Icing on a TBM

[peterh337]

This (http://www.zen74158.zen.co.uk/misc-files/Icing%20TBM.pdf) has appeared following the recent crash in the USA.

[vanHorck]

a good read! Thx

B

[007helicopter]

Very relevant and specific to the recent NYC incident

Ice is definately not Nice

What do you guys use as the best forcast of icing levels?

I very rarely have flown in icing conditions, occasionally in FIKI aircraft and once or twice light icing unintentionally but there were plenty of outs.

I tend to get an icing forcast from the USAF via Orbifly MET'MAP - ORBIFLY FLIGHT SCHOOL - IFR ET CPL AMERICAIN EN EUROPE - FAA IFR AND CPL IN EUROPE (http://www.orbifly.com/member/metmap.php?region_choose=WLD&mode=hazards&icao_choose=KICT&lang=ENG)

I wanted to know from the more experinced guys how much you can rely on these as been accurate and what degree of safety regarding icing can you expect when outside or below the forcast levels?

[n5296s]

For some reason the thread title made me think of something slightly more festive... some kind of cake decoration, in large quantities.

[peterh337]

I tend to avoid icing conditions in the first place so don't claim much "experience", though I have been up to ~30mm in ~ 5 minutes on the leading edges (on a brief local flight which had an escape route into warmer air) and that was definitely the absolute limit of the aircraft.

The most I have ever picked up in normal flying was about 5mm, which on the TB20 doesn't seem to do anything.

I don't think icing conditions are usefully forecast. Stuff like icing sigmets are IMHO just ar*se covering exercises; they tell you nothing that a quick glance on the MSLP chart won't show.

This site (http://ows.public.sembach.af.mil/index.cfm?section=Hazards) which has been around for yonks has icing hazard charts, but I have not found the areas shown there to be valuable, over and above avoiding what is obviously nasty frontal weather on the MSLP chart.

Maybe people who routinely fly through most frontal weather find it valuable.

Same with the SigWx chart...

The worst icing I have seen (above) was in stratus cloud (NS probably), base 1500ft, tops 4000ft, in -5C which is normally the worst icing temperature in stratus cloud. I have never picked up ice below -10C in stratus, or above 0C anywhere (OAT gauges, 2x, verified accurate).

But with only prop TKS, and aerodynamic heating hardly exceeding 1C, I am not about to push it :) A TBM can probably achieve about 10C of heating, at a TAS of ~300kt, and that alone almost takes you out of the potential icing band which is about 15C wide - in stratus cloud (but you shouldn't be boring along at full power in any other kind of cloud :) ).

[007helicopter]

Peter I also have used the 21st operational site but I believe the info on orbifly is the same source just a bit quicker and easier to access.

Either way its a pretty good warning to stay away from.

[englishal]

Icing is one of those mysteries that one had better read about before venturing into that realm....There are a lot of variables - do I climb, do I descend, do I turn around, how much can we take...etc...I am sure it is a book on its own (anyone recommend a book on the subject?).

I tend to stay away, it is the things like tail stalls or full deflection of the control surfaces that scare me!

[peterh337]

I don't think icing is a big issue if like me you avoid flying through the nastier kinds of frontal weather, and always aim to fly VMC on top when enroute, but that gets you a despatch rate of only about 75% and with something like a TBM one will depart perhaps 99% of the time, and then one encounters a lot more stuff. I know people who despatch 99% in a TB20 and they have some pretty scary stories to tell :)