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US HEMS Accident

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US HEMS Accident

Old 18th Mar 2019, 00:55
  #101 (permalink)  
 
Join Date: May 2002
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Memory serves me we removed the Water Filters from the Barrel Pumps in the Winter up in Alaska.....two reasons....water becomes ice and jet fuel gets awfully thick and hard to pump by hand.

We are talking Temps of 0 degrees F and colder....down to like -45F.

I went South after I saw -50F on any OAT Gauge as I was a fair weather pilot.....and not a real Sourdough.

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Old 18th Mar 2019, 02:02
  #102 (permalink)  
 
Join Date: Dec 2018
Location: Canada
Posts: 112
Icing in cold temps

Originally Posted by Outwest View Post
Don't let anyone ever tell you you can't have fog (ice fog) at -40C I have iced up badly at -40C, ice fog rising off the open sea in the Canadian arctic
Very true.

Strong winds = open leads = ice fog. Often you will see a "Moon Dog" associated with these conditions.

I have picked up heavy clear at -45C in the Lougheed Island area in November/December/January.

I experienced the same icing conditions in the Beaufort Sea on 212/61/76's every winter I flew there (8 years).
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Old 18th Mar 2019, 02:29
  #103 (permalink)  
 
Join Date: Mar 2019
Location: Cartersville, GA
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Originally Posted by megan View Post
Water can remain liquid down to -40C. Then you can have ice fog which only forms under specific conditions; the humidity has to be near 100% as the air temperature drops to well below 0 C (32 F), allowing ice crystals to form in the air.
Well... I guess I'm just allowing my ignorance to shine brightly. Just a very lower-48 kind of guy.
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Old 18th Mar 2019, 07:35
  #104 (permalink)  
 
Join Date: Apr 2000
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Most aviation meteorology books with a section on icing will tell you about supercooled water droplets - ie those existing below 0 degrees C which can be found in temperatures as low as -40 degrees C, normally in cloud with lots of vertical movement.

However, it requires the absence of appropriate freezing nuclei in the atmosphere for the water to freeze onto.
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Old 18th Mar 2019, 09:57
  #105 (permalink)  
 
Join Date: Mar 2019
Location: Cartersville, GA
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Originally Posted by [email protected] View Post
Most aviation meteorology books with a section on icing will tell you about supercooled water droplets - ie those existing below 0 degrees C which can be found in temperatures as low as -40 degrees C, normally in cloud with lots of vertical movement.

However, it requires the absence of appropriate freezing nuclei in the atmosphere for the water to freeze onto.
I remember the "supercooled water droplets" and "condensation nuclei" questions but have never had any experiences related to it.
It was wayyy back in my head-noodle. I would guess it's pretty hard to find modern day sky that is not packed with condensation nuclei.
I was just searching for weather related reasons this HEMS crash could have happened. I know fast-forming fog could put a pilot in a
situation with no "out."
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