ILS vs LPV

[rbp]

19 hours ago, jaylw314 said:

Admittedly, the fact that they have the magnetic north pole in their country is a pretty reasonable argument, but I'm pretty sure the rest of the world might not agree.  Except maybe people in Antarctica?

all the data (cartography, procedures, etc) is stored in the garmin and jeppesen databases as true. GPS units and INS units operate in true.  true is converted on demand to magnetic when shown to a human. the only humans using primary magnetic headings are those who are using the whiskey compass. 

[Hank]

15 minutes ago, rbp said:

all the data (cartography, procedures, etc) is stored in the garmin and jeppesen databases as true. GPS units and INS units operate in true.  true is converted on demand to magnetic when shown to a human. the only humans using primary magnetic headings are those who are using the whiskey compass. 

What about those of us who use gyroscopic Directional Gyros? That's what I use to fly by, if properly set for wind correction it will keep me right on the pink line. But when Approach says "fly heading XXX", I move the heading bug on the DG, and the pretty pink line on the Garmin drifts away. And yes, I periodically adjust the DG to match the compass, but I certainly don't look at the compass to hold headings!

[EricJ]

27 minutes ago, rbp said:

all the data (cartography, procedures, etc) is stored in the garmin and jeppesen databases as true. GPS units and INS units operate in true.  true is converted on demand to magnetic when shown to a human. the only humans using primary magnetic headings are those who are using the whiskey compass. 

Any DG/HSI representation is still magnetic.   HSIs still use magnetometers and display magnetic heading.

That said, a conversion to true is not a bad idea, since the magnetic poles will continue to become less stable until the next pending flip.    During the flip, which may take a long time, magnetic indicators won't be very useful at all.

 

[rbp]

14 minutes ago, Hank said:

those of us who use gyroscopic Directional Gyros

there are two kinds of DGs -- slaved and non-slaved.

if you have a non-slaved gyro, then you need to spin the compass card to the current heading, which could be magnetic (if setting to a whiskey compass) or true. the DG itself doesn't know the difference

if you have a slaved compass, like the KCS 55A, then it is slaved to a KMT 112 Magnetic Azimuth Transmitter, which keeps the copmass card oriented to magnetic north. 

EHSIs are also slaved, but to an AHRS, but the AHRS works off true north and the electronics convert it to magnetic

[rbp]

I guess I can ask this trivia question: when does a pilot have to use true north (below 70 degrees)? 

 

[Hank]

4 minutes ago, rbp said:

I guess I can ask this trivia question: when does a pilot have to use true north (below 70 degrees)? 

 

Hmmm . . . . Below 70°? Never in Florida!

[kortopates]

1 hour ago, rbp said:

EHSIs are also slaved, but to an AHRS, but the AHRS works off true north and the electronics convert it to magnetic

Maybe its just the wording, but I think its more true to say for GA AHRS that heading is slaved directly off a magnetometer. Granted if we did change to True North, they could be referenced directly off of GNSS to perhaps even improved heading accuracy. 

But imagine the need/cost for most of the world to renumber all their runways to true north, all the VORs to re-calibrated to True North and then all the navigation and approach charts to be redone. Seem like a herculean task but seems would have less maintenance needs going forward since they wouldn't be constantly updating for a shifting magnetic pole. Still alot of work to avoid changing reference systems crossing the 70 degrees Latitude. Plus not every GA plane has glass panel equipment yet,

Edited February 28, 2022 by kortopates

[jaylw314]

6 hours ago, rbp said:

all the data (cartography, procedures, etc) is stored in the garmin and jeppesen databases as true. GPS units and INS units operate in true.  true is converted on demand to magnetic when shown to a human. the only humans using primary magnetic headings are those who are using the whiskey compass. 

Uh, I guess I should have used a smiley, my comment was mostly tongue-in-cheek! 

[carusoam]

5 hours ago, jaylw314 said:

Uh, I guess I should have used a smiley, my comment was mostly tongue-in-cheek! 

Better Nate, than lever!

-a-

[rbp]

Regarding true/magnetic north, i came upon this in the GTN650/750 manual

 

[RobertGary1]

On 12/9/2018 at 8:44 PM, Jim Peace said:

if there was ever an approach that could be flown below a DH it is an ILS.....below DA or MDA is a different matter....

Yea I think the previous commenter misunderstood. DH is not a limit like MDA it’s when you decide. It’s intended that you’ll go below as it takes a reaction time to start missed. For reasons only God knows an lpv has an MDA while an ils only has a dh. So I’m low fog I’ll do the ils. 

[Jim Peace]

On 2/27/2022 at 5:22 PM, jaylw314 said:

Admittedly, the fact that they have the magnetic north pole in their country is a pretty reasonable argument

Want to put money on that the earths magnetic north pole is nowhere near Canada....

[Fly Boomer]

where do you think it is?
 

[Fly Boomer]

i'll do a mea culpa.  As of 2021, the pole is projected to have moved beyond the Canadian Arctic to 86.400°N 156.786°E

[Fly Boomer]

[Fly Boomer]

Been awhile since my last geography class.

[rbp]

1 hour ago, RobertGary1 said:

Yea I think the previous commenter misunderstood. DH is not a limit like MDA it’s when you decide. It’s intended that you’ll go below as it takes a reaction time to start missed. For reasons only God knows an lpv has an MDA while an ils only has a dh. So I’m low fog I’ll do the ils. 

LPVs have a DA -- decision altitude 

 

https://code7700.com/lpv.htm

[Raptor05121]

On 2/24/2022 at 3:05 PM, rbp said:

On this week's episode of Opposing Bases (ATC/Pilot podcast), one of the hosts claimed that in 5 years we will be treating ILS equipment like we treat VORs (and NDBs and four course ranges): as historical equipment. Expensive and complex to maintain. 

 

Are any of the hosts ATP-rated? GA me would agree with that but since being hired on 121, there is a huge prevalence on ground-based nav in the industry.

On our 40 million dollar airliner that shoots 5+ approaches a day, we aren't certified for WAAS-based navigation. When it comes to RNAV, we can only do LNAV with 50 feet added to the minimums, which means several hundred feet higher than a standard ILS. But with a glideslope and CATII, we can go down to 100RA. Bigger airliners of course have CATIII. Sure one day I could see it. In 5 years? No freaking way. It would take 5 years alone for us to simply get the OpSpec paperwork for WAAS to even *allow* us to shoot LPV let alone getting the fleet equipped, trained, etc etc.

Edited March 5, 2022 by Raptor05121

[RobertGary1]

On 3/4/2022 at 12:25 PM, rbp said:

LPVs have a DA -- decision altitude 

 

https://code7700.com/lpv.htm

Did they finally change that? They’d been talking about it forever 

[rbp]

On 3/4/2022 at 11:14 PM, Raptor05121 said:

On our 40 million dollar airliner that shoots 5+ approaches a day

Probably not for the airlinesProbably not for the airlines

[Raptor05121]

On 3/6/2022 at 7:22 PM, rbp said:

Probably not for the airlinesProbably not for the airlines

?