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Guest D17S

Questions about Step Climbs

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Guest D17S

Step-climb questions: Can you help? I really can

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On my last flight across the pond i was cruizing at FL370 which was my OPT altitude in the FMC. When i clicked to the VNAV page the FMC was instructing me to climb "NOW" to FL390 even though my OPT was FL370. My understanding of step climbs was that the FMC will automatically enter an "S/C" marker for when your OPT altitude is the same as the FL you want to step climb to on the VNAV page?For my example i was 2000ft out. Just something ive noticed recently especially on longer flights.


Paul McMahon

Ireland

747400.jpg

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Guest Jpanford

Hey guys let me help a bit. The real airplane always calculate your ETA and Arrival fuel based on the Step climb because its telling you that is the most efficient altitude. That being said if you like to ignore the step climbs change the ICAO value to 0..in the real aircraft you can enter 0 to 9999. After you enter zero all fuel calculations and ETA's will now be based on the cruise altitude. Step climb will dissappear. If you like to see to step altitudes while in RVSM put 2000. Well I have a test on, Autopilot, Electrics, and TCAS in the morning going to bed hope this helps.Joe

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Guest s_L_Y_F_a

you can also enter ICAO into the step climb box.This will base the step climb calculation on the vertical seperation minimums determined by the International Civil Aviation Organisation.

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Not sure where the flashing comes from Sam. I haven't seen it yet. I haven't seen anything flash in the real world FMC. In the other thread there was comment about step climbs on 3 engs. Once you have selected engout and EXECuted it all the step climb info should relate to 3 eng operation. CheersSteve


Cheers

Steve Hall

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Guest D17S

There's an interesting point. I am currently flying on 3 engines. After the engine failure at FL360, I LSK'd 'ENG OUT.' There was no EXEC light. The ENG OUT page remainded an info only page. Vnav did not respond to any ENG OUT calculations. It would not even initiate a normal Vnav CRZ descent so I could drift down to my engine out OPT. It tried, but after it had descended about 500 feet, it went into a VNAV SPD / THR > (part-power) HOLD nose up 'mush' as if it was trying to claw its way back up to somewhere . . . all this with FL240 in the crz page CRZ ALT line. That was entertaining, for a while. I finally had to use FLCH to get on down. Once at ENG OUT OPT, I could re- engage Vnav in a VNAV PATH/SPD cruise. Buggy, or an I doing something wrong?

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No you are not doing anything wrong. When the eng fails the autothrottle thrust ref should change to CON. Select eng out and EXECute. what happens next depends on the current speed v's 3 eng LRC speed and current Altitude v's FMC max altitude. generally a drift down will commence at about 300 fpm. If you do not release the MCP altitude it will not descend. Our real life initial procedure is:1. Set MAX CONT.2. Identify eng.3. Trim out rudder.4. Select VNAV ENG OUT and EXECute.5. When ready to descend reset MCP and press!Obviously securing the failed eng comes in there somewhere and the urgency of that depends on the nature of the problem. Arguably most inflight eng failures are shutdowns rather than failures ie. Vibration, lack of oil quantity, press etc and the situation is a little more leisurely.Personally if VNAV was screwing up I would use vert speed instead of FLCH. The reason being that FLCH would take all the thrust off to get down to the alt in the MCP panel. Only when it went to HOLD would you be able to creep the power back up. Trouble is is that there would be some massive trim changes and that can be unsettling. With Vert SPD you can set the speed in the speed window and vary the vertical speed to adjust the descent. It does need to be closely monitored though as there is no stall speed protection in Vert spd and if you got distracted it could get exciting. Once the whole thing is heading down smoothly you could consider the use of cruise thrust rather than Max CON but of course this depends upon your current fuel/terrain situation and you still need to cover the depressurised fuel scenario as well.I have noticed a few errors in the FMC regarding the EXECute function. For example when selecting an approach or transition there is no EXECute light and there should be. Any change to the active route should bring up an EXECute light. This provides the pilot with an opportunity to "bug out" or to verify the route modification to the other pilot before EXECuting. I am not sure what changes (if any) were made in the F version. The other frustrating thing I find is not being able to view a star and approach in the map mode prior to EXECuting. This is used all the time in the real world and it is dissapointing not to see it modelled correctly.I know the folk at PMDG are busy folk and have their sights set on grander things but it would be nice to see regular patches to fix these small issues and make it a really exceptional flight Sim experience. CheersSteve


Cheers

Steve Hall

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Guest D17S

Great. I

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Guest D17S

Step climb annunciation still flashing away. Now the Engine-out sequence: Engine now shut down. I observed identical functionality as before. 'ENG OUT' LSK press does NOT get an EXEC lite, but there on the other hand, what is this EXEC function supposed to do? EICAS thrust limit goes to CON. That

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