Boeing 777-200 A/T or CLB/CON

[macpilot 22]

I have loaded a flight plan into the FMC. I flew the plan and it worked fine except. At every waypoint I had to set the new altitude and speed as indicated on the LEGS page of the FMC. I have pressed the CLB/CON button. I thought that was supposed to follow the altitude and speed from the FMC. LNAV and VNAV is on. Below is my sequence after positive rate of climb. Should A/T be off for the CLB/CON to work?

 

What am I missing? Thanks in advance to all who reply.

 

Bill

 

 

Takeoff Procedures:

After Positive Rate Of Climb:

Gear up.

A/P ON

A/T ON.

CLB/CON

FLAPS UP

[jcomm 5,933]

A/T should always be ON in the 777. Or... did you mean TO/GA ?

 

Have you set derrates?

[macpilot 22]

 

Jcomm,

 

 

I'm just learning how to fly this baby. Please enlighten me as where and what is derrates.

 

Thank You.

 

Bill

[jcomm 5,933]

When setting the PERF for your flight you have the option for takeoff and climb derrated modes. There are 3 options for each. You should, according to published tables, choose the right one for you, and / or even set an assumed temp.

 

This is accessible through the PERF page of the FMC.

[macpilot 22]

 

 

I am half way through my flight. Can this be set in flight?

 

I don't see anything on my current PERF INIT page that looks like what you are talking about. But, I know what you are talking about. If that makes sense to you. I think I pressed the first one on the list. Preparing for the current flight. Maybe it's too late in the flight to set this.

 

On my "Thrust Lim" page I have

<GA CLB>

<CON CLB 1>

<CRZ <ACT> CLB 2>

 

Bill

[jcomm 5,933]

You're right, sorry... My fault...

 

It's on the thrust LIM page. You can change it on-the-fly though, or at least you should...  But I'll to look at it at home and report back...

 

In the meanwhile, here's an helpful link:

 

http://www.smartcockpit.com/aircraft-ressources/Reduced_Thrust_Operations.html

[macpilot 22]

 

Thanks for the link. I have some reading to do.

 

 

I just can't see what I'm missing. It's like VNAV is not following the FMC. But LNAV is.

 

Thanks

[jcomm 5,933]

 

 

I just can't see what I'm missing. It's like VNAV is not following the FMC

 

Ah, ok! Now I get you - yes, the FMC in the FF 777 has various problems / limitations when it comes to VNAV functionality :-/  even when you set mandatory ( AT ) restrictions in altitude. It doesn't even follow it's own predictions :-/

[macpilot 22]

So, you think this is a problem with the FMC not me.

 

I left a similar message on the XPlane B777-200 forum. See if I get any feed back from there.

 

Thanks.

 

Bill

[jcomm 5,933]

Yes Bill, I'd say definitely not your fault....

 

Also check that you aren't able to edit your next LEG in the legs page, and sometime to access a LEG data you have to use the LSKR bellow the one you should be using :-/

 

I'm waiting for 1.6

 

Now, at the .ORG you also mention not reseting your Alt to higher than 10000'. This might present a problem for LEGS with altitude constraints above it of course, but you can easily notice that the VNAV logic in this aircraft fails to follow those LEG restrictions bellow that altitude...

 

I usually set ALT at my first cruise alt when I set the baro to STD, which is a lot lower than when you're flying in the USA....

 

On descent you can also verify that the VNAV logic has problems...

[macpilot 22]

 

 

I'll have to wait for the weekend to try the altitude as you recommended. I heard from the other forum. They also mentioned the altitude being set to 10,000 could be the problem. VNAV won't go over the altitude setting. BTW does your VNAV follow the FMC?

 

Thanks.

 

Bill

[jcomm 5,933]

BTW does your VNAV follow the FMC?

 

Thanks.

 

Bill

 

Nope, not as I think it should, also basing my oppinion on previous PS1 and recent PMDG 777 experience...

[jcomm 5,933]

Well,

 

I just came from an EDDF -  LPPT flight.

 

I was able to get the FMC following the alt constraints on climb up to cruise. Thrust modes were also consistent.

 

The innability to edit your next LEG is still a bug, and cruise speed is not being respected either, specially if you make inflight adjustments to your COST Index.