Suggested Unofficial Instrument Approach to 46CA?

[stevekirks]

I'm trying to write up a personal, non-FAA instrument approach for 46CA and here's what I have so far.

IAF: BONDO at 8000

1. Fly heading 083 inbound to the Julian VOR (JLI)
2. Cross JLI at 7000, turn right heading 145.
3. Cross the point of 9 DME outbound Julian R145 at 5000.
4. Turn left heading 273, airport is now 6 miles

I really don't see how to do this at night on a straight in approach. The only other thing I can think of is start at KUMBA, come in from the southwest, spot the field and do a circling approach of some type when visibility is VFR.

Also, since there's no beacon or runway lights, is it "fair" to have those on the scenery?

[jagipson]

I'm almost certainly wrong about this so I'd be interested in the remarks, but there's probably a maximum angle that instrument approaches are written for, and the descent to the runway at 46CA would probably be steeper than that angle -- too steep because of the ridge. If the angle isn't too steep, then I'm going to guess that you need CAT-III (or perhaps CAT-II) minimums and a terrestrial-based glidescope to ensure you don't hit the ridge on the way down. At least, what I'm trying to say is that a CAT-II approach DH is typically 100 ft, so if the distance between the ridge and the decided glide path is less than 100 ft then I'm supposing it's a CAT-III approach which may have a 0 ft DH.

Does the GNS V-NAV use GPS-based altitude or does it read your altimeter? If it reads your altimeter then you'd be in jeopardy of hitting the ridge, since there's no ASOS/ATIS at 46CA to calibrate against. If it uses GPS-based altitude, what is the error interval for altitude data from GPS?

[stevekirks]

In my ideal "FSEconomy" world only, I would love to put in new lighting, ILS and change the approach to be runway 28.

That said, it might make more to start at KUMBA, pickup the JLI 145 radial, overfly the field at 3000 and left turn circle for landing.

[Keith Smith]

Would the missed approach procedure read something like "kiss your a** goodbye!" by any chance?

This is a VFR airport, embrace it. It's also in the desert, you're not going to deal with much IMC

[stevekirks]

Would the missed approach procedure read something like "kiss your a** goodbye!" by any chance?

Yes! What would be the right symbol to use for that on the chart?

This is a VFR airport, embrace it. It's also in the desert, you're not going to deal with much IMC

The guy who runs the FBO doesn't seem like he will tolerate diversions. Trying to cover my bases...many many LOLS to be had.

[Peter Grey]

Yes! What would be the right symbol to use for that on the chart?

TERPS standard is a note as demonstrated below.

http://155.178.201.160/d-tpp/1502/02335N24.PDF

For bonus points, why is the airport elevation and threshold height 300 feet apart?

[Peter Grey]

To answer the other questions.

I'm almost certainly wrong about this so I'd be interested in the remarks, but there's probably a maximum angle that instrument approaches are written for, and the descent to the runway at 46CA would probably be steeper than that angle -- too steep because of the ridge. If the angle isn't too steep, then I'm going to guess that you need CAT-III (or perhaps CAT-II) minimums and a terrestrial-based glidescope to ensure you don't hit the ridge on the way down. At least, what I'm trying to say is that a CAT-II approach DH is typically 100 ft, so if the distance between the ridge and the decided glide path is less than 100 ft then I'm supposing it's a CAT-III approach which may have a 0 ft DH.

Simply put this is 100% wrong. it is 100% impossible to put an ILS into runway 10, and most likely impossible to runway 28 (missed approach segment) without outrageous minimums.

Does the GNS V-NAV use GPS-based altitude or does it read your altimeter? If it reads your altimeter then you'd be in jeopardy of hitting the ridge, since there's no ASOS/ATIS at 46CA to calibrate against. If it uses GPS-based altitude, what is the error interval for altitude data from GPS?

This is actually a pretty complicated question. VNAV = baro altimeter, LPV = GPS altimeter. Average error on a WAAS enabled GPS is negligible. So in simple terms more accurate then your baro altimeter.

[Keith Smith]

For bonus points, why is the airport elevation and threshold height 300 feet apart?

I'll take "Airports With a 7.1% Gradient" for $100, please.

[stevekirks]

Wow...

"CAUTION: Rwy located on a slope of a 3415' mountain with W end at the base of cliff, APPROACH ONLY FROM THE EAST"

...and I thought Rancho Vallecito had something for everyone.

[jagipson]

To answer the other questions.

Simply put this is 100% wrong. it is 100% impossible to put an ILS into runway 10, and most likely impossible to runway 28 (missed approach segment) without outrageous minimums.

Huh. That's the most violently someone has agreed with me in a long time.

My post was suggesting reasons why there cannot be an ILS at 46CA, e.g. Steepness of terrain resulting in impossible minimums. Good point about an ILS and missed approaches on 28. Of course, I wasn't even considering that case, since that's landing in the wrong direction.