Non-Approach Certified GPS to IAF?

denverpilot

denverpilot

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Probably a brain-dead simple question but was just thinking about Instrument stuff today...

Let's say you have an enroute-only IFR certified GPS. You have no ADF. You have DME.

Can you file to CASSE at KAPA on the ILS 35R using the enroute certified GPS to navigate to CASSE, then transition over to your localizer receiver from there?

The Approach plate says "ADF required". But I believe the GPS can substitute for ADF up until the Approach.

Just wrapping my non-IFR brain around the details here.

It's a "real-world" question for us since we had our ADF fail and we yanked it. We have NOT installed a certified GPS yet.

Was just looking over the home 'drome's approaches and realized "we can't file to get TO that approach right now".

My thought here is that the cheapest/simplest fix is an enroute-only GPS in the panel. The *best* fix and likely longer-term one is an Approach certified GPS, of course.

Obviously, filing the SID requires radar vectors and would get you there, but without ADF if you go lost-comm, the question is "How do you navigate to CASSE w/o an ADF or GPS on board, right?

Am I analyzing this correctly, Instrument pilots?
 
Brain fart. Replace SID with STAR of course. Question remains the same.
 
Yes, you can. Your non-approach IFR GPS is almost certainly certified for enroute and terminal operations, which means you can use it from takeoff to the IAF, and again after you pass the MAP to fly the missed. After the IAF, it's still usable to sub for DME or ADF for crossbearings, but not for lateral guidance. The only thing for which you can't use it is lateral guidance on the approach (IAF to MAP) or on an approach where GPS is the only system in the title.
 
Thanks Ron.

That was my understanding but wanted to make sure I wasn't missing something.

So it's looking to me like we really need to replace the ADF with something or we're going to have problems actually utilizing the rest of the well-working stuff in our IFR panel.

Hmm. Now the hard decisions begin... ;)
 
denverpilot said:
So it's looking to me like we really need to replace the ADF with something or we're going to have problems actually utilizing the rest of the well-working stuff in our IFR panel.
Click to expand...
If your IFR plane is down to two VOR's and nothing else, that approach will be a problem.

Just remember that once you figure in the cost of installation, the differential between a non-approach GPS like a GX55 and something that is approach-certified like a KLN89B is going to be very small, and the approach certification gets you a lot more utility. Even looking at a more modern GPS like a KLN94 isn't that big a cost leap over something really old like the 89B (with installation), and it's a lot better unit -- more capable, easier to read, easier to use.
 
"AC 90-100A U.S. Terminal and En Route Area Navigation (RNAV) Operations" has an associated spreadsheet compliance table that specifies amongst other things the approved uses for substitute or alternate navigation. See http://www.faa.gov/about/office_org...fs/afs400/afs470/media/AC90-100compliance.xls for a copy of the spreadsheet. There is a note on several of the GPS units "Eligible to use RNAV Substitution or RNAV Alternate means of navigation (US only)" column that reads "Yes, but not for VOR substitution". Some of the GPS units that this note applies to are the Apollo GX55, GX50/60, HBK KLN89B, KLN90B, KLN94 and GPS155XL, GNC300XL and others.
 
Understood. We're /A but the Cessna/ARC ADF puked and we yanked it during an avionics shop visit earlier this year to install new panel covers. (No holes cut in the right side "box" for the ADF receiver and left side where the indicator was located.)

The rest of the stack is nice working King stuff, including a single glideslope on the Nav 1 radio, and none on Number 2. The only non-King instruments left is the Cessna/ARC 200 wing wobbler, er... leveler, and the Mode C transponder which keeps plugging away.

I took the bird out VFR and let the AP capture some VOR radials and do its usual flopping around like a dying fish trying to level with the Turn Coordinator and without proper rudder inputs from me, and it did as well as can be expected from a "dumb" autopilot. It'd keep you right side up, but barely. It also tracked the localizer just fine on the ILS mentioned above during a light crosswind.

Mostly just a "systems test" just to see if the AP repair at the same shop visit really got it working again.

So, the homework we need to do now is whether or not our King CDI's can be used with specific GPS units. We don't think they can be used with anything Garmin-branded so doing an approach-certified Garmin gets spendy real fast. The older Kings are tempting if they work with our CDIs, and I think we have just enough space in the center rack with minimal shuffling. They're limited in number of waypoints they'll hold and King seems like they're getting out of that biz, so... Hmm.

With all that crap piled there in the rack, I'm not sure the standard avionics cooling blast hose in a 182 is going to cover the cooling needs properly, so we might need an avionics cooling fan back there to move some air. We'll see.

It's pretty "open" back there. Pretty easy to get at harnesses and move things. At least our avionics guy doesn't start cussing uncontrollably when we come in like he does when a Mooney shows up. He likes 182s. Can't tell if it shows up on the final labor bill or not, though. ;)
 
If the #1 CDI is a KI-209A, it works with the 89B/94 (you'll need to add a switch to go back and forth between VOR/LOC/ILS and GPS). If it's a straight 209, it's a $1K tradeup to the A-model which works with the 89B/94 (or at least it was when I did it in 2003).
 
John, "Not for VOR substitution"?

Thinking through this, they're saying that an operable VOR receiver must still be on board, not that you can't navigate to the waypoint of a VOR via the GPS, correct?

(Hadn't seen that Excel spreadsheet before. Filed away in the Dropbox folder I keep for the aircraft research stuff.)
 
denverpilot said:
John, "Not for VOR substitution"?

Thinking through this, they're saying that an operable VOR receiver must still be on board, not that you can't navigate to the waypoint of a VOR via the GPS, correct?
Click to expand...
That's pretty much it as I understand it. It's the big difference between the TSO c129 "supplemental" like those named and TSO c146 "sole source" boxes like the Garmin WAAS units. But you can still use the KLN-89B/94 to navigate an airway when the underlying VOR is out, or to be the second VOR on a "DUAL VOR REQUIRED" or "DUAL VOR MINIMA" approach as long as your VOR receiver is operable.
 
denverpilot said:
So, the homework we need to do now is whether or not our King CDI's can be used with specific GPS units. We don't think they can be used with anything Garmin-branded so doing an approach-certified Garmin gets spendy real fast. The older Kings are tempting if they work with our CDIs, and I think we have just enough space in the center rack with minimal shuffling. They're limited in number of waypoints they'll hold and King seems like they're getting out of that biz, so... Hmm.
Click to expand...

As Ron pointed out, you most likely have a KI208 or KI209 CDI. These units are not compatible with any GPS, King , Garmin or otherwise. The KI208A or KI209A can be shared with a KX155 and a GPS, the GPS can be King or Garmin or Apollo. The difference between a 208 and 209 is that the 209 has a GS indicator. If you are going to share a CDI with a GPS and a NAV receiver, there needs to be a switch to control the source to the KI209A and for IFR operation there need to be several annunciators.
 
Yes, I used to do similar things with a KLN-90A.
 
Nate,
I think you'll find that the minimum cost for installing any IFR (enroute or approach) certified GPS is going to be around $6000. You'll need a new CDI head, annunciator/switch, and the box itself.

I wouldn't even bother with the older non approach boxes since you'll be running into support issues very soon. The 94 is the oldest box that is worth putting money into and there's still factory support for it. I got a quote for $9000 to install a used 94.

If you're really on a budget a used DME or ADF would be money better spent.

If you want IFR GPS get one with WAAS. It'll give you more utility down the road.
 
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