"While flying VFR with advisories we realized that the broken clouds below now completely obscured the ground. Without declaring an emergency, what would be the call we could make to ATC for an instrument letdown through the clouds? The pilot was instrumented rated." - Ed S.
“Simply request a pop up IFR clearance. Provided that you are at or above the MIA (minimum instrument altitude) and subject to workload, the controller should be able to provide an IFR clearance.
MIA is the minimum instrument altitude, that can be the minimum enroute altitude (MEA), minimum vectoring altitude (MVA) or minimum obstruction clearance altitude (MOCA).
In most cases if you’re on top, you are already above the MIA, in which case a clearance shouldn’t be a problem.
But if you’re under an overcast and may be below the MIA, your options then become…climb if you can still maintain VFR; maintain your own terrain and obstruction clearance until reaching the MIA; or land and file a flight plan.
After issuance of the pop-up clearance the controller may also direct you to call flight service to file an IFR flight plan for search and rescue purposes. And that’s where you would record the information such as color of the aircraft, number on board, fuel, etc.
Once you get the pop-up IFR, the clearance may be all the way to your destination airport. It may be to another airport, to allow you to shoot an approach and continue VFR underneath. Or it may simply be to a fix (such as a VOR or intersection) to allow a descent or climb to VMC.”