This might be "yet another lost comms questions", but I've tried to read a lot and there are different answers everywhere. Here's the scenario:

(The flight plan as filed is - KSSI SSI V441 MONIA GNV OCF V581 DADES KTPA)

I'm taking off from an uncontrolled airport - KSSI to fly to KTPA (ICAO IDs). The current weather at KSSI is 003 OVC and 2 SM. I call MACON FSS for my clearance on 121.5, and here's what I get -

MACON FSS: "ATC clears N123CW to KTPA Direct SSI and then as filed, climb and maintain 4000 expect 8000 two-zero minutes after departure, departure control will be 126.75, squawk 1234. Released for departure, clearance void if not off by 20:45, time now 20:30, frequency change to advisory approved."

After read back, I take off exactly at 20:35 and after a couple minutes I contact Jax Center on 126.75 as I'm crossing 1300ft. I hear no other traffic on the frequency, and I try to contact them 2 more times while I'm heading direct to the SSI VOR. I try to contact MACON FSS with whom I'd just spoken a few minutes ago - and I hear nothing back. I try a couple of other frequencies that I can get from charts - no luck anywhere. I'm in complete IMC.

Now, I know that I've lost my radio communications capabilities and hence squawk 7600, and figure out my route and altitude to fly.

I was cleared direct to the SSI VOR, and then as filed. Looking at "AVEF", ATC expects me to fly the route I filed. Looks good - no problems here.

I was asked to climb and maintain 4000ft, and expect 8000ft 20mins after departure.

Looking at "MEA", ATC expects me to be at 8000ft since it's the highest amongst the Minimum En-route Altitude, the expected altitude (which is n/a) and the assigned altitude).

I'm still at 2400ft, climbing to 4000ft.

My questions are:

1) When should I start my climb to 8000ft? Should I level off at 4000ft and wait until 20:55 (which is 20 minutes after my departure time) before initiating my climb, or does ATC expect me to be at 8000ft by 20:55?

2) Along my route (not immediately after departure, but after a while), for e.g. at the GNV VOR, if I briefly enter VMC, should I go ahead and land at the nearest airport as practicable or should I still continue through my route? I do know that the regulations advise to land as practicable when you're in VMC, but if the airspace ahead is being cleared for you when you're under IFR, is it advised to try and land into VFR traffic who have no idea that you're coming-in out of nowhere?

Appreciate all the answers. Thank you!

PS - Here's the Low-Enroute chart for quick reference:

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3 Answers 3


The answers to these questions can be found in the AIM in section 6-4-1. All quotes are from that page.

To the first question, you should expect to receive a clearance to 8,000 feet twenty minutes after departure; therefore, don't climb above 4,000 until that time. If you are still in radio contact after 20:55, the "expect" portion of the clearance expires:

If the pilot received an “expect further clearance” containing a higher altitude to expect at a specified time or fix, maintain the highest of the following altitudes until that time/fix:

(1) the last assigned altitude; or

(2) the minimum altitude/flight level for IFR operations.

Upon reaching the time/fix specified, the pilot should commence climbing to the altitude advised to expect. If the radio failure occurs after the time/fix specified, the altitude to be expected is not applicable and the pilot should maintain an altitude consistent with 1 or 2 above.

For the second question, the answer comes down to the definition of "briefly". Is your hole big enough for you to get under the clouds, and is the ceiling high enough that you can remain VMC to land? If so, you should do so. But if you just briefly see the ground, or aren't confident that you could safely fly VFR to a suitable airport, then you should maintain IFR and continue flying your clearance. You may inconvenience a few controllers, but if you leave your cleared route only to discover that your intended airport is socked in, getting back to your route to resume your original destination puts you potentially low to the ground, and not along the route that ATC is expecting you:

Pilots should recognize that operation under these conditions may unnecessarily as well as adversely affect other users of the airspace, since ATC may be required to reroute or delay other users in order to protect the failure aircraft. However, it is not intended that the requirement to “land as soon as practicable” be construed to mean “as soon as possible.” Pilots retain the prerogative of exercising their best judgment and are not required to land at an unauthorized airport, at an airport unsuitable for the type of aircraft flown, or to land only minutes short of their intended destination.

That said, VFR traffic should always be looking for other aircraft - with and without radio contact. Radios are not required equipment, at least at non-towered airports, so landing among VFR traffic without a radio should not be a big deal.

  • $\begingroup$ What, no squawk 7600 anywhere in your answer? $\endgroup$
    – user
    Commented May 29, 2018 at 8:21
  • 2
    $\begingroup$ @MichaelKjörling Procedures like squawking 7600 are mentioned in the question. This answer is strictly about what route and altitude to fly. $\endgroup$
    – NathanG
    Commented May 29, 2018 at 14:07

The reference to “small private jets” and altitude is invalid. Our C550B has a ceiling of FL450, and the B737-800 I used to fly had a ceiling of only FL410. Most “small” jets fly higher than “large” jets. Many times due to limitations, and most of the time due to climb performance and or speed envelopes based on weight.

As for making a cell phone call from the plane... fly first, then comm. Sure, try it, but digital cell towers are directional in the vertical plane and are sketchy above a few thousand feet. Also, cell tower hand-off is hard to rectify when above a few thousand feet. Analog would be the way to do it, but you’d better be operating to FAR compliance first. Remember, ATC isn’t waiting for your attempted cell call.

I’m assuming this OP aircraft only had a single comm radio? Not ideal. Even a handheld makes a good backup. I’ve lost COMMS several times over the last 30 years. Some were single point failures, some were electrical failures... only one required light gun signals at the destination.

Know your clearance ‘limit’ and ‘expect’ status. How many note OFF time? How do you know your expect clearance time without it? Guess? Not ideal.

In the case of the OP, the limit is direct SSI and 4000. The expect is AF and 8000 in 20. With lost COMMS, expect trumps limit after the time expires. Then fly as AF, arrive at approach FIX on time, fly the approach. Look at the tower for the green. If VMC en route is encountered, squawk 1200 and that will cancel your IFR. But, think about that clearly before you make that commitment. 152 cloud clearance until you can land.

With newer multifunction GPS/NAV/COM units, you drop a lot of gear with a single point failure. Have a backup for both COM and NAV.

  • $\begingroup$ Also, at some point, check to make sure you didn't accidentally hit the radio's on/off switch. $\endgroup$
    – Vikki
    Commented Dec 15, 2021 at 3:02
  • $\begingroup$ "The limit is SSI... the expect is as filed." I don't believe that is accurate. The clearance limit is Tampa Airport—just like FSS said, "cleared to the Tampa Airport via direct SSI, then as filed." Now the assigned altitude is 4000 and the "expect" is 8000, that is correct. $\endgroup$
    – randomhead
    Commented May 2, 2022 at 20:05

Cell phone, Call the tower, that's what the controllers want. Might not work with a jet, but most GA should be low enough. Always try to have the towers number.

Your over complicating things.

  • $\begingroup$ I suspect you'd be hard pressed to use a cell phone reliably at much of the altitude where IFR flight is common. (And if you're really in a pinch, there's no reason why you couldn't slow a jet down to make a call, so the distinction between "jet" and "most GA", which I take that you're using to refer to piston aircraft, isn't the relevant one.) Cell phone base stations are designed to direct the signal along and toward the ground, not into the air. If able then using a cell phone to contact ATC is a possibility, but it sure isn't one I'd count on having available above a few thousand feet AGL. $\endgroup$
    – user
    Commented May 29, 2018 at 8:20
  • $\begingroup$ the Op was talking 4-8k, for terrain clearance even a small privet Jet would plan higher than that, and since cell towers are usually put on the tallest mountains around, actual vertical distance to the cell tower would be much less. have seen 3 bars + at around 5k + agl. $\endgroup$ Commented May 29, 2018 at 8:31
  • $\begingroup$ @wanna-beCanadianPilot However, cell phones signal is not omnidirectional and you may not maintain good signal throughout the journey. In Europe, your better luck would probably be 112 as that gets signal from any station, no matter which GSM provider you run under. $\endgroup$
    – yo'
    Commented May 29, 2018 at 12:49

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