Sunday, June 1, 2008

Instrument Departures

The IFR world is always changing, and change comes faster and faster.  

In the old days, there were two main sources of instrument charts in the USA, the government (under a continually changing variety of names) and  Jeppesen, a commercial provider.  I still use Jeppesen charts for most of my flying, but now government charts, which are public domain, are widely available on the internet, through sites like AOPA,, Airnav, and probably others. For this trip, I have downloaded government charts for the airports I am likely to use, although I am unlikely to fly IFR.

Let me say it out loud: I am unlikely to fly IFR because the airplane does not have an IFR GPS.  Yes, I can and may fly IFR, but the lack of a GPS makes it much more difficult, and it reduces the options.

This was reinforced while catching up on my chart revisions.  (Actually, I was getting ahead, since some of the charts are not valid until Thursday, but I determined that none of them will affect my flying between now and then.)  One of the advantages of the Jeppesen charts is that they tell you why the chart has changed.   Lately, there have been a lot of changes to departure procedures.

Departure procedures are strange to begin with.  Generally, they are optional.    They are not optional when Air Traffic Control (ATC) includes the departure procedure in a clearance, which they will do if they need it for separation.  This tells me that when a departure procedure changes, ATC would like to use the new one in order to move more airplanes more efficiently.  Why change a procedure that has worked for 20 years unless you want to actually use the new procedure?  (It used to be that the exact statement about departure procedure being pilot's choice was only published in the controller's handbook, not in any publication for pilots, but now it is in the FAA's Instrument Procedures Handbook, FAA-H-8261, available online.)

Look first at Driggs, Idaho.  (Unless you have a Jeppesen subscription you'll have to wait until Thursday to look, because charts are not available online until they become effective.)  The chart had a minor change this time around, but in looking it over I noticed that there is no non-GPS departure.  There are no ground-based navaids at Driggs, which is in a narrow U-shaped valley, so the only alternative to a GPS-based departure is to pick a smart heading, climb steeply,  and hope that the winds aloft forecast is correct.  There is no radar coverage, so nobody looks over your shoulder.  No thank you.

The Cherokee Six we're in this week has DME but no GPS. Suppose that we decide to stop for lunch at Driggs on the way home (the restaurant there is excellent), and find that we need to depart IFR. No can do! This alone wouldn't keep us from stopping, but it still makes me pause.

Next, look at Pocatello, Idaho, which has a new departure procedure, even though the old one had worked well keeping airplanes out of the rocks for at least 15 years.  The new procedure involves a "departure gate" at SICOY; in other words, every departure ends up about 13 miles west of the airport, even for an easterly flight.  Also, you need DME (or some equivalent) to identify SICOY, so many KPIH-based airplanes cannot fly the procedure.  You can see SICOY on the VOR 3 chart at right.

I think a lot of Pocatello-based pilots will react to the change by saying "ATC seldom clears us via the departure procedure." But this is may be about to change.  Pocatello is generally below radar coverage, so ATC keeps airplanes apart procedurally.  The old departure procedure used the same airspace as the ILS missed approach, which meant that no airplane could depart while another was on the approach.  Now, ATC can send the departure to SICOY and be sure that the missed approach area is clear.  In other words, it will be easier to get out of Pocatello, as long as you have DME.

If you keep or rent an airplane in Pocatello, you have to ask whether departure delays will cost enough to justify an avionics upgrade.

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