Unusual (for me) event inside Class C. Can ATC terminate flight following inside Class C and approve frequency change.

Background: Requested and received VFR FF at 6500 msl prior to approaching ONT Class C (top is at 5000). Intent was to over-fly ONT and not enter Class C, however after reaching north of the field, ATC said “free to descend altitude at your descretion ” (Point A). My response, “6500 ft decending to 4500”. At about point B, I dropped into Class C and continued to 4500. After leveling off, still in Class C, ATC said “Squawk VFR, frequency change approved.” I responded “Squawking VFR, and immediately departing Class C to the North”. (Point C) His response, “You don’t have to do that as the tower still has you on radar.” I said “departing Class C to the north”

Here is my confusion: First squawking VFR is not an issue, I’ll squawk whatever is requested and maintain my own flight separation but when he said “frequency change approved” I would no longer be in radio contact in Class C if I actually did as approved. This would mean, to me, I am illegally in their airspace. What am I missing???

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Jim S asks an interesting question. Can ATC ask you to do something which is contrary to the regulations? The answer is they can, and just because they do, does not change the regulations.

The practice of advising aircraft to switch to advisory frequency and squawk VFR is common here, in Class C airspace, and I have experienced it in Class B airspace as well.

Discussing this with the ATC supervisor once, it was explained to me this way: The controller knows where you are going, knows your intent, and believes that he can manage the traffic in the area effectively if you leave the frequency. So for the controller it is an issue of risk and workload management.

With students, this creates a good learning opportunity to have them "monitor" one radio, while using another. No official guidance on this, but it is common practice. So if you are not familiar with this, have an experienced pilot or CFI demo it to you.

Keep in mind that this is the same process for IFR aircraft making approaches to non-towered airports.

Arguably, ATC can authorize deviations from 91.130, as @DaveCFII points out. Certainly that covers temporary frequency changes to check WX and things like that, but it could be interpreted to have broader scope is that it could be used to terminate communications near to the point where an aircraft leaves Class C.

Having said this, I would prefer that ATC state something like, "communications deviation approved." Of course that will not happen on a busy frequency.

Having said all this, it is important to remember that the pilot has final authority over a flight, and the FAA in the Granby LOI makes it clear that ATC does not have the requirement to point out to pilots what regulations apply to their operation. So a pilot who is uncomfortable with this procedure, might monitor ATC on one radio, and broadcast their intents on the advisory frequency. This way they can fully comply with the regulations. Most aircraft have dual COM radios. If not, delay your frequency change until you are clear of Class C, to remain in strict compliance.

Ref: Granby LOI https://www.faa.gov/about/office_org/headquarters_offices/agc/practice_areas/regulations/interpretations/data/interps/2006/granby%20-%20(2006)%20legal%20interpretation.pdf

  • $\begingroup$ Thank you for the detailed discussion. This was my first experience of being “cleared” for something “questionable”. You said, “The controller knows where you are going, knows your intent, and believes that he can manage the traffic in the area effectively if you leave the frequency. So for the controller it is an issue of risk and workload management.” I believe that sums it well. $\endgroup$ – Jim S Dec 26 '18 at 17:51
  • $\begingroup$ FYI - PPL/IFR 500+ hrs w/about half w/CFI/dual. One would think that I would have been taught or experienced this before. Note to CFIs: teach this anomaly (perhaps you already do). Thank you for your discussion. $\endgroup$ – Jim S Dec 26 '18 at 19:09
  • $\begingroup$ FWIW, CFIs should be teaching students how to monitor a second frequency for things like picking up ATIS/ASOS while still talking to ATC/CTAF. $\endgroup$ – StephenS Dec 26 '18 at 20:23
  • $\begingroup$ I agree StephenS, but in this case it was a singlle radio without monitoring capability. Although, still possible by getting permission to temporarily leaving the frequency. Probably doesn’t apply here. $\endgroup$ – Jim S Dec 26 '18 at 21:57
  • $\begingroup$ @JimS, if you asked for a temporary frequency change, and then you were outside Class C, then that would be similar to the controller switching you when you were close. This is an example, of when judgment comes into play, and you decide whether you really break the rules, or you stick to the strict interpretation of the rules. One could always ask the FAA for a LOI on this topic, however, think carefully about that, because the FAA tends to stand by their previous LOIs in enforcement actions. It might be better for someone if the matter was not formalized. $\endgroup$ – mongo Dec 26 '18 at 23:05

The requirement to maintain two-way radio communications is FAR 91.130(c). But regulations have to be read as parts of a whole. Read 91.130(a), which says:

Unless otherwise authorized by ATC, each aircraft operation in Class C airspace must be conducted in compliance with this section...

"Frequency Change Approved" is ATC authorization to deviate from the requirements of 91.130(c).

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    $\begingroup$ I think you're right, and it looks like this is an important point that all of the other answers have missed: ATC can authorize you to deviate from 91.130(c), in which case deviating from 91.130(c) is completely legal. I didn't know that until I read this answer. I had posted an answer previously, and my answer said that you're still required to obey 91.130(c) even if ATC says that you don't need to. It looks like that was incorrect, so I've deleted my answer. $\endgroup$ – Terran Swett Jan 16 '19 at 4:41

Were you perhaps inbound to CCB?

If so, I agree with the comment by @StephenS: That once you are cleared all the way out of the airspace, ATC will release you by effectively saying, "I'm not going to have anything more to tell you, you don't really need to stay on frequency anymore" (even if this might be a technical violation under 91.130.)

Because ATC expects you to go to the CTAF frequency, they know where to find you. They may well be monitoring that frequency, and can broadcast on it if needed.

If you have dual radios, and want to be extra safe, keep ATC on Radio #1, and start your CTAF calls on Radio #2. Double-check your mic-setting with each transmission, so you know which frequency you're transmitting on. You can still hear ATC if they try to reach you even after approving a change.

  • $\begingroup$ Your speculation is correct. ATC was informed that KCCB was the destination and that my course was to the common visual point of entry (San Antonio Dam). I only have one radio (but he wouldn’t know that) so I now believe he expected no further issues with me and had other things to do..... I do believe it was correct to remain on frequency until clear of C (one radio). $\endgroup$ – Jim S Dec 26 '18 at 18:02
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    $\begingroup$ If ATC tells me "no traffic observed, frequency change approved", he's saying he has no reason to call me again. If I had one radio, I'd switch to CTAF then and make my first call. Might be a violation, but IMHO that seems a smaller concern than hitting another plane due to not making CTAF calls early enough. $\endgroup$ – StephenS Dec 26 '18 at 20:33

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