IFR / GPS Question

[ahramin]

Correct, in the US the minimum is 200' & 1/2 sm.

[Beefitarian]

It is true that I was and might be again in a few hours from now, ignorant regarding the fact that Cat II & III approaches do not publicly exist yet.

[AuxBatOn]

Aux don't you need different/specific equipment to use the (p(y) code)? which is a legitimate argument for the airplane I believe Canada can not really afford.

Yes. The codes are only available to military aircraft (we fly with them). The civilian GPS is just technically less accurate than the P(Y) code...

[ahramin]

Cat II and III approaches exist , but not based on GPS guidance. All ILS.

[Beefitarian]

IFR is a magic I have not participated in beyond flying a single straight in approach to YYC once last century dual.

I was using a vision limiting device and instruments, turning and descending where ever my instructor told me to. We entered cloud and he said I could take off the hood. I said, "Cool!" then continued to fly our decent. Suddenly we descended out of cloud and I was lined up on final. I don't remember what I said then because I kind of focused on the fact that I was about to land.

[triplese7en]

Could always be wrong, but I believe US LPv's are right down at 200 feet.

Yes, the US and Canada are capable of LPVs to 200'.

Canada doesn't have any LPVs down to 200' yet as this was recently added to the Canadian Instrument Procedure design manual (TP 308) about a year ago. They should be coming out in the next little bit.

As for Garmin transitioning to the missed approach using GPS guidance—that is because, as specified in TP 308 and the US TERPS, missed approach segments are to be flown with 1.0nm RAIM and CDI sensitivity. The older GPS units like the KLN90B don't have this capability included in procedures unless specifically a GPS approach or an overlay approach. The newer units (Garmin) have this capability included. You'll notice that you can load virtually any instrument approach into the GPS, even an ILS approach but it will let you know with a popup message that you need to use your trusty traditional navaids for final approach guidance.

As a side note, the name of the approach lists the navigation equipment which provides final approach identification and guidance. You can use your GPS as navigation to fly a procedure turn for the ILS approach and then fly the missed approach using the GPS because Garmin has included the feature of 1.0nm RAIM and CDI sensitivity for that. The TC AIM is not specifying any legal regulations—the CARS do that. There is no CAR that says you can't fly a non-overlay missed approach using a GPS. The GPS needs to be certified under TSOs which specify these requirements. If the GPS unit is TSOd (or CAN-TSOd) and is authorized in your country of operation then it must meet all the certification requirements, therefore, you are allowed to use its features.

[photofly]

There is no CAR that says you can't fly a non-overlay missed approach using a GPS.

I think that's a highly debatable assertion.

602.127 says an approach has to be made in accordance with an instrument approach procedure, and 101.01 says that an instrument approach procedure is what's published in the CAP. Absent an overlay, the plate says navigate to the NDB, which you can only be sure of doing with an ADF tuned to it.

If you want a get-out that lets you use a GPS in Canada you had better have a document (such as the AIM) which you can wave at TC and say 'you permitted it' - and that only applies in the circumstances dictated in the AIM itself.

You can use your GPS as navigation to fly a procedure turn for the ILS approach...

Yes, because the AIM explicitly permits that...

and then fly the missed approach using the GPS because

... and no, because the AIM explicitly forbids it ("when the missed approach procedure requires flying a published track to or from an NDB or VOR."). Respectfully, I see no regulatory or regulatory-like document that says you can do it if your GPS is set to 1.0nm RAIM etc. I see no evidence of a get-out-of-jail for Garmin: What is permitted in the US is explicitly forbidden in Canada.

[Colonel Sanders]

Is the AIM really good enough? It's not regulatory.

I'd go to the Tribunal with an Advisory Circular, though:

http://www.tc.gc.ca/eng/civilaviation/s ... r-1744.htm

Commercial and Business Aviation Advisory Circulars (CBAACs) are intended to provide information and guidance regarding operational matters. A CBAAC may describe an acceptable, but not the only, means of demonstrating compliance with existing regulations.

[photofly]

I see I'm not the only one with connection problems to Avcanada tonight...

I'd go to a TC tribunal with something that's explicitly permitted in the AIM, sure. Checkout the doctrine of "officially induced error".

[triplese7en]

There is no CAR that says you can't fly a non-overlay missed approach using a GPS.

I think that's a highly debatable assertion.

602.127 says an approach has to be made in accordance with an instrument approach procedure, and 101.01 says that an instrument approach procedure is what's published in the CAP. Absent an overlay, the plate says navigate to the NDB, which you can only be sure of doing with an ADF tuned to it.

If you want a get-out that lets you use a GPS in Canada you had better have a document (such as the AIM) which you can wave at TC and say 'you permitted it' - and that only applies in the circumstances dictated in the AIM itself.

What exactly does an instrument approach procedure tell you? Where on it does it say that GPS is approved for use or not? And if it is approved, where on the instrument approach procedure does it tell you which parts of the approach can be flown using GPS guidance? Answer: it doesn't.

As pointed out before, the name of the approach specifies the equipment used for final approach identification and guidance—you must have that to fly the approach. As for getting setup on the final approach course, that's up to you and you have a variety of approved means depending on the specific approach.

which you can only be sure of doing with an ADF tuned to it.

Not true. You can use the GPS, provided it is operated in the proper mode: enroute, terminal, or approach. For navigation during the missed approach segment the GPS must be in terminal mode. You also must be in terminal mode for departure procedures.

As for that document you want to wave at TC, check this out: http://www.navcanada.ca/EN/products-and ... 008_16.pdf

It says:

Under "En Route and Terminal Equipment" — "The avionics for GPS equipment must meet Technical Standard Orders (TSO) C129/C129a (any class) issued by the U.S. Federal Aviation Administration (FAA);"

then...

"GPS or WAAS may be used for all en route and terminal operations." ...emphasis is mine.

and then...

"Course deviation indicator (CDI) sensitivity and integrity alerting shall be appropriate for the phase of flight."

Integrity alerting is RAIM.

Then if you look at the TSO C129 document you'll find this:

"2. If the pilot manually sequences to the missed approach holding point, the equipment shall:

a. Transition from approach integrity performance to terminal integrity performance as specified in Table 2-1 of RTCA/DO-208.
b. Provide a smooth transition from 0.3 nm non-numeric display sensitivity to 1 nm sensitivity."

You could pull up that RTCA document too if you wanted.

[triplese7en]

What is permitted in the US is explicitly forbidden in Canada.

In this case, it is specifically approved by Transport Canada.

http://www.tc.gc.ca/eng/civilaviation/s ... t-3970.htm

In Canada we use the American TSO-C129a document.

[triplese7en]

To add to it: what CAR 602.127 is saying is that you can't make up your own approach—you must follow the instrument approach procedure in the CAP which is created following the rules in the TP 308 document.

Example: you can't OBS a 004 course on the ZWW NDB at CYWG and then fly down to your own minimums. You also can't OBS the CYSF waypoint on 240 and fly your own approach to runway 24. It'd be perfect—you'd be lined up perfectly on the centerline and you could easily make up some altitudes and distances so you know when to descend. Voila.. you have an approach! But CAR 602.127 says you can't do that.

Basically, descent below a minimum IFR altitude must be made in accordance with an instrument approach procedure.

[photofly]

What exactly does an instrument approach procedure tell you? Where on it does it say that GPS is approved for use or not?

When it says GPSS after the approach name. Other than that, you can only use GPS under the circumstances listed in the AIM. I'm not sure what the controversy there is, it seems very straightforward to me. If you're flying a LOC approach with a Garmin GPS for guidance, and the initial missed approach is a specified track direct to a VOR or NDB, then you had better be using a VOR receiver or an ADF to fly the missed approach. Not the GPS.

Not true. You can use the GPS, provided it is operated in the proper mode: enroute, terminal, or approach. For navigation during the missed approach segment the GPS must be in terminal mode. You also must be in terminal mode for departure procedures.

I think you're inventing your own rules here. The AIM gives you leave to use the GPS, except when the initial course for the missed approach is a published track to an NDB or VOR. It's quite explicit. At the time that was last published the capabilities of a Garmin GPS were well known. No exception was included for it.

I'm really struggling to see the relevance of quoting TSO-C129a here (and yes, I'm very familiar with its contents). the TSO says the equipment shall do X, Y and Z. It doesn't have any standing to say the pilot shall be permitted to use X, Y and Z in any particular circumstance.

If you're going to quote 16/08 at me, read para. 6 b) of the same. It's even less permissive than the AIM.

[photofly]

To add to it: what CAR 602.127 is saying is that you can't make up your own approach—you must follow the instrument approach procedure in the CAP

Agreed. If the missed procedure is climb on a track of 045° direct Sumspot NDB, then, absent an overlay to the approach you had better have your ADF tuned to that NDB, otherwise you're making up your own approach!

[triplese7en]

initial missed approach is a specified track direct to a VOR or NDB, then you had better be using a VOR receiver or an ADF to fly the missed approach. Not the GPS.

I'll admit I wasn't fully clear but yes, you can use GPS for your primary navigation, however, as you indicated in 16/08, you must monitor the underlying NAVAID.

Switching gears a bit.... What about when you're flying an NDB 01 approach into a particular airport with no GNSS designation at the end? Personally, I will fly the approach using the GPS while monitoring the NDB and having the FO listen to the IDENT throughout the approach. Am I illegally flying the instrument approach procedure?

It's quite well known that the GPS doesn't have the same errors as an ADF. Also, using the GPS helps quite a bit when there are magnetic disturbances up to 20 degrees at the airport. As long as the ADF needle is pointing approximating where it should and I'm within 5 degrees on the final approach course, why can't I go down to MDA? One RMI needle is pointing to the NDB waypoint via the GPS and the other is pointing to the NDB via the ADF.

[photofly]

Do you think you'd be legal to fly a missed approach, without an overlay, where the missed approach is not a specified track direct to an NDB, without an ADF on board, or if the NDB is u/s? Answer: yes, you would. Because you can use GPS as primary guidance in that case: the AIM says so.

But if the missed approach is a specified track to an NDB and it doesn't have an overlay, then you need an ADF on board and it had better be tuned and working.

I think deciding whether, in the second case, the ADF is primary and the GPS secondary, or vice versa, is too much hair-splitting even for me. I know what I read in the AIM though!

It's well known that GPS doesn't have the same errors as an ADF. But it's less well known that it does have errors, just different ones. I've wondered why the distinction between approaches with a specified track direct an NDB and approaches with a direct track not to an NDB, and it's certainly hard to imagine a circumstance where it would make a lot of difference. But they didn't waste the ink for no reason.

[Big Pistons Forever]

It's well known that GPS doesn't have the same errors as an ADF. But it's less well known that it does have errors, just different ones. I've wondered why the distinction between approaches with a specified track direct an NDB and approaches with a direct track not to an NDB, and it's certainly hard to imagine a circumstance where it would make a lot of difference. But they didn't waste the ink for no reason.

Compared to the ADF all errors of a GPS are trivial. As for your contention that "But they didn't waste the ink for no reason", I could not disagree more. There are a ton of TC generated obsolete/unnecessary/stupid/wrong ink in various regs/directives/guidance.

Personally while I agree with your interpretation of the TC direction, I think it is stupid. The last time I flew a for real in IMC approach with only the ADF needle to provide final approach track guidance was 1994. Since then I have used the GPS for primary guidance for the final approach track with the ADF needle(s) as a very secondary source of information. The big difference between pre and post 1994 approaches was the fact that after 1994 the aircraft track and the runway centerline was always nicely aligned when I broke out.

As for the missed approach I will have the ADF tuned but I will be making sure that the magenta line is going to the right fix and that the little white airplane is sitting on top of the line. If the ADF needle is pointing in the general direction of where I want to go, if I even remember to look at it, only provides an unnecessary and not very accurate confirmation of what I already know.

[photofly]

Regardless of whether you think it's sensible or not, someone, somewhere in a TC office thought it was a good idea. I'd still like to know why.

[triplese7en]

Yes, I agree with your interpretation of what is written.

think deciding whether, in the second case, the ADF is primary and the GPS secondary, or vice versa, is too much hair-splitting even for me. I know what I read in the AIM though!

You can still kill yourself by following all the rules! The smart pilot will be primarily using an IFR GPS, provided it is not giving a RAIM error message. If you know what a GPS is capable of and you know what an ADF is capable of then there should be no discussion in this matter!

It's well known that GPS doesn't have the same errors as an ADF. But it's less well known that it does have errors, just different ones.

Comparing the errors of a GPS to the errors of an ADF is similar to comparing a computer from 2013 to a computer from the 1980s—they don't compare!

As BPF said, the errors on a GPS are trivial. Not only that, they are calculated and you're given a warning when they exceed a certain threshold—2.0NM, 1.0NM, and 0.3NM for enroute, terminal, and approach mode, respectively. Do you have any clue how much error is in your ADF at any given time? Nope!!

Regardless of whether you think it's sensible or not, someone, somewhere in a TC office thought it was a good idea. I'd still like to know why.

I'm all for understanding rules and regulations but I really am disinterested in knowing why TC thought at the time they should write what they wrote in this regard. You can be assured that I'm using my GPS in all cases where it will enhance the safety of flight including on ILS approaches.

[shahidkhan]

Totally agreed with ahramin. I had same scenario in my flight test LOC30 at CYHM upon missed my GTN650 took over for missed approach.

BTW I failed my flight test because never did any localizer approach before flight test and busted minimum but now I am doing it practice anyone there who is good with Localizer and want some practice with me. I have PA28 at Grimsby

[shahidkhan]

I have questions on localizer as LOC30 at YHM minimum is 1100 with 1NM. If you are at 1NM 1180. Still I would fail my approach. I mean what is maximum tolerance for None precision approach