Hi there!

 

I set FL350 in PERF INIT. But when I go through the legs I see the cruise at FL410.

I also notice that the STEP TO on 2/3 of the ECON CRZ page shows FL410.

AUTO STEP CLIMBS in FS ACTIONS/AUTOCRUISE is set to NO.

 

Can anyone assist why FL350 is not showing as the cruise in LEGS?

 

Thanks!

 

Maniac59

Go to Vnav - Climb - Cruise - Descent - Approach page's, that's how I fixed mine...

Thanks for the reply.. I don't see that option.

ALL ENG or CLB DIR is all I have.. not Climb - Cruise - Descent.

 

Maniac59

Press the "Vnav" Button for the FMC, after it brings you to the first page press "Next page, or previous page...

How did you enter the flight level in the pref? 350 should do

 

 

I set FL350 in PERF INIT. But when I go through the legs I see the cruise at FL410.

 

If your STEP SIZE is anything other than 0 (it probably says RVSM), then the aircraft is working properly and you're just misunderstanding what's going on.

 

When you put a CRZ ALT in there, what you're doing is telling the aircraft your initial cruise altitude.  Below that field, you'll see a STEP SIZE field.  This step size is you telling the aircraft how it should expect to increase in altitude over the course of the flight to optimal higher altitudes as fuel is burned off and flight at higher altitudes becomes the more efficient option.

 

When you added FL350 in the initial cruise altitude and left RVSM (the default value) in the STEP SIZE box, you're telling the aircraft:

1. I will start off at FL350
2. You may use any altitude above that using RVSM standards to maintain an optimal profile
   These altitudes, in your case, are: FL350, FL370, FL390, FL410 (and I think FL430, but that's rare)

So, since the step size is above zero, the aircraft is assuming that you want to fly at the optimal altitude for the expected weight.  Since the OPT ALT is closer to FL410 than any of the other altitudes, the FMC is saying you should be at that altitude for that portion of the flight.

 

If you want to force FL350 in there, you can set FL350 as the cruise altitude, and set your STEP SIZE to 0.

 

 

 

In the future, it might be better to ask the question first, before assuming something is incorrect.

Thanks Scandinavian..That did it...

I meant to title the topic incorrect FL.. not just incorrect.

But I couldn't change the topic title after posting..

Have a great weekend!   

 

Maniac59

 

 

Thanks Scandinavian..That did it...

 

Glad to hear you got it.

 

 

 

I meant to title the topic incorrect FL.. not just incorrect.
But I couldn't change the topic title after posting..

 

Gotcha - yeah.  That makes more sense.

 

 

 

Have a great weekend!   

 

You too!

 

 

FL410 (and I think FL430, but that's rare)

 

FL430 is the other direction, after FL410 the next valid step would be 450.

FL430 is the other direction, after FL410 the next valid step would be 450.

 

Good catch!  In my mind I was just thinking 2000s up to the service ceiling, forgetting RVSM which I had just mentioned...oops.

 

*Runs to get another cup of coffee*