Hi, I usually fly a complete predefined route with LNAV and VNAV that I enter in the CDU before flight and do also automatic ILS landings. Today I decided to fly with ATC guidance in FSX, without entering the runway in the DEP/ARR section in the CDU since I didn't know which one the ATC would tell me.Departure was from ELLX and the destination GCTS (Teneriffa, Spain). Entered the needed SID for my departure and no waypoints or VOR's. I chose a STAR, which seemed to be not a bad one since the direction I'd had to come in was almost perfectly aligned with my route. 30 nm before my destination, I called the ATC at GCTS, they gave me runway 8 for the landing, so I chose ILSY RW08 in the CDU for arrival (though I don't know what the 'Y' in ILSY stands for) and somehow the rest of the route got messed up in the CDU and I got the message DES PATH UNACHIEVABLE. Tried to correct it but no luck, the route for the final approach on the CDU was colored in blue stripes which means the FMC won't accept it I guess :/ Is it even possible to add the runway that late to your route when you ask for landing or is there another way to do this?

"Y" is just an identifier for a specific approach based on the navigation equipment to the runway, for example 'Y' may be based on DME from the ILS 'Z' may be based on DME from the VOR over the field. If you posted the chart I could explain in more detail.Regarding the message DES PATH UNACHIEVABLE, If VNAV cannot cope then use the other tools at your disposal and fly the thing ;) If it is not possible to make it then request vectors or go missed!

Y and Z and X approaches are just different routes to the same runway, I believe. If you're unsure what route to follow, you could load one STAR/App that is fairly restrictive and see how that has you descend and start your ToD on that. You might start down earlier than you would like for fuel burn, but you won't be too high. Try to be proactive. Tell ATC what you want.

Try to be proactive. Tell ATC what you want.

Yep. Otherwise, you get assigned something and you may not want it. You can always request something else, but the proactive stance is showing up with the alternative:Pilot: "Hey, can we get the ___ app instead?"Controller: "Sure, expect the ___ approach."The alternative is likely just going to annoy the controller:Pilot: "We'd prefer another approach..."Controller: *blank stare* "There are 12. Pick one..."

Edited January 24, 201214 yr by scandinavian13

lol ok I think I'm gonna do the next flights as usual. Otherwise, if I'd have to make an IFR flightplan in FSX, does that work with the NGX (by still using the FMC programming method) or is it better to switch to ATC addon software?

FSX ATC is terrible.ATC add-ons are slightly better.Nothing better than ATC from a human network, like IVAO or VATSIM (listed in alpha order before I get flamed).

lol ok I think I'm gonna do the next flights as usual. Otherwise, if I'd have to make an IFR flightplan in FSX, does that work with the NGX (by still using the FMC programming method) or is it better to switch to ATC addon software?

Why on earth do you do auto landings every time? Apart from the fact that it is unrealistic, don't you want to fly the a/craft and feel the satisfaction of making a good landing?Iain Smith

Why on earth do you do auto landings every time? Apart from the fact that it is unrealistic, don't you want to fly the a/craft and feel the satisfaction of making a good landing?Iain Smith

EDIT - Nevermind, he probably isn't talking about a full autloand but flying an automatic approach on the ILSRegards

EDIT - Nevermind, he probably isn't talking about a full autloand but flying an automatic approach on the ILSRegards

Ah! Didn't think of that Rob! That makes more sense. :smile:Iain Smith

Good day all.ILS Y and Z are a bit different type of approaches and as for the routes so the routes are the same because you'll use same STAR for the same RWY and it really doesn't matter if you execute Y or Z, the STAR will be the same.When there exists more than one approach of a given type to a specific RWY, the approaches will be titled uniquely by including Z, Y, X, etc… Thus the presence of (KJAC for example) an RNAV X Rwy 9 approach at an airport implies there are at least three RNAV approaches to runway 9. If only two exist, they will be Z and Y; the convention starts at Z and works backwards into the alphabet. Letters at the end of the alphabet are used so there is no confusion with the labeling for circling-only approaches, which are named with letters starting with A, moving into the alphabet.So why would there be more than one approach of a given type to the same runway? The Y and Z ILS seem to be identical procedures. A careful look shows the ILS minimums are different, though. The Z approach brings a plane down to 200’ above TDZE, and requires 3/4 mile visibility, while the Y only goes down to 612’ above TDZE, and needs 2 miles visibility. So why would anyone shoot the Y? The answer lies in the notes. On the Z approach is stated “Missed approach obstructions require a minimum climb gradient of 245 feet per NM to 11200; if unable to meet rate of climb, see ILS or LOC Y RWY 19.” As for this- "30 nm before my destination, I called the ATC at GCTS, they gave me runway 8 for the landing, so I chose ILSY RW08 in the CDU for arrival and somehow the rest of the route got messed up in the CDU" you said that you chose STAR, which seemed to be not a bad, but when you enter RW 8 something went wrong. In case like this you need to check what is your position. If you are after STAR transition, you have to be a bit careful with any changes. If you are after STAR transition you may double existing STAR and it will screw up whole profile. You may even see in FMC that same fixes are shown twice. When you are past STAR transition, I would only change RWY and RW transition, not the STAR transition, don't be confused otherwise you will find yourself in the middle of a spider net

Edited January 25, 201214 yr by speedbird144

Ah! Didn't think of that Rob! That makes more sense. :smile:Iain Smith

I never autoland ;) only automatic ILS approaches and before touchdown I turn off the AP

Good day all.ILS Y and Z are a bit different type of approaches and as for the routes so the routes are the same because you'll use same STAR for the same RWY and it really doesn't matter if you execute Y or Z, the STAR will be the same.When there exists more than one approach of a given type to a specific RWY, the approaches will be titled uniquely by including Z, Y, X, etc… Thus the presence of (KJAC for example) an RNAV X Rwy 9 approach at an airport implies there are at least three RNAV approaches to runway 9. If only two exist, they will be Z and Y; the convention starts at Z and works backwards into the alphabet. Letters at the end of the alphabet are used so there is no confusion with the labeling for circling-only approaches, which are named with letters starting with A, moving into the alphabet.So why would there be more than one approach of a given type to the same runway? The Y and Z ILS seem to be identical procedures. A careful look shows the ILS minimums are different, though. The Z approach brings a plane down to 200’ above TDZE, and requires 3/4 mile visibility, while the Y only goes down to 612’ above TDZE, and needs 2 miles visibility.So why would anyone shoot the Y? The answer lies in the notes. On the Z approach is stated “Missed approach obstructions require a minimum climb gradient of 245 feet per NM to 11200; if unable to meet rate of climb, see ILS or LOC Y RWY 19.”As for this- "30 nm before my destination, I called the ATC at GCTS, they gave me runway 8 for the landing, so I chose ILSY RW08 in the CDU for arrival and somehow the rest of the route got messed up in the CDU" you said that you chose STAR, which seemed to be not a bad, but when you enter RW 8 something went wrong. In case like this you need to check what is your position. If you are after STAR transition, you have to be a bit careful with any changes. If you are after STAR transition you may double existing STAR and it will screw up whole profile. You may even see in FMC that same fixes are shown twice. When you are past STAR transition, I would only change RWY and RW transition, not the STAR transition, don't be confused otherwise you will find yourself in the middle of a spider net

Hmm that makes sense. In fact I only added the runway to the CDU (didn't change anything about the STAR) and then I had the issue. Maybe it's because I didn't pay attention to my route at that moment. I saw the runway straight in front of me and then realized that I hadn't updated the CDU, so I quickly changed it.

Edited January 25, 201214 yr by Hunzibunzi

Just a question on one of the op question that he stated he got a des path unachieveable thought this was due to that you havnt changed your pressuation alt to the correct descent alt?

My advice is to always fly with charts, your best bet is Navigraph to stay up to date, however you can find plenty of resources online to get them free.Another thing to keep in mind is trying to conduct an approach brief. Now I dont sit there talking to myself before TOD :( but I do get out the charts, plan my missed approach, study any other runways/appraoches that I may have to switch to (secondary flight plan page is very handy for a quick runway switch) And also plan where I intend to vacate the runway etc etc...And as I first mentioned, if you get a last minute change and you do comply the last thing you want to do is be heads down punching away at the FMS. If you plan ahead and weather permits take control and fly raw data, or if the aircraft is getting ahead of you request to be put in a hold if onlne or do it yourself and then build the new approach.This is just sim advice, flying these things for real is not a one man job.Regards

Being so new as I am to the use of the FMC, I some times make a mess of it all and really need to start all over. Is there a way to "reset" the FMC? (scrach all - escape - CTRL....)I know one answer: "Read the manuals". But please, a little bit of help would be highly appreciated.RegardsCarl Michael

[...]If you plan ahead and weather permits take control and fly raw data, or if the aircraft is getting ahead of you request to be put in a hold if onlne or do it yourself and then build the new approach.This is just sim advice, flying these things for real is not a one man job.

Very good points. Never hesitate to ask for a hold from ATC. It's not something that only ATC can assign. All you need to do is request it, and you'll likely get it. The only difference between coming in on the arrival without the hold and with the hold, is that you may be told to descend in the hold to free up the altitudes above for the inbound traffic behind you (could also be told to stay higher as well - all depends on the situation/area/terrain/weather/traffic/how the controller is feeling/etc).