Icing Go/No Go practice problem

[tonycondon]

tommorow morning 12Z departure at Ames, IA. Des Moines TAF:

KDSM 050529Z 050606 33010KT 3SM BR OVC003
FM1200 35010KT 1 1/2SM BR OVC007
FM1800 36012KT 1SM -SN BR OVC003
FM2300 36015G22KT 1/2SM SN BLSN FG OVC001

so weather will be above minimums for the ILS and Localizer
approaches, as well as the VOR/DME.

Winds Aloft forecast for 3,6,9 thousand feet for 0900 to 1800 Z:

DSM 0321 3108+02 2622-02

+2 at 6000 feet looks encouraging.

Area Forecast for Iowa:

IA
CIG OVC010 TOP 050. VIS 3SM BR. 13Z CLDS LYRD FL180. OTLK...IFR
CIG BR BECMG IFR CIG SN FG 18Z-20Z.

Forecast Icing Potential at 3000 feet is shown next. 1000 and
5000+ show no potential for icing.

to compliment that chart here is the Forecast Icing Potential from the Experimental ADDS site for 1100Z (closest available):

Seems that the charts are of the same form, but the Experimental version has at least a 20% lower chance of icing than the chart from the mainstream site. Oh here is the forecast icing severity from Experimental ADDS too:

So the way im seeing it so far is somewhere between a 50 and 100% chance of light ice at 3000. The RUC Sounding for 1200 Z at Ames:

I can see the 700ish AGL ceilings, followed by what seems to me to be "thin" (not fully saturated) clouds with tops around 3600 MSL. So it seems about a 2000 foot thick layer of possible icing. Would the slight temp/dew point spread be what is holding the experimental FIP from going to the 75-100%? There is a little bit of above freezing temps up there around 5000 thanks to the inversion that is dying. Even the next hours sounding shows temps right around zero going up, never greater than.

So whats the call? I would like to see a couple things before I was really comfortable departing in this:

1) It would be nice if the mainstream CIP/FIP came down on their probability from the 75-100% range

2) If they didnt, the severity in the Trace range would be good

3) more warmer air aloft to help shed any ice that may be picked up on the quick trip through the layer.

4) being darn sure that ceiling and vis would hold so I wouldnt have any worries about getting home on the first try!

How about you?

 

[deafsound]

Nope,
Not going. Not comfortable with the situation.
Just my opinion. I would rather it be 20 below.

 

[Steve]

4) would be my main concern The general trend after 12z is worsening conditions. It seems things tend to worsen more than forecast when the trend is in that direction. You didn't say how long until your return flight. The FG could easily develop earlier, pushing both CIG and RVR below your capabilities.

 

[sba55]

I agree with Steve. Others here will be able to shed more light onto this from a weather standpoint.

What I would do is wait until departure time, confirm the tops, check pireps, see if anyone has departed recently and got through without lots of ice...and if it came to it, 2000' with a chance of light ice would be fine with me. Unlike the Cirrus/Columbia, the Bo wings are quite good dealing with ice. Worst I've had was about 3/4 inch, and I didn't notice any loss of airspeed/handling.

-Felix

 

[vontresc]

On a side note, I am just getting into reading the Skew-T charts. Is there any good resource for explaining how to read those?

Pete

 

[tonycondon]

4) would be my main concern The general trend after 12z is worsening conditions. It seems things tend to worsen more than forecast when the trend is in that direction. You didn't say how long until your return flight. The FG could easily develop earlier, pushing both CIG and RVR below your capabilities.

yes of course i shouldve noted that those were not listed in order of priority

 

[RMCN172RG]

too many ifs and not enough options for me.

 

[bbchien]

Tony, you need FIKI for this one. You can make the flight but you have NO out. Surface is too cold. You're right that the warm nose at 5,000 is pretty dry- but NOT completely.

 

[TMetzinger]

Information needed and not given:

Type of flight - is this a flight departing Ames, arriving at Ames, or local instrument practice? If an X/C, what's the route of flight.
Type of airplane.
Reasons for the flight.

I wouldn't go launching into that stuff unless I had a very good reason, and either a deiced airplane or current confirmation about tops and icing, and high confidence in my ability to clear the tops with minimal ice.

So, in a Deiced Caravan, Cheyenne, KingAir, or Bravo/Bonanza/Baron/Cirrus- I'd launch if I was going somewhere where the weather was better AND I had a need to get there.

In anything less capable, or for any less urgent reason, I'd wait for better conditions.

 

[TMetzinger]

Trust, but verify... that's my motto. The PIREP is solicited for the icing, but the confirmation of the tops is helpful, because they show the conditions right then, not when the last sounding or IR pic or other model run happened. The key word is "current" in current conditions. The products are very clear about where the tops WERE located when the measurements were taken and the model was run.

I'll take an ounce of reality over a pound of modelling any day. I hope my point is clear, I'm not trying to run down the products, but getting a pirep 10 minutes before departure would be very useful to me. Getting that "We just went through and it was what we expected, trace rime, tops 3600" from someone could be the balance point for a go/no-go in a standard non-deiced single.

Make sense?

 

[TMetzinger]

Where's the "went over my head" icon? Actually I do understand that the uncertainty makes it unlikely that a high potential translates to a high probability.

Now I thought the CIP was operational and the FIP was not (except for dispatcher/meteorologists)?

 

[TMetzinger]

I hear ya Tim, but as soon as you put down that mouse...current becomes the past. It's the future that is important to me. Sure the past can provide some clues, but knowing what might happen in the future is more important...and yes, it is a risk...and "safe" doesn't imply "risk free" either. So forecast model soundings help depict how these conditions will evolve, otherwise you are using a snapshop in time.

In this case, the confidence was high. The "kind" of weather system made it that way. In other words, it has all the characteristics of a low and highly capped stratus regime with well-defined tops and dry air aloft.

Sorry, I'm still not clear. I want a PIREP less than 10 minutes old, over the radio, as I'm about to depart. So I want a "right now" verification in addition to the future predictions.

I think my previous post might have read I want a pirep (which could be quite old) 10 minutes before departure.

 

[gismo]

The best way that I can try to explain it to the layman is that the longer the forecast length, the more uncertainty there is, so the more difficult it is to have a high potential for icing actually translate into a high statistical probability.

I guess that explains why it seems that the icing probability always seems to get worse as the time for departure gets closer.

 

[flyingcheesehead]

tommorow morning 12Z departure at Ames, IA. Des Moines TAF:

KDSM 050529Z 050606 33010KT 3SM BR OVC003
FM1200 35010KT 1 1/2SM BR OVC007
FM1800 36012KT 1SM -SN BR OVC003
FM2300 36015G22KT 1/2SM SN BLSN FG OVC001

so weather will be above minimums for the ILS and Localizer
approaches, as well as the VOR/DME.

Winds Aloft forecast for 3,6,9 thousand feet for 0900 to 1800 Z:

DSM 0321 3108+02 2622-02

+2 at 6000 feet looks encouraging.

Area Forecast for Iowa:

IA
CIG OVC010 TOP 050. VIS 3SM BR. 13Z CLDS LYRD FL180. OTLK...IFR
CIG BR BECMG IFR CIG SN FG 18Z-20Z.

Wow, this thread is really making me question myself.

Given the above, one piece of the puzzle is missing: Surface temps. Below freezing, there's an inversion. Count me out - I can't descend into warmer air if I do encounter ice on the way up.

If it's +5 at the surface, I'd guess via interpolation that the freezing level is roughly 7500 feet, and the tops are supposed to be at 5,000. I'd file for 6 or 7 depending on direction of flight, and if I hit those "13Z CLDS LYRD FL180" and the freezing level is a bit lower (6500?) and I'm at 7, I'll descend to 5. I still have warmer air below if necessary. In this case, I'd say "Go!"

But now, I see all this stuff:

Forecast Icing Potential at 3000 feet is shown next. 1000 and
5000+ show no potential for icing.

to compliment that chart here is the Forecast Icing Potential from the Experimental ADDS site for 1100Z (closest available):

Seems that the charts are of the same form, but the Experimental version has at least a 20% lower chance of icing than the chart from the mainstream site. Oh here is the forecast icing severity from Experimental ADDS too:

So the way im seeing it so far is somewhere between a 50 and 100% chance of light ice at 3000. The RUC Sounding for 1200 Z at Ames:

I can see the 700ish AGL ceilings, followed by what seems to me to be "thin" (not fully saturated) clouds with tops around 3600 MSL. So it seems about a 2000 foot thick layer of possible icing. Would the slight temp/dew point spread be what is holding the experimental FIP from going to the 75-100%? There is a little bit of above freezing temps up there around 5000 thanks to the inversion that is dying. Even the next hours sounding shows temps right around zero going up, never greater than.

So whats the call? I would like to see a couple things before I was really comfortable departing in this:

1) It would be nice if the mainstream CIP/FIP came down on their probability from the 75-100% range

2) If they didnt, the severity in the Trace range would be good

3) more warmer air aloft to help shed any ice that may be picked up on the quick trip through the layer.

4) being darn sure that ceiling and vis would hold so I wouldnt have any worries about getting home on the first try!

How about you?

...And now I think I'm dumb. This stuff is still over my head. Tony, learn it well and you can teach it to me next time I see ya.

 

[tonycondon]

kent,

thanks to the generosity and patience of Scott and Bruce and others, I have managed to learn the tools. Sit back, crack open a cold one, and read and re-read these threads, and you too will figure it out somehow, like I did (sorta)

 

[tonycondon]

I'd suggest a case of cold ones...since you've only scratched the surface here Tony. So much to learn and so little time. I don't know if I want to sell you my CDs...it would be like a kid in a candy store.

LOL!

 

[TMetzinger]

Okay, now you've got that PIREP that provides you with the icing threat on departure. You decide to launch. You pick up some trace ice through the deck. Now you are bound for your destination which is two hours away.

Scott,

In my original post, I clearly stated that the among the unknowns for the decision was the route of flight - it's wasn't stated, so you can't take me to task for not thinking about it. Obviously an X/C flight would require looking at forecasts for the route. In fact, I said a "go" decision would require better weather at the destination.

We've now strayed far from our original point of divergence (which I think was due to the misunderstanding about my wanting some current information before departing through that particular cloud layer in a non deiced airplane), and you're assuming I disagree with the points you made. I don't. Depending on what the answers were to the unanswered questions about route and airplane and external pressures, I would make different go/no-go decision, using the forecast products.

Best wishes,

 

[flyingcheesehead]

I'd suggest a case of cold ones...since you've only scratched the surface here Tony. So much to learn and so little time. I don't know if I want to sell you my CDs...it would be like a kid in a candy store.

Tony,

I'm coming over with the CD's and a case of beer.

Real soon now.

When's your spring break?

 

[deafsound]

Okay, now you've got that PIREP that provides you with the icing threat on departure. You decide to launch. You pick up some trace ice through the deck. Now you are bound for your destination which is two hours away. You call EFAS and there's no PIREPs available along your route. How can you be sure you can stay on top and how can you be sure the icing situation won't change as you descend down through a similar layer at your destination?

Even if you had a dozen PIREPs at your destination before you left, there's no guarantee they will be available when you arrive. That stratus deck you were flying over now changed to a statocumulus deck 2,000 foot thick.

Here's an example of a thin stratocumulus deck. This is obviously a broken deck, but how much ice could one pick up here in these thin clouds?

Here's the result of going through that 500 ft deck....and no, I wasn't in the airplane. Fortunately, this airplane had TKS and was able to successfully remove the leading edge clear ice.

Those photos are of either a SR 20 or SR 22. Which is it?

 

[Dave Siciliano]

We're planning on flying from Addison (ADS) to Rockford (RFD) then Oshkosh (OSH) tomorrow. Looks like the current icing will have moved east a bit. We'll be in front of what ADDS labels an occluded front. Guess we'll have to wait until we get a little closer to see the Skew-T or CIP/FIP forecast. All I see on ADDS is forecast icing until later today right now. So, how does one kinna look in advance for planning purposes other than look at the major systems? And what about the planned return around lunch on Sunday?

Best,

Dave

 

[bbchien]

We're planning on flying from Addison (ADS) to Rockford (RFD) then Oshkosh (OSH) tomorrow. Looks like the current icing will have moved east a bit. We'll be in front of what ADDS labels an occluded front. Guess we'll have to wait until we get a little closer to see the Skew-T or CIP/FIP forecast. All I see on ADDS is forecast icing until later today right now. So, how does one kinna look in advance for planning purposes other than look at the major systems? And what about the planned return around lunch on Sunday?

Best,

Dave

Once you get about 12 hours out, Dave, I go to the progs as to where the front lines are. In the east, you look a the midwest currently and the progs for the future. But nobody can tell how quickly a front will move- there are only suggestions from the power of the baro drive pushing them; and you have to look at the upper level winds and pressures for a clue.

Dave: the Skew-T and CIP/FIP are tactical tools. We still have no new strategic tool. Those who shake their heads and say the weather is only what I see and it's "guessing", deny that the tactical tool is of any use; but I say with good tacticals live online and up to date, one has a good crack at avoiding Waterloo.

http://forums.aopa.org/showthread.php?t=39048

 

[B25Flyer]

Tony,

Let me answer your question quickly. Hell no, don't go!
Do not fool around in ice with low ceilings. There is not a good way out.

Always have a way out and often the best way out is to land. Landing an airplane with an iced up windshield requires ceilings high enough to be absolutely sure of no missed approaches and the option of circling to land if the w/s is iced up. I don't fly low IFR in the winter in non-deiced airplanes.

No matter what the forecast tools predict, often when they predict ice, it won't be there and sometimes when they don't call for ice, there will. In short, if you fly in the clouds in the winter, sooner or later you will get in the ice.

Scott D. has an amazing handle on the weather and doesn't agree with "rules of thumb." He is probably correct, but I don't understand the weather like Scott and I don't trust the forecasts. Sorry Scott.

I learned about ice hauling freight in Twin Beech and C-402's in North Iowa. It was a way of life for us. We had deiced airplanes, but deice is over-rated. Deiced or not, when you get in, get out. Deicing only prolongs the agony. I know it is not legal, but I would much prefer to be in a lightly loaded C-182 without deice than a gross weight FIKI C402.

When I started hauling freight it seemed like I got iced up all the time. After ten years of freight doggin' I seldom got iced up. The difference was learning how to get out and stay out of the ice.

Here are my thoughts about ice. These are rules of thumb, they did not come off a mountain carved in granite. For instance #9, there are times when climbing is the wrong thing to do. Turning around might make more sense, or if you know there is warm air below, descending is an option. Managing winter weather can't be boiled down to 12 bullet points, but it is a start.

#1 Never fly in Freezing Rain.
#2 Have a Plan, and a plan B. Landing is often plan B don't fly with low ceilings.
#3 Upon encountering Ice, take immediate action, in accordance with #2
#4 Never fly in Freezing Rain
#5 If the plan falls apart, implement Plan B and formulate Plan C. Repeat as necessary.
#6 Pilots almost always stop flying before the airplane. NEVER QUIT FLYING!!! Most airplanes will fly with OBSCENE amounts of ice on them. NEVER QUIT FLYING!!!!
#7 Never fly in Freezing Rain.
#8 95% of all icing encounters are less than 3000 feet vertically.
#9 Upon encountering ice, the default reaction should be to climb immediately. Descending is always an option, but if you descend and guessed wrong, climbing is no longer an option.
#10 Never Fly in Freezing Rain. Two exceptions to #9 if you encounter ice pellets or freezing rain turn around, as quickly as you can, do not climb.
#11 Do not let ATC fly your airplane. If you are on top and they want you to descend into the ice 40 miles from the airport, do not do it. Stay up high, then dive for the airport as late as possible. If you need to climb, ask once, and then insist on a climb even if it means you have to change heading to clear traffic.
#12 You guessed it, Never Fly in Freezing Rain.

In Frozen North Iowa I remain....

Tailwinds,
Doug Rozendaal

 

[gismo]

Tony,
I learned about ice hauling freight in Twin Beech and C-402's in North Iowa. It was a way of life for us. We had deiced airplanes, but deice is over-rated. Deiced or not, when you get in, get out. Deicing only prolongs the agony. I know it is not legal, but I would much prefer to be in a lightly loaded C-182 without deice than a gross weight FIKI C402.

That's worth emphasizing. Contrary to popular opinion, the total weight of airframe ice is rarely if ever a significant issue but the weight of the airplane and it's contents has a huge effect on the ability of any airplane (deiced or not) to cope with ice. The first thing you lose with an ice accumulation is climb rate and being light means you can lose a lot and still be able to climb. It also means getting through the typical 2000-3000 ft icing layer much more quickly and/or at a higher speed so you will collect less ice there.

#1 Never fly in Freezing Rain.
#4 Never fly in Freezing Rain
#7 Never fly in Freezing Rain.
#10 Never Fly in Freezing Rain.
#12 You guessed it, Never Fly in Freezing Rain.

So Doug, how do you feel about flying in freezing rain?

I'd add a few things I've learnedThey're pretty obvious but IMO worth mentioning)

If you are climbing and the sky is getting brighter, you are getting near the tops of the layer you are in and since ice tends to accumulate faster in the tops, it may be worth it to pitch up for a steeper climb briefly.

It's much easier to stay between layers and avoid ice during the day than at night.

Using a 1000 or 2000 ft block altitude can make the difference between being able to fly between layers and being stuck in the clouds. It also allows flying "WAFDOF" (wrong altitude for direction of flight) when ATC can't/won't give you an odd altitude and you need that for ice avoidance.

 

[bbchien]

Good to see you here, Doug. Bruce Chien

 

[sba55]

He is probably correct, but I don't understand the weather like Scott and I don't trust the forecasts. Sorry Scott.

I'm not Tony, but something bothers me about this post. This thread is specifically about using forecasts and weather models. It's not about "rule of thumb". Lots of people get killed by "rule of thumb", which is why we're all trying to learn how to use the tools that are available.

Tony,

Let me answer your question quickly. Hell no, don't go!

That's what bothers me I think. It's a very absolute, self-assured way of expressing a point of view. I happen to disagree with it, yet I'm not going to go out there and say "Yes! Go! You'll be fine!".

No matter what the forecast tools predict, often when they predict ice, it won't be there and sometimes when they don't call for ice, there will. In short, if you fly in the clouds in the winter, sooner or later you will get in the ice.

Very true. I believe it was Scott who said that it's not about getting ice or not getting ice. It's about evaluating the risk and keeping it at a level one is comfortable at. I will launch if there's a chance of ice (like, sub-zero in the winter) if that chance isn't too great for my personal risk limits and if the severity of the icing isn't too bad.

#9 Upon encountering ice, the default reaction should be to climb immediately. Descending is always an option, but if you descend and guessed wrong, climbing is no longer an option.

No, that shouldn't be the default reaction. If you know there's warmer air above (and there isn't any below), and you know the tops aren't far away, which is hard to know, then climbing might be a good option.

Your other points are well taken.

-Felix

 

[tonycondon]

Doug,

glad to see you here and I appreciate your input. I agree that always having an out is paramount. I know that the tools sometime predict no ice when there is ice and vice versa. shoot the other night on the way back from Decatur in the 421 we flew through a large area of 75-100% icing probability and only picked anything up in a small portion of it. This is why I'm trying to understand the why's behind the forecasting.

You should know that Matt Sawhill, who you gave a PP-ASEL checkride to a year and a half ago in his gorgeous C-140, read your recent article in IFR magazine about ice, which apparently was very good. I havent had a chance to read it yet. The discussion between us that came out of that article has led us down this road of enlightenment where a deeper understanding of the situation is desired.

And finally, pull up a chair and stay a while. You have found probably the best aviation community on the web.

 

[bbchien]

WOW. An awesome plea of the case for knowledge.......

What's happened here is that a terrifc tactical tool has been developed. Still no strategic tool, but much better than what we had before. I'm really glad my Aviation Safety article from Jan 2002 is obsolete.

I'm amazed by another boarders's disparagement as "weather guesser"; the weather is "only good for ten minutes" and it's "whatever I find". Ten years in aviation ....yahbut his IR only this winter.

Yes it's whatever you find. But the probabilty of finding out what's out there an hour ahead of time just went WAYYYyy up. You have to use all the tools you can find.

 

[tonycondon]

thanks to MATLAB and an optimization project I will have to digest another great Scott D post at a later time. thanks though, skimming over it it looks great!

 

[TMetzinger]

Scott's posts are always informative. But the part that bothers me here is the disconnect between two things he says:

"... in the weather world, it's not black and white -- it's shades of grey. Forecasting is all about the probability of an event occurring, not whether it will occur or whether it won't occur."

And

"I'm not sure why there's a need to be "guessing" with any of this."
=====================================================
In Dave's example (climb first, so that you still have the descent option), one is "guessing" that the icing will be reduced at a higher altitude. That "guess" should be based on all available knowledge, but let's not pretend that it's anything but an informed guess, or, if you will, a bet on the relative probabilities based on your knowledge, including the predictions of the meteorologists. Dave also gives two indicators that would suggest even worse conditions above.

This is starting to sound like the perpetual motion thread. Staying on the ground when the temps are below freezing and there's visible moisture is the only guaranteed method of avoiding inflight ice. Everything else is a risk management decision, or, put plainly, a bet. Everything Scott says helps you make a better bet, but it's still a bet. If you don't like to gamble, don't fly.

Speaking for myself, Scott, I sometimes feel that your knowledge of and passion for the subject of weather comes across as an expression of confidence in forecasts that isn't justified, leading to things like the two contradicting statements listed above. I may be misunderstanding you, or reading a "tone" into your written words that isn't there.

We've doubtless got better weather products now than ever before, and our odds improve as a result, but as a pilot what I WANT (unabashedly) is the black-and-whitest weather I can get. I'm grateful for the good bookmaking, but I never forget that it's still a bet, and what I'm betting is my life, and those of my passengers.

 

[bbchien]

Scott's posts are always informative. But the part that bothers me here is the disconnect between two things he says:

"... in the weather world, it's not black and white -- it's shades of grey. Forecasting is all about the probability of an event occurring, not whether it will occur or whether it won't occur."

And

"I'm not sure why there's a need to be "guessing" with any of this."
=====================================================
In Dave's example (climb first, so that you still have the descent option), one is "guessing" that the icing will be reduced at a higher altitude. That "guess" should be based on all available knowledge, but let's not pretend that it's anything but an informed guess, or, if you will, a bet on the relative probabilities based on your knowledge, including the predictions of the meteorologists. Dave also gives two indicators that would suggest even worse conditions above.

This is starting to sound like the perpetual motion thread. Staying on the ground when the temps are below freezing and there's visible moisture is the only guaranteed method of avoiding inflight ice. Everything else is a risk management decision, or, put plainly, a bet. Everything Scott says helps you make a better bet, but it's still a bet. If you don't like to gamble, don't fly.

Speaking for myself, Scott, I sometimes feel that your knowledge of and passion for the subject of weather comes across as an expression of confidence in forecasts that isn't justified, leading to things like the two contradicting statements listed above. I may be misunderstanding you, or reading a "tone" into your written words that isn't there.

We've doubtless got better weather products now than ever before, and our odds improve as a result, but as a pilot what I WANT (unabashedly) is the black-and-whitest weather I can get. I'm grateful for the good bookmaking, but I never forget that it's still a bet, and what I'm betting is my life, and those of my passengers.

Tim, my perspective is, as you know, a smidgen different when I'm operating turbochargers and FIKI. But here I have no qualms (provided enroute has a "probable" clear path, e.g way on top or the like) about going through a 2500 foot ice containing stratus deck to surface temps below 0C. Here the yes/no function will not kill you- only cause you to use your gear.

I'm looking to avoid SLD which will down me (or a Twin Comanche for that matter), however- no matter what the gear.

It's different in an unprotected aircraft where the yes/no step function might kill you. It will never get to the point of there WILL be definite clear ice. It can, however get to the point where in Tony's example, were the tops -20 (as they will be this Sunday in the midwest) there won't be enough moisture in them to give much ice. That's of little comfort to a guy in a Twinkie with laminar flow skinny airfoils that don't do ice nicely. But he too needs to know where the SLD are likely to be e.g, the presence of the warm nose up above. If there's no likelihood of SLD, and really cold clouds (as on the backside of some of the midwest winter Low pressure centers) flight can actually be made in the unprotected single.

Thus, the information has different impact depending on what you're going to fly.

In a year the CIP/FIP tool will be validated and become a frontline tool. 50% probability is Okay for a FIKI ship. Maybe it's 25% for an unprotected one, or 75% if the surface is warm. Each to his own.

But you HAVE to learn the tactical tools. And a guess (a probability) the next minute becomes an "it did" or "it didn't" occur item.

 

[TMetzinger]

Tim, my perspective is, as you know, a smidgen different when I'm operating turbochargers and FIKI. But here I have no qualms (provided enroute has a "probable" clear path, e.g way on top or the like) about going through a 2500 foot ice containing stratus deck to surface temps below 0C. Here the yes/no function will not kill you- only cause you to use your gear.
<snip>
Thus, the information has different impact depending on what you're going to fly.

In a year the CIP/FIP tool will be validated and become a frontline tool. 50% probability is Okay for a FIKI ship. Maybe it's 25% for an unprotected one, or 75% if the surface is warm. Each to his own.

But you HAVE to learn the tactical tools. And a guess (a probability) the next minute becomes an "it did" or "it didn't" occur item.

Bruce,

You and I are in sync about how to handle icing - 100%. You get the best information possible, map that against your need to fly and the equipment you're flying, and make your decision to go or not, and use that information to pre-plan your alternatives.

The only reason I commented at all at this point was the apparent semi-contradiction between the statements about forecasts being probabilities and how pilots shouldn't be "guessing".

But perhaps what Scott meant was that in Dave's situation, the up or down choice shouldn't be a "flip-a-coin" type of guess, because the pilot should already know which choice is the better one based on the forecasts. It's still a guess, as we don't know for sure what will happen, but we do know which way to bet.

Now, what I want to know is, when these products are operational, will they be added to the XM weather data stream and presented on my datalink? Tactical tools arent as effective if they aren't available in the cockpit on long flights.

Best wishes,

 

[Everskyward]

We've doubtless got better weather products now than ever before, and our odds improve as a result, but as a pilot what I WANT (unabashedly) is the black-and-whitest weather I can get. I'm grateful for the good bookmaking, but I never forget that it's still a bet, and what I'm betting is my life, and those of my passengers.

That might be what you want, but as Scott points out, that's beyond the capability of weather forecasting at this moment. The best they can do it come up with probabilities and educated guesses. Just in the past few months I've encountered weather that ended up being much worse than forecast on several different occasions. That's why you have Plan B. Really, all of flying is a calculated risk. There are some black and whites but there are also many shades of grey.

 

[B25Flyer]

See, I told you Scott knew alot more than I do.

First of all I agree with almost everything Scott says, because he does know alot more than I do.

Sba55 said my approach was the wrong way to answer Tony's question. Tony's question was, based on the information provided should I go? I said hell no! I based that on the information provided. Because the forecast said there was a pretty good probablilty of ice and the ceilings were low. In a non deiced airplane, that breaks a pretty simple rule for me, Have a plan B.

Hauling freight, as a practical matter, we did not have the option to say no. We went, so what I am relating here did not come from Flying magazine, or IFR. I am sharing the rules and rationalizations that I used to stay alive.
Now for Scott,

I agree wholeheartedly that this is not a black and white business. It is a risk assesment exercise and the more information you have the better you can assess the risk. in the situation Tony presented, the lower the ceiling, the lower my risk apetite. If the underlying weather is day VFR, I will fly in nearly any kind of forecast.

Scott here is how I see it. I know and fly with LOTS of instrument rated pilots. Personal flyers and corporate types. VERY few of those people, including myself, understand the weather patterns to your level.

When the errors in the forecast combine with misunderstanding of the information and a pilot finds themselves in the ice, the adrenaline flows, the brain slows down and pilots need some simple rules to follow.

As for climbing upon encountering ice, that is the default choice if you have no information. If your forecast plan fell apart, then what info do you have that you can trust?

Obviously if you are in ice pellets, don't climb. If you are in convective activity, use your 396 to get out of the precip. But if you are flying along in the midwest and start accumulating a slight amount of rime ice, unless I have solid information to support a different plan, I am going to climb. If I am wrong, I can still descend or turn around. If I descend and I am wrong, the area of options gets much smaller.

I think it boils down to this. Scott want to educate us and make us smarter.

Based on first hand experience, I know that pilots aren't very smart (The smart people ride in back) and when the horse hockey hits the fan, we get pumped up on adreanaline, we get real stupid and we need simple rules.

I almost got killed twice in ice, once in a 402 in freezing rain. I was on top at 5000 in 50 deg and rain. The weather on the ground was 1000 overcast and 3 miles vis with ice pellets and 5 deg F. The tops of the lower layer were at least 1000 feet below me so I surmised that the ice was only 1000 ft thick. that was true, I also surmised that there is no amount of ice you can put on a 402 in 1000 ft coming down the GS with the gear up that will render it unflyable. I was almost wrong. My plan was to circle to land on a different runway so I would be able to see. I left the gear up until 100 feet and never saw the runway until I saw the runway lights out the side window. 3 inches of clear ice back past the spar. and the W/S was totally covered.

The other time I was 40 miles from the destination and got in the ice. I knew I would have to climb to 6 or 7000 feet to get out of it, and with only 40 miles to go I decided to just slug it out. Both in deiced airplanes. Both times I flew down the ILS with full power. No options.... I knew the rules and but I was a freight hound, I thought the rules were for other lesser corporate types etc....

I think pilots need pretty simple rules......

Tailwinds,
Doug Rozendaal

 

[TMetzinger]

That might be what you want, but as Scott points out, that's beyond the capability of weather forecasting at this moment. The best they can do it come up with probabilities and educated guesses. Just in the past few months I've encountered weather that ended up being much worse than forecast on several different occasions. That's why you have Plan B. Really, all of flying is a calculated risk. There are some black and whites but there are also many shades of grey.

Just to be sure I'm communicating clearly - did my post not convey that I understood that it's grey? I tried really hard to express that I'm grateful that we've got vastly better information on which to base our risk calculations, while trying to remind everyone that our duty is to remember that it's grey, and make the best decisions we can.

I'm really not trying to pick on Scott in particular or meteorologists in general. But just as some pilots look at the BRS chute as an excuse to do poor risk management, (and others looked at XM weather as a tool to challenge fronts in real time, and still others look at FIKI as a reason to not think about ice anymore), some are going to look at the FIP/CIP and say "Look, ma, probability of ice is low, let's launch!" and NOT do the necessary follow-on "what if?" thinking. That's all I'm trying to discourage.

My point on wanting black and white was that we should not forget what our ultimate goal would be, no matter how impossible it is at the present.

 

[B25Flyer]

Scott,

Reading your last message, I think I figured the difference in our points.

My plan A is often to climb and see if I can climb out of the ice and continue my trip. That decision is based on how much ice is accumulating, if the accumulation is significant, I agree with turn back. If plan A doesnt work, then plan B is to turn back, and descend to keep the speed up. At that point, plan C is probably to land at a nearby airport ASAP

A more conservative approach is to turn back initially, and I totally support that, but I strongly caution against descending and continuing unless you have strong evidence of warm air or good VMC below. If you are wrong about the warm air or VMC, and the ice continues to accumulate, you can be in big trouble quickly.

Tailwinds,
Doug Rozendaal

 

[bbchien]

Bruce, You and I are in sync about how to handle icing - 100%.....when these products are operational, will they be added to the XM weather data stream and presented on my datalink? Tactical tools arent as effective if they aren't available in the cockpit on long flights. Best wishes,

They'll be the hottest thing since AvGas.....

 

[TMetzinger]

I think you are correct with your last statement. Any forecast must be based on probabilities...but we're not talking "rolling the dice" probabilities. There are weather situations where I am entirely confident in the forecast. There are weather situations where I don't have any confidence. I am not speaking for anyone else, but my goal is to minimize my exposure to adverse weather.

I can see you really don't understand weather forecasting Tim. I don't believe those statements were contradicting at all. I don't guess when it comes to my decisions. "Hmmm, I think I'll climb this time for ice since that worked the last time I got into icing." That's a guess. But, at the same time, I can't tell you black and white that icing at 9,000 feet WILL occur and that icing at 6,000 feet will NOT occur. But I can say for sure that there's a greater likelihood that icing will occur at 9,000 feet versus 6,000 feet. That's the difference between the two statements Tim. A guess is based on zero knowledge (maybe experience, but zero knowledge).

If you read my follow-on post, you can see that I thought some more and "guessed" that you were referring to your confidence in probabilities to take them out your definition of guessing. Well, I think we've identified our point of divergence. To you, a "guess" is based on zero knowledge.

To me, zero knowledge defines "random chance". A "guess" is based on some amount of knowledge, and remains a "guess" until approaching the sort of certainty applied to the "laws" of physics and math. So, if you plot them on a scale of confidence going from 0-100%, you'd have:

Random Chance-WAG-SWAG-Pretty Sure-Very Sure-Damn Sure.

So in the end, I think we are in agreement on what we MEAN, but are saying it in different ways.

Best wishes,

 

[TMetzinger]

Agreed. Sometimes it's not how much you know, but what you don't know that can hurt you. With respect to weather, I work real hard to discover those things I don't know.

Agreed. I hated the meteo part of the instrument rating so much that I decided I needed a course. So now I'm working my way through Ahrens while waiting for NOVA to offer a more formal class.

And don't forget the most dangerous part - the stuff you KNOW that isn't so! That kills you, and you die in a high state of indignation to boot!

Take care,

 

[bbchien]

In thinking more about what Doug said, "Pilots need simple rules"....well yes, but when they get away with something they discard the rule.

CFIs, to NOT BE PART of the problem, need sophistication. They need all the tools. None of those tools are taught in 141 schools. They are taught by the time tested airmen, and learned from experts. I am just AMAZED that the FAA has not responded with any official materials that equip the airman with "vertical slice" information, when it's been there for TWO YEARS.

 

[foka4]

This may be a little off topic, but maybe it'll lighten the mood:

Where would you expect the cloud ceilings and tops to be in this sounding? How confident would you be in the accuracy of your estimates? Where would you look to pin things down a little better?

Matthew