If you have SVT

[spiderweb]

. . . do you use it?

I have done about half the approaches during this checkout period with, and half without. Especially on an ILS or LPV, it is really nice, because you just put the flight path marker on the beginning of the runway, and you'll notice the D-bar is centered, and the GS dot doesn't move!

But it isn't really harder to just fly the HSI, and in some cases SVT could even be distracting (too busy on the screen).

I hate the rectangles.

 

[HPNPilot1200]

. . . do you use it?

I have done about half the approaches during this checkout period with, and half without. Especially on an ILS or LPV, it is really nice, because you just put the green circle thing (I think it's called a track marker or something) on the beginning of the runway, and you'll notice the D-bar is centered, and the GS dot doesn't move!

But it isn't really harder to just fly the HSI, and in some cases SVT could even be distracting (too busy on the screen).

I hate the rectangles.

Yes. Synthetic terrain good. Rectangles (Pathway) bad. Personal preference I suppose.

 

[Alexb2000]

I don't use Highway in the sky much, other than to show new passengers and get a wow, cool! The flight path marker (FPM) is the money IMO. Fly an approach is a strong crosswind, it's so easy to use the FPM to double check your alignment, etc. I am also a big believer in using it in an emergency to know your glide range and if you'll make the runway, etc. Of course the most common use is something like Night VFR around terrain, nothing better.

I'm sure it won't be long until almost all GA aircraft have it.

 

[TMetzinger]

I've used it. I worry about getting "sucked in" by the FPM sometimes. It's hard to focus on the command bars and the raw data on the HSI and believe them FIRST because the FPM is so compelling.

I guess I'm not quite sure I trust that the FPM will always be correct, although I've yet to see it disagree with the other symbols on a properly flown approach.

 

[spiderweb]

I've used it. I worry about getting "sucked in" by the FPM sometimes. It's hard to focus on the command bars and the raw data on the HSI and believe them FIRST because the FPM is so compelling.

I guess I'm not quite sure I trust that the FPM will always be correct, although I've yet to see it disagree with the other symbols on a properly flown approach.

Those were my reservations, as well! So for now, I'm training 50/50, and always cross-checking.

 

[Jaybird180]

I've used it. I worry about getting "sucked in" by the FPM sometimes. It's hard to focus on the command bars and the raw data on the HSI and believe them FIRST because the FPM is so compelling.

I guess I'm not quite sure I trust that the FPM will always be correct, although I've yet to see it disagree with the other symbols on a properly flown approach.

What's driving this fear? Is it the pilot philosophy of 2=1, 1=0? Software writers screw up sometimes, yes. I suppose a remedy would be more understanding about what's behind the FPM calculations.

Can with avionics software knowledge comment on this?

 

[Alexb2000]

Here is something that is fun to try: When in Texas I fly out of KADS. The preferred approach is always the ILS (usually 15). You can fly the approach dead nuts on the needles and you'll still be slightly off the runway every time. I assume this has to do with the placement of the transmitter, I don't know. Anyway, it's not a big deal and you just make a small correction and land. I can fly just using SVT and literally hit the numbers every time. I've tried it a bunch of times with different pilots, and while I would never advocate it, you could literally fly a near zero/zero using SVT.

 

[TMetzinger]

What's driving this fear? Is it the pilot philosophy of 2=1, 1=0? Software writers screw up sometimes, yes. I suppose a remedy would be more understanding about what's behind the FPM calculations.

Can with avionics software knowledge comment on this?

The raw data (deviation bars) on an ILS are "Reality".
The flight director is "derived reality", telling you what corrections to make to get the needles centered. It can lie to you (especially in older analog airplanes).
The FPV/FPM is "predicted reality". It tells you where your airplane is going based on current position and velocity and attitude. It's possible it can lie to you as well. There is a lag when you make abrupt attitude changes.

The SVT terrain is also derived reality - it's SYNTHETIC, after all. An inadvertent or deliberate error in the terrain database might have you think you're going to clear that ridge, but it if's 2000' higher in reality than in the database...

I guess what it comes down to is how much trust to put in the abstracted reality, and how much benefit there is to it versus the additional effort to cross-check it with things that are more "real".

Don't misunderstand. I love SVT. But when it comes to the FPM, I don't trust it enough to make "put the FPM on the synthetic threshold" my primary method for flying an approach to landing.

 

[denverpilot]

Here is something that is fun to try: When in Texas I fly out of KADS. The preferred approach is always the ILS (usually 15). You can fly the approach dead nuts on the needles and you'll still be slightly off the runway every time. I assume this has to do with the placement of the transmitter, I don't know. Anyway, it's not a big deal and you just make a small correction and land. I can fly just using SVT and literally hit the numbers every time. I've tried it a bunch of times with different pilots, and while I would never advocate it, you could literally fly a near zero/zero using SVT.

The runway and ILS are one degree off each other at KADS, just looking at published information in the A/FD and the approach plate.

 

[Alexb2000]

The runway and ILS are one degree off each other at KADS, just looking at published information in the A/FD and the approach plate.

OK. What am I missing 155 on the runway 155 on the approach course?

 

[denverpilot]

Foreflight's saying 156.

 

[Alexb2000]

Foreflight's saying 156.

Interesting, so it is. I've been flying out of there a long time its always been 155. Humm, maybe they need to update the approaches as well. Good eyes.

 

[aterpster]

The runway and ILS are one degree off each other at KADS, just looking at published information in the A/FD and the approach plate.

I check both those references and don't find any reference to an offset localizer for Runway 15.

 

[aterpster]

Foreflight's saying 156.

The magnetic bearing of a runway may or may not be accurate. It depends upon when the mag var for the airport was last updated. The localizer, if offset, will clearly state that on the approach chart.

 

[aterpster]

The raw data (deviation bars) on an ILS are "Reality".
The flight director is "derived reality", telling you what corrections to make to get the needles centered. It can lie to you (especially in older analog airplanes).
The FPV/FPM is "predicted reality". It tells you where your airplane is going based on current position and velocity and attitude. It's possible it can lie to you as well. There is a lag when you make abrupt attitude changes.

The SVT terrain is also derived reality - it's SYNTHETIC, after all. An inadvertent or deliberate error in the terrain database might have you think you're going to clear that ridge, but it if's 2000' higher in reality than in the database...

I guess what it comes down to is how much trust to put in the abstracted reality, and how much benefit there is to it versus the additional effort to cross-check it with things that are more "real".

Don't misunderstand. I love SVT. But when it comes to the FPM, I don't trust it enough to make "put the FPM on the synthetic threshold" my primary method for flying an approach to landing.

SV certainly can have errors, especially the placement of the synthetic runway. The terrain data is probably good enough to serve as TAWS, at least in rapidly rising terrain situations. But, it is simply not good enough to use as a virtual reality presentation of the terrain. I presume we are speaking of IMC; that is what approach charts are for.

Having said that, speaking for the G-1000 only, the flight path vector symbol is independent of the SVT, and can be very good provided it is understood and used properly. On LNAV-only approaches that do not have a vertical advisory path the vector symbol, if placed on the synthetic runway threshold will provide a good vertical path to MDA (not to landing) if on altitude crossing the FAF. Of course any final segment stepdown fixes need to be crosschecked. The path vector properly used, should clear the stepdown fixes, but never as the primary indication that will happen.

 

[TMetzinger]

SV certainly can have errors, especially the placement of the synthetic runway. The terrain data is probably good enough to serve as TAWS, at least in rapidly rising terrain situations. But, it is simply not good enough to use as a virtual reality presentation of the terrain. I presume we are speaking of IMC; that is what approach charts are for.

Having said that, speaking for the G-1000 only, the flight path vector symbol is independent of the SVT, and can be very good provided it is understood and used properly. On LNAV-only approaches that do not have a vertical advisory path the vector symbol, if placed on the synthetic runway threshold will provide a good vertical path to MDA (not to landing) if on altitude crossing the FAF. Of course any final segment stepdown fixes need to be crosschecked. The path vector properly used, should clear the stepdown fixes, but never as the primary indication that will happen.

Hang on... if the synthetic threshold is misplaced, how can the FPV be placed on it and used for a good vertical path?

I agree that the FPV is useful, don't get me wrong. I think we're saying the same thing, that it's not a primary technique. The problem I see is that it's SO compelling that people will not notice they're busting the stepdown fixes if the SV runway is misplaced.

The tech is wonderful, but it takes a certain amount of discipline to cross-check it with other stuff, particularly because it seems so reliable.

 

[Wingsofglass]

I have seen the runway displaced with SVT. I have a waas G1000 and the last time I was in Bryce Canyon (KBCE) the runway was about 50 feet to the east while I was on it.

I know many people do not like the pathway in the sky but I think it's great. When intercepting a localizer, it is really nice to "see" it on the PFD. Same thing with flying a DME arc. Also "seeing" the missed approach course on the PFD provides good situational awareness on turning points and how high to climb.

Without SVT, cross checking instruments is essential and with SVT nothing changes. I can't imagine putting the flight path marker on the end of the runway flying an ILS and not looking at the HSI or green diamonds to make sure everything agreed. A word of caution though. In the absence of any other approach guidance, if all you do is put the flight path marker on the end of the runway, it is really easy to fly a low & flat approach that "looks" normal. You can try this with a hood one day and see for yourself. I believe this illusion may have already resulted in one fatal accident on a night landing into an airport with no visual glide slope or precision approach.

 

[aterpster]

Hang on... if the synthetic threshold is misplaced, how can the FPV be placed on it and used for a good vertical path?

I agree that the FPV is useful, don't get me wrong. I think we're saying the same thing, that it's not a primary technique. The problem I see is that it's SO compelling that people will not notice they're busting the stepdown fixes if the SV runway is misplaced.

The tech is wonderful, but it takes a certain amount of discipline to cross-check it with other stuff, particularly because it seems so reliable.

The threhold is not where the offset occurs. It is a lateral offset.

In any case what I advocated is using the vector symbol for vertical, not lateral guidance, and not below MDA.

 

[TMetzinger]

You're saying that a north-south runway might be in error to the east or west, but never to the north or south?

I'd expect a data error could misplace the runway in any direction... while a display (processing) error could be limited in the way you describe.

 

[aterpster]

You're saying that a north-south runway might be in error to the east or west, but never to the north or south?

I'd expect a data error could misplace the runway in any direction... while a display (processing) error could be limited in the way you describe.

Jeppesen and Garmin generally know where the thresold is because of source data for the IAP. But, that doesn't account for the lateral placement of the runway.

In this country the FAA maintains a website with precise data for all IFR runways. I don't know whether Jeppesen or the vendors use those data. I suspect they use a less accurate source, based on not all SV runways line up laterally without any error.

Outside the U.S. it can get interesting. A while back I ran an IAP in India in the G-1000 trainer where the runway was a full width laterally offset on the ILS at this airport. I presume the ILS was correct because the location of the ILS facilities is available on state source.

Then again, Garmin may have mislocated the ILS in the trainer. That is possible, but incorrect information on an RNAV approach happens only when it is in error in the database, which would then have the same errors in an airplane.

Bottom line: treat virtual runways as a general guideline rather than a representation of exactly where the real pavement is located.

 

[TMetzinger]

Jeppesen and Garmin generally know where the thresold is because of source data for the IAP. But, that doesn't account for the lateral placement of the runway.

In this country the FAA maintains a website with precise data for all IFR runways. I don't know whether Jeppesen or the vendors use those data. I suspect they use a less accurate source, based on not all SV runways line up laterally without any error.

Outside the U.S. it can get interesting. A while back I ran an IAP in India in the G-1000 trainer where the runway was a full width laterally offset on the ILS at this airport. I presume the ILS was correct because the location of the ILS facilities is available on state source.

Then again, Garmin may have mislocated the ILS in the trainer. That is possible, but incorrect information on an RNAV approach happens only when it is in error in the database, which would then have the same errors in an airplane.

Bottom line: treat virtual runways as a general guideline rather than a representation of exactly where the real pavement is located.

On that we fully agree. My issue is that the display is very compelling. I took a sim check once where the instructor set it up so that my flight director was lying to me and disagreeing with the raw data. It took longer than it should have to catch the discrepancy and disable the flight director. And that's nowhere as compelling as SV.

I expect that just as we see people using XM for tactical avoidance (and coming to grief), we'll see people using SV for tactical terrain avoidance, and for approach guidance, instead of paying attention to MEA/MOCA/MDA and the needles, and they'll come to grief too.

 

[aterpster]

On that we fully agree. My issue is that the display is very compelling. I took a sim check once where the instructor set it up so that my flight director was lying to me and disagreeing with the raw data. It took longer than it should have to catch the discrepancy and disable the flight director. And that's nowhere as compelling as SV.

I expect that just as we see people using XM for tactical avoidance (and coming to grief), we'll see people using SV for tactical terrain avoidance, and for approach guidance, instead of paying attention to MEA/MOCA/MDA and the needles, and they'll come to grief too.

Lot's of folks agree with both of your points including me.

 

[Alexb2000]

I know many people do not like the pathway in the sky but I think it's great. When intercepting a localizer, it is really nice to "see" it on the PFD. Same thing with flying a DME arc. Also "seeing" the missed approach course on the PFD provides good situational awareness on turning points and how high to climb.

Without SVT, cross checking instruments is essential and with SVT nothing changes. I can't imagine putting the flight path marker on the end of the runway flying an ILS and not looking at the HSI or green diamonds to make sure everything agreed. A word of caution though. In the absence of any other approach guidance, if all you do is put the flight path marker on the end of the runway, it is really easy to fly a low & flat approach that "looks" normal. You can try this with a hood one day and see for yourself. I believe this illusion may have already resulted in one fatal accident on a night landing into an airport with no visual glide slope or precision approach.

I hadn't thought about a hand flown DME arc using HITS. That might be really fun, good idea.

 

[TMetzinger]

I do like HITS for arcs, and for vectors to final. It's "meh" for cruise use but on approaches I think it can add to the situational awareness.

 

[cirrusmx]

Its one of those features that's there, in the background at least in the cirrus. However, I dont really pay attention to it when flying approaches. I am to busy scanning the instrument data, which is what matters and will render SVT useless. Maybe on a missed approach were you get disoriented, lost and **** hits the fan it might help. If flying proper IFR and stay ahead of the airplane, SVT is just overkill.

 

[olasek]

I think SVT is a phenomenal invention. Why should I be constantly worried if I am about to hit a mountain, etc. It seriously reduces butterflies in my stomach, I can divert more attention to other high level tasks like weather decisions, etc. If you look at some recent accidents, for example like this whole family that perished last year around Thanksgiving after taking off out of Phoenix and hitting the Superstition mountain in excellent weather, at night - this accident would not have happened had they had SVT.

 

[Jaybird180]

Its one of those features that's there, in the background at least in the cirrus. However, I dont really pay attention to it when flying approaches. I am to busy scanning the instrument data, which is what matters and will render SVT useless. Maybe on a missed approach were you get disoriented, lost and **** hits the fan it might help. If flying proper IFR and stay ahead of the airplane, SVT is just overkill.

You forgot to put your flame suit on...I'd give ya one, but there's no smilie for it on this board.
(this one means I'm waiting for differing opinions, which should be along in 5...4...3...2....)

 

[cirrusmx]

oh and not to mention svt is one of those gadgets that will grow balls on lowtime doctors, lawyers, etc and make them push onto hard ifr conditions any sane person would not.

 

[olasek]

oh and not to mention svt is one of those gadgets that will grow balls on lowtime doctors, lawyers, etc and make them push onto hard ifr conditions any sane person would not.

Yes, and even invention of aircraft (specially twin engine aircraft) is in itself such a 'gadget' since such lowtime doctors and lawyers would otherwise be confined to throwing their monies (and killing themselves) in more Earthly endeavors.