Fly-by waypoints on non-overlay NDB approaches.

[Raptor256]

I am looking for some information regarding some NDB approaches.

On some stand alone NDB approaches there are fly-by waypoints on the inbound/outbound track. For instance I am currently looking at the NDB RWY 33 TRUE in Arviat. Is this waypoint there so you can initiate the procedure turn without having to fly all the way in to the station? Is there another purpose? Is there any documentation on these waypoints or their explicit purpose that someone can see?

Thanks.

[ywgflyboy]

I like looking at charts like this to try and keep my mind up to par while I . bags around and don't get to fly actual approaches!

My thoughts:
I was always under the impression that it was for the most part to "un-complicate" the approach. With the beacon being directly on the field, it makes it difficult to determine location and time to field etc since the NDBs give no sort of distance. Also allows for a straight if weather and runway conditions are present.

For your remark about the procedure turn. Remember the proc turn is within 10nm of YEK not EBDAX.

[Raptor256]

Ok I understand the will to un-complicate the approach. So are you saying that the waypoint is there to allow you to fly a visual approach in from that point if weather permits? Its my understanding that you couldn't fly to that point and execute a straight in IFR approach.

I know that a lot of guys will use that point as an IF and do a straight in NBD approach from there, which as far as I understand is not legal. If not radar vectored the only way to avoid a procedure turn is if the approach is designated with a NO PT. But depending on the direction of travel you could use EBDAX as a point to start a procedure turn without having to go the extra miles to the beacon. I don't know the legality of doing that though. Thats why I am wondering about that point.

Is it legal to go to EBDAX and do a straight in approach? If you believe so, what in the regulations allows us to do that?

Alternatively, I guess EBDAX could also be there simply to provide a waypoint to fly to when you are intercepting the final approach course inbound. You do the normal procedure turn via the NDB, and fly outbound past EBDAX, then when you turn in fly to EBDAX and then direct the beacon. It would be simple to program most GPS units for this option. Of course legally you are still using the beacon as the primary nav-aid. The GPS would be used as reference only, but it will give you very useful track information once you are inbound. Is this the sole purpose of that point?

[AuxBatOn]

I was always under the impression that it was for the most part to "un-complicate" the approach. With the beacon being directly on the field, it makes it difficult to determine location and time to field etc since the NDBs give no sort of distance.

The NDB will also be in the GPS database. You point is moot.

Also allows for a straight if weather and runway conditions are present.

On any IFR flight if you break out of clouds and are confident you can finish the flight without going back IMC, you can cancel IFR and continue VFR. Same goes on an approach. As soon as you are visual, you fly with visual references, line up and stabilize your approach as far as possible on final.

Its my understanding that you couldn't fly to that point and execute a straight in IFR approach.

No you cannot. Unless you have (GNSS) following the approach title.

I know that a lot of guys will use that point as an IF and do a straight in NBD approach from there, which as far as I understand is not legal.

It is technically not legal.

If not radar vectored the only way to avoid a procedure turn is if the approach is designated with a NO PT.

You need an Intermediate Fix in order to be allowed to do a straight-in transition. This is not the case here.

But depending on the direction of travel you could use EBDAX as a point to start a procedure turn without having to go the extra miles to the beacon. I don't know the legality of doing that though. Thats why I am wondering about that point.

The goal of the procedure turn is to get you on the final approach course at a safe altitude and in a good position to make the minima on time for a transition for a landing. In the case you are describing, if you have EBDAX selected on your GPS, how do you know how far you are from the NDB? You cannot use timing as you did not cross the NDB and you cannot use your GPS as you have an other point selected. Don't forget the intent of the procedure turn is not to make your life complicated, but to put you in a position to succesfully complete the approach in a safe way. Doing what you describe is not only technically incorrect but could be dangerous. Maybe not at that specific airport, but definately at other airports where there is more vertical development.

Is it legal to go to EBDAX and do a straight in approach? If you believe so, what in the regulations allows us to do that?

No, unless you are VMC

I think that GPS point is designed for Contact Approaches.

Plus, if you had a GPS, why the hell would you shoot the NDB approach?

[300_hour_wonder]

Can anyone post a scan of the plate I'm really intrested in this but I don't have CAP's for up north

[AuxBatOn]

[Raptor256]

Plus, if you had a GPS, why the hell would you shoot the NDB approach?

There are still some operator that are not certified for a GPS approach and still do NDB approaches on a very regular basis. Now you can say thats not acceptable, and I agree with you to a certain degree, but aircraft equipment, and differences in GPS equipment throughout a companys fleet and all that can lead to that situation. These issues are being resolved, but there are certainly many companies that cannot legally do RNAV or GPS approaches in this country.

[300_hour_wonder]

The only thing I can come up with is some GPS's have trouble with true tracks so this waypoint is there so you can set up a gps track on the inbound track off the NDB in the gps. This could also work with Non IFR GPS as a back up nav.

note: if you are using a gps to fly a NDB or any approach that is not followed by (GNSS) you MUST use the NDB as your primary navigation source I'm not going to get into a debate about it being safer to use a GPS vs a NDB this is the law as it stand right now in Canada.

Also I do not know if this is true or not but when an approach is given the GPS overlay (GNSS) designation TC or Nav Canada will look into the effects of shore effect and NDB errors so ensure the GPS co-ordinates are in the place where the NDB says you are. Like I said I'm not sure if its true or not just somthing I have been told.

edited to add:

I don't have much experiance looking at northern plates but I have never seen a fix like this on southern if someone with access to better plates then me could look to see if it mainly exsists on TRUE or GRID plates it would be helpful for my aurgument

[x-wind]

Is there and RNAV for this place?

The GPS waypoint is within the procedure turn radius, about 3.5-4 NM out. Everything in the 10NM ring is to a uniform scale.

Was in the process of becoming an overlay, then stopped because they decided not to go that way?

[AuxBatOn]

Is there and RNAV for this place?

The GPS waypoint is within the procedure turn radius, about 3.5-4 NM out. Everything in the 10NM ring is to a uniform scale.

There are 2 RNAV, one for each end of the runway.

It is within the procedure turn radius but you cannot navigate with reference to that in your PT or base your timing/distance off of the GPS fix.

[Raptor256]

I don't have much experiance looking at northern plates but I have never seen a fix like this on southern if someone with access to better plates then me could look to see if it mainly exsists on TRUE or GRID plates it would be helpful for my aurgument

NDB RWY 08 in Brandon

NDB RWY 25 in Churchill

[x-wind]

Is this waypoint common to the other approachs?

[Raptor256]

Is this waypoint common to the other approachs?

No

[x-wind]

Cool, so what you up too?

[300_hour_wonder]

well there goes my theory anyone else have one?

[x-wind]

AIM:
Holders of air operator certificates (AOC) issued under Part VII of the CARs, and private operator certificates issued under Subpart 604 of the CARs, are required to be authorized by an operations specification to conduct GNSS instrument approach operations in IMC. This is explained in Commercial and Business Aviation Advisory Circular (CBAAC) 0123R, dated 25 March 2004.

Not looking in the Cars though....

Or/and?

GPS overlay approaches were intended to be a transition measure to allow immediate benefits while waiting for the commissioning of a GNSS stand-alone approach for a runway.For this reason, in most cases, the GPS overlay approach will be discontinued when a GNSS stand-alone approach is published for a given runway. There are still over 120 GPS overlay approaches published in the CAP.

So they took away the overlay part after they got the RNAVs... or started then stopped the overlay planing and threw it on cause they had it.

[ywgflyboy]

CYAV also has one similar to this.

[x-wind]

And some of guys going in there need all the situational help they can get... just kidding, former instructor in that area.

[GoinNowhereFast]

GPS overlay approaches were intended to be a transition measure to allow immediate benefits while waiting for the commissioning of a GNSS stand-alone approach for a runway.For this reason, in most cases, the GPS overlay approach will be discontinued when a GNSS stand-alone approach is published for a given runway. There are still over 120 GPS overlay approaches published in the CAP.

So they took away the overlay part after they got the RNAVs... or started then stopped the overlay planing and threw it on cause they had it.

That's the theory I've heard.
If you look at Manitoulin East, it has a stand-alone RNAV and a stand-alone NDB for one runway. For the other runway it has a NDB approach with an overlay. So they only got part way through making stand-alone RNAVs for each runway, maybe?
I don't have the plates in front of me, but if I remember correctly, it also has the unusable waypoints too.

[300_hour_wonder]

The overlay theory makes sense too bad we have no apporach desginers here to help us out

[x-wind]

well i feel a little insulted.

It provides a 1.5 degree slope down to the runway.

Speed 120 times by 5 = 600 divide by two = 300 hundred on the VSI and you're on the numbers....ish

always with the ish.

[captainginyu]

Nav Canada and Transport Canada are working at converting traditional non-prescision northern approaches to GPS overlay approaches and eventually just GPS stand alone approaches. Whether this will take 1 year or 25 years I have no idea, but it is definitely the way things are going, and the way they should be going. Looks like the Arviat RWY 33 TRUE approach has had a GPS waypoint placed along the inbound track as a means of satisfying one of the conditions of continuing on a GPS approach and having the approach go into ACTIVE mode (fancy word for saying that you will have satellite coverage for the approach).

The conditions that need to exist (these may be slightly different with different GPS models) in order for someone to continue on a GPS approach (whether it be stand alone or overlay) is that you need RAIM, you need to be heading towards the FAF, and you need to have the approach armed/loaded 2NM prior to the FAF. With this Arviat approach, since the NDB is located at the field, and there is no FAF with the traditional approach, you would not be able to do this approach via an overlay or stand alone approach because you could not satisfy the GPS approach criteria of having the approach armed/loaded 2NM prior to the FAF since there is no FAF, so they put EBDAX in as a FAF so that pilots would be able to load the approach, have the GPS predict RAIM, and as long as the approach was armed 2NM prior to the FAF (EBDAX) the approach would be active and they could continue with the GPS approach. CYAV (Winnipeg/St. Andrews) NDB 31 approach is structured the same as well as most NDB approaches with the NDB right at the field.

I could be completely wrong on this as I am not an approach designer, but that would be my best guess.

[righthandman]

I posed this question in an email to an approach designer at Nav Canada. He might offer an answer here in the coming days???

[Ref Plus 10]

I know that a lot of guys will use that point as an IF and do a straight in NBD approach from there, which as far as I understand is not legal.

It is technically not legal.

Do you have a CARs reference for this? So long as you're above the sector altitudes, it really doesn't matter where you go. It is in fact completely legal, though probably ill-advised, seeing as you will be much higher going direct to the waypoint, then descending to minimums, than doing the full approach, where you will be allowed to descend to procedure turn altitude on the outbound leg.

If not radar vectored the only way to avoid a procedure turn is if the approach is designated with a NO PT.

You need an Intermediate Fix in order to be allowed to do a straight-in transition. This is not the case here.

So far as I can tell, the only things you need to conduct a straight in approach are a means of ascertaining wind direction and confirmation that the runway is clear

But depending on the direction of travel you could use EBDAX as a point to start a procedure turn without having to go the extra miles to the beacon. I don't know the legality of doing that though. Thats why I am wondering about that point.

...Doing what you describe is not only technically incorrect but could be dangerous.

Agreed, however, again I refer you to sector altitudes. You could do your procedure turn at 17 miles if you wish, so long as you are at your 25 mile safe altitude. Which would defeat the purpose in most cases.

Ref

[Raptor256]

So far as I can tell, the only things you need to conduct a straight in approach are a means of ascertaining wind direction and confirmation that the runway is clear

That is the requirement for a straight in landing, not a straight in approach.

Refer to AIM RAC 9.16 for Straight in Approach information.

As for doing a procedure turn 17 miles out, that is only legal is the approach plate states that you can do it 17 miles from the fix. Certainly you can do it, but it isn't part of the approach procedure for that runway. On the Arviat approach we were talking about, its 10 miles from the fix. I'm not saying a procedure turn 17 miles out at the 25NM MSA isn't safe, its just not part of a legal approach for that runway.