Thursday, March 15, 2012

More on Procedure Turns

One of the things I often encounter is confusion over when a procedure turn may be started. This generally occurs when an approach has both a DME arc and a procedure turn. Consider the ILS-27 at Duluth (DLH). The government-issue approach plate is shown below.

The procedure turn is shown outside of the DME arc. I believe it is depicted this way for chart clarity, so it doesn’t get too cluttered. But depicting it this way often leads pilots to believe they must be beyond the 15-mile DME arc before doing the procedure turn. This however is not true. The only requirement is that the standard procedure turn be completed within 15 nm of ANDOE, the OM, and it must be done on the north side of the localizer. Other than that, the point at which to start the turn, as well as type and rate of turn are pretty much left up to the pilot. This of course is not true if the procedure turn is accomplished in a holding pattern or teardrop pattern. Those must be flown exactly as depicted.

A glance at the profile view confirms that the distance requirement is simply remain within 15 nm of ANDOE, the OM. If the procedure turn were a holding pattern, the profile view would say something like “One minute holding pattern”. If it is a teardrop pattern, the profile view would say something like “Teardrop within 12 nm of LNK VORTAC”. See the ILS-18 for LNK (Lincoln).

There are some other things worth noting on ILS-27 for DLH. In big bold letters on the plan view there is the statement DME OR RADAR REQUIRED. Anytime you see a note like this on the plan view, it is talking about the requirements to get from the enroute environment to an IAF. This approach has three IAFs. The two ends of the DME arc can be identified with DME of course (or GPS). The OM, ANDOE, has the word RADAR above it, meaning ATC can identify this fix for you.

Another item to note on this approach is the existence of an alternate holding fix. It is PYKLA, which is an LOM for the ILS-9 at DLH. Alternate holding fixes are becoming more common. They exist in most cases when the navaid for the primary hold is not the same as the navaid for the approach and it is out of service. In this case, the primary hold is based on the DLH VOR. If that is down however, PYKLA becomes the holding fix. There are no charted directions on how to get to the alternate holding fix. In the event however that the primary navaid is out of service, directions to the alternate will generally be found in NOTAMS or of course ATC can give them to you.

Jeppesen shows this same approach in a better manner or least a less confusing manner. The procedure turn is shown inside the DME arc. The Jeppesen chart is shown below.

For a longer discussion of procedure turns, you can go to the May 2007 archive.

One final note on procedure turns. For the standard procedure turn the AIM states the type and rate of turn is left up to the pilot. So you can fly the charted 45° turn outbound, do a 90°-270° turn or whatever works for you. One thing to remember is that on the 45° turn outbound, when you are ready to do a 180° turn to come back to the course, you may turn either right or left. It does not matter. If the charted procedure turn shows the standard right-hand 180° turn and you are getting close to the limit specified in the profile view, turn left! It’s perfectly legal to do so.

No comments: