft) doesn't change anything - not for the sake of trying to get the plane into FMS altitude managed mode. Nor does it work to set the altitude manually up until 1500 ft and waiting for the FMS to take over. Now, there is another part of information in the manual that almost contradicts this (p38):"FCU altitude window is not dashed when in managed guidance. The altitude selected in ALT window always have priority over vertical flight plan profile. For example, if managed guidance is performing a climb to FL340, and altitude window is set at 18000, the aircraft will level off at 18000 ft and selected ALT mode will engage."So, the ALT setting always has prio over the alt entered in the flight plan, and the alt setting is never dashed out. That means that whatever altitude is set in the FCU is going to be the active altitude, since it has prio over the MCDU - even if I leave it untouched at 100 ft. Like I mentioned, pushing down the ALT set button ctreating a small dot to the side does not activate any altitude management from the flight plan. This must be why the plane takes off, hits 1500 ft, no altitude magement activates, the plane goes for 100 ft and crashes. "Open Climb is automatically engaged at the acceleration altitude if managed CLB mode doesn

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Guest vrandar

"...and leave the ALT meter at default setting of 100..."Why do you do that? You should be entering the alt you want in the FCU and left clicking for managed mode. Say you want to climb to FL350: enter 35000 and left click. If you have any intermediate alt constraints it will adhere to those but then climb up to FL350.

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Guest Toke

Ah, so that's how. It seems so obvious now that you mention it :(In the manual it says "If NAV managed lateral mode is active, the managed CLB mode will automatically engage when aircraft climbs above acceleration altitude, which defaults to 1500 ft AGL."The FS Airbus climbs to 1500 ft directly from takeoff which had me thinking that the managed CLB would kick in once over that altitude and take me to the altitude set in the flight plan, no matter what the FCU altitude meter was showing.I guess I got kind of nearsighted after all my attempts. Thanks for sorting that out for me. :)

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Guest vrandar

Most welcome. It can take a while to get used to the ways of the Airbus, so if you have any further questions just shout.

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