Then you tell them how long you think it will be (say, 20 minutes), and they will give you a "hold for release" clearance. You get the route/altitude/squawk/freq, but also an instruction to "hold for release". They will then tell you to call back when you're ready to take off (engine running, run-up complete, route loaded in the GPS, etc,), and they will give you the release for IFR departure and a short (3-5 minute) void time -- and off you go.
If you were given a "hold for release" clearance and take off without obtaining a release, or if you get a clearance and release with a void time and take off after your void time, they will be very upset with you. You can certainly take off VFR without having obtained a clearance, but then you're at the mercy of a lot of factors including other traffic and controller workload as to getting your IFR clearance in the air.
This is one of those "it depends" things. Anywhere I've flown in Michigan, I'd agree with you. If the MIA is xxxx feet they typically ask you if you can maintain your own terrain and obstruction clearance through xxxx. In Vermont, if you try to pick up in the air ZBW will tell you they can't give you the clearance until you reach xxxx. If that happens to be in the clouds, tough teletubbies. Or they word it as "reaching xxxx feet cleared to Nashua airport via..." or whatever. Even so you can usually GET the clearance before entering the clouds with a little finagling, but it's a hassle. Today when I drove to the airport to leave for Michigan there was a low cloud deck that was in the process of scattering out. By the time I was ready to depart I could have gotten above it okay VFR, but it was really no harder to just call them up on the ground. For reasons I don't understand, that actually works - they give you the void time clearance with no restrictions on the altitude at which it takes effect, and usually no heading restriction either, maybe because there's so little traffic it's not needed.
That may be your personal decision, but I find it works all over the Eastern 1/3 of the USA just fine, including some really busy places like around Solberg NJ with NY TRACON.
You do not get your clearance like that. What you get is an expected routing, and what you get from ATC isn't always the same as what you got in that email/text.
You can do that, but there's no greater guarantee of actually getting your clearance from ATC promptly with that method than with any other method which involves departing VFR. You are always at the mercy of other traffic and ATC workload, so you could have a very long wait for a clearance if you're at the bottom of their IFR priority list.
I know. I was just countering the general "always depart VFR if you can" tone of the thread, since there are places where it's not a good idea even when under the same wx conditions it would be fine somewhere else.
Just as it says in Section 4-3-4b. Nothing there says you can only issue a "hold for release" clearance when the pilot is ready for departure, and every TRACON in the eastern third of the US is doing that, and doing it the way I described, so it must be pretty standard.
There is nothing in FAA Order 7110.65 authorizing controllers to issue a clearance on the ground and then a release once airborne. If you're going to do this, make sure ATC knows your plan before you take off so they can coordinate things properly and you don't set off alarms (say, by using your IFR clearance code).
Yes, if conditions are VFR you can always turn back. But when the only inconvenience of getting the clearance on the ground is having to read back a void time, what's the downside? As I said, if you try to pick up the clearance in the air in VT they will not issue it easily until you are at the MIA for the area, which around my home field is 5400. To me it's a no brainer to call them from the ground if there are any clouds around lower than that.
