March 26, 201610 yr I understand the process better now. So Type 1 - 4 are deicers then? Type 1 is a deicer, type 4 is an anti icer. Type 4 is applied to keep contamination from collecting on lifting and control surfaces. It sheers off on take off. Type 1 is normally a 55/45 mixture of propylene glychol to water mixture heated to 180 F. Type 4 is an unheated 100% jelly like substance. I used to call the gun we applied it with the snot gun. It's also colored green to be able to see where you've applied it. Every airline has their own procedures on how deicing is done.
March 26, 201610 yr Type I fluids are primarily used for deicing and do not offer any significant anti-icing holdover protection. Because of this Type I fluids are commonly used as part of a two-step de/anti-icing procedure when the final application of a Type II or Type IV fluid provides the required extra protection. Type II fluids can be used for deicing purposes but (unlike Type I fluids) also offer extended antiicing holdover protection and can be used in a variety of ways: Unheated and undiluted (or diluted) for antiicing Heated and undiluted for deicing / antiicing as a one step process Diluted with water and heated for deicing / antiicing as a one step process Diluted with water and heated as the deicing stage in a two step process, when used with the unheated and undiluted fluid. Type III is not used very often. I cant remember why.. Type IV fluids offer maximum antiicing holdover protection, but can also be used for deicing purposes. Similar to Type II fluids, Type IV fluids can also be used in a variety of ways: Unheated and undiluted (or diluted) for antiicing Heated and undiluted for deicing / antiicing as a one step process Diluted with water and heated for deicing / antiicing as a one step process Diluted with water and heated as the deicing stage in a two step process, when used with the unheated and undiluted fluid as step two. Type 1 is a deicer, type 4 is an anti icer. Type 4 is applied to keep contamination from collecting on lifting and control surfaces. It sheers off on take off. Type 1 is normally a 55/45 mixture of propylene glychol to water mixture heated to 180 F. Type 4 is an unheated 100% jelly like substance. I used to call the gun we applied it with the snot gun. It's also colored green to be able to see where you've applied it. Every airline has their own procedures on how deicing is done. 0 Thanks alot. The above types i found on PPrune. So how long is holdover time Found this http://www.b737mrg.net/downloads/b737mrg_holdovertimes.pdf Also found this HOT app https://itunes.apple.com/us/app/deicing-holdover/id867627045?mt=8 Vernon Howells
March 26, 201610 yr Why aren't these included in the HOT There are no holdover times for Heavy Snow, Hail (defined as ice pieces between 5 and 50mm diameter), Snow or Ice Pellets (defined as hail of less than 5mm in diameter) and Moderate or Heavy Freezing Rain. Vernon Howells
March 26, 201610 yr As I said, every airline has their own procedures for deicing. We only used type 1 and type 4. Type 4 was never applied without using type 1 first. Pilots would occasionally ask just for type 4 and we would have to explain that there was no type 4 without type 1 first. Honestly, I forget what the holdover times were for type 4. The flight crews had the charts with the holdover times. We would give them the start and finish times for the final application of fluid and they would go from that. Snow was easy to deice because you can see if you had it all removed. Ice scared me because it was difficult to see, especially in the dark. You had to use massive amounts of type 1 to make sure you had it all removed. In heavy snow or icing conditions, it was not unheard of to empty an entire truck on one narrowbody aircraft. That's 1000 gallons of type 1.
March 26, 201610 yr This app does it all for you and its free https://itunes.apple.com/us/app/deicing-holdover/id867627045?mt=8 Vernon Howells
March 27, 201610 yr Vernon The Internet is your friend. Google "NGX min max hold over time" and several hits come up. This is one of them - http://www.skybrary.aero/index.php/Holdover_Time. Michael Cubine
March 27, 201610 yr Vernon The Internet is your friend. Google "NGX min max hold over time" and several hits come up. This is one of them - http://www.skybrary....p/Holdover_Time. 0 I found some good stuff Vernon Howells
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