VOR Radials

[david0tey]

As I'm preparing for the IR checkride with the King Practical videos, I came across a scenario that confused me. In the examiners clearance to Martha, he gives her the following instructions.


Cleared BONDO INT
VIA:
OKB 145 radial
JLI 250 radial
MZB 007 radial
DIRECT BONDO


Martha then proceeds to fly outbound from OKB, inbound to JLI, and outbound from MZB direct to BONDO. My question is: other than looking through the chart as to what 'makes the most sense', based on that clearance, how would she know to fly inbound or outbound on a given radial?


In a more practical situation, shouldn't the controller specify whether to fly inbound or outbound? Again, I know you can just look at the chart and see what leads you to the desired fix, but it bothers me to not have a definitive answer!

 

[bobmrg]

Remember this rule: Radial means FROM. Radials are named for their direction FROM the VOR antenna. Whether you are flying away from the station with your heading indicator in agreement with the radial name or inbound with your heading indicator 180 degrees from the radial name, you are still on the named radial.

Bob Gardner

 

[david0tey]

Remember this rule: Radial means FROM. Radials are named for their direction FROM the VOR antenna. Whether you are flying away from the station with your heading indicator in agreement with the radial name or inbound with your heading indicator 180 degrees from the radial name, you are still on the named radial.

Bob Gardner

So the controller is not required to specify direction of turns or inbound/outbound from VOR? You are supposed to assume?

 

[FORANE]

Seems esoteric. How many here have received a clearance like this? I sure have not.

 

[bobmrg]

So the controller is not required to specify direction of turns or inbound/outbound from VOR? You are supposed to assume?

You are supposed to have a general idea of the area in which you are flying. If, for example, your destination airport is southeast of your departure airport, it is reasonable to assume that the airways/fixes in your clearance will take you in a southeasterly direction. You are supposed to have a low-altitude enroute chart readily available so that you can follow the cleared route with your finger to make sure that the clearance takes you where you want to go.

I'm not familiar with the area involved, so the clearance is a mystery to me without having a chart to refer to...and I should have current charts available in either paper or electronic form. There is no reason for a controller to tell a trained instrument pilot how to follow a clearance (wiggle room for instrument students, but they have an instructor in the right seat).

When I was first introducing the wonders of VOR to primary students flying out of Seattle, I would ask them to use the VOR to fly me to Olympia, which is southwest of Seattle. As they were twirling the omnibearing selector around and around, searching for a centered needle, I would ask them in which direction they would drive to get to Olympia, and of course they answered southwest. "Why not turn the OBS to a number between 180 and 270? What you are looking for has to be in there somewhere." Common sense is a wonderful thing, and sometimes we let the gee-whiz factor of being able to fly overcome our common sense.

Bob

 

[roncachamp]

As I'm preparing for the IR checkride with the King Practical videos, I came across a scenario that confused me. In the examiners clearance to Martha, he gives her the following instructions.


Cleared BONDO INT
VIA:
OKB 145 radial
JLI 250 radial
MZB 007 radial
DIRECT BONDO

OKB doesn't have any radials. I believe that should be "cleared to BONDO via ...OCN.OCN145..JLI250..MZB007...", no "DIRECT".

Martha then proceeds to fly outbound from OKB, inbound to JLI, and outbound from MZB direct to BONDO. My question is: other than looking through the chart as to what 'makes the most sense', based on that clearance, how would she know to fly inbound or outbound on a given radial?

Martha should track outbound on the OCN R-145 for about 11 miles, where she intercepts the JLI R-250, track inbound on the JLI R-250 for about 14 miles, where she intercepts the MZB R-007, then track that radial to BONDO. She will not overfly JLI or MZB.

In a more practical situation, shouldn't the controller specify whether to fly inbound or outbound? Again, I know you can just look at the chart and see what leads you to the desired fix, but it bothers me to not have a definitive answer!

Should be no need for the controller to specify whether to fly inbound or outbound as the specified radials cross at distinct points.

 

[somorris]

And good luck on the checkride!

 

[bobmrg]

Let's go back to post #5 while thinking about roncachamp's post #6. As I said in #5, before reading the clearance back to the controller (readback constitutes acceptance, so you don't want to be too hasty), Martha would have told the controller to stand by, taxiing out of the runup area if necessary, and verified every airway and fix on the clearance using the low altitude enroute chart. She would have caught the fact that OKB has no radials, among other things, and asked for clarification. Only after verifying the clearance would she have read it back to the controller.

Let's get the TO-FROM thing out of the way. Assume that your clearance reads XYZ-V31-PDQ, (XYX and PDQ are VORs),and by looking at the enroute chart you determine that V-31 is the 224 radial of XYZ. Flying southwest, away from XYZ, you are on course when the needle is centered with the OBS on 224; in no-wind conditions your heading indicator also says 224. At a published changeover point (COP) or halfway between the two VORs you change the frequency on your VOR receiver to that of PDQ.....heading indicator is still on 224, OBS is on 224, but now the T-F flag reads TO, because you are heading TO PDQ. Needle won't be centered, though, because of radial spread. You will have to select a heading to re-intercept the radial. Oh, darn....on the chart, it says that V-31 is the 044 radial of PDQ! So what? All you care about is having the OBS and the heading indicator agree, and they do. No need for a controller to tell you because your instruments are telling you.

Bob Gardner

 

[david0tey]

Yes. I meant OCN. Not OKB.

 

[midlifeflyer]

So the controller is not required to specify direction of turns or inbound/outbound from VOR? You are supposed to assume?

No. You are supposed to know how to read a chart, understand the route, understand what a VOR radial is, have situational awareness and and fly a clearance.

The clearance you describe is obviously intended to test that knowledge. It's actually pretty easy and there is only one way in which to fly it correctly. It's not a trick question.

If you are having difficulty with it, sounds like a ground session with your instructor is in order. I doubt in explanations here will be much help.

 

[midlifeflyer]

I'm not familiar with the area involved, so the clearance is a mystery to me without having a chart to refer to...and I should have current charts available in either paper or electronic form.

I looked at in on SkyVector. It's not a VOR-to-VOR clearance, it's a series of interceptions in a triangular shape, obviously intended for training purposes.

For example OCN to JLI is on the OCN 083° radial and JLI to MZB on the R-222°. So it's a training clearance to fly southeast on the OCN R-145° until intercepting the JLI R-250° toward MZB (you never actually get to JLI), then back north toward BONDO, which is at the intersection of the MZB R-007° and the OCN R-083°.

 

[poadeleted20]

Cleared BONDO INT
VIA:
OCN 145 radial
JLI 250 radial
MZB 007 radial
DIRECT BONDO

First of all, as Steven noted, it's an inaccurate clearance. You would not be cleared "MZB 007 radial direct BONDO", just "MZB 007 radial BONDO". As for the rest, they do not tell you inbound/outbound -- they really do rely on you to realize that the only way to get to the MZB 007 radial on the JLI 250 radial is to fly that JLI 250 radial eastbound/inbound.

Martha then proceeds to fly outbound from OKB, inbound to JLI, and outbound from MZB direct to BONDO. My question is: other than looking through the chart as to what 'makes the most sense', based on that clearance, how would she know to fly inbound or outbound on a given radial?

There is no other way to do it.

In a more practical situation, shouldn't the controller specify whether to fly inbound or outbound? Again, I know you can just look at the chart and see what leads you to the desired fix, but it bothers me to not have a definitive answer!

There is simply no other way to get to the MZB 007 radial from the intersection of the OCN 145 and the JLI 250 other than to fly the JLI 250 inbound. That seems pretty definitive to me. But yes, you really are expected to look at the chart to get your answer.

 

[kgruber]

Sitting in an airplane , running, is a poor place to decipher such a clearance.

In some places it is not possible, but usually you can call for a clearance from your hand held right in the FBO. Then it is easy to spread out the charts while consuming free coffee and cookies.

 

[uncreative]

It was my understanding that they are usually expecting you to depart fairly soon after receiving your clearance, not expecting you to be in the FBO eating cookies. Do you just let them know that you're not ready to depart but would like the clearance now?

 

[poadeleted20]

It was my understanding that they are usually expecting you to depart fairly soon after receiving your clearance, not expecting you to be in the FBO eating cookies. Do you just let them know that you're not ready to depart but would like the clearance now?

When you call for a clearance from a nontowered airport, they'll ask you how soon until you're ready to go. Typically, if it's 10 minutes or less, you'll get your release and void time along with the clearance, but if more, you'll get a "hold for release" clearance. In that case, you call back when you're ready to take off, and that's when you get the release and void time. So, if you tell them 20 minutes or more, they won't bother with the release before reading you the route clearance, and you can call back for that release when you're close to being ready for takeoff without scrambling the system.

At a tower controlled airport, they don't much care about that because you'll have to call for taxi and then taxi out before you're going anywhere. In that situation, there's time for the Tower crew to coordinate with the TRACON or Center and get your release promptly when you call "ready for takeoff" at the end of the runway.

 

[peerlesscowboy]

It was my understanding that they are usually expecting you to depart fairly soon after receiving your clearance, not expecting you to be in the FBO eating cookies. Do you just let them know that you're not ready to depart but would like the clearance now?

In my experience at a non-towered airport you're normally asked "how soon can you depart" before being issued a clearance so if you're in the FBO lounge drinking coffee and eating cookies they'll either tell you to call when you're ready to go or else give you the clearance with a "....hold for release". At a towered airport you're not released until you get your takeoff clearance.

 

[Gucci Pilot]

I think he just gave her a box to fly that they had pre-arranged before shooting the scenes

 

[coloradobluesky]

ATC only talks in terms of "From" radials. "To" radials are something pilots use. So if ATC asks what radial you are on, give them the "From" radial, even if you are flying the "To" radial. ETC.

 

[roncachamp]

ATC only talks in terms of "From" radials. "To" radials are something pilots use. So if ATC asks what radial you are on, give them the "From" radial, even if you are flying the "To" radial. ETC.

All radials are "from". You can fly to the VOR on them, or away from the VOR on them, but they are all "from".

 

[david0tey]

Thanks everybody. Part of the reason I found this clearance so odd was that it didn't seem pre-arranged. He read her this clearance prior to taxi with the engine running. That would have taken me at least 10 minutes to work through.