Most of you here have a lot more experience than i do, so I'd like to ask some questions that I've been wondering about so I can learn from you all.
1) While flying in cold weather during VMC, and often at night, when the strobe goes off and I look at the area around the strobe, I see what looks like rain flying by... but there's no precipitation. Does anyone know what this is? When I turn the landing light on it also looks like precipitation flying at me, but again, its not. Are these the 'ice crystals' in the air?
2) The last experience I had flying in IMC below freezing was at 9,000ft and I was near the tops. OAT -6C and no ice. Is this because there wasn't enough moisture in the clouds?
3) I've heard people say if you get icing you should climb. Flying a Cessna 172, climbing isn't something its too good at if I'm already at 9,000 feet.. But assuming I had more power, why is climbing the better course of action?
4) The general consensus I'm getting from this thread is flying in IMC below freezing is not the definition of FIKI, but most people wouldn't fly into the clouds if the OAT is below freezing. Am I correct?
To add to my list of questions above..
5) Is flying through snow considered flight into known icing? It is frozen precip isn't it?
For the record: I have very little real winter weather IFR experience actually but I have a ton of time in studying weather, including some great college level aviation weather courses long ago.
1) Hard to say what you're seeing. If it isn't sticking to the aircraft (snow sometimes will by ramming into the leading edge but that's not quite the same thing as structural icing), nothing to do but monitor it.
2) Maybe. At -6C it may all be frozen and bouncing off.
3) Climb is recommended because you're more likely to descend into freezing rain than to climb into it, but if there's an inversion layer (seen best in a Skew-T chart for the area) that's not always going to hold true. Climbing in theory takes you to colder air where maybe ice won't form on the aircraft. It's a rule of thumb, not a guarantee.
4) I'd look at the Skew-T charts very closely along the route and also the frontal maps and see if I have both a reasonable "out" where there's little or no visible moisture to be able to "bail out" toward and whether or not there's any PIREPs. The PIREP system being what it is, and also because of a lowering of options, my personal alert level would be much higher overnight and early in the morning about possible ice before anyone is "up in it" because the PIREPs really don't start showing up until people start flying for the day. Nobody except the poor schmuck stuck at low altitudes in an underpowered aircraft without FIKI gear has a front row seat or knows the complete icing picture, until they're reporting it to ATC or Flight Service, or it's you with the front row seat seeing it form on the aircraft. And it's time to do something about it RIGHT NOW in most bugsmasher type aircraft when you see it. Plowing on and seeing if it'll "get better" obviously is the worst possible option. Think of it as the first poor schmuck that flew on a "maybe turbulent" day who now is being bounced off of the ceiling and has a divot from their headset in their head. Time to divert or turn around or climb or descend or whatever the hell will get you out of it. (Besides slowing to Va. Ha.)
5) In my opinion, no. Snow is forming somewhere above you and may be falling out of a cloud above. That's not structural icing conditions, that's just that you're getting snowed on. The thing to know if under clouds that are dropping snow is that icing conditions are above. Are you flying toward the front or away from it? Are you flying toward the shallow edge of the front or the deeper? Paralleling it? Where's your "out" if the freezing stuff comes down to meet you? Did you look at the Skew-T predictions along your path and do they show you headed for colder air or warmer? How about where the bump is where the bases should start? Can you see the bases? Do they match the prediction? If not, why not? Etc.
It's weather. It'll always surprise you.
For an analogy that isn't too bad, it's no different than having to divert around thunderstorms in summer over the Great Plains. (Which is a bit easier, since you're usually CAVU in-between them and just watching where you shouldn't be.)
Freezing stuff requires you imagine where the bad stuff is and visualize it in your head instead of with your eyeballs -- using all of your weather knowledge, whatever you've got.
Flying directly into known freezing stuff or a widespread area of conditions that are producing structural ice on other aircraft (often aircraft with better performance and more anti-ice gear on board than I) is as similarly deadly as flying into embedded thunderstorm activity -- where you can't see them to go around them, to continue the analogy.
You use every piece of information you can get your hands on and everything you know about weather to think it through before departing. If you encounter stuff you didn't expect, it's time to bail out via your pre-planned "out" and get out of it.
And like any other weather decision: If you're not comfortable going in the first place, don't. Especially if you're flying for "fun". Launching with a gut feel of a bad outcome often results in exactly that. I'll go if I can reasonably make a decision that says the outcome of the flight will be positive.
If I can't figure out a way that it would or there's a big question mark in the flight plan, I might call someone who's done more of it for an opinion (while knowing I'm still PIC) who can peek at forecasts with me, or I might just say it's not worth it and scrub the flight.
Or maybe there's a way to go a couple hundred miles out of my way and circumnavigate the crud? If I don't mind the bigger fuel bill and another fuel stop, the "penalty" of flying more is rarely a show stopper for me. I'll just fly around it.
All sorts of options. Welcome to being PIC in adverse weather... I hear there's a two drink minimum at the far end if you screwed up enough to make your knees shake and vow to never do something that stupid again. Heh.
Going back to your original scenario: Night IMC by the numbers is the absolute most dangerous thing anyone can do single pilot, GA, single engine. It should give you some significant pause that you're seeing something outside the window you don't know what it is. Which it sounds like, it did, which is why you're asking. Don't forget to check your operations against things you know are killers in the crash records. Anytime you're doing something people crash a lot doing, always ask yourself, "Should I really be doing this now?"
Some people won't even fly at night in a single. Let alone IMC. I respect that. There's a personal risk assessment that needs to be taken seriously by the PIC.
