Uncontrolled Inadvertent IMC to IFR - what to squawk?

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nbinont
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Uncontrolled Inadvertent IMC to IFR - what to squawk?

#1 Post by nbinont » Fri Jun 19, 2015 7:37 pm

Hypothetical scenario for the Centre/IFR Controllers...

Imagine there's an uncontrolled VFR aircraft squawking mode C (1200/1400), maybe scud running, maybe really unlucky with weather, or just maybe not very good at reading weather and flight planning :rolleyes: . Point is they're uncontrolled and not speaking to anyone. They happen to be instrument rated/current(fat chance, I know - but just roll with it) and determine the safest course of action is an immediate climb to MOCA/MEA(if they remember it) then to try speaking to someone. But they're horribly unprepared and it's going to take them some time to retrieve their IFR charts and figure out who to speak to while flying in cloud.

Is it generally preferable for the aircraft to squawk 7700 or remain on 1200/1400, given that they aren't speaking to anyone yet?

I'd think that since they're squawking mode C, whatever collision detection algorithms would pick it out on the screen regardless of what code it is squawking, and TCAS would likely trigger eventually. But would the extra attention of a 7700 be valuable or just irritating?
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Re: Uncontrolled Inadvertent IMC to IFR - what to squawk?

#2 Post by ahramin » Fri Jun 19, 2015 7:56 pm

Fairly simple. If you want to tell ATC you're in trouble 7700.

I would think flying the airplane would keep you fairly busy. Navigating clear of terrain would be a priority. Contacting ATC on the radio would be the next priority. Once you've done that there's no point in 7700 as they already know.

As for TCAS, no effect.

So I can't think of any time during a VFR in IMC emergency that it would make sense to take time to do that.
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Re: Uncontrolled Inadvertent IMC to IFR - what to squawk?

#3 Post by photofly » Sat Jun 20, 2015 5:10 am

It doesn't make any difference if in that situation you are instrument rated and current, or an IFR Virgin. The correct thing to do is to exit IMC right away. If you decide to climb and stay in IMC because you think it's safer, you're improvising. Of course that's your absolute right as as a PIC, but if you cause a midair by doing so, you're decision as to what was safer probably wasn't the right one.


Looking at the question another way: after your flight, when you sit down with tea and biscuits to chat with a CASI, how much of the discussion do you think will focus on whether you picked the right transponder code?
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Re: Uncontrolled Inadvertent IMC to IFR - what to squawk?

#4 Post by nbinont » Sat Jun 20, 2015 11:57 am

Thanks for the responses ahramin, photofly.

photofly, yes, in the scenario the aricraft would be well off it's original plan (if it had one!), so it would be improvising. No sane person plans inadvertent IMC. But if it does happen, the instrument pilot has an additional escape route that would be (statistically) fatal to the VFR pilot - namely climb to the MOCA. A VFR pilot entering cloud has to get out fast - certainly an emergency. But an instrument pilot entering cloud is not necessarily an emergency - instrument pilots fly in cloud every day.

The question really is: what's the safest way to make the VFR -> IFR transition from inadvertent IMC from a controller's perspective. The controller may not know the pilot is in IMC until the pilot tells them. And unless anyone tells the controller otherwise, the controller can reasonably assume that that an aircraft squawking 1200 is in VMC and is managing their own separation, when in fact this is not the case here.

As ahramin mentioned, priority #1 is obstacle clearance and flying the plane. Priority #2 is to speak to ATC to ensure separation from other aircraft and avoid that midair. But there's two ways to communicate with ATC: radio or transponder.

The transponder is faster - it takes 2 seconds to get the code in. (obviously to be followed up by the radio.)

With the radio, the frequency needs to be determined(did they get the right frequency for their altitude and location?), then there may be a lot of radio chatter and the aircraft has to wait a bit to speak, and once they are speaking, ATC still has to assign them a code and find them on the radar screen.

So basically, as a controller, if there's an uncontrolled aircraft you're not (yet) talking to on a collision course with an IFR flight you're managing, would the squawk code make any difference?
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Re: Uncontrolled Inadvertent IMC to IFR - what to squawk?

#5 Post by PostmasterGeneral » Sat Jun 20, 2015 12:09 pm

Fly the plane first. Get to MEA. in the meantime, ATC will keep other traffic clear of you. Then, squak 1000, find your appropriate frequency, and pick up a clearance. Simple. It's not an emergency.
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Re: Uncontrolled Inadvertent IMC to IFR - what to squawk?

#6 Post by photofly » Sat Jun 20, 2015 2:32 pm

Last time I tried to pick up a pop-up clearance, the controller asked me point-blank if it I was declaring an emergency, and if I wasn't he refused to talk to me. He said I should get in touch with London FIC and file a flight plan with them. And only get back to him to ask for a clearance when I had done so.

I'd say (and that ATCO would probably agree) that flying in controlled airspace in IMC and being unable to see and avoid, and not having a clearance, probably does constitute an emergency.
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Re: Uncontrolled Inadvertent IMC to IFR - what to squawk?

#7 Post by kev994 » Sat Jun 20, 2015 4:30 pm

I pick up pop up IFR clearances almost daily, I've never had a problem.
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Re: Uncontrolled Inadvertent IMC to IFR - what to squawk?

#8 Post by photofly » Sat Jun 20, 2015 5:02 pm

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