I am flying EGLL-KEWR and the flight plan calls for a speed and altitude restriction for the oceanic track portion of the flight (M0.83/FL360)  The legs page has the FMC calculated values, which include a step climb in the middle of the NAT.  I have tried to override by entering the required speed and altitude at each oceanic waypoint, but I get an "invalid entry" message, no matter now I try to enter it.  I can do speed intervene and not perform the step climb until exiting the track, but I'd like the performance calculations (fuel predictions) to be correct.  Am I missing something? 

 

Bill Rowe

Speed is straight forward: enter ".83/" on the legs page at the oceanic entry point and "E/" at the exit point.

 

You can force a step by entering "/380S" for example. I'm not at the PC but you may need to combine this with changing the step from RVSM to 0.

 

 

Am I missing something? 

 

Yep.

 

You'd imagine those smart guys who wrote the tutorial would've given a hint about that...

 

(Tutorial #1 - page 0.0.35)

Yep.

 

You'd imagine those smart guys who wrote the tutorial would've given a hint about that...

 

(Tutorial #1 - page 0.0.35)

 

I was putting in the constraint as speed and altitude.  I entered .84/340 and got "invalid entry"  I tried multiple formats for speed (e.g. 0.84, .840) and altitude (340000, FL340) but nothing worked. 

 

I couldn't even enter an altitude constraint of FL340 by itself even though the FMC was planning FL340 at that point (I was making the mod on the ground so it wasn't that the waypoint was active).  I tried a waypoint later  in the route and was able to enter FL340 after the step climb.

 

So there was something about that waypoint (a regular intersection) that the FMC wouldn't let me apply an altitude constraint.  I couldn't enter a speed constraint on any waypoint.

 

Bill

I couldn't enter a speed constraint on any waypoint.

 

On the 777 you cannot enter a speed only constraint, it has to be speed and altitude or just altitude.

 

 

 

I am flying EGLL-KEWR and the flight plan calls for a speed and altitude restriction for the oceanic track portion of the flight (M0.83/FL360)

 

 

 

I entered .84/340 and got "invalid entry"  I tried multiple formats for speed (e.g. 0.84, .840) and altitude (340000, FL340) but nothing worked

 

What was your initial cruise altitude and did you want to enter the NAT and maintain .83/FL360?

 

 

I tried a waypoint later  in the route and was able to enter FL340 after the step climb.

 

It was allowing you to do that because it was seen as a restriction for the descent.  I won't let you enter a restriction for your current cruise, or a level above your current cruise...

 

...unless you use the S modifier at the end of the altitude.  This overrides the basic step climb function and alerts the system that you're telling it where the steps are occurring.  You don't necessarily need to force the altitude restriction if you're currently at FL360.  All you need to do is set the FL380S on the other side of the NAT.

 

 

It was allowing you to do that because it was seen as a restriction for the descent. I won't let you enter a restriction for your current cruise, or a level above your current cruise...

 

OK.  That makes sense, but if I can't enter an altitude restriction, then how do I enter a speed restriction on a cruise leg where the FMC calculated altitude is the planned altitude (which would be a normal situation since you would file for an altitude that was economical for the weight you were planning). 

 

Basically the initial waypoint in the NAT is showing (in small font): .833/FL340 and I want to put .83 Mach restriction through the NAT and then add ECON/ at the last NAT waypoint to return to econ speed.  I've been looking at the FCOM vol.2 pg 11.42.28 and it talks about entering a constant speed cruise segment.  I've been trying to replicate what is shown there (unsuccessfully).

 

Bill Rowe

If you want to fly a specific mach number that isnt ECON, then you enter the mach number on the VNAV cruise page, then when you exit the NAT, hit the ECON prompt.

 

EDIT, looks like i misunderstood the cruise part, now i see what you are talking about regarding the speed, i will try it out in a few and let you know the result

I just tried it  and it works fine for me, i entered .84/ and inserted it, then a couple waypoints down i entered E/ and it worked.

 

You were probably having problem entering the speed because of the incorrect way you were entering the altitude restrictions as mentioned above.

OK. That makes sense, but if I can't enter an altitude restriction, then how do I enter a speed restriction on a cruise leg where the FMC calculated altitude is the planned altitude (which would be a normal situation since you would file for an altitude that was economical for the weight you were planning).

 

Basically the initial waypoint in the NAT is showing (in small font): .833/FL340 and I want to put .83 Mach restriction through the NAT and then add ECON/ at the last NAT waypoint to return to econ speed. I've been looking at the FCOM vol.2 pg 11.42.28 and it talks about entering a constant speed cruise segment. I've been trying to replicate what is shown there (unsuccessfully).

 

Bill Rowe

I already gave you the answer for this one.