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Safe to fly through TCU ?

I'm flying IFR to Lille LFQQ tonight. The Gramet shows frequent TCU with tops at around FL120. My IR flights so far were always in relatively stable air.

I was just wondering: Is it safe to fly through TCU? I'll be below icing level.

TAF's and SIGMET show no CB's...

Nothing in aviation is "safe", only "safer" or "less safe". TCU is bumpy (often more so than certain later stages of CB lifecycle), and the tops are usually wet (hence icy if cold). It is certainly best avoided if possible, but it's often not possible to do so. Like all convection, you need to assess what you see and experience, not just what it says on the forecast, and respond accordingly.

Just remember to slow down if it gets bumpy.

EGTK Oxford

Make sure you are not flying through well developed TCU/CB thunderstorm clouds with rain falling from below, etc. Better to ask for 10 degrees to the left or right in order to avoid. Make sure that if you are IMC you can still 'see' the TCU activity ideally on both a stormscope and weather radar or at least on a stormscope if the forecast was not too bad. Or otherwise stay visual if the TCUs are not embedded or become visual soon again.

EDLE, Netherlands

And remember that TCU can develop further to CB if stability conditions change :(

So, if isolated you can usualy avoid; if embeded and you fly in IMC you obviously :) can't see it.

Generally, you have to be causious flying through TCU because it can mean autopilot disconnect and hand-flying in convective IMC which can be challenging combined with other stuff you have to handle in cockpit.

LDZA LDVA, Croatia

Just remember to slow down if it gets bumpy.

Know your maneuvering speed Va (or "penetration speed" as some manufacturers call it) and try to fly as close to that as possible before entering the cloud with the aircraft trimmed out well. Flying slower is not good either, because turbulence and ice accumulation may bring you close to the stall fast. When it gets bumpy, don't touch the power lever and don't chase altitude and airspeed, just keep it level in pitch and roll and sit it out, it usually lasts less than a minute. If your altitude deviates by more than plus or minus 200 ft (I have had almost 1000ft excursions in TCU tops with singles and light twins with the VSI showing 3000ft/min up and down in quick succession...) tell ATC about "encountering severe turbulence, unable to maintain altitude" and they will keep the airspace around you free of other traffic.

TCUs are unpleasant (especially for passengers!) but certainly not life threatening. If you to see them, ask for avoiding headings just like every airliner does. If you can climb or descend to a clear level which will give you the chance to see them, ask for a level change! ATC is most helpful in these cases.

EDDS - Stuttgart

Thanks for the insights! I have no stormscope or weather radar, so my best option is just to be high in VMC on Top and avoid visually.

EHLE-LFQQ is a short flight (160 NM) but I'm going to put my O2 cylinder in the aircraft nevertheless, and use it if needed...

The maneuvering speed Va for the DA40 is 108KIAS (with the expected load). I'll keep that in mind as I might need to enter TCU in the arrival phase.

lenthamen: in most cases you can avoid entering the TCU cloud. Just be bold and ask ATC something like "Requesting 10 degrees to the right to avoid". Have fun and a save trip!

EDLE, Netherlands

In addition, be prepared for static electricity effects, especially in the DA40. I once had a complete temporary radio failure before hitting an embedded TCU [of the wannabe CB variety].

The flight was smooth in solid IMC through a weak occluded front, with OCNL EMBD TCU but no CB in the forecast. It started with the squelch opening and fuzz in the headsets, then the receiving radio became quieter and quieter and finally stopped altogether. All hair on my arms stood on end, and I got this "static electricity feeling" you get when hooked up to a van-der-Graaf generator... I asked for descent [not related to the weather, simply needed to for my destination] and got no reply. I was just about to squawk 7600 when all returned to normal... and a few seconds later the roller coaster ride started.

I had similar cloud encounters on other flights, but never with these pronounced static effects. I'm sure the best way to avoid the embedded TCU would have been to turn on the ADF, and fly at right angles to the needle...

Biggin Hill

not a good idea to fly thru TCU when you are serving dinner in the cabin ...

EDxx, Germany
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