NDB approaches

RotorAndWing said:
In the Airbus that's exactly how we fly it. The PF uses the ND and the NFP uses the ADF rose.

And yes, that's how it's done on the type ride (FAA).
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Oh crap. Are you saying the airlines still fly NDB approaches? I just threw up a little bit in my mouth.
 
spiderweb said:
Oh crap. Are you saying the airlines still fly NDB approaches? I just threw up a little bit in my mouth.
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There are still places in the world where that is your only option.

I'm flying into day VFR only airports on occasion with an A320. You work with what's available.
 
If you look all over Russia and the old ussr, they have dual-NDB approaches, both aligned with the runway, one off each end. Two ADF receivers and a to-needle ADF display, if both needles are aligned, you're on the runway centerline. Stone-simple, sort of a cheap Localizer.
 
taters said:
hit direct to the apt on the GPS and then select OBS mode and put a course through it...a million times more accurate....
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I think that's a great technique for flying ADF approaches when you have an IFR GPS and there is no GPS overlay, and I recommend it without reservation -- when you have an IFR GPS. However, in preparation for the IR practical test, if you have an operable ADF in your plane, you'd better learn how to fly an NDB approach without GPS assistance, because you may just have to fly it that way on the test.
 
SCCutler said:
If you look all over Russia and the old ussr, they have dual-NDB approaches, both aligned with the runway, one off each end. Two ADF receivers and a to-needle ADF display, if both needles are aligned, you're on the runway centerline. Stone-simple, sort of a cheap Localizer.
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That's the layout they had in former Yugoslavia when a USAF CT-43 crew tried to fly one of those approaches with only one ADF in the plane in a howling crosswind about 20 years ago (i.e., before GPS was common). They hadn't flown an NDB approach since UPT, and (it appears from the track they flew) homed on the beacon at the airport rather than flying proper NDB tracking. They ended up many miles off course and hit a mountain -- all dead. Since a Cabinet member and his entourage were aboard, it got a lot of publicity (not to mention conspiracy theories).
 
I'm currently training a guy for the IR in a C-310 he will be flying to Mexico. He just spent God-knows-how-much to replace the panel with a really modern glass package -- G500 PFD/MFD, GTN750/650 with GTX-33, GDL-?? ADS-B, and JPI EDM-960. He left the old King ADF in the panel because in Mexico, there are places he will be going where there is only an NDB approach.

I'll certainly teach him how to do it using that GPS OBS-mode Clay mentioned above, but since it's in the plane for his IR test, I'm going to have to make sure he can fly an NDB approach without the GPS because "killing" the GPS during that approach is within the realm of things an examiner may do. It will probably add at least one day to his training, but it's something he needs to be able to do, and he understands the situation. The good news is the only ADF needle in the plane is part of the G500 display as an RMI needle on the HSI, so at least he doesn't have to do MH+RB=MB in his head while flying the approaches. Good thing the sim we have now has an RMI option, too.
 
Captain said:
Ron, we don't use a "published" overlay either. We just take any old NDB approach and fly the approach coupled to the FMS in 'nav' mode. We do have to put the bearing pointer up pointing to the station...but that's it.

Same with a VOR approach. Coupled to the FMS with a pointer pointing at the VOR. Yes...a pointer. That's all.
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Hell, I shoot VOR approaches that way in piston singles when I'm doing it for real. I load the approach into the 430, keep the nav 1 CDI in GPS mode and set up the nav 2 as the backup (along with time if it's required).
 
Last year I shot an NDB to minimums because it was the only option in my club's /A Warrior. I was glad my instructor gave me the training (partial panel in actual). Nice to have it when you need it.

Of course the crop dusting pilot I met on the ground thought I was nuts…
 
GCA319 said:
Hell, I shoot VOR approaches that way in piston singles when I'm doing it for real. I load the approach into the 430, keep the nav 1 CDI in GPS mode and set up the nav 2 as the backup (along with time if it's required).
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Come up to MI and try that on the VOR 27 into KFNT. Your NAV 2 CDI will be at half scale or worse if you're keeping NAV 1 centered.
 
azure said:
Come up to MI and try that on the VOR 27 into KFNT. Your NAV 2 CDI will be at half scale or worse if you're keeping NAV 1 centered.
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Same with VOR 14 at KRAP. Looking at the approach for KFNT I can see that the VOR is to the left of centerline. I think a lot of VOR approaches are like that, I know I've come across several already and I've only been doing this a couple months. Certainly something to keep in mind... personally I put the 430 in VLOC and fly it off the HSI and put it in to my VOR as backup. They read the same, but the HSI is closer and it's well an HSI. It's also connected to the 430 so I've got VLOC and GPS available, though not at the same time.

Since I'm bored tonight I pulled up that approach. I've never seen an approach where the IAF is the VOR and it's on the field. So you hit the VOR at or above 2,500 and go outbound, then basically turn around and get back on the 267* radial for the approach?
 
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Z06_Mir said:
Since I'm bored tonight I pulled up that approach. I've never seen an approach where the IAF is the VOR and it's on the field. So you hit the VOR at or above 2,500 and go outbound, then basically turn around and get back on the 267* radial for the approach?
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That's correct but there are two issues with this type of approach you need to deal with. One is that there's no timing other than what's necessary to "remain within 10nm" because the FAF is also the MAP. The other more important issue is that it requires a little forethought to manage the required descent by adjusting the outbound leg taking any wind aloft in account. A common mistake is to begin and complete the procedure turn too close to the VOR and end up without enough room to make it down to the MDA early enough to allow a "normal" descent rate on final. If that does happen reject the instinct to dive for the runway as this is a good recipe for an overrun or worse. Part of the problem is that if you've been doing VOR approaches with a VOR conveniently located 4-8 nm from the field you're used to initiating a PT shortly after crossing the VOR outbound since there's plenty of time to descend. And that VOR gives you a nice reference point to help decide what rate of descent is optimal on your way down to the MDA, with an approach like the FNT VOR 27 no such reference is available, many don't even have a fix like JOBGO to provide clues.

Of course if you have a GPS along your SA is greatly enhanced but unfortunately (maybe actually fortunately) for me there was no such thing as GPS or even GA LORAN when I was learning this stuff.
 
Z06_Mir said:
Since I'm bored tonight I pulled up that approach. I've never seen an approach where the IAF is the VOR and it's on the field. So you hit the VOR at or above 2,500 and go outbound, then basically turn around and get back on the 267* radial for the approach?
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They are called "On Airport, No FAF" VOR approaches. They have been around for many years. Same for "On Airport, No FAF" NDB approaches. The TERPs manual has chapters devoted just to them.

KFNT still has several of them.
 
Z06_Mir said:
Same with VOR 14 at KRAP. Looking at the approach for KFNT I can see that the VOR is to the left of centerline. I think a lot of VOR approaches are like that, I know I've come across several already and I've only been doing this a couple months. Certainly something to keep in mind... personally I put the 430 in VLOC and fly it off the HSI and put it in to my VOR as backup. They read the same, but the HSI is closer and it's well an HSI. It's also connected to the 430 so I've got VLOC and GPS available, though not at the same time.
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That's the way you're supposed to fly it. It's not an overlay approach and the GPS isn't legal to use for primary navigation on the final approach segment (which I take it is basically once established inbound after the procedure turn, since there is no FAF on this approach). My DPE likes to use this one to test whether candidates know which navigation source to use. Personally the only thing I use the GPS for on that approach is the DME to identify JOBGO. It's not just that the VOR is left of the runway extended centerline, the Jepp-synthesized course on the GPS is several degrees off from the published VOR radial. It might be that Jepp neglected to take station declination into account, or else got the station declination wrong.

Since I'm bored tonight I pulled up that approach. I've never seen an approach where the IAF is the VOR and it's on the field. So you hit the VOR at or above 2,500 and go outbound, then basically turn around and get back on the 267* radial for the approach?
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Yep. Once established inbound you begin descending from 2500. But unless you ask to do the approach own nav or you're lost comms, you'll never be in that position. (And if I was lost comms in IMC, that's about the last approach I'd choose at that airport.) You always get vectors to final there.
 
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azure said:
That's the way you're supposed to fly it. It's not an overlay approach and the GPS isn't legal to use for primary navigation on the final approach segment (which I take it is basically once established inbound after the procedure turn, since there is no FAF on this approach). My DPE likes to use this one to test whether candidates know which navigation source to use. Personally the only thing I use the GPS for on that approach is the DME to identify JOBGO. It's not just that the VOR is left of the runway extended centerline, the Jepp-synthesized course on the GPS is several degrees off from the published VOR radial. It might be that Jepp neglected to take station declination into account, or else got the station declination wrong.
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Jeppesen did it deliberately to deliver the aircraft to the runway threshold for FMSes that are authorized to fly the final approach course with LNAV. (Some FMSes are under high-end equipment authorizations.)
 
Ron Levy said:
That's the layout they had in former Yugoslavia when a USAF CT-43 crew tried to fly one of those approaches with only one ADF in the plane in a howling crosswind about 20 years ago (i.e., before GPS was common). They hadn't flown an NDB approach since UPT, and (it appears from the track they flew) homed on the beacon at the airport rather than flying proper NDB tracking. They ended up many miles off course and hit a mountain -- all dead. Since a Cabinet member and his entourage were aboard, it got a lot of publicity (not to mention conspiracy theories).
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They never switched to the NDB on the airport. They continued to fly the outer NDB, tracked incorrect, and flew into the high terrain to the left and just prior to the airport.

What was really sad is that the airplane had one INS, which they could have used to determine the wind correction angle.

LDDULctrRwy12_zpsfff71728.jpg
 
Z06_Mir said:
Same with VOR 14 at KRAP. Looking at the approach for KFNT I can see that the VOR is to the left of centerline. I think a lot of VOR approaches are like that, I know I've come across several already and I've only been doing this a couple months. Certainly something to keep in mind... personally I put the 430 in VLOC and fly it off the HSI and put it in to my VOR as backup. They read the same, but the HSI is closer and it's well an HSI. It's also connected to the 430 so I've got VLOC and GPS available, though not at the same time.

Since I'm bored tonight I pulled up that approach. I've never seen an approach where the IAF is the VOR and it's on the field. So you hit the VOR at or above 2,500 and go outbound, then basically turn around and get back on the 267* radial for the approach?
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KRAP is different than KFNT in that it is not an On-Airport, NO FAF VOR IAP. Most VOR approaches do not line up perfectly with the runway.
 
azure said:
That's the way you're supposed to fly it. It's not an overlay approach and the GPS isn't legal to use for primary navigation on the final approach segment (which I take it is basically once established inbound after the procedure turn, since there is no FAF on this approach). My DPE likes to use this one to test whether candidates know which navigation source to use. Personally the only thing I use the GPS for on that approach is the DME to identify JOBGO. It's not just that the VOR is left of the runway extended centerline, the Jepp-synthesized course on the GPS is several degrees off from the published VOR radial. It might be that Jepp neglected to take station declination into account, or else got the station declination wrong.


Yep. Once established inbound you begin descending from 2500. But unless you ask to do the approach own nav or you're lost comms, you'll never be in that position. (And if I was lost comms in IMC, that's about the last approach I'd choose at that airport.) You always get vectors to final there.
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The GPS track on the VOR 4R approach at KCHD is wrong too. If you fly it correctly without looking at the 430 you won't go straight in, you'll be pretty far left (though not as far as KRAP) but the GPS gives you a straight track to 4L. And that was my other question "Will you normally get vectors to final" - thanks for answering! I'd just never seen an approach like that, glad to know I at least sort of figured it out! :lol:
aterpster said:
KRAP is different than KFNT in that it is not an On-Airport, NO FAF VOR IAP. Most VOR approaches do not line up perfectly with the runway.
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I was just saying that navigating towards the VOR will get you noewhere but in a field a few miles from the runway. So even though the distance to the VOR is published, one shouldn't follow it like a DME and say "The airport is around here somewhere..." and it does dump you far left of the runway.
 
Otto the pilot said:
At work, we don't fly NDB approaches in the traditional way anymore. If we use them, it's with a GPS overlay approach with a constant descent to a DDA. (derived decision altitude; or DA +50').

While the old way was kinda fun, it was almost worthless as an approach. I called them "very non-precision".
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Do the 737 avionics generate a 'glideslope' for a non precision approach or just use constant rate of descent?
 
Z06_Mir said:
The GPS track on the VOR 4R approach at KCHD is wrong too. If you fly it correctly without looking at the 430 you won't go straight in, you'll be pretty far left (though not as far as KRAP) but the GPS gives you a straight track to 4L. And that was my other question "Will you normally get vectors to final" - thanks for answering! I'd just never seen an approach like that, glad to know I at least sort of figured it out! :lol:


I was just saying that navigating towards the VOR will get you noewhere but in a field a few miles from the runway. So even though the distance to the VOR is published, one shouldn't follow it like a DME and say "The airport is around here somewhere..." and it does dump you far left of the runway.
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If it "dumps" you far (a few miles) from the runway either the procedure doesn't meet criteria or your VOR has issues.
 
aterpster said:
If it "dumps" you far (a few miles) from the runway either the procedure doesn't meet criteria or your VOR has issues.
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A few miles isn't accurate. It was an exaggeration.
 
Z06_Mir said:
A few miles isn't accurate. It was an exaggeration.
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So, it would seem.:)

VOR approaches aren't RNAV, and some VOR IAPs that push the limits (FAF 30 miles from the threshold) can be quite bad. But, this one is not that way. The attached graphic shows the plotted centerline of the final approach course, which passes a mere 24 feet to the right of the threshold at centerline.

Nonetheless, with a maximum permitted total system error of 4.5 degrees, you could be approximately 2,500 feet to the left or right of centerline at 5.2 DME. Even with a small VOR error, say 1 degree, that still places you 550 feet off to the side.

The idea is to see the runway ideally not later than the VDP in this case.
 

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Z06_Mir said:
Same with VOR 14 at KRAP. Looking at the approach for KFNT I can see that the VOR is to the left of centerline. I think a lot of VOR approaches are like that, I know I've come across several already and I've only been doing this a couple months. Certainly something to keep in mind... personally I put the 430 in VLOC and fly it off the HSI and put it in to my VOR as backup. They read the same, but the HSI is closer and it's well an HSI. It's also connected to the 430 so I've got VLOC and GPS available, though not at the same time.

Since I'm bored tonight I pulled up that approach. I've never seen an approach where the IAF is the VOR and it's on the field. So you hit the VOR at or above 2,500 and go outbound, then basically turn around and get back on the 267* radial for the approach?
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Just issued:

!FDC 3/9063 RAP FI/T IAP RAPID CITY RGNL, RAPID CITY, SD. VOR OR TACAN RWY 14, ORIG-E... PLANVIEW NOTE: DME OR RADAR REQUIRED.
 
NDB approaches are fun to fly, are a good test of flight training and airmanship, and increasingly useless in the CONUS. To be honest, an NDB approach would be my LAST choice if other procedures were available. I deep-sixed the ADF when I put in IFR GPS. Don't miss it.
 
They're aren't that hard. It all works out better it you make special attention to make sure your DG is aligned with the heading card on the ADF pointer. To simplify though, tune the NDB on the ADF and use a GPS to fly the approach. Do this by making the NDB the active waypoint, putting the unit in OBS mode and set to the final approach course. Follow along with the ADF and it's perfectly legal and safe to do this.
 
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