Accidental IMC

[Wally]

What’s missing in this discussion so far is reference to the fact that the term IIMC covers a whole lot of ground. Especially so considering the fact that helicopters are allowed tremendous latitude in VFR operations. What we’re really talking about is flying without adequate external visual reference.

You could have unobstructed VIS without “adequate surface reference” in lots of technically legal VFR conditions, for instance in a white-out/flat-light condition, or at night without lights on the ground, both of which have resulted in loss of control and/or CFITs. Also, I’ve been offshore on calm, hazy days with official VFR vis and ceiling when altitude determined effectiveness of surface contact- too high, and reference sufficient to control the aircraft was problematic. You can also overfly your reaction time, your ability to ‘see and avoid’, in nominal VFR conditions. It’s not as simple as just flying into a cloud and crashing.

In a VFR ship, it IS as simple as NEVER, EVER allowing yourself to be trapped. That means I chicken out long before the weather is IMC, and no regrets- I have been what we’re talking about as IIMC- day and night; 200’ to 10,000 AGL; and I don’t like it. If you’re not equipped and proficient, IT WILL KILL YOU! Even with equipped and proficient, it’s an emergency that requires the pilot do everything right transitioning into the IFR system- fly the aircraft, confess, climb, communicate, etc.

If it’s becoming more work than you like and there’s any doubt about outcome, there is no doubt- land! If you find the weather pushing you lower and slower than normal and prudent, it’s time to quit. If quitting under complete control means landing in a pasture, parking lot, or elsewhere, do it- and survive. If you have some time for discretion and picking a place, head away from the most threatening weather, but never leave a potential landing site for another unless you’re dead certain you can reach it. The idea is always to land before it’s an emergency, don’t push it.

Edited February 9, 2009 by Wally

[Gomer Pylot]

Yeah, I've been there. Vermilion Bay, with the brown water blending into the brown sky, it can be hard to tell up from down, even with several miles visibility. I've been fairly uncomfortable flying there, and also flying offshore at night with no lights, or maybe worse, just one light way out. That light starts to move around due to the autokinetic effect, and it can get really strange feeling. The only cure is to get on the instruments. There are people who fly 206s around offshore at night, and all I can say is good luck to them, because they really need it. I know of one R44 that crashed offshore on a moonless night, killing the owner of the company, and that same company had previously lost a 206 out there, and no trace of it was ever found. While technically VMC, it was more than those pilots could handle, and the R44 pilot was >70 years old, with lots of experience.

[Linc]

I'd like to echo Wally, Gomer and JD. Make the weather call on the ground. If I encounter x ceiling or y vis, I'm going to abort. If I'm uncomfortable, I'm going to abort. Too many IIMC accidents happen from pilots pushing a marginal situation, presumably because the pilot is relying on the hope that he can make it or that the weather will improve in the next minute. Now, hope is a plan, just not a very good one, and certainly not one you can count on all the time.

 

If you can't control the weather, control the weather decision.

[JDHelicopterPilot]

Wally started to hint in a good direction. Remember, IIMC doens't have to mean flying into a cloud. Just loss of visual reference of ground/horizon. This could be on hazy days offshore like Wally and Gomer pointed out. I had a fellow pilot tell me once an interesting thing. They were flying back to base offshore and the CIG was about 400' with glassy like seas. They said they saw a bouy which was obviously in the water. Only problem was after looking at it they got the feeling like it was floating in the air. Such was the light conditions through the clouds and reflecting off the water made it all blend in. Sometimes in this case it will be like that while you are heading one direction but if you turn around it is different. It's all in where the sun is and going sometimes.

 

 

It could even be at night with limited or no ground/celestial lighting. Just food for thought.

[Wally]

Down is a very, very serious direction when you have attitude reference problems. You give up your obstacle clearance against the chance that you'll recover surface reference.

Often it works, way too frequently it doesn't. It's especially dangerous if you're low- like Rotor91, or in a situation of marginal surface reference- like offshore, but especially at night. If you're normal cruise is 1000 or better (I highly recommend this), a descending turn, or a descent out of a cloud is less risky- Repeat, descent OUT of a cloud, implication that you know the cloud is there and the base is high enough that you have lots of safe altitude when you recover reference. Fog, smoke, haze, rain, etc., limit your vis all the way to the surface. Best practice is if you're low and you're uncomfortable, especially if you're slowing down, it's time for careful consideration of what you're doing, and unless you have really good options- you KNOW what the weather situation IS and you have IFR recovery available, it's time to quit.

As to an autorotation as a means to recovery to better reference, all the preceding is still true. In an auto descent, you're still going to have attitude reference and control issues in a high speed descent, hoping to get down before you lose control and praying that your vis is adequate for the decel and landing, otherwise you're just rushing to the crash site.

Me, I plan on a hard minimum vis- when it's less than that, I quit- period. No hoping or praying or guessing, I'm going to be on the ground wishing I was flying.

 

You want the instant benefit of 40 years of helicopter flying? I'm very, very good at not going, or not continuing the flight. The cliche is "practice makes perfect" so I recommend you start practicing now if you want to get 40 years of experience.

Edited February 10, 2009 by Wally

[heli.pilot]

You want the instant benefit of 40 years of helicopter flying? I'm very, very good at not going, or not continuing the flight. The cliche is "practice makes perfect" so I recommend you start practicing now if you want to get 40 years of experience.

 

Thanks for the advice, Wally. I wish your conservative ADM was the norm.