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Lowest temperature you have flown in?

It’s not very linear 1C at 100KTAS, 2C at 140KTAS, 6C at 200KTAS

I gather +6C could get one out of the icing band?

Last Edited by Ibra at 06 Mar 13:31
Paris/Essex, France/UK, United Kingdom

Last time I worked this out on my Jepp circular slide rule (CR5?) I got 1.5C at 150kt TAS.

Gosh; I almost didn’t need to install TKS

It is highly nonlinear. 350 TAS gets you 15C and that is what protects jets when enroute. You need way more than 6C. It just happens that around -6C you get the most rapid icing.

Administrator
Shoreham EGKA, United Kingdom

I learned to fly in central Canada, before the term global warming had been invented. The mid-winter days were cold, dry, and sunny but short. The temperature hardly ever impacted the flight school reservation book. That is, it was never a reason to cancel operations. However, the number of student reservations would drop once the temp reached the -40°C range. My ab-initio training was often flown in -25 to -35°C weather and 15-20kt wind. The biggest challenge was squeezing into the PA28-140 cabin with a 200lb instructor, both of us bundled up in heavy winter coats, toques and gloves. The preflight walkaround was a challenge to complete without completely freezing extremities. On the first flight of the day, it took a while for the defroster heat to clear the windshield from our steamy breath so we could see out to taxi. Airplane performance easily beat book numbers, and in general the planes performed brilliantly! Much better than in summer +35°C heat of course.

I’m sure that at altitude, say 9000’, we would have beaten the -38°C number. Of course that was long before mobile phones or digital cameras, and taking photos in the cockpit using a 35mm camera wasn’t vogue unless needed for a press photo-op. So no photographic proof.

Last Edited by chflyer at 06 Mar 15:05
LSZK, Switzerland

Peter wrote:

Gosh; I almost didn’t need to install TKS

When I started my IR on the venerable Seneca, my instructor was adamant about flying at high speeds to prevent ice formation and having to use the boots. And yes, it made a difference. A minute one.

Dan
ain't the Destination, but the Journey
LSZF, Switzerland

Very very minute… especially as you will be in IMC and thus limited to Va or some such because you don’t know what is hiding in there.

Administrator
Shoreham EGKA, United Kingdom

Ibra wrote:

It’s not very linear 1C at 100KTAS, 2C at 140KTAS, 6C at 200KTAS

it’s approximately quadratic. The rule of thumb is the square of the TAS in 100’s of knots.

ESKC (Uppsala/Sundbro), Sweden

IN case someone interested the actual formula is 99.99% an isentropic flow as described herein by NASA:

Hence it is exactly quadratic with TAS, M and even IAS.
Since density also affects it one could be tempted to use IAS instead of TAS for the calculation of the effect, but then it is also affected inversely by pressure (altitude) for a given IAS , or absolute temperature for a given TAS.
The only way to kind of isolate speed from atmospheric conditions (altitude and temp) is to use Mach no and then it is exactly, in absolute temp the simple formula:

Tt/T= 1+ 0.2 M^2

You can play with numbers in the NASA webpage and you will see that due to temp change in ISA as you climb, temp rise for a given TAS is very similar at all ISA altitudes or 1.4 deg C at 100KTAS or 5.6C at 200KTAS and 12.6C at 300KTAS and so on…

Last Edited by Antonio at 06 Mar 19:53
Antonio
LESB, Spain

This is my personal record last January just off the coast of French Provence

Last Edited by Antonio at 06 Mar 19:51
Antonio
LESB, Spain


-30°C @FL250

EDLE

europaxs wrote:

-30°C @FL250

How did you get to FL250 in an uncertified? Or were you flying IFR?

EGTR
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