Lost comms over Ukiah

[Keith Smith]

Interesting one tonight, 2 pilots flew to Ukiah and arrived at nearly the same time. The 2nd to arrive was put into holding. In addition, once each plane descended below 9000ft, we were no longer able to maintain communication. We had not swapped them to the frequency depicted on the plate and were still on a frequency based on a transmitter near Red Bluff. The system evaluates transmissions/reception distances every 3 seconds for every plane, and descending through 9000ft was enough to tip the scales.

One of the pilots swapped back to a previous approach frequency and was able to raise us, while the other pilot had to be contacted through a simulated Guard transmission, asking him to swap to 127.80, the freq published on the UKI VOR-A plate.

Controller error (mine) lead to the loss of comms, but it was an interesting situation to resolve. We're still working on the norcal procedures, but this scenario does show the importance of swapping the pilot to the frequency with the closest transmitter. It was something which we planned for in socal (particularly for the desert airports outside of TRACON airspace), but it looks like we'll have to do the same thing in norcal, too!

The next trick will be to have the reception degrade slowly as we approach the reception limit, rather than cut out abruptly, but this is still pretty neat!

[Charan Kumar]

It was freakin awesome to watch...I was just signing out. Interesting though how he was able to raise you on 125.25 which is SMF_APP!!

[Keith Smith]

Yep, he was close enough to the transmitter for SMF_APP, even at 9k and below.