Hi all

 

i'm still a newbie on the 738 even after reading the FCOM

 

When planning a flight on pfpx, i had a step climb planned, so I'd entered the step climb altitude on the VNAV CRZ page and the FMC gave me the remaining distance to the S/C. At 10NM for S/C, i update the MCP altitude to the S/C Altitude but when the A/C was at 0NM, the aircraft didn't start to climb, and the S/C pseudowaypoint ( sry airbus word, don't know if it's the same for boeing ) kept drifting forward the A/C, by the way the S/C distance was always 0 NM, so i had to use the LVL CHG mode, but I'm pretty sure that if the A/C is in VNAV mode, you just have to change the MCP altitude and the plane will descend or climb by itseft to the mcp altitude. I don't know what i'm doing wrong, if someone can sheld the light on this issue.

 

By the way, can we planned a step climb at a waypoint ( equivalent to the  "S" feature in the B777 ) or at coordinates ?

 

thanks in advances

 

 

Camille MOUCHEL-BLAISOT

France

 

 

so i had to use the LVL CHG mode, but I'm pretty sure that if the A/C is in VNAV mode, you just have to change the MCP altitude and the plane will descend or climb by itseft to the mcp altitude.

 

Somewhat of a common misconception here:

In order for it to leave an altitude after capturing VNAV ALT, you must either affect the change yourself (as you did with FL CH, though V/S would also work), or hit ALT INTV when you're ready to begin the climb.  It won't do it automatically as it would when it begins a VNAV descent.

 

 

 

By the way, can we planned a step climb at a waypoint ( equivalent to the  "S" feature in the B777 ) or at coordinates ?

 

I don't think so, but I'm not entirely sure.  Either way, it still would require you to be there and press ALT INTV to begin the step.

ok thank you for the explanation

I think this is due to the fact that step climbing with a 737 is not really as common as with a 747 or 777. On the 1-2 hour flights a 737 normally operates on, there is no need for a step. Only on the longer 4+ hour flights. So I think they just didn't find it necessary for the FMC to have this feature.

 

 

i had a step climb planned

 

Make sure you cabin altitude on the Overhead Panel reflects your new altitude.

Cabin Alt should not need adjusting. At least not unless you are doing massive steps...

You don't adjust the Cabin altitude manually, but you would adjust your FLT ALT on the overhead panel.

Doing this will indirectly adjust cabin altitude as well, to maintain a scheduled differential pressure.