How cold is too cold (OAT)

[BorealOne]

Ok - 

 

I thought I saw a thread on this recently, but a search doesn't turn it up. What are people's personal limits for cold weather ops?

 

Maybe I'm getting old, but when I look at forecasts that have temps below -30 on the ground/-40 in the air, I think about going commercial. Too many things break or don't work right in those temperatures.

 

What about the rest of you?

 

 

[201er]

Never thought of it being that cold. I'll go in whatever the coldest we get but in NYC it's never less than 15F

[aviatoreb]

Ok - 

 

I thought I saw a thread on this recently, but a search doesn't turn it up. What are people's personal limits for cold weather ops?

 

Maybe I'm getting old, but when I look at forecasts that have temps below -30 on the ground/-40 in the air, I think about going commercial. Too many things break or don't work right in those temperatures.

 

What about the rest of you?

 

-30C or -30F?

 

Depends on if it is windy or not - but below 0F is mostly too cold for me for fun ops and roughly -10F is a no go.  The plane can handle it but this poor pilot gets cold and feels rushed during preflight if its that cold.  This last week there were two beautiful clear blue still air days that were -27F in the morning that I skipped because that's too cold for me.

[Joe Zuffoletto]

If I ever found myself factoring those kinds of temps into my go/no-go decision, I'd move to a warmer climate.

 

http://www.nfl.com/videos/nfl-super-bowl-commercials/09000d5d81e2ab01/Acura-MDX

 

That's some serious cold. I've done my share of flying in the low to mid 20's (as in thousands of feet) year round and have never seen an OAT less than -20F.

 

But if it ever got that cold here in Denver I'd definitely go commercial.

[dsimes]

My coldest Mooney takeoff was at -34C. Field elevation was 850 asl, but density alt was way below sea level...I dont remember the figure. It quickly warmed up to -20C by about 1000' after a very short takeoff roll. We used to fly practise CASARA missions to -25C, but the real thing had no limits, it was pilot discretion. I never had to make that call. The most important consideration is not the aircraft, but what you will do with yourself overnight waiting for rescue. Days are short when it is that cold. As you saw with the Antarctic with the sad Borek mission, it could be a while. Also, things break when it gets that cold. Gear doesn't work as well, condensation inside instruments adds stress, you can rush your preflight, windscreen will fog up if you dont have a blower, your headset gives you an ice cream headache, does your destination have a hangar, the list goes on. The upside is clear crisp skies, exceptional performance (watch overboost on turbos), no bumps, and no bugs to clean off after. There is also an infinite number of pillowy soft places to land if the fan quits. General rule of thumb, if you see an IRS guy with his hands in his own pockets, it's too cold to fly.

[aviatoreb]

My coldest Mooney takeoff was at -34C. Field elevation was 850 asl, but density alt was way below sea level...I dont remember the figure. It quickly warmed up to -20C by about 1000' after a very short takeoff roll. We used to fly practise CASARA missions to -25C, but the real thing had no limits, it was pilot discretion. I never had to make that call. The most important consideration is not the aircraft, but what you will do with yourself overnight waiting for rescue. Days are short when it is that cold. As you saw with the Antarctic with the sad Borek mission, it could be a while. Also, things break when it gets that cold. Gear doesn't work as well, condensation inside instruments adds stress, you can rush your preflight, windscreen will fog up if you dont have a blower, your headset gives you an ice cream headache, does your destination have a hangar, the list goes on. The upside is clear crisp skies, exceptional performance (watch overboost on turbos), no bumps, and no bugs to clean off after. There is also an infinite number of pillowy soft places to land if the fan quits. General rule of thumb, if you see an IRS guy with his hands in his own pockets, it's too cold to fly.

 

Exactly!  Esp, "...what you will do with yourself overnight..."  That is a primary thing in the back of my mind, but all the other things you said are spot on.

 

I like to think I'm as tough as the next guy regarding cold.  On Sunday I did a 15k cross country ski race that was "3F OAT" at the start.  Cold isn't the problem when you go hard, its that you sweat...I have big eyebrows and its fun watching icicles form on my eyebrows and I knock them off after awhile.  But doing an hour or so race, well dressed, with safety folks at the turns, and then back to the warming house is a whole different thing than thinking of an overnight.  3F in the day is -20F at night and that can start to get dangerous if you don't know what you are doing.  Esp if injured.

[The-sky-captain]

Exactly!  Esp, "...what you will do with yourself overnight..."  That is a primary thing in the back of my mind, but all the other things you said are spot on.

 

I like to think I'm as tough as the next guy regarding cold.  On Sunday I did a 15k cross country ski race that was "3F OAT" at the start.  Cold isn't the problem when you go hard, its that you sweat...I have big eyebrows and its fun watching icicles form on my eyebrows and I knock them off after awhile.  But doing an hour or so race, well dressed, with safety folks at the turns, and then back to the warming house is a whole different thing than thinking of an overnight.  3F in the day is -20F at night and that can start to get dangerous if you don't know what you are doing.  Esp if injured.

I agree 100%. I always thought I was able to handle cold wx until I got stranded in the Colorado backcountry on a backpacking trip due to blizzard conditions. That was COLD!! At one point I was in my tent for 27 hours straight as it was to windy to have a fire. Luckily I had good gear and after 3 days was still kicking and ready to continue the climb.

[BorealOne]

-43C in CYZF today. Density altitude -7548. Needless to say, I flew commercial. My Mooney thanked me.

 

On survival in the bush - absolutely echo the above comments. I wrote a post on this a while back:

 

http://mooneyspace.com/topic/4505-northern-survival-notes/http://mooneyspace.com/topic/4505-northern-survival-notes/

[Hank]

-30C or -30F?

 

Depends on if it is windy or not - but below 0F is mostly too cold for me for fun ops and roughly -10F is a no go.  The plane can handle it but this poor pilot gets cold and feels rushed during preflight if its that cold.  This last week there were two beautiful clear blue still air days that were -27F in the morning that I skipped because that's too cold for me.

 

There's not much difference between -30C and -30F [-30F = -34.4C]. Don't think I could tell which it was . . .

 

My coldest departure to date was 8F, and my wife stayed at home in bed. Performance was great! Preflighting inside the [unheated] hangar helps, but it's still cold, just not windy.

 

Things to consider are terrain below you, and how thickly it is or isn't settled. There's "country" and then there's "bush." I know which I would prefer to make an unscheduled landing!

[carusoam]

Minus 40 is minus 40. C or F!

It's a good temperature for long term storage of coffee standards.

-a-

[dsimes]

BorealOne, great post. You got it nailed. I've flown PXG into Churchill back when I lived in The Pas, CYQD, but no further north. I've seen Yellowknife and Inuvik in the summer, but I went commercial. Lots of nothing up there. I think it's great that we can show our southern brothers and sisters how versatile our aircraft are. Say hi to Joe and Mikey. Cheers.

[BorealOne]

...Say hi to Joe and Mikey. Cheers.

 

Funny...one of my trips North saw me pay the boys @ Buffalo a visit. I lost my throttle cable inbound to CYLK (file under 'things break in the cold') so diverted into CYZF and did a deadstick landing there. My journey log accordingly has a maintenance entry from Chuck Adams, the curmudgeon mechanic (and a real star on the Ice Pilots NWT series) who replaced it.

[jlunseth]

I haven't decided on a "too cold" limit yet, but am working on it.  In the flight levels it is often well below zero even in the summer, but the sun combined with the plane's heater and the fact that the air is thin and therefore does not cool things as fast, allow comfortable cabin temps.  I did do one flight from KISN to KFCM last fall at FL210 which was mostly night and temps were around -55 dF, and the cabin heater only sort of kept up.  I was find, the copilot, being skinny, was cold. 

 

For many reasons I have not flown much in the winter months.  However, I have been trying it a little this year.  When it falls below 10dF, the Tanis heater does not seem to help much even if left plugged in all the time.  It takes some heat from a propane blower to start the engine.  It is also necessary to let the engine warm up for quite awhile in order to avoid temp. issues.  My minimum is an oil temp of 130 before I will take off.  Last fall I tried some fast approaches and landings at a small noncontrolled airport.  I had the cowl flaps open on the ground, which is fine for summer but I no longer do it in winter.  The air/oil separator froze, causing oil to spew out of any available orifice of the engine.  This winter I tried a takeoff when the OT had just cleared 100F, and saw intermittent low oil temps on takeoff, down as low as 84F.  That all led me to do longer warmups, and now 130 OT is my minimum.  I also rarely open the cowl flaps.  Plane is going in for the annual, so I am going to have an oil cooler block installed and see if that helps.

 

On a separate but related subject, there is a little bit of a disagreement between the GAMI people, and the Mike Busch method of leaning to LOP by engine temp.  The GAMI people advocate against using CHT (which Busch advocates for) because in some circumstances, superior cooling will keep the CHT's down when the engine is very much in the "red box" and experiencing high Internal Cylinder Pressures.  Under most normal conditions in the summer the Busch method works.  But I have noticed that in cold temp operations, somewhere below 10F or so, the engine cooling is so good that it would be possible to run at 100%HP dead center in the red box and still not have CHT's over 380.  At 80%HP it can be hard, at those temps, to get CHT's out of the high 200's/low 300's no matter where you run the engine LOP/ROP wise.  The engine cooling is simply too efficient.  So you would be running cool cylinders that may be in pre-detonation inside.

[aviatoreb]

What are you flying with that kind of super cooling jlunseth?

 

On a separate but related subject, there is a little bit of a disagreement between the GAMI people, and the Mike Busch method of leaning to LOP by engine temp.  The GAMI people advocate against using CHT (which Busch advocates for) because in some circumstances, superior cooling will keep the CHT's down when the engine is very much in the "red box" and experiencing high Internal Cylinder Pressures.  Under most normal conditions in the summer the Busch method works.  But I have noticed that in cold temp operations, somewhere below 10F or so, the engine cooling is so good that it would be possible to run at 100%HP dead center in the red box and still not have CHT's over 380.  At 80%HP it can be hard, at those temps, to get CHT's out of the high 200's/low 300's no matter where you run the engine LOP/ROP wise.  The engine cooling is simply too efficient.  So you would be running cool cylinders that may be in pre-detonation inside.

 

This remark could easily tumble into a long LOP methods thread.  At risk of that - I have the same issue and worry.  If it is -frigid F degrees out, then low 300s is what I also see on my engine at all mixture settings even at high power settings.  So that seems to be a bad idea to run on temp below if the pressure is too high if cooling baffling and temps are working against the Busch method.  I have long wondered about your remark.  I am only guessing here - I am guessing that it is impossible to get detonation even at high power settings like 80% if you are running 300F due to good cooling - rockets are well cooled too.  If I am right, then the danger of such a setting is simply the extreme wear of high power settings leaned to dead center.

 

BorealOne - I had what I suspect to be a "things break" in extreme cold breakage just this past december.  My KFC200 autopilot broke - thankfully in a very inexpensive way.  The plastic switch mechanism connected to the on switch/solenoid - the thing on the switch box I use to turn the system on - the plastic broke inside.  So out came the box, off to AP central, and just got the unit back nicely repaired and ready for re-install.  I am wondering if that bit of plastic would not have broken on a warmer day.  It was not even extreme cold, but probably 20F-30F in the cabin at that point since I did preheat the cabin by ceramic heater but probably not as long as I should have.  It broke before cabin heat kicked in as I was still on take off climb at maybe 1000ft,

[jlunseth]

M20k 231. Tsio-360lb1 merlyn and turbo plus. Willmar put in new baffling three years ago, and I also had the fuel system rebuilt. Made a big difference in temps.

[BorealOne]

On this topic, a friend of mine who flies for Air Canada Jazz in the CRJ tells me that their SOP is not to fly when it is -40 on the ground at destination. Apparently things break on the bigger birds too.