Understanding Approach Charts

[Jimm 437]

This year, I went ahead and bought a subscription to Navigraph Charts.  I find it to be a very useful product when planning flights.  I have come across something I am unfamiliar with, and perhaps has gotten me in some sticky situations, more specifically with approaches.  When determining a given arrival, I typically get a runway from PFPX, to which in turn, I complete my flightplan via the MCDU, where it asks for a runway and then a STAR.  When conferring with the charts, I see that some airports have many different approaches for the same runway.  For example, at LGAV, runway 03R, I have an option for ILS X/Z 03R ILS Y 03R, but I cannot tell the difference.  Other airports seem to be cut and dry for approaches to their runways, but for the example above, I don't know which ILS to choose from.  I am still able to complete the route and fly to the STAR, but every once in a while, on approach, I cannot get the APPR to engage, and I have to override the aircraft and fly in manually.

 

I am still learning quite a bit now, but for these approaches, I am wondering if I am still missing something that I should understand or something I should already know to pick out the correct approach from the charts.

[pete_auau 1,154]

I am still learning quite a bit now, but for these approaches, I am wondering if I am still missing something

 

4 parts series

[Gregg_Seipp 565]

Often these approaches will have different minima for obstacle clearance on the missed approach.  See if the chart has a minimum climb rate requirement on it and check the minima.

 

Also there's a Flight School forum where you might find some answers here and there...which needs a great deal more participation.

 

http://www.avsim.com/forum/498-the-flight-school-hangar/

[TurboTomato 90]

Good question, as I'm in a similar position. Have watched a few video tutorials on youtube and that has helped - the Baltic Aviation Academy one is pretty clear and straightforward.

[Jimm 437]

I did watch the video(s) that Pete recommended and they did shed some light on things, but most I already knew.  I looked at the STAR charts for LGAV for RWY03R, which have a X,Y, & Z option.  I did find that X and Z are for CAT I & CAT II landings, so that is what differs for those.  I think a more broad answer to my own question would be that looking at the charts in greater detail will help differentiate.  I just need to provide myself more time planning my STARs and not rushing them before takeoff.  As I said before, many STAR approaches are cut and dry, but it's these approaches with X,Y and Z options that got me, but I think I'm a little wiser now.

 

Thanks guys.

[tttocs 301]

Lettered variations to an approach simply indicate that there are differences between the various versions.  Often these differences are subtle and as Gregg notes one of the most common is a difference in the approach minimums.  You have to be extra careful with these as lower approach minimums are typically coupled with some very aggressive climb gradients on the missed approach.  If your aircraft can't meet these climb requirements you'll want to fly the approach with the higher minimums.

 

Scott

[Gregg_Seipp 565]

 

 

Lettered variations to an approach simply indicate that there are differences between the various versions. Often these differences are subtle and as Gregg notes one of the most common is a difference in the approach minimums. You have to be extra careful with these as lower approach minimums are typically coupled with some very aggressive climb gradients on the missed approach. If your aircraft can't meet these climb requirements you'll want to fly the approach with the higher minimums.

Scott

 

Yeah, I looked for the original question where you answered the same thing for me a long time ago but couldn't hunt it down.  So, credit where it's due...this guy knows his sh...stuff. :smile:

 

Gregg

[tttocs 301]

 

 

...this guy knows his sh...stuff. :smile:

 

As long as it's been since I've flow as PIC IRL, I think I've forgotten more than I ever knew! :-)

 

Scott

[fppilot 4,352]

Surprised someone currently instrument rated has not chimed in here.  The differences are based on pilot certification, equipment, and avionics performance. So the pilot must know the parameters and limitations of his equipment and pick the appropriate approach.  For ILS approaches the aircraft's V^ref  speed and the level of pilot certification are the determining parameters and the V^ref is relevant to obstacle clearance.  The same is generally true for RNAV (GPS) approaches, but I was way too early for instrument certification for those so I will point to the best reference I could quickly find.  Scroll to page 4-8 and use that as your starting point. The link points to a large pdf file so it may take some time to load.  It may well be worth the wait for you.

 

http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/instrument_procedures_handbook/media/chapter_4.pdf

[Jimm 437]

Now I feel like I've opened a huge can of worms.  I appreciate everyone's input and I'll get back to you all in about a month while I study. lol

[fppilot 4,352]

Now I feel like I've opened a huge can of worms.  I appreciate everyone's input and I'll get back to you all in about a month while I study. lol

Can of worms? No! but your question is a good one for many here to ask and you have opened a door for yourself to new knowledge and sense of accomplishment!

[tttocs 301]

Surprised someone currently instrument rated has not chimed in here. The differences are based on pilot certification, equipment, and avionics performance.

 

Yes, and no.  An RNP approach seems to be one of the things you're referencing here, where pilot certifications and equipment certainly apply.  But an X,Y or Z approach (be it ILS, RNP or whatever) simply means that while these approaches are of the same type, something is different.  It may be different minimums and associated differences in perfomance requirments for the same class, it may be different equipment requirements, it may mean different approach fixes.  But strictly speaking it doesn't necessarily indicate different pilot certification, avionics performance or equipment.

 

It just means there's a difference of some sort even though the base approach type is the same.

 

See for example the KJAC ILS 19 Y and Z approaches.  In this case, the approach fixes are different, with one using GPS fixes and (obviously) requiring an IFR certified GPS), the other simply requiring ILS/VOR capabilities.  This is one of many examples of the kind of differences inherent.  Some may require different performance, some different equipment, some none of the above - simply an alternative with different parameters.

 

http://155.178.201.160/d-tpp/1605/00504IZLD19.PDF

 

http://155.178.201.160/d-tpp/1605/00504IYL19.PDF

 

In the case of an ILS X,Y or Z approach, for example, there would never be a difference in pilot qualifications - only differences in procedure (fixes), avionics and/or performance.

 

Scott

[Orlaam 306]

Regardless, one should never choose an approach and runway based on departure. The weather can change and winds can alter the active making changing the approach in flight a pain. Especially with one pilot flying a two man aircraft, it can be a hassle trying to fix an approach last minute. It's better to be ready to enter it as soon as you are cleared (or you've heard ATIS). Of course there are times in the real world when they'll give a change 15 miles out but that's another story. It's a little more difficult in sim simply because ATC is so poor (unless online with good controller) and operating the plane can be tasking.

 

Last night for example I flew into KEWR. ATIS reported RWY 4L and R as active. I thought great, my assumption based on minimum winds was wrong so I'm probably gonna be high. Well after hurrying down for the IAF to 4L I hear ATIS say runway 22s are now active. Not a happy camper. I never fly into KEWR and was not prepared to go around and land opposite downwind. It was the MD11 and I rarely fly it anymore so I was even less prepared. Either way, it happens in the real world too.

 

To assume that you'll be cleared to a specific STAR and IAP is poor practice. In the real world those plans are altered frequently for traffic and other routing. If you are on a STAR to filter for a specific set of runways and those runways change direction, then you'll be vectored or cleared to a new fix entirely.

 

Be more concerned about airspace, MOAs and TRFs than anything. That's my opinion.

[ckyliu 1,749]

To assume that you'll be cleared to a specific STAR and IAP is poor practice. In the real world those plans are altered frequently for traffic and other routing. If you are on a STAR to filter for a specific set of runways and those runways change direction, then you'll be vectored or cleared to a new fix entirely.

 

I think most FMS's require you input a complete route, with SID and STAR before departure? I agree it's bad practice but you kinda have to assume at departure and then update it later if things change.

[KevinAu 441]

In the real world, we would have a good idea of what to expect for arrival beforehand. Atis for the destination can be pulled up via acars at anytime so that the expected runway and arrival transition can be programmed already. And many stars will have different transitions based on the runway in use, so even if you don't have the atis, the controller working you at the time of beginning the arrival will inform you of which transition you're doing. With the ability to pull up whatever information we need via acars, we would have the arrival briefing completed about 40 minutes prior to arrival. If things change, and they do, we just reprogram and rebrief. Obviously, you don't have all this info in msfs, but you can always check the real world weather ahead if you use real weather and you do have some influence on what runways will be active if made some afcad adjustments. So it does't have to be a complete surprise in msfs.