When to line up with runway if the VOR final course is offset?
 

Hi all,

When I am flying a VOR approach which is several degree offset of the runway. May I deviate from VOR guidance and line up right after visual contact with the runway? Or, I should keep on the VOR final approach course until MDA or some other point, then go visual and line up? Is there any regulation concerning this?

Thank you!


Edit:
Thank you all for replying. For the airport I am planning to go, the VOR is offset due to a mountain alongside of final. It is NOT VOR-A, which require a circle. But only 7 degree offset. I would like to go visual and lineup, make it stable as early as possible. But if so, I may trigger the annoyed EGPWS caution, then have to do a lot of paperwork to report and “justify”. Since I am still under IFR approach even though it is VMC outside and I can see the runway and mountain clearly, I am anxious if I violate any regulation if I deviate from the VOR lateral guidance too early. I can not find any regulation concerning this. It would be appreciate if you can list one. Thank you so much!

Edit:
Thanks to mmm345. For Australia, please refer to #24. But for other countries, I still have not found any specific regulation.

If you are visual I would say go visual.

I seem to recall Heraklion RW 27 was one of many.

It's an instrument approach. The trajectory intersects the extended runway centerline appropriately and the profile enables a controlled descent with stable rate towards the threshold.

What's the urge to deviate? In other words, go visual as long as you keep following the procedure you have been cleared for. :ok:

The VOR might be offset due to an obstruction on the extended centreline. Dalaman 19 is an example.

Stay on the procedure until you can make a normal visual approach to the runway.

Once you deviate from lateral (and vertical) guidance you’re on your own.
It’s easy to calculate a VDP (Visual Descent Point ) if one is not depicted.
Your HAT (Height above Terrain) x 3 equals distance.
So with an MDA that is 500’ above airport elevation your VDP is at 1.5 NM.
If the weather is significantly better then minimums for the approach I’ll consider to line up further out but still using the 3:1 rule.
So at 1500’ AGL I’d have to be at 4.5 NM.
Once you practice this a couple of times it’s real easy.
Gives you a 3 degree descent angle and a stabilized approach.

thegypsy

Thank you for your reply!
Kinda like LGIR, the terrain around my concerning airport is very complex. They put VOR 7 degree offside to keep distance with a high mountain alongside. So I am wondering what is the best time to line up without causing any EGPWS cautions, either violate any regulation.

Peter G-W

Indeed! So, if I lineup too early, I may trigger the EGPWS, that would be a BIG trouble for me in our company. They don’t care if you are visual or not.

B2N2

Thank you for your useful tips!

B2N2

You could do all that or just look out the window and land the sucker.

Dorf

Haha, good to review this flight school knowledge though. But it is getting more and more hardly to find VDP in nowdays chart. Everything is changing to CDFA or GPS with vertical guidance..I suppose ILS may disappear in some years.

FlightDetent

Agree! But a lot of captains in our company, especially those from Air Force, are soooo eager to go visual. Seems they even wanna shut off all the screen as long as they can see the runway. So I need a regulation clause clearly saying they may or may not deviate from the guidance to avoid both of us getting into trouble.

B2N2

Be careful with that one, as there are plenty of VOR approaches deviating from the standard 3° for a good reason, mostly being terrain - fe. TSL 28/34 with 3,80°, or OPO 17 with 2,80°...

Nonetheless, if the weather's fine and you briefed it, I see no problem in continuing / aligning visually and not staying madly on the VOR App all the way to MDA.

Fly the offset. It's there for a reason.

It is. I usually leave it til I'm within the circling range then line up.

In Australia at least, when flying a non-precision approach ( ie. a VOR Approach), you can only align with the runway centreline if not already aligned when within the cirlcing area, continuously insight to ground/water and visual ref. with the runway environment can be maintained. However, if the offset angle is >5 degrees, the approach coarse will intersect with the final approach track not less 1400m of the runway, making it not really nessecary to deviate from the inbound coarse any earlier then when the approach naturally intersects with runway track.

It is not permissable to simply discontinue the cleared NPA and decide to manouvere visually when outside the circling area in less than VMC but still visual ( ie. poor visibility or not continuously in sight of ground/water).

Dorf

Good reply - practical solution to a practical problem!

flyfan

11072437]B2N2

I couldn’t tell you without seeing the instrument approach plates.
In any case once passed the FAF a descent to MDA should not get you in conflict with terrain.

flyfan

I couldn’t tell you without seeing the instrument approach plates.
In any case once passed the FAF a descent to MDA should not get you in conflict with terrain.

B2N2

Dude, check VNKT VOR 02

Hmm. He says should and even if it was must that does not equal to will. On the line, everyone needs to keep checking facts against pre-conceptions. Even the correctly trained ones. Truly well spotted. I'm sure B2N2 omitted the additional "unless there are step-down fixes published" for brevity (didactic reasons).

https://cimg7.ibsrv.net/gimg/pprune....72be0b49c2.png

What a peach. Dropping from FAF [D9=8900 ft - not on the picture] to the next step-down fix of 5510 [D3] would indeed compromise the OCAs. Bit of work to dive steeper than 5,3°, but it surely can be done. Those OCAs shouldbe made into step-down fixes.

BTW it is no longer clear to me if it is lateral or vertical being discussed above under "following procedure".

Haha, thank you for your reply. Of course, I am concerning lateral guidance since VOR doesn’t have glide slop. And mmm345 answered my question so well! I am still looking for the counterpart in FAR. Should be similar. In spite of this, thanks B2N2 help us review VDP and the formula. While CDFA is taking place VDP. I nearly forget this theory.

BTW, where did you get this lovely chart? Far better than Jeppesen. I tried use VNAV to fly this approach several times, but it always end up with very high speed. Seems by manual is still the best way. But it will greatly increase the work load. Especially when fly in this narrow valley. Not quite correspond to the topic, but very glad to talk about it in another thread if anyone interested.

As per your example, following the vertical profile (#exists) is perhaps of greater importance than lateral. Or the margin for error is less, if you will, namely for the GWPS case.

There are 2 or 3 more companies other than Jeppesen producing aeronautical charts for public use. Each of whom tried to enter the market with a superior product and the hard work paid off. The above is Lido.

What is your type?