What to tune?

spiderweb

spiderweb

Final Approach
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Ben
Reviewing approach procedures for the G1000, and specifically the Perspective, I came upon a basic philosophical question. If one is flying an RNAV (GPS) approach (zulu, or not), and no NAVAID is specified (which is often the case), do you tune anything?

For example: http://155.178.201.160/d-tpp/1206/05034RZ21.PDF

If you are flying this approach, and you have it either on kneeboard or on the screen (I don't like that), what would you tune? You can't see it on this plate, but there is a VOR and also an ILS.

My instinct would be to have the VOR tuned and ready on NAV 1 and the ILS on NAV 2, or vice versa. My reasoning basically boils down to this: Why not?
 
If it's an ILS to the same runway, I would tune it, heck I would fly the ILS if it was available.:D
 
Personally, I would tune the ILS freq to NAV1 and the VOR freq to NAV2 and turn the bearing pointer on, set to Nav2. As back-up of course.
 
I'd probably set up the nav radios to help with the missed, if applicable, or for the local VOR.

Not sure the ILS has a lot of value. I'm not going to switch to the ILS mid-approach. If the GPS remains functional I'll probably continue to use it for the missed approach and transition to a different airport or a different approach. If the GPS fails, then having the VOR tuned is probably the most useful, particularly if it's part of the airway system or common to other approaches.
 
My DPE chastised me when I started a backup timer on an ILS that also could be a LOC approach...

"Don't fly two approaches. One approach at a time."

I immediately understood the wisdom of it in that case. You might convince yourself to read and fly the wrong set of minimums.

But perhaps it applies here as well. One approach at a time.
 
Well, the starting the timer is one of this arguable things, but if the ILS had loc-only minimal, it isn't really a SECOND approach. It's still the same approach you were cleared for. On the other hand, doing anything with a localizer on the GPS approach is certainly using a procedure you were NOT cleared for.

No GPS approach will need a VOR for the published missed, so unless they gave you some goofy alternate missed procedure...
 
TMetzinger said:
Not sure the ILS has a lot of value. I'm not going to switch to the ILS mid-approach. If the GPS remains functional I'll probably continue to use it for the missed approach and transition to a different airport or a different approach. If the GPS fails, then having the VOR tuned is probably the most useful, particularly if it's part of the airway system or common to other approaches.
Click to expand...

I see your point Tim, and it is a good one. The reason why I would choose to tune the ILS in is not for backup on the final segment of the GPS approach but for handy reference prior to beginning the approach. For example, you are on radar vectors for the RNAV/GPS Z 21 and lose RAIM. It's handy to have the ILS freq available so you can quickly go green needles (on the G1000) and request the ILS. Of course in the G1000 once you load or activate the approach, the ILS frequency is auto-tuned, but I would prefer to tune it before the approach out of habit.

At least in the northeast US, if you lose RAIM and request the ILS, approach could very well turn you for a slam dunk and having it tuned already is helpful.
 
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denverpilot said:
You might convince yourself to read and fly the wrong set of minimums.
Click to expand...

I see that all the time in the simulator when I conduct student phase checks. Especially GPS approaches with WAAS. I usually fail WAAS either prior to the FAF or close to it and see if the student catches the downgrade to LNAV minimums. Some do, some don't. I had one student last month dive down to the LPV minimums with no glidepath and drive along for 4 miles before going missed. Sigh.
 
HPNPilot1200 said:
I see your point Tim, and it is a good one. The reason why I would choose to tune the ILS in is not for backup on the final segment of the GPS approach but for handy reference prior to beginning the approach. For example, you are on radar vectors for the RNAV/GPS Z 21 and lose RAIM. It's handy to have the ILS freq available so you can quickly go green needles (on the G1000) and request the ILS. Of course in the G1000 once you load or activate the approach, the ILS frequency is auto-tuned, but I would prefer to tune it before the approach out of habit.

At least in the northeast US, if you lose RAIM and request the ILS, approach could very well turn you for a slam dunk and having it tuned already is helpful.
Click to expand...

Jason,

Of course on this approach, RAIM isn't relevant. If the integrity doesn't exceed the required VAL, there will be no downgrade to LNAV. You will have to miss the approach.
 
There is a separate procedure for the LNAV using the RNAV Y. I would not expect to get advisory vertical guidance on this approach with a WAAS GPS. Anyone want to proffer why this might be true? RAIM wouldn't be a factor on this approach either unless you were flying it with a non WAAS GPS.
 
John Collins said:
Jason,

Of course on this approach, RAIM isn't relevant. If the integrity doesn't exceed the required VAL, there will be no downgrade to LNAV. You will have to miss the approach.
Click to expand...

I was envisioning a loss of RAIM prior to beginning the approach (say on the downwind via radar vectors). Since this approach has LPV only mins, you would not be legal to start the approach and if you were already established, would have to go missed.
 
HPNPilot1200 said:
I was envisioning a loss of RAIM prior to beginning the approach (say on the downwind via radar vectors). Since this approach has LPV only mins, you would not be legal to start the approach and if you were already established, would have to go missed.
Click to expand...

On a WAAS GPS, you are not going to get an indication of a loss of RAIM as long as you are in the WAAS service volume. RAIM is not used enroute for the WAAS GPS except under extreme circumstances of a total loss of the WAAS system.
 
John Collins said:
On a WAAS GPS, you are not going to get an indication of a loss of RAIM as long as you are in the WAAS service volume. RAIM is not used enroute for the WAAS GPS except under extreme circumstances of a total loss of the WAAS system.
Click to expand...

That has happened already, once.
 
flyingron said:
Well, the starting the timer is one of this arguable things, but if the ILS had loc-only minimal, it isn't really a SECOND approach. It's still the same approach you were cleared for. On the other hand, doing anything with a localizer on the GPS approach is certainly using a procedure you were NOT cleared for.

No GPS approach will need a VOR for the published missed, so unless they gave you some goofy alternate missed procedure...
Click to expand...

I always thought it was kinda dumb that you could continue an ILS approach down to LOC mins if the glideslope failed during the approach. Who would really do that? If i'm tracking the GS and it fails all of a sudden, i'm going missed
 
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I know... maybe i'm just new but if the GS fails i'm going to suspect the localizer might be freaking out too, or my radio is messed up, and I am not going to continue descending while trying to verify the localizer is working
 
spiderweb said:
Reviewing approach procedures for the G1000, and specifically the Perspective, I came upon a basic philosophical question. If one is flying an RNAV (GPS) approach (zulu, or not), and no NAVAID is specified (which is often the case), do you tune anything?

For example: http://155.178.201.160/d-tpp/1206/05034RZ21.PDF

If you are flying this approach, and you have it either on kneeboard or on the screen (I don't like that), what would you tune? You can't see it on this plate, but there is a VOR and also an ILS.

My instinct would be to have the VOR tuned and ready on NAV 1 and the ILS on NAV 2, or vice versa. My reasoning basically boils down to this: Why not?
Click to expand...

Here are the reasons I don't do that on the G1000.

I worry less about the approach and more about executing the missed correctly (especially in the mountains). So on the G1000 I am not going to use the ILS because I want to leave the CDI on GPS and follow the Flight Director on the missed. Then if ANYTHING happens I don't like, throttle forward, hit the Go Around button and fly the missed.

Then just reload the approach for the ILS at altitude so you have the same benefit of the ILS missed on the FD.

In other aircraft I used to always used to tune the localizer for a cross check. At least I could be sure I was on the extended centerline if something went TU.
 
dell30rb said:
I know... maybe i'm just new but if the GS fails i'm going to suspect the localizer might be freaking out too, or my radio is messed up, and I am not going to continue descending while trying to verify the localizer is working
Click to expand...

When in doubt, go around.

The GS is a separate receiver from the localized. As long as the LOC is not flagged it's still working.

But no one will slight you for being conservative, go around, figure out the problem before proceeding.
 
spiderweb said:
Reviewing approach procedures for the G1000, and specifically the Perspective, I came upon a basic philosophical question. If one is flying an RNAV (GPS) approach (zulu, or not), and no NAVAID is specified (which is often the case), do you tune anything?

For example: http://155.178.201.160/d-tpp/1206/05034RZ21.PDF

If you are flying this approach, and you have it either on kneeboard or on the screen (I don't like that), what would you tune? You can't see it on this plate, but there is a VOR and also an ILS.

My instinct would be to have the VOR tuned and ready on NAV 1 and the ILS on NAV 2, or vice versa. My reasoning basically boils down to this: Why not?
Click to expand...

FLG VOR
 
denverpilot said:
My DPE chastised me when I started a backup timer on an ILS that also could be a LOC approach...

"Don't fly two approaches. One approach at a time."

I immediately understood the wisdom of it in that case. You might convince yourself to read and fly the wrong set of minimums.

But perhaps it applies here as well. One approach at a time.
Click to expand...

I was always taught to start the timer for every approach.
Habit patterns, less likely to miss starting the timer when you need it.
Timing for a backup LOC approach if the GS fails before your done.
 
BillTIZ said:
I was always taught to start the timer for every approach.
Habit patterns, less likely to miss starting the timer when you need it.
Timing for a backup LOC approach if the GS fails before your done.
Click to expand...

This used to be the standard but apparently not so much anymore.

Sent from my ADR6300 using Tapatalk 2
 
I bet you could find folks who argue both ways on that one and make good points for both sides. Especially /U without a step down fix. With /A you have better data to act on, even though the clock is the legal charted approach for the LOC only approach.

(Something else the DPE asked as a question during the ride, and liked that I said the clock was the legal controlling factor on a LOC approach without the DME required, but that ignoring the DME data was a good way to bust your butt with a strong tailwind.)
 
dell30rb said:
I know... maybe i'm just new but if the GS fails i'm going to suspect the localizer might be freaking out too, or my radio is messed up, and I am not going to continue descending while trying to verify the localizer is working
Click to expand...

Meh. Depends on the circumstances.

Localizer and Glide Slope transmitters are completely different devices, frequencies, everything. I always tune in both navs to the Localizer anyway, so if both flagged the glide slope at the same time, I would know it was an unreliable GS, and treat it appropriately. Otherwise stable approach and able to be safely completed as a LOC approach, might be better and safer than vectorating around for another shot.
 
Unless you brief the approach and include the localizer only alternative in the briefing, I would not suggest trying to save the approach. It would take an emergency situation for me to not fly a do over. The same would be true for a LPV that downgraded to a LNAV. At least with the LPV approach, you get a positive message one minute prior to the FAF for the downgrade. Once you have started your descent on the ILS/LPV, I don't think it is a good idea to switch procedures mid descent. In fact with the LPV, it isn't permitted, downgrades will occur no later than one minute prior to reaching the FAF. After the FAF, you get an abandon approach message.
 
N747JB said:
If it's an ILS to the same runway, I would tune it, heck I would fly the ILS if it was available.:D
Click to expand...
I used to tune the ILS if the RNAV followed the same path but for the most part quit doing so because if the GPS quits I'm going around anyway and even if the LOC provides the path for a viable exit I can switch to that shortly after initiating my initial climb on the runway heading. In any case it's guidance on a miss rather than the approach that I might want.

And WRT flying an ILS vs RNAV, I'll take a LPV hands down unless there's enough difference in the DA to matter given the conditions at the time (pretty rare circumstance IME). The LPV provides far more stable guidance both vertically and laterally and it doesn't get hypersensitive close in. If the choice is ILS vs LNAV/VNAV or LNAV, I'll take the ILS if there's any chance that I need the lower minimum altitude/visibility limits.
 
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