freezing fog
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freezing fog
Just wondering if anybody can tell me what freezing fog is like. Does it form ice on an airplane, or is it more like ice crystals? I have never flown through the stuff and have never really seen much written on it in any books. Curious to know what to expect if one were to shoot an approach in the stuff.
Thanks for any info.
Thanks for any info.
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- Rank 1
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Freezing fog is different than ice crystals. Freezing fog is supercooled fog and with cause ice on surfaces that it comes in contact with (just like freezing rain). If you flew through it you'd be picking up ice so you'd need engine and probably wing de-icing/anti-icing systems operating.
Ice crystals (or ice fog)on the other hand is composed of ice only. This occurs in temperatures that are too cold for supercooled water droplets.
Hope this helps.
Ice crystals (or ice fog)on the other hand is composed of ice only. This occurs in temperatures that are too cold for supercooled water droplets.
Hope this helps.
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Two words: PROP ICE! Even taxiing in the stuff for a few minutes can cause the props to ice up badly. We were on takeoff roll one day in ice fog after a maybe 10 min. ATC delay and there was very poor acceleration. My copilot had more experience with the stuff and had warned me about it. We rejected and shut down. I have never seen so much ice on a prop and lots outboard of the deice boots which I must admit were not selected on for the takeoff.
Another day after landing in ice fog with only about a minute in the soup prior to landing then the usual 3 min. taxi, the props were likewise loaded up incl. the prop. boots which were turned off after landing. The wings had only a minor skiff in that case.
A heavy overshoot after an approach in the stuff might be interesting not to mention the consequences of losing a fan.
Not my idea of fun! Be careful in this stuff.
Another day after landing in ice fog with only about a minute in the soup prior to landing then the usual 3 min. taxi, the props were likewise loaded up incl. the prop. boots which were turned off after landing. The wings had only a minor skiff in that case.
A heavy overshoot after an approach in the stuff might be interesting not to mention the consequences of losing a fan.
Not my idea of fun! Be careful in this stuff.
Another interesting fact about freezing fog is that it can form in temperatures above 0*C. Up to +3*C if I recall. The hold time tables for Type I and type IV give times for -3*C and above... The books say they cannot duplicate the effects of freezing fog above 0*C in the lab, however the effects of freezing fog still exists.
I operated a flight last November in YVR where the tempurature was +2*C in freezing fog. Our ops considers Freezing Fog to be precipitation, and as such the appropriate de-icing/ anti-icing is required. Type I at the gate does not provide enough hold over time to get you to the departure end of the runway. A Type IV was required that day. Caution in the use of a pre-take-off inspection... very difficult to tell on most Jet Aircraft... Ice can form on parts of the airframe that do not have anti-icing equipment. Use of engine anti-ice is required as Ice can collect on the stador vanes very quickly... especially at engine spool up. Wing anti-ice is often ineffectual (on many airliners) until the aircraft is airborne as it is often limited to lower operating tempuratures (or not at all) while the aircraft is on the ground. Type IV is really the only answer for this scenerio if you are departing....
Fly safe
Good post.
I operated a flight last November in YVR where the tempurature was +2*C in freezing fog. Our ops considers Freezing Fog to be precipitation, and as such the appropriate de-icing/ anti-icing is required. Type I at the gate does not provide enough hold over time to get you to the departure end of the runway. A Type IV was required that day. Caution in the use of a pre-take-off inspection... very difficult to tell on most Jet Aircraft... Ice can form on parts of the airframe that do not have anti-icing equipment. Use of engine anti-ice is required as Ice can collect on the stador vanes very quickly... especially at engine spool up. Wing anti-ice is often ineffectual (on many airliners) until the aircraft is airborne as it is often limited to lower operating tempuratures (or not at all) while the aircraft is on the ground. Type IV is really the only answer for this scenerio if you are departing....
Fly safe
Good post.