lost comms with Pt Mugu

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Steven Winslow
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lost comms with Pt Mugu

Post by Steven Winslow »

Flew from L54 to SBA last night. Great flight, but had a communication problem with Pt Mugu Approach. At 21:01:26 - 01:49 I am instructed to switch from SoCal to Pt Mugu. I switch to Pt Mugu on 128.65 and make contact (at which point I get to say "WEEZL"...heh!) From that point, I wait and wait for Pt Mugu to hand me off but I never hear the instruction to contact SBA Approach. Listening to the recording for Center/Approach/Departure for the 21:00 hour I can hear Pt Mugu telling me to switch to SBA Approach, but I never received any of the transmissions from Pt Mugu between 03:40 through 04:47. At 05:15 - 05:37 I try to contact Pt Mugu Approach on the same frequency, 128.65, because I haven't touched my radio, but I get no response. I'm 9 miles from SBA so I know something has gone wrong. I contact SBA Tower and learn that Pt Mugu had been wondering what happened to me, at which time I'm told to contact SBA Approach. The rest of the flight was uneventful, other than a rapid descent and 14 to 20 knot crosswind.

Not sure what the problem was.
Steven Winslow
CEO/Owner - Air Northwest Virtual Airlines • http://www.airnorthwest.org
People should get what they want when they want it once in a while. Keeps them optimisitic.
Kevin_atc
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Re: feel free to post your own

Post by Kevin_atc »

Steven Winslow wrote:Flew from L54 to SBA last night. Great flight, but had a communication problem with Pt Mugu Approach. At 21:01:26 - 01:49 I am instructed to switch from SoCal to Pt Mugu. I switch to Pt Mugu on 128.65 and make contact (at which point I get to say "WEEZL"...heh!) From that point, I wait and wait for Pt Mugu to hand me off but I never hear the instruction to contact SBA Approach. Listening to the recording for Center/Approach/Departure for the 21:00 hour I can hear Pt Mugu telling me to switch to SBA Approach, but I never received any of the transmissions from Pt Mugu between 03:40 through 04:47. At 05:15 - 05:37 I try to contact Pt Mugu Approach on the same frequency, 128.65, because I haven't touched my radio, but I get no response. I'm 9 miles from SBA so I know something has gone wrong. I contact SBA Tower and learn that Pt Mugu had been wondering what happened to me, at which time I'm told to contact SBA Approach. The rest of the flight was uneventful, other than a rapid descent and 14 to 20 knot crosswind.

Not sure what the problem was.
Hi Steven,
I was on approach at the time. Your frequency was indicating something that began with 126... rather than the 128.65 that you were initially assigned and that you initially contacted Mugu on. Not sure if it was a glitch in system (I know you claim you never changed your frequency) but as far as the network was concerned, you were tuned to a 126. something which is why you didn't hear the numerous calls from Point Mugu. However, I do give you props for choosing to contact SBA tower as you knew from past experience that something just didn't seem right as you were nearing the airport and still very high. That was certainly a good decision rather than just automatically assuming radio failure and trying to land.
Kevin
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Steven Winslow
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Re: feel free to post your own

Post by Steven Winslow »

Kevin, if I had the incorrect frequency selected, then why did Pt Mugu respond when I switched from SoCal to Pt Mugu? If I indeed had the wrong frequency, I should not have gotten a response from Pt Mugu when I checked in at 21:01:26 - 012:49, right? If Pt Mugu responded to me on the wrong frequency, then I think that's where the problem began. It is totally plausible that I may have had Com 1 tuned to 126.65, but if so, it was the same frequency I set to contact Pt Mugu initially and should not have gotten a response from that contact. As I said, I did not touch my radio between the time I checked in with Pt Mugu Approach and the time I switched to SBA Tower and the recording clearly indicates contact between Pt Mugu Approach and ANW570. Not a big deal on my end. Probably some kind of glitch.
Steven Winslow
CEO/Owner - Air Northwest Virtual Airlines • http://www.airnorthwest.org
People should get what they want when they want it once in a while. Keeps them optimisitic.
Keith Smith
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Re: feel free to post your own

Post by Keith Smith »

Not a glitch. Just something that shows the radio system in action :)

When you swapped from Socal to Pt Mugu, if you did indeed use 126.65 instead of 128.65, you were actually tuned to a LA Center frequency, with the transmitter being located on top of a mountain (Mt Laguna, just SE of the JLI VOR). The controller may not have caught this, depending on his workload (we get an alert when pilots change freqs so we can more easily wear multiple hats) and when you checked in calling Pt Mugu approach, he put on his Pt Mugu hat and responded. All is well, right? Does it really matter what freq you're on if it's really the same controller working both positions?

It very much does.

When you initially checked in with "Pt Mugu" (really, LAX Center at the Mt Laguna transmitter), you were at the outer range of the radio transmission/reception limits based on your altitude and the altitude of ATC's transmitter atop the mountain (I kid you not, we model all of that, down to the foot).

Once you exceeded 118.2nm from Mt Laguna, with you being level at 8000ft, it was all over and you lost comms. At that point, you would not have heard any more transmissions from ATC.

What should've happened is that when you checked in on the LAX Center freq, a bewildered center controller should've said, "go back to your previous frequency and ask for a new frequency," or perhaps, "say location..." followed by, "try Pt Mugu Approach 128.65, you're on 126.65." etc. However, that didn't happen, and the voice behind the mic responded as "Pt Mugu approach" so you had no reason to suspect an issue.

In the future, you'll hear ATC's transmissions becoming distorted and mixed with static as you approach the reception limits, that will be a clue that it's time to ask for a new freq (this happens in real life quite frequently out in the boonies).

The only thing you could've done differently, Steve, was try going back to the previous freq once you realized you lost comms (not always possible if you've already erased the previous freq, which is reasonable if you've established comms with the new controller), OR try looking up an approach frequency for the 'local' area, ie, the nearest airport with an instrument approach, pull up any of the approach plates (such as OXR, CMA, or NTD), and try that freq. Advanced stuff, but a good skill to have :)

Fascinating scenario!
Alex Stjepanovic
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Re: feel free to post your own

Post by Alex Stjepanovic »

*Chimes in*

125.65 is the ZLA one near JLI(Plus a few other places nearby).

126.65 is Nellis Control

You may have also seen 126.85(Quite a common transposing of those numbers, which is NSI Tower(Unstaffed)).

*Runs to avoid the food...or whatever....thrown at him*
Keith Smith
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Re: lost comms with Pt Mugu

Post by Keith Smith »

You're slippin', Alex :)

Nellis is a red herring, it's a lot further away than the LA Center transmitter at JLI...the system would've discarded Nellis as a possibility.

The NSI tower is off the table because Steve did establish comms on the freq....and then without touching the radio, the comms later failed until he swapped to SBA tower. This is a classic "slipping out of range" incident.
Alex Stjepanovic
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Re: lost comms with Pt Mugu

Post by Alex Stjepanovic »

While running away from KS, I found shelter in a few RCAGs themselves. Luckily enough, they were the right ones for this very mystery. Turns out that the last time I was out there doing field maintenance, I turned the knob a little too much to the right on one of the transmitters, and it set up as 126.65 instead of 125.65.

FE honor saved...somewhat! 8-)
Keith Smith
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Re: lost comms with Pt Mugu

Post by Keith Smith »

Very interesting. So if the ctr freq was set correctly, then the nearest matching freq would've been Nellis instead, not the Mt Laguna transmitter and Steve would've been dead in the water the moment he tuned the freq and would've probably gone straight back to Socal (since the freq would still be in the stdby, fresh and ready) and said, "no joy on that freq..."

I'll play with the knob tomorrow morning before we open and get it back to its usual position.
Alex Stjepanovic
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Re: lost comms with Pt Mugu

Post by Alex Stjepanovic »

The knobs hath been fixedth.
Steven Winslow
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Re: lost comms with Pt Mugu

Post by Steven Winslow »

So, does this mean it wasn't my fault? :roll: Heh, I really shouldn't embarrass myself this way, but it seems there may have been multiple issues. I looked at my nav log, as such, and noticed I wrote the frequency for Pt Mugu Approach as 128.6, rather than 128.65. I'm pretty sure I actually tuned in 128.65 and simply didn't finish writing the frequency down, but it could be that I tuned in 128.6. But that doesn't explain how Pt Mugu Approach heard me initially.

At least from this experience, and one from today, I know now, if after changing frequencies I don't get a response within a few seconds, I should go back to the previous frequency and ask for the correct frequency to be repeated.
Steven Winslow
CEO/Owner - Air Northwest Virtual Airlines • http://www.airnorthwest.org
People should get what they want when they want it once in a while. Keeps them optimisitic.
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