Go/No Go: 12/24/08

[flyingcheesehead]

Just gonna post another scenario for discussion here (I was gonna post 2 threads, one with the same mission but for the 23rd, but apparently I forgot that I rebooted my computer and it loaded the latest info, so I don't have any of the data I was looking at on Tuesday. Doh!)

The mission: Fly an Archer from KMSN to KSBM to pick up the 182 from its annual, and ferry it back. 2 pilots in the Archer on the way up, one in each plane on the way back. Departure at MSN 2100Z, returning by 00Z.

Here's the weather as it looked when I was attempting to make the Go/No-Go decision:

FA:

CHIC FA 241946 COR
SYNOPSIS AND VFR CLDS/WX
SYNOPSIS VALID UNTIL 251400
CLDS/WX VALID UNTIL 250800...OTLK VALID 250800-251400
ND SD NE KS MN IA MO WI LM LS MI LH IL IN KY
.
SYNOPSIS...LOW PRES CNTR 20Z OVR NERN LWR MI-NRN LH FCST MOV
RPDLY ENE INTO CANADA BY 00Z. HI PRES RIDGE 20Z CNTRD OVR NERN
KS-NWRN MO FCST MOV EWD INTO NERN IL-NWRN IN BY 14Z. LOW PRES
TROF DVLPG DURG PD ALG ERN SLPS ROCKIES FROM MT-ERN NM.
.
WI
WRN...BKN030 BKN080. TOPS FL180. BECMG 2100 SCT030. 05Z SKC.
OTLK...VFR.
ERN...OVC010-020. TOPS FL200. OCNL VIS 3-5SM SCT -SHSN. BECMG
2201 SCT030 BKN060. TOPS FL180. 04Z SCT035. OTLK...VFR.​

TAFs:

KMSN 241824Z 2418/2518 28011G18KT 5SM -SN BR OVC010
TEMPO 2418/2419 3/4SM -SN BLSN BR OVC008
FM241900 28012G20KT P6SM OVC015
TEMPO 2419/2421 3SM -SHSN BR OVC010
FM242100 28012G21KT P6SM OVC030
FM250000 28012G21KT P6SM BKN060
FM250200 28012KT P6SM SKC
FM251000 26005KT P6SM SKC
FM251600 18008KT P6SM SKC

KGRB 241727Z 2418/2518 29005KT 1 1/2SM -SN BR OVC007
TEMPO 2418/2422 1/2SM SN FZFG VV004
FM242200 27010G16KT 3SM -SN BR SCT008 OVC015
TEMPO 2422/2424 1 1/2SM -SN BR OVC008
FM250000 28012G20KT 6SM -SHSN SCT015 BKN035
FM250300 27010KT P6SM SCT035
FM250800 26005KT P6SM SKC
FM251500 21006KT P6SM SCT100 SCT200
(yes, I know the GRB TAF is technically irrelevant, but it can be good to compare with the FA.)​

METARs:

KMSN 241953Z 28013G21KT 5SM -SN OVC019 M05/M09 A2972 RMK AO2 SLP075 P0000 T10501089
KSBM 241953Z AUTO 29009KT 1 1/2SM -SN BR FEW011 BKN014 OVC018 M01/M03 A2960 RMK AO2 SLP034 P0000 T10111028​

PIREPs:

MSN UA /OV MSN180005 /TM 1851 /FL033 /TP CRJ2 /SK OVC020-TOP033 /RM HZ LYRS ABV
UGN UA /OV UGN /TM 1855 /FLUNKN /TP C550 /SK OVC007 /IC NEG /RM RWY 23 BRAG /TA UNKN
MOP UA /OV HIC270015/TM 1858/FL060/TP BE58/TA M06/IC LGT RIME
ORD UA /OV ORD310005 /TM 1901 /FL072 /TP CRJ7 /SK OVC014-TOP072 /TA M09 /IC MOD RIME
AZO UA /OV AZO270010 /TM 1927 /FL026 /TP E145 /TA M02 /IC LGT RIME 080-026 /RM IMC 080-026
ARP UAL614 4159N 08754W 1937 F180 TB LT-MOD CHOP​

AIRMETs: I don't have the text any more, but here's the icing airmet graphic:

Drat. The stupid ADDS thing is too smart for its own good - It's continuously reloading the icing forecast map, so I don't have the "old" one any more. IIRC it was showing from 5% to 25% probability along the route, with higher probabilities down in northern Illinois (well south of our northeasterly route).

Radar:

OK, here's the Skew-T's:
Madison:

Sheboygan:

So... Do you go, or not? What do you expect to see?

 

[AcroBoy]

The answer is of course- "it depends". Without slogging through the whole post again, were both pilots instrument rated and comfortable flying with the wind conditions? I live along the route in question, in UES, and on Christmas eve there were low ceilings, with gusting and blowing snow, although not a lot of accumulation. It was fairly close to freezing on the ground, which probably means at least a chance of ice in the low clouds, along with the probability that both an Arrow and 182 are not equipped and certainly certified for flight in known ice. Both airports have crosswind runways available that would have minimized the crosswind component, so the wind would'nt have been as much of a factor as the the low ceilings and ice. Local runways and taxiways are still covered with patchy ice, which would also have been a challenge with the winds.

So, if the two pilots were VFR only, then no way. If both were IFR rated and comfortable and experienced, then maybe, depending on the importance of the mission. If both planes were capable and equipped with boots/TKS, etc., as well as the pilots, then it could have been a pretty easy flight.

What did you end up doing?

 

[rollcloud2001]

If they can still answer they didn't go.....

 

[sba55]

Kent, I'd go if I could fly at 2000' in VMC conditions. SBM seems close enough for that. This is one of those cases where VFR might be better than IFR. That said, I would try to wait until 2300Z or later. It seems like the weather is forecast to get a lot better.

As far as IFR goes, I'd expect ice. Maybe it wouldn't be there at all, buy you've certainly got the potential. It's also evident in some of the PIREPs. In an Archer, which doesn't exactly have a lot of excess power, that means a No-Go for me if the flight is going to be IMC.

There's a critical piece missing, which is the CIP/FIP graphs. You might want to include them in your briefing - they give a good overview.

From the Skew-Ts, I don't think that classical SLD would be likely. But, the MSN Skew-T shows cloud tops that might be warmer than -12*C, which means that non-classical SLD is a possibility and that the clouds are most certainly not fully glaciated due to the warm temperatures (no, -10 or -20 *F doesn't mean that you can't get ice). The icing PIREPs support at least the latter assumption. Furthermore, you don't really have any good outs. The bases are pretty low, tops are forecast to be very high and even the PIREPs show them being too high to climb in ice.

You might be able to make the flight IFR and be just fine. But there's also greater-than-i'm-comfortable-with chance that you'll be looking for an out and it's not worth the risk to me. Personally, IFR would not be an option for me.

-Felix

 

[Everskyward]

If they can still answer they didn't go.....

??

Isn't this them?
http://flightaware.com/live/flight/N8483F/history/20081224/2055Z/KMSN/KSBM
http://flightaware.com/live/flight/N8483F/history/20081224/2210Z/KSBM/KMSN
http://flightaware.com/live/flight/N271G/history/20081224/2255Z/KSBM/KMSN

FlightAware is a little spooky...

 

[Ted]

It's a short flight, but I don't think I'd try it due to icing concerns. It looks like you might be able to go through it without any trouble, but it's not just popping through a layer, it's staying in the soup for the duration of the flight both ways based on what I'm seeing on there. I'll stay on the ground, thanks.

One question: Where are you getting those Skew-Ts? I've not found them on aviationweather.gov and from Googling I've found a few sources, but I'm wondering what the "official" source for them is?

 

[Steve]

I have two locations bookmarked:

http://www-frd.fsl.noaa.gov/mab/soundings/java/

http://rucsoundings.noaa.gov/gifs/

One or the other usually works. Not all airport locations are included in the database, but a nearby location is probably good enough for your purposes.

One question: Where are you getting those Skew-Ts? I've not found them on aviationweather.gov and from Googling I've found a few sources, but I'm wondering what the "official" source for them is?

 

[flyingcheesehead]

??

Isn't this them?
http://flightaware.com/live/flight/N8483F/history/20081224/2055Z/KMSN/KSBM
http://flightaware.com/live/flight/N8483F/history/20081224/2210Z/KSBM/KMSN
http://flightaware.com/live/flight/N271G/history/20081224/2255Z/KSBM/KMSN

FlightAware is a little spooky...

Drat Mari, I was starting to think I'd have a little fun with the naysayers.

The answer is of course- "it depends".

As with many things aviation!

Without slogging through the whole post again, were both pilots instrument rated and comfortable flying with the wind conditions?

Yes. Part of the difficulty in getting the planes home before tomorrow was that the only VFR to be had was today, and it's hard to peel people away from their families on Christmas. So, I had to find another pilot who was instrument rated, current, and a member of the club. Of the 30 club members, 14 are instrument rated and only about 6 are current. With the holidays, some of those are either already out of town or were already entertaining guests.

But, I did find another pilot who was available, rated and current, and comfortable with the winds. The combo that makes it a little worse is the potential for slippery runways and ramps, which we did have.

Both airports have crosswind runways available that would have minimized the crosswind component, so the wind would'nt have been as much of a factor as the the low ceilings and ice.

MSN had a path plowed from the south ramp to 18/36 via taxiways Delta and Bravo. Runway 18/36 was the only one that was plowed - The conga line was working on 14/32 when we left. SBM had been plowed, but still had some snow and ice left behind.

That left us with nearly a direct crosswind at MSN on a 150 foot wide runway, which had been fully plowed, deicing fluid sprayed 100 feet wide, and sanded 60 feet wide. It was actually in great shape, way better than the roads on the way to the airport! at SBM we used runway 31 which was more aligned into the wind.

Local runways and taxiways are still covered with patchy ice, which would also have been a challenge with the winds.

Not so much at SBM - The snow piles beside the runway and taxiways are already over 4 feet high, and just barely wide enough to fit the Archer's wingtips between on the taxiways, so that pretty effectively blocked the wind from the wing once we were on the ground!

BTW, "fly the plane all the way to the chocks" is especially true on icy ramps and runways. Having aerodynamic control surfaces makes a lot of difference!

If they can still answer they didn't go.....

You need to read more than the doom-and-gloom Area Forecast and Airmets.

Kent, I'd go if I could fly at 2000' in VMC conditions.

FWIW, the OROCA is 3000 MSL for most of the trip, which is roughly 2000 AGL. The only sector that it's not 3000 is the one right by MSN, where it's 3700, but that's due to a pair of TV towers that are to the southwest.

I assume you meant 2000' AGL?

As far as IFR goes, I'd expect ice. Maybe it wouldn't be there at all, buy you've certainly got the potential. It's also evident in some of the PIREPs.

Okay, so I left all the PIREPS within 200nm on there to make this into kind of a trick question. The only one that was anywhere near our route was the one that was climbing out of Madison:

MSN UA /OV MSN180005 /TM 1851 /FL033 /TP CRJ2 /SK OVC020-TOP033 /RM HZ LYRS ABV

That right there told me that the FA, as I'd suspected based on the Skew-T, was way off.

The reason the rest of the PIREPs are confusing is that they're all down at the south end of Lake Michigan in the greater Chicago and northwest Indiana area. That also corresponded with the FIP map, which showed a very high chance of icing in that area. However, it wasn't on or near my route of flight.

There's a critical piece missing, which is the CIP/FIP graphs. You might want to include them in your briefing - they give a good overview.

As I said in the OP, I did use them - I just left everything open so that I could post it here later, and the forecast icing page on ADDS apparently reloads constantly, so the map I actually used before the flight was long gone when I went to post it. It was showing between 5% and 25% probability.

Furthermore, you don't really have any good outs. The bases are pretty low, tops are forecast to be very high and even the PIREPs show them being too high to climb in ice.

Again, the only PIREP that I posted that was anywhere near my route of flight stated OVC020-TOP033. I know the Archer isn't a mighty Beech, but it can climb higher than 3300 feet.

Also, the system that was causing the bad wx was moving through, and wx was improving. This METAR became information Xray, which was issued as we were taxiing out at MSN:

KMSN 242053Z 28010G20KT 7SM BKN024 M06/M09 A2977 RMK AO2 SNE08 SLP094 P0000 60000 T10561094 53041

This was what SBM did in the course of our short flight:

KSBM 242053Z AUTO 28017G27KT 1SM -SN BR BKN016 BKN022 OVC045 M04/M06 A2966 RMK AO2 PK WND 28028/2024 SLP053 P0000 60001 T10391061 53028
KSBM 242112Z AUTO 29014G25KT 2SM -SN SCT018 OVC050 M04/M07 A2968 RMK AO2 P0000
KSBM 242122Z AUTO 29016G24KT 3SM HZ SCT018 BKN050 OVC070 M05/M08 A2969 RMK AO2 SNE18 P0000

Before departing for the return flight, I had this:

KSBM 242245Z AUTO 28018G27KT 4SM UP SCT020 OVC110 M07/M09 A2978 RMK AO2 PK WND 27029/2231 UPB41SNE02 PRESRR P0000

I actually would have been holding short of the runway calling for my clearance right about then, but I could see it getting even better to the west, which is reflected in the next METAR issued only 8 minutes later:

KSBM 242253Z AUTO 28017G28KT 4SM UP FEW020 BKN110 M07/M09 A2979 RMK AO2 PK WND 27029/2231 UPB41SNE02 SLP097 P0000 T10671094

Here's MSN upon my return:

KMSN 242353Z 27008KT 7SM FEW015 M10/M14 A2998 RMK AO2 SNE41 SLP164 4/015 P0000 60000 T11001139 11022 21100 53066


So, here's what actually happened. I carefully taxied out in 83F due to the abundance of icy surfaces and blowing snow. The runway was in good shape, they keep that one well-plowed even during storms because it's "the airline runway" for the most part. Readings from the sled were all greater than 40. Takeoff was uneventful, but it was bumpy as soon as we were in the air due to the strong winds. Climb rate was excellent. As advertised, the layer was thin, from about 3400 to 4200 feet, no ice, and the haze ended only a few hundred feet later and the bumps ended with the haze. On top at 5000, it was beautiful and clear, with glass-smooth air (I love winter).

I was given a pilot's discretion descent to 2600 only about halfway there, but I stayed at 5K as long as possible to stay in the clear, smooth air and stay out of the bumps and potential ice. I asked for vectors to the VOR 3 approach, and timed my descent perfectly - I was cleared for the approach while descending, and went through the FAF right at the prescribed altitude. I spotted runway 3 at maybe 2200 feet, continued a bit, and then circled to land on 31.

On the flight back, I took off from 31, and at around 500 AGL turned towards Madison (clearance was "Upon entering controlled airspace, fly direct Madison") and ended up not hitting any clouds at all. There was an undercast layer for a while, but there were some big holes in spots, too. I descended through a pretty big hole with only a couple of tiny tufts of cloud in the way. I probably could have cancelled IFR at that point, as I could see the city lights and the capitol quite well, but it was night and I still hadn't spotted the field despite it being closer to me than the capitol. I got vectored onto the ILS 36, and spotted the field almost as soon as I made the turn onto the localizer, about 12 miles in front of me.

So, despite the doom and gloom from the FA, I hardly even got any actual, didn't get any ice, and it wasn't much of a challenge at all. The ceilings were high enough that any ice, or even an inability to break out on top like I'd predicted we could, would have allowed an easy return to Madison.

 

[flyingcheesehead]

It's a short flight, but I don't think I'd try it due to icing concerns. It looks like you might be able to go through it without any trouble, but it's not just popping through a layer, it's staying in the soup for the duration of the flight both ways based on what I'm seeing on there. I'll stay on the ground, thanks.

The conclusion I reached was that the FA was wrong, and I was right. Thin layer, on top at 5,000. And there was no ice in the layer, either. Had either of those not been the case, I'd have turned around.

One question: Where are you getting those Skew-Ts? I've not found them on aviationweather.gov and from Googling I've found a few sources, but I'm wondering what the "official" source for them is?

http://rucsoundings.noaa.gov/

 

[sba55]

Drat Mari, I was starting to think I'd have a little fun with the naysayers.

Yea, that's what I'm understanding now. Thought you wanted to learn something. It's very foolish to rely on a single PIREP and a very incomplete understanding of the Skew-T. Sorry I bothered.

-Felix

 

[flyingcheesehead]

Yea, that's what I'm understanding now. Thought you wanted to learn something. It's very foolish to rely on a single PIREP and a very incomplete understanding of the Skew-T. Sorry I bothered.

Felix,

I really wasn't intentionally making it a trick question... That was more of a comment on post number 3 which said I must surely be dead.

It wasn't only a single pirep - It was that pirep, plus seeing the occasional crack in the clouds clearly showing the layer was not nearly as thick as the FA had stated (17,000 feet), plus the Skew-T, plus having an idea of the motion of the weather as I'd been watching it closely because I originally intended to take the trip the day before. (I was going to post the data from that day in a different thread, but I accidentally closed that window. Doh!)

In particular, I'd love to learn why conditions that cause ice near you, don't cause ice near here - Except I think all those icing pireps down near Chicago were probably similar effects from Lake Michigan. Since I do fly around the lake occasionally, I'd like to know more of the mechanics of what's going on there, and what the skew-T's are actually saying.'

My apologies to anyone who thought that my original intent was a trick question - It wasn't. I did withhold the information that I gained after I left for the airport until later, because I wanted a more accurate picture of why someone else would or would not go given only that information - I certainly hadn't made up my mind 100% even when I left for the airport, and that's the state I wanted to recreate for the purpose of working through scenarios.

Now that I've put the rest of the info out there, a discussion of the limits of the FA and such would certainly be interesting as well! And is there anywhere besides a WSI station where we can see the VAD wind profiler? I think that comparing the VAD WP with the Skew-T would help me a lot in learning about them, and it really ticks me off that the VAD WP isn't available to pilots on the web. I'd sure love to know why.

 

[EdFred]

Looks like an easy VFR flight.

 

[flyingcheesehead]

Looks like an easy VFR flight.

Might have been possible, but I'd have never departed VFR. KSBM didn't technically turn VFR (3 miles vis) until just a few minutes before we landed. And it was very bumpy down low.

 

[TangoWhiskey]

I actually would have been holding short of the runway calling for my clearance right about then, but I could see it getting even better to the west, which is reflected in the next METAR issued only 8 minutes later:

KSBM 242253Z AUTO 28017G28KT 4SM UP FEW020 BKN110 M07/M09 A2979 RMK AO2 PK WND 27029/2231 UPB41SNE02 SLP097 P0000 T10671094

Kent, what were you seeing for precip during these METARS? Curious what the Unknown Precip was that the ASOS couldn't identify.

 

[EdFred]

Kent, what were you seeing for precip during these METARS? Curious what the Unknown Precip was that the ASOS couldn't identify.

UP is the catch all in the midwest for

FZDZFGGRSNPLSLRA

 

[flyingcheesehead]

Kent, what were you seeing for precip during these METARS? Curious what the Unknown Precip was that the ASOS couldn't identify.

Troy,

I saw no precip, just the cloud layers breaking up. I'm guessing it was blowing snow, as there was plenty of that! It wasn't coming out of the sky, though.

 

[flyingcheesehead]

Not a good idea to use the WSR-88D NEXRAD Doppler Velocity Azimuth Display (VAD) Wind Profile (VP) or VDP for much of anything (especially cloud tops or icing). It's a volumetric parameter around the radar site.

Scott,

Interesting. Here's the nearest for roughly the time of the outbound flight:

MKX 12-24-08 2100Z:

And the return flight - MKX 12-24-08 2300Z:

Given that this station is somewhat south of the route and there were additional layers to the south, and it was clearing up for the return flight, I'd say that this is at least within the bounds of accuracy that I normally would expect out of weather products.

I didn't realize that there even was a temperature scale (I'm assuming that's what the colors are), and I've never used it to try to determine ice. But doesn't this product give us a better picture of cloud tops/layers than anything else? The only other place I know of to get that sort of information is from the FA or PIREPs, neither of which can really be relied upon either.

So, what are the limitations of the VAD wind profiler? Why not use it?

Thanks for the link, BTW - I'm gonna keep looking at it if for no other reason than to see for myself how right or wrong it is.

 

[rollcloud2001]

"but it was night"....so you did the flight at night on top of everything else....all I can say is you are lucky....I would never have made the flight, but I guess that is why I have made it through 44 years as an ATP...I learned from Mason Camp, one of Lindberghs friends and fellow aviator not to ever push my luck with the weather....and why almost every weekend you can read about some doctor/lawyer/etc. driving his bonanza into the ground....(not picking on them, I am a lawyer too...)

 

[flyingcheesehead]

This is the problem. The colors are not temperatures.

Aha. Good thing I never used it that way then.

The simple answer is no.

What's the complex answer?

I first saw the VAD wind profiler on an in-person FSS visit. They were commenting on the winds aloft it showed, but were also pointing out that altitudes where it said "ND" would be clear. Their explanation was also that it was basically pointing the radar almost straight up, so it was showing only the vicinity of the radar. I had always wondered how they seemed to have more accurate tops than the FA called for, and thought that this is what they were using. (Actually, it was still more accurate than the FA!)

 

[flyingcheesehead]

"but it was night"....so you did the flight at night on top of everything else...

No - The entire outbound flight was daytime, and the takeoff for the return trip as well. The sun had just set when I got above the layer on the return trip. So, I had a good idea of what to expect long before it got dark. If I had to make the outbound trip at night, I wouldn't have gone either (and in fact, that was part of the reason I didn't make the trip the previous day, as I'd have needed to do it at night).

The part where I said "but it was night" was when I was getting vectored for the approach back into KMSN.

 

[rollcloud2001]

Glad it wasn't all at night...It turned out to be an uneventful flight, but if, for instance, on the climb out or descent through the clouds you had picked up even a thin layer of ice on the windshield, with no hot-plate it would have been really tough to land, especially with a crosswind and nearly no vision, only the little storm window on a Cherokee to see through...just so many possibilities when ice is around....and even a small freezing rain shower can spell disaster...and the next day was crystal clear.....