Why does this approach have higher LNAV/VNAV minimums than just LNAV?

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Rockie
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by Rockie »

photofly wrote:I think the FAA funds the costs of the LPV approach, much like they provide a lot of airport funding, out of tax dollars.

Canada doesn't have nearly the same level of federal investment in aviation. But if we did, those dollars aren't free - they come out of everyone's pocket. Most people would probably say that the people who would benefit from better approaches should pay, so that means higher airfares and more investment from airlines into airports. I think everyone "gets it" but nobody has an economic incentive to do anything about it.
Oh no Photofly, very few people in TC, at airports or in the airlines here in Canada "get it" yet, and you just inadvertently said why. They don't see the economic (or safety) incentive to do so.

But they will eventually.
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photofly
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by photofly »

I'm afraid I don't share your certainly that riches and safety nirvana await us as soon as Sleeping Beauty in the airport finance department wakes up from her slumbers and notices the LPV possibilities. I think they do the sums as carefully as they can - certainly more carefully than you and with better data than you - and act if the results show a benefit.
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by valleyboy »

The problem is LPV requires WAAS which costs money. Money most (not all) airlines will not spend until they're forced to
I have not seen a GPS not WAAS enabled in the last 12 years but then again I never worked for a level 1 carrier. I can remember the day and that was about 25 years ago when were were laughing at the "big red" going vor to vor with no area nav and to us it was a no brainer that it was required equipment even back then. Now fast forward to close to present day and the "modern" fms systems with no GPS module -- DAMN!!!
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Rockie
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by Rockie »

And I wish I could share your certainty Photofly that decision makers are as good as you seem to think. Evidence doesn't support it though. How many companies have sacrificed safety and their very future to present a good quarterly bottom line?

No, I don't share your rosy certainty at all.
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55+
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by 55+ »

Actually an Instrument Approach Procedure(including anything with vertical guidance) can be designed to any airstrip without any type of runway assessment, however the lowest MDA/DA/DH authorized is 500ft HAT. There are many examples where this has indeed happened, I did designs to such locations and it was certainly better than nothing.
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by photofly »

So LNAV and NDB approaches don't need any survey at all? If so, that would certainly be a bit cost differentiator compared to LPV.
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by 55+ »

Correct, if a specific landing surface/runway is assessed as non-instrument(no survey) the lowest minima authorized is 500ft HAT, no matter what the procedure, even WAAS LPV. As mentioned there are good many examples in the CAP and more specific in the RCAP. If ROC + governing obstacle in the final approach segment show by calculation a HAT under 500ft on a non-instrument runway, it is a requirement to bring up the HAT to 500ft or above.
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Rockie
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by Rockie »

55+ wrote:Correct, if a specific landing surface/runway is assessed as non-instrument(no survey) the lowest minima authorized is 500ft HAT, no matter what the procedure, even WAAS LPV. As mentioned there are good many examples in the CAP and more specific in the RCAP. If ROC + governing obstacle in the final approach segment show by calculation a HAT under 500ft on a non-instrument runway, it is a requirement to bring up the HAT to 500ft or above.
A LPV could still be produced for the airport with 500' minimums. That would still provide precise IFR lateral and vertical guidance toward the touchdown zone that would be unaffected by temperature. Still a win as far as anybody would be concerned even with higher minimums. Lots better than no instrument approach.

And guess what? No navaid required on the ground to pay for, monitor or maintain.

What was the argument against LPV's again?
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by photofly »

I don't think most people would be slightly enthused to see an LPV approach to 500' - there's not much point. In fact I can hear the bitching on AvCanada about it already.

Most new GPS boxes will give you an advisory glide slope on any non-precision approach - the benefit of an LPV is ILS-like minimums.
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by Rockie »

photofly wrote:I don't think most people would be slightly enthused to see an LPV approach to 500' - there's not much point. In fact I can hear the bitching on AvCanada about it already.

Most new GPS boxes will give you an advisory glide slope on any non-precision approach - the benefit of an LPV is ILS-like minimums.
That's hardly the only benefit. Independence from any ground navaid, and a big one for Canada is their immunity from barometric errors. And I'll bet there are lots, and lots, and lots of communities in Canada without any kind of IFR approach who would welcome one even with 500 foot minimums (not to mention pilots and operators) and many more who would love to have true LPV minimums and the accuracy they provide since the terrain already has to be surveyed. Plenty also who would gladly pay for the survey since they don't have to pay for a ground based navaid.

Come on Photofly, quit trying to invent reasons to not get one of these. They're the greatest thing to come around in ages and I'm surprised they aren't sprouting up everywhere. The only thing better as far as I'm concerned are GLS's, and I can't wait until they become the new standard everywhere.
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by 55+ »

Rockie wrote:
55+ wrote:Correct, if a specific landing surface/runway is assessed as non-instrument(no survey) the lowest minima authorized is 500ft HAT, no matter what the procedure, even WAAS LPV. As mentioned there are good many examples in the CAP and more specific in the RCAP. If ROC + governing obstacle in the final approach segment show by calculation a HAT under 500ft on a non-instrument runway, it is a requirement to bring up the HAT to 500ft or above.
A LPV could still be produced for the airport with 500' minimums. That would still provide precise IFR lateral and vertical guidance toward the touchdown zone that would be unaffected by temperature. Still a win as far as anybody would be concerned even with higher minimums. Lots better than no instrument approach.

And guess what? No navaid required on the ground to pay for, monitor or maintain.

What was the argument against LPV's again?
Sorry sir, but I didn't state any objection against WAAS LPV if that is your suggestion. I am just stating criteria of which I do have a background in, having said that any designed Instrument Approach Procedure which has gone through the many quality control stages by Nav Canada and it's affiliates prior to official publication, regardless of design landing minima is far safer than nothing at all as you correctly stated.
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by Rockie »

I was referring to Photofly, not you. Sorry for the misunderstanding.

I referenced statistics showing how the FAA has unquestionably seen Jesus not just with WAAS but the whole space based navigation system. For further information on just how invested the Americans are with this go on the FAA website, search for "SATNAV News" and subscribe. It's very easy to see how this will be a HUGE benefit in Canada especially in remote and northern communities.
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goingnowherefast
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Re: Why does this approach have higher LNAV/VNAV minimums than just LNAV?

Post by goingnowherefast »

Last I heard a couple years ago, the cost to do initial development for a LNAV only approach, including surveys was $12,000. Then required to do the flight testing, which could be done in an IFR certified 172. So lets say $15,000 today.

An LPV approach into the same airport, including surveys, was quoted at about $60,000.

So that extra 250-300' lower is going to cost you at least $45,000.

As stated earlier, the required ongoing surveying is also more expensive for LPVs.

Is it worth it for that airport to spend that extra money? That's up to the airport operator and any other invested parties.
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