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Slick9

Looking for a quick lesson...

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mornin' ladies and gents,

 

I've been flying the 777 since it was released and i love it. my typical MO is to take off and hand fly to approximately FL18 and on landing I usually hand fly  to touchdown once I've completed the approach checklist (FS2Crew), usually around 9,000 or 10,000 feet.  I normally use the ILS approach for vertical guidance.

 

Now I want to simulate the ILS being inoperative, I read somewhere (can't remember where) that the 777 can generate it's own glide slope if there is not one available.  I've been going through the manuals trying to find the instructions on how this works but no luck so far.

 

If it's simple procedure, could one of you training captains give me a brief synopsis of how to get this working? If it's more detailed which manual and where would it be?  

 

Thnx for the help!!!

 

Richard Bansa

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Hi Richard

There is a short and long answer to this so I'll try to be brief. Basically you will end up using vertical navigation guidance here.

There would be no such thing as a 777 provided glide slope but a glide path, almost the same thing caveats. The little bar that appears on your map display (nd) at top of descent and if the option in the settings is active on the right hand side of your horizon display (pfd) is what you'll be using.

To use that accurately and to a point on the approach where you can continue visually to land you'll need four things. An approach path set using the cdu deparr page, vnav pth mode on the fma, speed intervene on the mcp and an altitude between the faf altitude and zero on the mcp.

The best reference would be the fctm non ils approaches using vnav section.

I'm sure that someone else will offer better instruction shortly but I'm ready to assist in the interim.

Cheers

Matthew knight

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Hi Mathew,

 

Thanks for the answer.  So if I understand correctly, the crew would select an approach path on the dep/arr page, ensure that VNAV was enabled on the MCP (I'm assuming that this would also enable speed intervene), and then set and altitude restraint on the MCP below the FAF altitude.??  

 

Ok, I'll go check the FCOM on vertical guidance to read some more. Thanks though.

 

Richard Bansa

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Basic procedure would be. Select say a loc approach at the arrival airport.

Use appropriate modes to take the craft to the final fix, say Lnav / vnav. With vnav engaged and either the faf as the to waypoint or flaps out of up, open the speed window on the mcp and select an appropriate speed for the flap setting. Before the faf set the minima in the mcp altitude window. Aircraft should follow the vnav path profile indicated on the nd and you can then set the missed approach altitude. (Fcom says more than 300 feet below missed approach) loc mode can be used as normal on a loc approach. Plus you'll have the glide slope (from the ils) as reference.

Cheers

Matthew

The fctm is a better reference for this than the Fcom I think. The Fcom will give you some tips on "on approach logic" which will answer your question about speed intervene with vnav path. Also (I'm not sure of the layout) normal procedures should be in the Fcom and there my be a non ils approach procedure using vnav in there.

Final thought is that if you are not flying a route to test out this procedure make sure your cruise altitude in the cdu is the same as the final approach fix altitude, this will help because it should mean that you never leave vnav path from the time you capture the cruise altitude. (You'll still need the faf to be the active waypoint or flaps out of up to speed intervene though)

Cheers

Matthew

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If you want to get into it a bit deeper you can use the following procedure, which is also relevant if flying an aircraft that does not have a coupled VNAV option (i.e. the autopilot will follow a programmed Vertical Navigation Profile):

 

Generally speaking, all ILS approaches have a glide path of approximately 3°. 3° works out to be roughly 1nm per 1000ft of altitude so 3x your altitude (divided by 1000) will give the distance you should be. For example, at 1000ft you should be 3nm, 2000ft should be 6nm and so on. You can get your distance information either from a dme (remember though that the dme location may not be at the runway threshold) or the distance to waypoint on the ND.

 

If you are "on slope" then descent rate using vertical speed (VS) is simply ground speed divided by 2 and multiplied by 10 (e.g. 160kts/2 = 80 x 10 = 800feet per minute). If you were at 4000ft at 9nm (you should be 12nm for 4000ft) then you'd be high so should increase the descent rate. How much you increase the descent rate is a judgement call depending on where you are in the approach. If you were at 4000ft at 3nm you'd be 3000ft to high and obviously would need a very high rate of descent. That close to the landing runway you'd be non-compliant with stable approach and the best course of action would be to conduct a missed approach and try again. If you're low (e.g. 3000ft at 12nm) you simply reduce the feet per minute until you catch up to where you should be. I normally do it every 1000ft on an approach.  

 

With the glideslope out you would still load the "ILS" into the FMC as per usual to allow auto-tuning of the localizer frequency and then use just "LOC" mode (rather than approach mode) to track the localizer only.

 

Using Vertical Speed (VS) mode certainly increases your workload and mental processing, and may take some practice to get used to it (especially at the high speeds that the 777 can move at). This procedure is what I use daily at work flying a high performance turboprop with no VNAV for descent profile planning and monitoring. For practice and monitoring the autopilot is doing what it's supposed to, let it fly the ILS in approach mode on autopilot and cross-reference the above method with what's displayed on your PFD/ND.

 

Hope that helps, if you need anything clarified please let me know!

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Thanks Haydn - I'll be heading out this afternoon from AYPY (Papua New Guinea) to Anchorage, I'll be trying a VS descent using your suggestions.

 

Richard Bansa

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I am looking for some stuff I have posted before and will paste it here.

 

EDIT: I probably copy/pasted more than you asked for, but I kind of like to have it all in one place. 

 

Here is a first bit that is not exactly what you were asking about, but to understand how to do a Vnav approach one has to have some background knowledge.

As said by others, that info can also be found in the FCTM but is harder to read.

 

1st copy/paste:

 

yes, the confusing ghost pointers...."anticipation cue" actually.
First, Yes you were on Lnav.....otherwise you would not have had the white ghost pointers.
In HDG sel mode, as soon as the Loc is received, it will show an open magenta diamond (not white)......just like it allways looked like before we had Lnav and Vnav aircraft.
But why do we have ghost pointers?

The ghost pointers were invented when Rnav approaches were introduced.
Before Rnav approaches, those LOC/GS diamonds were only used for Loc and GS deviation.
And on the left top of the PFD, you would see what theses diamonds refered to......(to the ILS frequency displayed there).

But now that we also use Lnav and Vnav for approaches, with the same diamonds, you need a way to identify what the diamonds are linked to.
Are they displaying a Loc deviation or an Lnav deviation?

So on top/left of the PDF we now not only have the ILS frequency displayed, but also Lnav/Vnav. 
This is important because:
- with Ils frequency top/left: the diamonds give Loc and GS deviation
- with Lnav/Vnav top/left: the diamonds give Lnav and Vnav deviation from your programmed FMC path.

Do not mix this up with the FMA (flight mode Anunciation) indications on the very top of the PFD (HDG Sel/FLCH SPD/ Lnav/VS etc) as they indicate what mode the AP or FD is in.
Not what the diamonds refer to!

When you are in Lnav then the diamonds will automatically show Lnav and Vnav deviation.
So how do I see when the LOC/GS become alive if I want to fly an ILS?
That is where the white ghost pointers come in :-)

But dont forget to arm APP mode!
Because them pointers will just stay white as long as your AP/FD are in Lnav/ Vnav mode.
Without APP armed (or if Loc never captures for other reasons, like parallelling) the FMA will stay in Lnav/Vnav, on the top/left of the PFD it will say Lnav/Vnav and the diamonds give Lnav/Vnav deviation.
The whole system would never switch to Loc and GS on the FMA, nor ILS frequency on the top left of the PFD and the ghost pointers stay white to indicate you are receiving the ILS, but you have not told the AP/FD to actually follow it.

The FCOM SOPs actually advices you to not intercept an ILS from Lnav but use HDG Sel instead.
It is possible and we do Lnav to loc intercepts in real life as well.....but allways with the back of our mind thinking.......hope it captures!
Because as Kyle said, Lnav may parallel the Loc all the way untill short short final. Even if this is only paralleld by a little, it is possible for the LOC to never capture.
If that happens (parallelling) then just engage HDG sel for a second, steer to the left/right to intercept the loc and arm APP again. 


Copy/paste part 2:

 

Just to confirm, YES, to fly an Rnav approach you have to choose an Rnav approach from the database. 
An Rnav approach is not the same as a VOR approach that is flown with Lnav!
It seems the same but is not.
In have posted that before.....quite a while back.....maybe I can dig it up.

In real life you are not allowed to change or add or remove any waypoint from the selected Rnav approach!
(this is FSX so you can do as you please ofcourse, but just saying).


Just before the final descent point/final approach fix:
- have flaps 5 and flaps 5 speed max.
- in the CDU check to make sure the final approach altitude is entered.....and that after that a 3 degrees (can vary a little bit) is displayed.
- set MDA
- make sure you are in Vnav Path......if in Vnav Alt you can change that to Vnav Pth by clicking the altitude selector once.
- immediately after changing from a non Vnav mode (like altitude hold) to Vnav Pth the speed window will blank and you need to reopen it (click speed switch) to prevent the target speed to jump somewhere you do not want it to go!.....the jump could be unsafe as often Vnav will automatically set the target speed to something well below your current flap speed!!

Vnav approaches can be precision as well as non precision by the way.
For the precision approaches the temperature is not allowed to exceed certain minima and maxima.....otherwise you would end up too low or too high while following the Vnav profile (it is after all based on following your barometric altimeter.....not a glide slope signal!)

Oh.....and once established on final approach and below the missed approached altitude (at least 300ft below) you can and should set the missed approach altitude!
(you can also wait with that untill the AP levels off at the MDA but that would cause an unstable short final if you dont disengage the AP right away).
So to repeat; you first have the MDA set in the altitude window......then at the FAF, Vnav starts the descend.....and while descending to you minimums you can wind up the altitude selctor and set the missed approach altitude.
While you wind up from MDA to missed approach your AP will NOT level off as you dial it to your current altitude (.......nice real world feature and works perfect......well done PMDG :-)

Once you reach the MDA the AP will not level off if you do what I said above because the missed approach altitude is already set.
And since an Rnav approach or an Rnav/Vnav approach is created without a level phase at the end (unlike some VOR or NDB approaches that can have a level segment at the MDA), you have to either:
- rwy insight: disengae the AP once below 200ft AGL (minimum AP enaged altitude unless you do an autoland) and land.
- rwy not in sight at MDA: immediately fly a go around.....hit TOGA, do everything you usually have to do for a go around and watch how the airplane levels off at the already set missed approach altitude :-)

I have not done many Rnav (=Lnav) approaches with the P,DG777 but those that I did worked excellent.

Great fun.....lots of new things and traps you could fall into, lots of ohhh and ahhhh and what is it doing now?!.... I highly recommend playing with it.
Just keep asking when it did something you did not expect.....it is bound to happen. 


copy/paste 3:

 

Vnav Approach:

Once certain criteria are fullfilled on approach, the FMC switches to "on approach" mode.

You dont see this indicated anywhere, but at that point you can use speed intervention while the pitch mode remains in Vnav PATH :-)


copy/paste 4, more about Rnav then Vnav really:

 

There are some things you can/should check before starting an Lnav Vanv approach, but I guess what exactly to check also depends on aircraft equipment and company SOPs.

For ultimate realism :-), these are my personal notes:
EO Non Precision straight in flown with LNAV and VNAV:

The minimum required equipment to accomplish a RNAV approach is: 
 Two FMC (One is required if missed approach is not based on RNAV) 
 One CDU 
 One IRS 
 Flight Plan Data on two ND´s 
 One FD and one A/P on PF side 
 Sensor receivers as required by approach (e.g. GPS for GPS/GNSS RNAV approaches, DME/DME update for DME/DME RNAV approaches, etc.) 
 Current onboard navigation database including coded approach procedure 
 Other items if restricted by approved MEL 

So basically if any EICAS message appears in flight, then you have to check this list and make sure the failure does not effect Rnav capability.

For RNAV GNSS approaches check FMC for:
-RNP 0.3 entered on FMC position page
-Radio position updating disabled (disabled wIll have ON displayed in green, telling you disabled =on). This is probably just us though....we are not allowed to have radio pos updating enabled for Rnav approaches.
-Runway threshold coordinates (check approach plate runway coordinates to be the same as FmC database runway coordinates (as this is after all the point Lnav is taking you to)

For Vnav flown approaches, additionally check:
3 degrees glide path is indicated in the FMC LEGS page. 

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copy/paste 5, more lateral stuff about non precision approaches:

 

The 777 is an LNAV/VNAV airplane that uses GPS to determain its position. An ILS is the only approach that is still flown old fashioned stile. VOR approaches (and NDB for some airports) are both still in the FMC database because if ATC clears you for one you have to fly that. When you select that approach from the database, you will see how the magenta line gives you a visual display of the VOR approach. And then these Emirates guys follow this magenta line into LFMN with LNAV. So GPS is used to follow the magenta line with LNAV. Now officially this procedure is based on the VOR (you can see on your approach chart what equipment is required to folllow the approach down to the minimum descend altitude. and it will say VOR or VORDME). So there is actually still a requirement to cross check the VOR needles (make sure the VOR bearing pointer on the ND points to the inbound course) as you fly this with Lnav. And if the needles dont match with what Lnav is flying you would have to go around and find out what is wrong. I know it sounds silly to cross check Lnav/ GPS with ,in comparison, inaccurate VOR needles, but it is a fact that you have to!

 

EDIT: it was brought up in the thread I copied this from, that cross checking with needles might not be a requirement for all airlines. This is true of course, it could be an SOP thing.

The next step down from using LNAV is using Track Select, to follow the magenta VOR route and to keep those needles pointed where you need them. You would do this if Lnav failed for example.
Again, cross check with those VOR needles!

And the next step down from that would be to use heading select, to follow the magenta VOR route and to keep them needles where they need to be . This mode would be used for instance if the ADIRU can not calculate track anymore due to some failures. You now have to correct for wind drift yourself.
Again, cross check required.

And then finally comes your practice VOR approach.
If enough things have failed that there is no depiction of a map mode on the ND anymore then you have to revert to old school VOR flying.
Not having a MAP displayed on the ND is ofcource quite a bit more challenging as you cant easily see where you are going.
This requires true IFR skills!
Something you would hate to have to demonstrate into a mountain airport with pooring rain and wind gusts after a 10 hour flight through the night ;-)
Select VOR instead of MAP mode on the EFIS panel.
You now have a HSI displayed in full rose or expanded mode (selectable with the black button inside the left knob on the EFIS panel) and you need to fly a heading (or track if that still works) to keep the CDI (cource deflection indicator) centered.

Vertically you can follow your path with Vnav or VS or FPA.
Whatever you like using, but again Vnav would be the easiest (once you get comfortable with using Vnav that is....it takes a little getting used to but is a fantastic mode and perfectly simulated :-).


And then there are true GPS flown approaches.
Approaches that are based upon GPS, not VOR or NDB.
They are called RNAV GNSS or RNAV GPS or RNAV RNP approaches.
These are also selectable from the FMC database.
They are not called VOR 31 or VORDME 31 approach but RNAV 31 approach.
So there is a difference between them!
They are normally flown with LNAV and VNAV but again you could use Track select and VS just as well. The difference is that no cross checking of VOR needles is required to follow these approaches down to the published minimums. You are using GPS as the only source for position determination.

Hope this helps in the jungle of approaches out there :-)           


copy/paste 6, even more lateral stuff:

 

Does it make sence to be cross checking accurate GPS signals with inaccurate VOR signals?......that is something else. But requirement is requirement.
This cross checking requirement might all disappear in the future, but you have to realize that Lnav/Vanv approaches are relatively new to aviation (compared to VOR approaches) so we are in a kind of inbetween time/situation where both old school and modern stuff are used.
EDIT:
Also,VOR approaches and Rnav approaches are designed based on different requirements.
An Rnav approach for example gives you the runway coordinates on the approach plate. You have to check the printed coordinates against your FMC database coordinates for this point. This to make sure that the magenta line actually takes you where you want to go and not to the parking lot next to the airport!
A VOR approach plate does not (have to) provide coordinates as it is based on you following your needle.
If your VOR coordinates are not correct in the FMC, cross checking with the VOR needle will save your day!

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ok Rob, just when I was feeling like i had this whole 777 thing under control you drop some serious knowledge and show me how little i really know.  :lol:   Thanks for all the info, I have a lot of work to do. One question I have which is a little embarrassing because it's really basic is this.  With the GPS and VOR approaches, can they be hand flown like an ILS approach?  Also, I'm assuming that if it is legal to hand fly these approaches one would still engage the appropriate flight modes ie. VNAV/LNAV, SPD, etc in order for the FD/ND to display the appropriate guidance. (I think you said this but not sure if it only related to AutoPilot flight or if it would indeed still be true for manual flight.)  

 

On a slightly separate note, one issue that I have been  frustrating time with is the lack of the ILS DME being displayed after the ILS is active (I even get the name of the ILS eg. ILX TDE, but no distance to the runway).  I've been using the VOR DME as a guide if it's based on the field. Not sure if I'm doing something wrong or just missing something.

 

THanks for the help Rob, I've got some experimenting to do!!
 

Richard Bansa

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The display of ILS DME is one that I'm not sure of either. To be honest I nearly left it out of my post, but decided in the end it was still relevant for the overall discussion with a disclaimer regarding the location of the DME.

 

Regarding hand flown GPS/VOR approaches, I'm certainly not aware of any legal reason you can't do that. Boeing (and other aircraft manufacturers) recommend using automation wherever possible because it's safer and generally is a little smoother. It's mostly safer as it frees up mental space for the pilots to monitor and concentrate on things. There's much talk in human factors circles though regarding the degradation of hand flying skills due to autopilot usage. That's not to say it's bad... just like every system you have to be aware of the downsides as well.

 

I would say like most things there are multiple ways to do it. You could continue to fly what's known as raw data with the autopilot. In that case it's simply a matter of dialing up the frequency via the FMC and then using the course bars for your outbound track (and inbound if it's a reversal procedure). If you want to completely hand fly it with no flight directors that would be substantially more complex (not impossible). In that situation the Pilot Monitoring would become crucial in a two crew aircraft as you'd ask them to make the MCP changes to ensure the bugs are set correctly to allow you to monitor. If you use the Autopilot but not coupled to LNAV there's no reason why you can't use the LOC function to track the course or even use the course deviation and heading mode to track the VOR radial.

 

For GPS it obviously does require LNAV/VNAV (although the same 3° profile still applies) and you can hand fly following the the flight directors. In a general sense the mode selectors control the flight director outputs (what you see on your PFD) and then the autopilot flies the flight directors. There's no reason you can't hand fly the flight director outputs!

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