AOPA ASI Icing Video

[Great Ozzie]

I have noticed in various posts... I wish A2A would model icing etc.

I just watched an AOPA Air Safety Institute video Picking Up Ice. Just four minutes long but worth the time.

Also, there is a "Real Pilot Story" link on that page - an interview of a guy that survived an icing encounter in a C172. Audio mainly, but it does include some of the transmissions between ATC and the pilot. Very good too, to check that.

One of the points the pilot makes at the end is, "it's much simpler, if you're clear of clouds, and you notice you're below freezing, stay clear of clouds." This was precisely my primary tactic to avoid an encounter with ice.

As one of the last slides in that presentation states, Icing conditions are no place for an aircraft without approved de-icing capability. They're often no place for aircraft with that capability either!

[Lewis - A2A]

It's the difference between sim flyers and real pilots. Sim flyers often fly in conditions real pilots are either forbidden or would never fly in. Some of the Autopilot support issues simmers have encountered show some of this.

I would like to think that one bit at a time Accu-sim technology is helping to change some thinking and bring some aspects of simming inline with the real world. I know I'm learning so much myself every month.

Thanks,
Lewis


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[taildraggin68]

Great video Rob.

[ft]

It's certainly one aspect of FS which could be expanded upon.

If you have ever seen the ice shapes used for certification, you gain a certain amount of awareness that in-flight icing is not to be taken lightly.

I've spent a fair amount of time watching ice accumulate on the airframe as our mission pretty much had us stuck in the much where ice forms, and it is pretty amazing how fast it builds. You literally see the ice horns growing on the leading edges. Even with anti/deicing, snow grains in the METAR was one of the things which usually meant a scrubbed flight. It can go from nothing to bad very quickly indeed. And I don't think I've even seen icing which should be termed heavy, when looking at the definitions... although that was a subject of debate within the crews.

In the bugsmashers, I won't go near exposing myself to icing. The zero-degree isoterm is a barrier to cloud-flying as far as I'm concerned. I've gotten icing in solid cloud in cruise once in a C172 (including carb ice) and while it wasn't to a degree which had me concerned it certainly had me thinking. I was grateful that my own personal requirement for single-engine IMC flight is to have enough clear air under the cloud coverage to be able to descend and, if deadsticking it, have a reasonable chance of finding a landing spot. That also leaves an 'out' for ice accretion. Don't ever count on being able to climb on top in the SEPs!

That said, I'd say it is one of the trickier things to get right in a flight simulation. It's been tried and gotten all wrong before (I think it was a feature of AS?), and it was by far worse than not having it simulated at all. The risk has to be real, but it can't be a simple and predictable on/off thing. Once you have icing, it has to be gradual and then you have to get the feedback right and in tune with the performance degradation.

Cheers,
/Fred

[Tailspin45]

AVSIM library has a freeware add-on called Ice Gauge, and Sim Physics X does a credible job of modeling ice and effects.

You can't see it on windshield or wings, of course, but the effect is there.

If you go the Sim Physics X route be sure to turn virtually everything else off so it doesn't fight with built in Accusim features.

Interesting discussion of FSX icing, BTW, at http://a2asimulations.com/forum/viewtop ... 86&start=0

Years ago I had an interesting ice experience in a Tri-Pacer late at night over Eastern Pennsylvania enroute from New York to Columbus. A layer of clouds and ice extended from 6000 to 9000, clear above and 40F+ below, so when I started picking up ice I decided stay in the goo to see what would happen after telling Center I might want a descent. Windshield was quickly completely covered, and within minutes wings developed about 2" of rime, and apparently the prop did too, because even at full throttle I couldn't maintain altitude.

One unplanned part of the experience was that I lost comm just at the point I was going to ask for lower. Squawked 7600, started down, and shed the ice quickly. Turned out the ice broke the VHF whip off the aircraft. I faintly heard the controlled say I was cleared to landed nordo at KPIT. So turned back, and after watching cars on the Pennsylvania Turnpike pass me while I was showing 120mph IAS landed about midnight. Spent the rest of the night on a couch in the FPO, and snuck out next morning in CAVU weather after coordinating a no-radio taxi and departure.

Probably not a smart idea, in retrospect. But a valuable and convincing lesson about what ice can do.

[AKar]

A proper dynamic simulation of icing would be very cool one day. I'm with Fred in following:

That said, I'd say it is one of the trickier things to get right in a flight simulation. It's been tried and gotten all wrong before (I think it was a feature of AS?), and it was by far worse than not having it simulated at all. The risk has to be real, but it can't be a simple and predictable on/off thing. Once you have icing, it has to be gradual and then you have to get the feedback right and in tune with the performance degradation.

Especially, given the limitations in FSX weather system, care should be taken so it won't get overdone. While icing can get one in serious trouble, not every winter day and each cloud up there should try to kill you all the time. It's not entirely unlike wind and turbulence simulation in today's weather programs in certain circumstances.

While serious encounters and close calls with icing get much attention in scary stories, it is of course good to remember that in many places big part of the year is prone to introduce icing conditions at altitudes where GA airplanes fly. In general, it is a part of business that needs to be understood and handled accordingly. Airplanes that lack approval for FIKI lack quite a bit of utility, making them practically day VFR (or good visibility IFR) airplanes. But today quite many GA airplanes can be equipped with prop anti-ice and with de-ice boots and/or TKS system. With those, winter flying gets rather practicable, though of course they add costs in maintenance. But regardless of anti-ice equipment, even planes like commuter/regional turboprops pick some quite visible amounts of ice that often won't even shed until flight's over, it is important to be able to follow the accumulation, make educated conclusions of it, and be prepared to adjust one's plan once the icing is not insignificant in amount any more.

-Esa

[Nick - A2A]

Rob,

Thanks for posting the video. In particular I found the section towards the end on pitot and drain port blockage useful. Perhaps this is something we may see in a future enhancement to the Accu-Sim ASI behaviour? As far as I'm aware, currently there's no scope for pitot drain blockage in Accu-Sim (or FSX in general). I'm aware that A2A uses custom coding for pitot tube obstruction (by the pitot cover anyway) and presumably the static port blockage coding is also outside of FSX. (I've never flown with the static port blocked, but if I encounter another sinister taped-over static port during a future pre-flight, I may be tempted to!)

My understanding is that the default FSX static port failure leaves a bit to be desired, in that the ASI needle should move but over-read in descent but under-read in climb instead of just 'freezing'. (ref). Not sure if the Accu-Sim version improves on this behaviour, but if the aggrieved individual with the roll of tape returns, I made get the opportunity to test it out...

With respect to airframe icing simulation in FSX, I've been hoping we'll see something really good developed since reading the rather terrifying fifth chapter in Ernest Gann's Fate is The Hunter. The Majestic Q400 does seem to be pretty impressive in this area...

Cheers,
Nick