step climbs any body?

[FunkymonkeyNZ]

hey all

im going to replay a sitiuation i had in flightsim a few flights back and i was wondering if someone might be able to point me in the right direction.
loaded the PMDG 747 to the brim with gass and decided i'd take a flight to KSFO, chose a cruize Alt of FL360, all seemed to go as planned when i noticed the aircraft slowly loosing speed once she was established in the cruize. i now know since then why this was happening (to heavy for the alt) and i fixed it by changing my thrust setting in the FMC to GA instead of ECON but this isn't the right way to go about this issue. how do i calculate step climbs? my manual should say so but im to lazy to pour over the manual, should the FMC auto calculate the steps and me (the pilot) to manually inishiate the next climb? or do i have to calculate when to step? i thought i had this Aircraft sussed but this has got me stumped!
so if anyone has some pointers or has even experienced what happened to me then please share. i know if i dont find out the problem then its going to bugg the cr@p out of me all holiday LoL

Regards

Chris

[ardypilot]

QUOTE

all seemed to go as planned when i noticed the aircraft slowly loosing speed once she was established in the cruize.[/quote]
Not that I know anything about the PMDG models work, but it sounds simular to this probelm I was having.

[SA227]

If you have a look at the VNAV pages in the FMC you will find on page 2 that it shows the optimum altitude and the maximum altitude for your current weight.
This page will also give you your step climb information.

[cowpatz]

The VNAV cruise page will show you what the current optimum alt and max altitudes are. The STEP climb info displayed will give you a distance and time when you should climb. You will also get a green donut with s/c displayed on the ND. You can configure the step climb increment to whatever you like. It usually defaults to ICAO which is a 4000 ft step climb. You can just type in 2000 over ICAO and it will display step climb info based on 2000 ft altitude climbs (RVSM airspace). If you want to know when you can expect a climb to a certain altitude then this can by typed over the step to altitude on the VNAV cruise page. This is useful if ATC ask something like "......when are you able FL390?". Just type it in and it will give you a time to climb. Once you reach your final cruise altitude you should set the step increment to 0 in order to get correct FMC fuel predictions. Otherwise the FMC will display predicted fuel data based on predicted step climbs which will be a slight error. You can also load a step climb increment in the PERF/INIT page when you are loading all the initial weight data.
When the setp climb point is reached you will have to initiate the climb. It is not done automatically. There are many ways to do this but the easiest way is to set the new altitude in the MCP alt window and then press the knob in. Alternatively you could set the alt and use FLCH or V/S modes. Just be aware when using the later 2 modes that the speed window will open and display IAS. You need to press the little IAS/MACH button to display the MACH number to use when climbing. Also in the V/S mode you will not have any stall protection. If you do not monitor the situation pwr will be applied to the Thrust ref limit and from then on the Autopilot will attempt to maintain the rate of climb even though the airspeed is decaying. Eventually the stick shaker will go. Just for interest the optimum altitude for a 747-400 increases by 100 ft every 8 minutes. The 747 performs better below optimum than above it.

[FunkymonkeyNZ]

QUOTE (cowpatz @ May 9 2008, 06:12 PM) <{POST_SNAPBACK}>

The VNAV cruise page will show you what the current optimum alt and max altitudes are. The STEP climb info displayed will give you a distance and time when you should climb. You will also get a green donut with s/c displayed on the ND. You can configure the step climb increment to whatever you like. It usually defaults to ICAO which is a 4000 ft step climb. You can just type in 2000 over ICAO and it will display step climb info based on 2000 ft altitude climbs (RVSM airspace). If you want to know when you can expect a climb to a certain altitude then this can by typed over the step to altitude on the VNAV cruise page. This is useful if ATC ask something like "......when are you able FL390?". Just type it in and it will give you a time to climb. Once you reach your final cruise altitude you should set the step increment to 0 in order to get correct FMC fuel predictions. Otherwise the FMC will display predicted fuel data based on predicted step climbs which will be a slight error. You can also load a step climb increment in the PERF/INIT page when you are loading all the initial weight data.
When the setp climb point is reached you will have to initiate the climb. It is not done automatically. There are many ways to do this but the easiest way is to set the new altitude in the MCP alt window and then press the knob in. Alternatively you could set the alt and use FLCH or V/S modes. Just be aware when using the later 2 modes that the speed window will open and display IAS. You need to press the little IAS/MACH button to display the MACH number to use when climbing. Also in the V/S mode you will not have any stall protection. If you do not monitor the situation pwr will be applied to the Thrust ref limit and from then on the Autopilot will attempt to maintain the rate of climb even though the airspeed is decaying. Eventually the stick shaker will go. Just for interest the optimum altitude for a 747-400 increases by 100 ft every 8 minutes. The 747 performs better below optimum than above it.

Steve you have out done your self again there Sir. thank you so much for that wealth of infomation! just one quick question, when you say once i reach cruise altitude i need to reset the value back to 0, where abouts do i place thus? is this where the default ICAO is or the where is says "step-to" on the 1R line select?
mate give your self a pat on the back! 10/10 for the advice

Regards

Chris

[cowpatz]

Once you reach final cruise altitude just put 0 in where the default ICAO is.