I think it's fairly obvious that you can't really turn-lead if you don't know the distance. You'd hope for something less than a 90 degree intercept and maybe querry ATC if you saw it leading up to this. Then just do appropriate race-track course reversal. You could ask ATC to let you know when you're a certain distance maybe.

 

Here is a link to one I fly often: http://155.178.201.160/d-tpp/1204/00591NB.PDF. Coming from the PDT VOR which is the route I fly puts you at more than 90 degrees, it gives you a DME off the VOR, but many times you lose DME info before arriving so not knowing the actual distance you need to see passage of the station. Just be sure to pay attention as there isn't a lot of room in the valley, or so it seems at times

 

Since this is the 'Technical' forum - to be technically correct, that is a feeder off of PDT and there is a DISTANCE shown, not a DME. There is no guarantee of DME coverage off of a feeder route in this case.

USMCFLYR

 

You are absolutely correct on that. This was more of an example to the greater than 90 degree intercept.

 

I'm not sure what the procedure designer had in mind. I *think* the design criteria is no more than a 120 degree divergence angle but I'm not sure. I do know that this NDB is basically restricted beyond 15 nm between PDT and ALW, so those feeder facilities are about the best they can do coming from the northwest it seems.

USMCFLYR

 

Hello Rexflyt,

thank you very much for your chart contribution! Something like that
approach at La Grande, was exactly what I had in mind when I started
this topic.
Since you said you are flying this approach often, I hope maybe you can answer a few more of my questions.

In the given scenario you arrive from the PDT VOR feeder fix, but loose DME info before arriving at the LGD NDB.
Now in that case ,as you said you have no reliable indication for distance to the NDB until you actually see the needle fall/station passage.

So how do you fly this approach in reality then after passing the NDB?
Immediate left turn to an intercept heading to re-intercept bearing 344 from the NDB?
And what kind of intercept angle do you use in these case to quickly re-establish yourself? 45degrees?30?

And another question, since you have to remain within 10NM of the NDB:

How do you determine/dead-recon roughly how far you are already away from the NDB when you have completed your intercept of the 344bearing?
Its kind of hard to guess,as you first overfly the station eastbound then re-intercept the 344 bearing from the east.
You would have to know this as to determine how much longer you can continue outbound on the 344 bearing and to stay safely within 10NM during the 180 degree procedure turn

Best regards and thanks for your help!

PA44

 

Since it is just a published PT I'd be configured before I hit the NDB. Turn outbound to a heading of 344 plus or minus 5 for any cross wind, just a direct entry to a holding pattern, while descending to 6600. Flying outbound for 2+1/2 to 3 minutes will keep you within 10 miles even at 150 knots. Left turn back around to find the inbound course and descend to 5600 till the NDB.

 

Hi Twin wasp,

maybe I'm a bit slow here, but isn't there a problem even if you hit the NDB configured already and then turn to a outbound heading of 344 +/- 5 degrees to fly a direct entry into the hold pattern like you said?
Because you can't fly a 2,5 to 3 minutes outbound leg on this heading.You're below 14.000ft here and the holding leg length should then be 1minute only as far as I know.

During your outbound leg on HDG344 you will end up east of the 344bearing from the NDB, plus you will extend the holding pattern to the north if you continue this 344 heading for 2,5 to 3 minutes so you might get quite close to the 5557ft mountain.
Not a problem if you maintain 6600ft though of course..

Maybe there is no ideal solution here, as the procedure is just not designed in a optimal
way with the huge angle from the Feeder Fix course to the NDB outbound course.

Best regards,
PA44

 

Oh, come on.. You know what an NDB is. It's what you try to get the scores for the game on.

 

You are altitude protected on the PT side. Since it is published as a PT (and not a holding pattern or teardrop) you can use whatever course reversal you want. Take a look in the Instrument Procedures Handbook under Approach and Course Reversal. You're not holding, you are doing a racetrack course reversal so none of that one minute and turn applies. You're worried about the 5557 hill. Ok, say you hit the NDB and turn on to the 344. When are you going to make your turn to 029? The only protection you have is the 6000 foot outbound altitude and TERPS builds the approach so whatever altitude they publish protects you where ever you in a sort of squashed oval anchored at the fix with the course towards one edge and the wide part of the oval where you're doing your course reversal.