what are these frequencies?

[erich weaver]

Was playing around at home in simulator mode on the Garmin 296 the other day and came across some frequency information on it I dont quite understand.

For some small, non-towered airports, it lists frequencies for approach/departure in adition to the CTAF/unicom. For Columbia (o22 - in California in the foothills of the Sierra Nevada) for instance, it indicates 123.70 and 125.10 for approach/departures to the north and west, respectively (nothing listed for for other directions - not sure why).

Who exactly are you talking to on these frequencies and when would you use them? I have always just comunicated on the CTAF at such airports, and only used other frequencies at the larger towered airports. What gives? Maybe these are frequencies to pick up flight following from? If so, seems lame to list them without providing any clues about who you would be communicating with. Probably some plot by you hot shot IFR guys to make us lowly VFR guys look stupid

thanks

erich

[Mike S]

Sounds like NorCal approach

[John Clark]

Mike is correct, it is Norcal Approach. VFR it is the place to call for flight following. IFR, it is where you get a release for takeoff into "the system." In this example, Columbia CA, (O22) you are dealing with Norcal approach/departure. Some places it will be "Center," but it doesn't matter, the worst case is they will give you another frequency. The North and West issue has to do with which sector you are flying into after departure. Pick the one closest to your initial heading.

Airport Communications for O22

CTAF/UNICOM: 122.975
WX AWOS-3: 124.65 (209-536-9384)
NORCAL APPROACH: 123.7 NORTH 125.1 WEST
NORCAL DEPARTURE: 123.7 NORTH 125.1 WEST
WX AWOS-3 at CPU (13 nm NW): 118.525 (209-736-2523)

John Clark
RV8 N18U "Sunshine"
KSBA

[erich weaver]

okay, good info John and Mike. Kind of surprising to me that the agency you would be talking to is not identified on the Garmin unit, but suppose I can always just dial it in and listen to figure that out. Or do it the old fashioned way - look it up in the Airport/Facility Directory.

erich

[Ron Lee]

Another source

http://www.airnav.com/airport/O22

[gasman]

Double check your GARMIN..... The BLUE BOOK (calif only) has Oakland Center as 126.85 for APP and DEP. for Columbia. So I checked my brand new (today) AOPA 09-10 directory, it has the same info. So I checked my AIRMAP 600C and it says 126.85 also..............

I see from above post...............

NORCAL APPROACH: 123.7 NORTH 125.1 WEST
NORCAL DEPARTURE: 123.7 NORTH 125.1 WEST
WX AWOS-3 at CPU (13 nm NW): 118.525 (209-736-2523)

* APCH DEP SVCS ALSO PRVDD BY OAKLAND ARTCC: FREQUENCY SECTORIZATION: EAST FREQUENCY 126.85/322.55 (ANGELS CAMP RCAG) FREQUENCY USE: APCH/P DEP/P

[erich weaver]

I checked the latest AFD on the FAA website
http://www.avn.faa.gov/pdfs/sw_66_15JAN2009.pdf
and it indicates the frequencies I cited are for Norcal, and apply for approaches from the north and west, while the 126.85 frequency is for Oakland center, and apply for approaches from the east. Interesting that (1) there are two different agencies involved for the same area; and (2) neither the Garmin GPS nor Airnav.com provided the whole story here. And hey - while we are at it, since approaches from the north, east and west are specifically called out, what about approaches from the south? None of my sources say squat about that.

A lot of fuss over nothing Im sure, since as John pointed out, any of the freuencies will work since even if it was "wrong" they would just give you the correct frequency and agency to call. Still odd that for a single point in space, its such a complicated answer and that all the info doesnt seem to be fully communicated in our various sources.

erich

postscript: another nuance to the story: If you "travel" to the Columbia airport using the simulator mode on the GPS, then click "Nearest" and then the "ARTCC" tab (Air Route Traffic Control Center), it indicates "Oakland Center" on 134.3 - different than all of the previous info above. Apparently, "nearest" doesnt mean its the right one to contact.

[John Clark]

Erich, You are over-thinking this, but that's fine, it is making me look at things I haven't thought about for a long time. Without getting too deep, it looks like Norcal Approach "owns" the airspace north and west of O22 below 12000 feet. The Oakland Center frequency listed has the airspace east and above the Norcal coverage. So, the problem becomes that there are several frequencies listed for the same spot on a chart, altitude being the difference. These "sectors" are shown in this Power Point. O22 isn't depicted, but it is on page 11. You can figure the position by comparing the graphic to a sectional. The traffic flow analysis is interesting.

http://tinyurl.com/b4a4b4

John Clark
RV8 N18U "Sunshine"
KSBA

[erich weaver]

Yeah I know - I just started realizing from this excercise that as pilots, we are only seeing the tip of the iceberg with respect to how the air traffic system is apportioned, and found it kind of interesting. Now, with that last link you provided, my head is really spinning. Ok, Im done with this already.

erich

[terrykohler]

Erich:
I'd encourage you to purchase an Airport/Facility Directory for your area and spend some time going thru it. These are fairly inexpensive, published every 8 weeks, and contain a wealth of information, including the answer to the question you first posed. Look at the back cover-the index tabs line up with the side edge of the book for easy reference. I amazed by how many people become aware of this publication while earning their PPL, and then never look at it again (I used to be one). The information within covers a great deal of the "all available information" that you are required to have before each flight. Enroute, don't hesitate to use the frequency from your Garmin to request flight following. If you aren't sure of the sector, just say, "Approach, RV N___ at (altitude) over (position), request VFR flight following. They'll tell you who they are.
Terry, CFI
RV9A N323TP