Bonus! Two Flying Friday posts in one day (here’s the other one.)
There’s a difference between flying under instrument flight rules (IFR) and flying in instrument meteorological conditions (IMC).
When you fly IFR, that means you’re flying on an instrument flight plan, along a defined route, in communication with and under positive control of ground-based air traffic control.
When you fly in IMC, that means you are flying “primarily by reference to instruments,” as the FAA puts it. That basically means that you can’t see a discernible horizon. You can fly IFR in good weather or bad. If you’re flying in IMC, you must do so under IFR. If you’re flying in visual meteorological conditions (VMC, what normal people call “good weather”), you can fly under visual or instrument flight rules.
Actually, I should clarify just a bit– VMC isn’t necessarily good, it’s just that IMC is defined as “weather worse than the standard VMC minimum visibility and/or ceiling.”
This whole post is basically just an excuse to post a short video showing one example of flight in IMC. I took it while en route from Decatur to Tampa Executive; on that 3h40min flight I was in the clouds for just under an hour.
You can’t see a visible horizon, although the sun was semi-visible through the clouds. (If you take a look at the iPad screen, you’ll see why it was so cloudy.) Surprisingly, on a sunny day, the inside of the cloud can be very bright with diffuse light, leading to the somewhat odd behavior of wearing sunglasses while flying inside a cloud that blocks the sun from the ground.