Help with VNAV on 777

[Swe_Richard 1,172]

OK Starting to clear things up.. Not sure what t/o is... still a newb with this stuff..

Another issue I have is that I am using simroutes.com to calculate out my waypoints to enter into the FMC but they hardly ever end up aligned with the runway. Am I better off just creating my own route using the x-plane map and finding VORs , waypoints etc myself so I can align with the runway better?

 

Sorry I answered after so long time (sleep is good for you they say). T/O simply means take off. Set your cruise alt on the MCP before take off. But I see you've gotten some good answers already. 

 

Remember to reset MCP altitude BEFORE you hit the T/D point, though. 

[JonRD463 146]

Sideburn, one more thing you can try is to go to page 3 of the VNAV page on the FMC. There should be a selection for "Pause at T/D". Arm that by pressing the line select key next to it. This will automatically pause the sim 10 nm before you reach the T/D point calculated on the route. This is a good reminder to set your altitude to the lower setting.

 

Obviously, real life doesn't have a pause button, but this is a handy trick for when you need a reminder.

[sideburn 0]

 

 

Altitudes that appear in waypoint entries in small print, 16500 are just predictive; VNAV will not treat them as restrictions. If the aircraft gets to the predicted altitude before that waypoint, it will still keep climbing.  But if the altitude is in large print, 15000 it is a restriction and VNAV should not go past that altitude until it passes that waypoint, whether climbing or descending.

 

OK, that explains why my plane was not climbing or descending ever. All of my waypoints in the FMC are all small print. This leads me to another question.. I am using simroutes to find the waypoints. Maybe I am taking the wrong path here. Maybe waypoints are always going to be predictive and I need to enter airways? I'm not sure how to go about finding those and making a good flightpath.. More learning to do there..

 

But I am about to try another method by doing the entire route completely from within the FMC, I just found out how to use the DEP/ARR page and let it generate the route for me. When I did this the altitudes are now in large print so I bet its going to work. And now since I selected the arrival runway, maybe I am closer to getting the ILS (IAP?)working.

 

JonRD463, I didnt see a pause at t/d mode but I did find the HOLD page.. Is that what you are talking about?

 

[JonRD463 146]

JonRD463, I didnt see a pause at t/d mode but I did find the HOLD page.. Is that what you are talking about?

 

hold.PNG

 

On the VNAV screen on Page 3. It will be available after you've set up your flight plan.

[sideburn 0]

I found thepause setting and it worked..

 

I've had some success now witht altitude issues.. When I set a direct route flight using the DEP/ARR pages. The plane now properly climbs after takeoff to the correct cruise altitude and decends when it reaches the arrival airport.

 

So the only problem I have now is getting a route programmed that will align the plane correctly to the runway and use the ILS to guide me in.

[sideburn 0]

Hi Mike,

 

On this:

Quote

 

Altitudes that appear in waypoint entries in small print, 16500 are just predictive; VNAV will not treat them as restrictions. If the aircraft gets to the predicted altitude before that waypoint, it will still keep climbing. But if the altitude is in large print, 15000 it is a restriction and VNAV should not go past that altitude until it passes that waypoint, whether climbing or descending.

Can you tell me what makes the FMC determine whether it will make the altitude entry for a waypoint small print (predictive) vs large (restriction) ?

[Mike777 163]

 

 

So the only problem I have now is getting a route programmed that will align the plane correctly to the runway and use the ILS to guide me in.

 

Hi, Tavis,

 

Glad things are going better for you! 

 

In the Arrival page -- same page that has the STAR -- there should be a list of runways with various types of approaches.  (These are called "IAPs".) Choose the one that says "ILS" with the runway number you want.  That will add a couple of waypoints that will line you up with the runway.  It should also tune the ILS receiver to the correct frequency and course -- look on the NAV RAD page. 

 

There is likely to be a discontinuity between the last way point of your STAR and the first waypoint of the IAP (final approach).  Depending on where these two waypoints are, you may want to use Heading Select to steer so that you can intercept the first IAP waypoint at a reasonable angle -- 45 degrees or less from the final approach course.  Then go back to LNAV, arm APP, and it should lock onto the localizer and then the glideslope.  You will need to manually intervene to slow airspeed down to final approach speed, extend flaps, lower gear, arm autobrake and spoiler.

 

Let us know how it goes!

 

Mike

Hi Mike,

On this:

Can you tell me what makes the FMC determine whether it will make the altitude entry for a waypoint small print (predictive) vs large (restriction) ?

Many SIDS and STARs, as well as most if not all IAPS,  have firm altitudes that you must not exceed.  So those large-print altitudes (also speeds) are generally coming from the SIDs, STARs, and IAPs.  However you can also enter altitudes and speed restrictions yourself, and they too will show up as large numbers and be treated as restrictions not to be exceeded.

 

For US airports, you can find charts that show these altitude and speed restrictions at flightaware.com.

 

Mike

[jcomm 5,889]

 

 

Can you tell me what makes the FMC determine whether it will make the altitude entry for a waypoint small print (predictive) vs large (restriction) ?

 

Either because the procedure ( SID / STAR / APP ) includes such a restriction itself or you have edited the speed/alt constraint ( clicking on the LSKR button at it's right, which sometimes fails in the 777 due to what I think is a bug - sometimes works using the LSKR bellow that one :-/ ) and entered a precise altitude like, say... 6000 or 6000A (at or above) or 6000B (bellow)

[sideburn 0]

OK I am getting really close to having this sorted out now. I finally got a flightpath programmed into the FMC with waypoints and it is aligning to the runway. I just had to figure out how to setup the DEP/ARR section properly.

 

 

 

I'm not sure what the looping path (INTC ?) it makes after the end of the runway is yet but I will read up on it tomorrow.

 

 

 

And I still need to get sort out when I have to set the altitude manually and when the FMC takes control. I was in my final approach and i thought at that point I could set my altitude to as low as I wanted and the FMC would hold at 2000 since that altitude was in large print for that waypoint but it kept descending. I'll get it sorted out..

 

I tried to run the flight and got all the way to it saying "glide slope, glide slope..." and then x-plane crashed. So I am going to crash as well and pick it up tomorrow.

 

Thanks again for all the resources and info.. This is going to be a useful thread to refer to..

[jcomm 5,889]

RAFFS has an hold ( the racetrack you see plotted in the ND ) - it's the fix you go to after a missed approach to RW 24 L on that particular APP. You'll climb to at least 2000' and hold at RAFFS, awaiting further clearance...

[sideburn 0]

RAFFS has an hold ( the racetrack you see plotted in the ND ) - it's the fix you go to after a missed approach to RW 24 L on that particular APP. You'll climb to at least 2000' and hold at RAFFS, awaiting further clearance...

I see.. Is the TOGA button on the A/P related to this in any way? I haven't even tried to mess with or read up on any of this yet so I probably shouldn't be asking about it

[jcomm 5,889]

Yep, you press it to get Go Around thrust mode, and initiate a go-around. 

 

Regarding the T/D, should you ever get an Airbus model, like the NEO A320, the big difference between Boeing and Airbus style is that in the Boeing, provided you have reset your ALT target bellow your cruising altitude before reaching the T/D, the aircraft will automatically initiate it for you, while on an Airbus you'll have to use the alt knob (push it) to start the descent.

[sideburn 0]

Either because the procedure ( SID / STAR / APP ) includes such a restriction itself or you have edited the speed/alt constraint ( clicking on the LSKR button at it's right, which sometimes fails in the 777 due to what I think is a bug - sometimes works using the LSKR bellow that one :-/ ) and entered a precise altitude like, say... 6000 or 6000A (at or above) or 6000B (bellow)

I don't see anywhere where you can edit the speed/alt in the FMC.. No sign of an LSKR button anywhere.

[Mike777 163]

I don't see anywhere where you can edit the speed/alt in the FMC.

 

Again, I don't have this particular 777 (don't have X-Plane), but typically on the Legs page you type changes in the scratch pad at the bottom of the FMC screen, and then you click on the Right FMC button next to the waypoint.  If you wanted to set constraints of 300 speed and alt of 15000, you would type 300/15000 then click on the right FMC button.

 

In some situations the FMC may not accept it, but usually it does.

 

In one of your recent posts you still had the nav display in Plan mode -- you need to keep it in Map mode while flying most of the time (unless flying an ILS or LOC approach; then Approach mode).

 

Mike

[sideburn 0]

Not harsh at all I agree. Thanks for the links. I'll go through them. I've got the basics down now and have has 2 successful fmc driven flights now. Once the ILS came in I clicked the LOC button and then the APP and it brought me down to the runway then I turned off autopilot, landed and maxed out the reverse thrusters. I was a little sloppy but not too bad for the first success on this size plane. Still a lot to learn but I'm off and running now I think.

I went from KSAN to KLAX and then from KLAX to KSAN it was a little tricky for me at first to let a klax to ksan runway 27 since I had to loop around but I finally got it sorted out.