VFR Icing

brcase

brcase

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Brian
Weather 10+miles visibility, 4000ft AGL ceiling, outside temp at 2000ft AGL 15F.

Was early morning flight, just before sunrise.
At 1st I thought it was just snowing south of us due to the reduced visibility ahead, but when we turned it turned with us and I thought it was the windshield fogging up, but wiping the windshield proved it was on the outside, Defroster was only keeping about a 3” diameter area clear on the 172 windshield.

We turned around and went back to the airport. The Ice slowly started dissipating so so opted to practice some take offs and landings. It is now daylight about the 5th trip around the pattern and ice starts building up on the windshield again. Still no visible moisture or reduced visiblity. We decided we had a enough and ended the lesson.

Windshield photo, reduced visibility is due to ice on the windshield, actual visibility is still 10+ miles.

Brian
 

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brcase said:
Weather 10+miles visibility, 4000ft ceiling, outside temp at 4000ft 15F.

Was early morning flight, just before sunrise.
At 1st I thought it was just snowing south of us due to the reduced visibility ahead, but when we turned it turned with us and I thought it was the windshield fogging up, but wiping the windshield proved it was on the outside, Defroster was only keeping about a 3” diameter area clear on the 172 windshield.

We turned around and went back to the airport. The Ice slowly started dissipating so so opted to practice some take offs and landings. It is now daylight about the 5th trip around the pattern and ice starts building up on the windshield again. Still no visible moisture or reduced visiblity. We decided we had a enough and ended the lesson.

Windshield photo, reduced visibility is due to ice on the windshield, actual visibility is still 10+ miles.

Brian
Click to expand...
I had this same exact thing happen last year. There wasn't any perceptible, visible moisture when standing on the ground and none was reported. But in the air there must have been a mist or something. Icing wasn't reported until 2-3k+ feet above me in the clouds.

At first I thought the windshield was fogging up a bit. Then I noticed they were tiny specks that looked like raindrops that weren't going away. Within only about 5 minutes it went from clear windshield to opaque. Like yours, the only clear section was the part around the defroster. Picked the nearest airfield and landed. Left it there for 2 days until it was severe clear then flew it back.

This photo was after about half the ice melted off the windshield and I was taxiing to the FBO. When I got out to push the plane into the rented hangar both me and the fbo guy noticed how much ice had built up on the wings. Scary. At the encouragement of a safety minded friend I ghost-wrote an article for the local EAA publication about it.

1705171245741.png
 
What was the dewpoint spread?
 
Look like about this…
A13/01/2024 14:15->METAR KMAN 131415Z AUTO 36005KT 10SM OVC039 M11/M16 A3011 RMK A01=

 

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What altitude were you at? I've seen little specks of moisture when I've gotten too close to the bases. Winter needs more margin. At least you have a defroster!
 
I had a similar event years ago, flying home VFR from Maine to Vermont with an excellent forecast. As I approached the Green Mountains the ceiling was lower than forecast but I flew through the Killington gap below the clouds, and five seconds later was pelted with freezing rain that completely and almost instantly covered the windshield. I was in familiar terrain (actually over my own house) so I flew through a lower gap and managed to use windshield heat enough to see ahead of me, landed and watched as a large amount of ice fell from the wings and tail.

After I landed FSS called me and asked if I had heard any transmission from a specific tail number, which I hadn't, but I later found out that a Piper Arrow had lost contact in the same area. It turns out that they flew right over the Killington ski area, loaded with ice, then the gear dropped down automatically and they crashed. Ironically he two passengers as a result of the accident became patients of mine at the hospital and described the event. They were cruising overhead on an IFR flight plan when the hit unexpected icing and approach began vectoring them to the airport. When they gear dropped they flew over several skiers and into the trees. Expecting to have the ski patrol come to help, nothing happened and the two occupants had to crawl into the tail cone for the night. The next day the pilot, who was less injured walked over to the ski trail and was able to get help. It turns out that their crash and my icing experience were minutes apart and within about two miles of each other. It was later documented on a TV show, I think called "Rescue 911".
 
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