Print from Airliners.net discussion forum
http://www.airliners.net/aviation-forums/tech_ops/read.main/325330/

Topic: Question About VOR Approaches
Username: rolypolyman
Posted 2012-11-14 19:02:38 and read 3098 times.

I'm a bit confused about VOR approaches depicted as in this diagram.



I've never understood these approaches. It seems to imply that you start over the SAC VOR on a heading of 44 deg, then wait until you're at the 20 DME point (ARTEY). Then somehow you're supposed to screech to a halt, make sure you're above 3500 ft, then turn your plane around to the reciprocal heading of 224 deg. In reality any turn like this will throw you many miles off the 044 radial. So how is the turn to 224 accomplished? Is the little 269 diagonal heading it shows implying that it wants you to do the turn south of the 044 radial? How is something like this flown in real world operations?

Topic: RE: Question About VOR Approaches
Username: asqx
Posted 2012-11-14 19:24:04 and read 3100 times.

Flying the apprach a pilot would fly over the SAC VOR and fly outbound on the 044 radial. After passing ARTEY (and remaining within 10 nm of ARTEY) a pilot will make a procedure turn back to the inbound course remaining at or above 3500ft MSL. Since there is only a barbed arrow the type of procedure turn is at the discression of the pilot, however it must be made on the south side of the 044 outbound radial.

Topic: RE: Question About VOR Approaches
Username: 113312
Posted 2012-11-14 20:27:46 and read 3100 times.

All of that is academic since the whole procedure, including the procedure turn, would only be done if no radar approach services were available. Normally, you would expect approach control to provide radar vectors to intercept the final approach course at some point northeast of ARTEY.

Topic: RE: Question About VOR Approaches
Username: N243NW
Posted 2012-11-14 20:49:55 and read 3100 times.

Quoting rolypolyman (Thread starter):
It seems to imply that you start over the SAC VOR on a heading of 44 deg, then wait until you're at the 20 DME point (ARTEY).

Not quite. The official start of the approach is ARTEY (note the letters IAF for Initial Approach Fix above the waypoint). Although the starting point isn't SAC itself, it would seem logical to either navigate to the VOR or the 044 deg radial before navigating to ARTEY, especially if you aren't equipped with any other means of finding it besides VOR and DME.

Quoting rolypolyman (Thread starter):
Then somehow you're supposed to screech to a halt, make sure you're above 3500 ft, then turn your plane around to the reciprocal heading of 224 deg.

Pretty much. Except for screeching to a halt. This maneuver is known as a procedure turn. The most typical procedure in a light aircraft is a 45-degree turn away from the outbound course, then a 180-degree turn back in after 1 minute. That's what the 089 and 269 refer to. There are other means of procedure turns, but this is the most common.

http://simfliteminnesota.blogspot.com/2007/05/procedure-turns.html

Notice on the profile view of the approach that you're not allowed to stray more than 10 miles from ARTEY during the procedure turn. Once you're done with the turn and established on the 224-degree final approach course (still outside of ARTEY), you can then descend from 3500 to 2000.

Quoting rolypolyman (Thread starter):
Is the little 269 diagonal heading it shows implying that it wants you to do the turn south of the 044 radial?

Yes...in this case, the procedure turn should be initiated to the southeast of the final approach course. As with a hold, this is the "protected side" of the approach, and it offers more room for terrain clearance while executing the course reversal.

Quoting 113312 (Reply 2):
All of that is academic since the whole procedure, including the procedure turn, would only be done if no radar approach services were available.

Good point. I don't think I've ever done an actual procedure turn outside of requesting the full approach from ATC for practice purposes. It's almost always radar vectors to the final approach course.

[Edited 2012-11-14 20:52:22]

Topic: RE: Question About VOR Approaches
Username: AAR90
Posted 2012-11-14 21:11:28 and read 3100 times.

Quoting N243NW (Reply 3):
I don't think I've ever done an actual procedure turn outside of requesting the full approach from ATC for practice purposes.

Very nice summation. I have only flown ONE actual procedure turn VOR approach in 26+ years with AA. MD80, RNO-SLC diverted to IDA (WOX0F at SLC), in heavy ICE --8 inches on front of gear doors after landing. In today's GPS/RNAV world, it is just not "needed."

Topic: RE: Question About VOR Approaches
Username: capnaux1
Posted 2012-11-14 21:54:04 and read 3100 times.

Quoting AAR90 (Reply 4):
Very nice summation. I have only flown ONE actual procedure turn VOR approach in 26+ years with AA. MD80, RNO-SLC diverted to IDA (WOX0F at SLC), in heavy ICE --8 inches on front of gear doors after landing. In today's GPS/RNAV world, it is just not "needed."

Good point. In my 22years with my airline, I've only done it once...in the sim!

And now, with RNAV approaches, things are even more streamlined. Procedure turns still exist, but as you said, only coming from certain directions, and out of RADAR contact...

Topic: RE: Question About VOR Approaches
Username: rolypolyman
Posted 2012-11-15 03:43:20 and read 3100 times.

Thanks all... great information. It makes a lot more sense now.

Speaking about obscure approaches it's interesting to see some of the "Hi-TACAN" approach plates to military bases in the older FLIPs. Most of those start out at around FL150. I guess those were kind of like an embryonic version of STARs at civilian airports since the whole procedure is pretty much mapped out descending out of class A airspace.

Topic: RE: Question About VOR Approaches
Username: Starlionblue
Posted 2012-11-15 05:01:37 and read 3100 times.

Procedure turns are typically performed for either course reversal or losing altitude, or both.

Quoting N243NW (Reply 3):
.in this case, the procedure turn should be initiated to the southeast of the final approach course. As with a hold, this is the "protected side" of the approach, and it offers more room for terrain clearance while executing the course reversal.

ATC doesn't actually care how you enter or execute a procedure turn. You could enter inverted, turn left, turn right... The two things of paramount importance are that you stay on the protected side (in this case southeast of of the 044 radial) and within 10 nautical miles of the Final Approach Fix (as specified in the profile view).

Same with holds. Staying on the protected side and within time or distance limits (as applicable) is really the only thing ATC cares about.

Having said that, ATC prefers you to be predictable, and best practices are best practices for a reason.

Quoting rolypolyman (Reply 6):
Speaking about obscure approaches it's interesting to see some of the "Hi-TACAN" approach plates to military bases in the older FLIPs. Most of those start out at around FL150. I guess those were kind of like an embryonic version of STARs at civilian airports since the whole procedure is pretty much mapped out descending out of class A airspace.

I think the reason is that they are made for aircraft with very high performance, like fighters. If you look at those approaches they often don't even include speed categories A or B.

Topic: RE: Question About VOR Approaches
Username: Mir
Posted 2012-11-15 13:01:36 and read 3100 times.

Quoting AAR90 (Reply 4):
I have only flown ONE actual procedure turn VOR approach in 26+ years with AA. MD80, RNO-SLC diverted to IDA

Funny, that's where I did my only procedure turn for an ILS. There was a radar outage at the time.

-Mir

Topic: RE: Question About VOR Approaches
Username: Goldenshield
Posted 2012-11-15 13:42:02 and read 3100 times.

Quoting Mir (Reply 8):
Quoting AAR90 (Reply 4):
I have only flown ONE actual procedure turn VOR approach in 26+ years with AA. MD80, RNO-SLC diverted to IDA

Funny, that's where I did my only procedure turn for an ILS. There was a radar outage at the time.

I've never seen a crew NOT do the procedure turn at IDA when it's not VFR.

Topic: RE: Question About VOR Approaches
Username: jgarrido
Posted 2012-11-15 14:49:45 and read 3100 times.

Quoting 113312 (Reply 2):
All of that is academic since the whole procedure, including the procedure turn, would only be done if no radar approach services were available. Normally, you would expect approach control to provide radar vectors to intercept the final approach course at some point northeast of ARTEY.

There are times which would necessitate doing a PT while in radar contact. I don't mean for training either. For example a controller can't vector to final if the final approach course isn't depicted on his scope.

Topic: RE: Question About VOR Approaches
Username: Alias1024
Posted 2012-11-15 19:13:07 and read 3100 times.

Quoting Goldenshield (Reply 9):
Quoting Mir (Reply 8):
Quoting AAR90 (Reply 4):
I have only flown ONE actual procedure turn VOR approach in 26+ years with AA. MD80, RNO-SLC diverted to IDA

Funny, that's where I did my only procedure turn for an ILS. There was a radar outage at the time.

I've never seen a crew NOT do the procedure turn at IDA when it's not VFR.


IDA is the only place I can recall performing a procedure turn in airline flying too. I was shocked last winter when Salt Lake Center offered vectors. Of course we accepted. That was a mistake. We were slowed down, put on right downwind that gave us an over 10 mile base leg, and vectored onto the localized close to 20 miles from the runway. The procedure turn would have gotten us to the hotel much more quickly.


The messages in this discussion express the views of the author of the message, not necessarily the views of Airliners.net or any entity associated with Airliners.net.

Copyright © Lundgren Aerospace. All rights reserved.
http://www.airliners.net/