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anti-icing fluid) before takeoff
Federal Aviation 8 8
Administration
FAA Icing Program Update
September 26, 2007
Winter 2005 FAA National Policy
Prohibiting Operations in Ice Pellet
Conditions (FAA Notice 8000.309)
Why?
– Human factors research conducted for Ground Ice Detection
Systems (GIDS) showed that the human eye was very poor at
seeing ice adhering to the wing surface treated with anti-icing
fluid, and the human hand (tactile check) was only slightly
better.
• This research invalidated the practice of conducting a pre-takeoff
contamination check in ice pellet conditions.
– With the increase in hard wing air carrier aircraft (no wing
leading edge devices, which makes them far more critical to
the effects of ice on the wing surfaces) we needed to establish
a prohibitive policy
Federal Aviation 9 9
Administration
FAA Icing Program Update
September 26, 2007
Testing Lead to 25 Minute Allowance
Time in Light Ice Pellet Conditions
Alone for 2006-2007 Winter
(FAA Notice 8000.327)
Why Allowance Time and Not Holdover Time?
– Holdover time limit is the time under a given conditions that the
anti-icing fluid will begin to show signs of failure. A sign of
failure is when the precipitation is not absorbed into the anti-icing
fluid but remain in its original state. Ice pellets are not absorbed
into the anti-icing fluid like other forms of precipitation but
remain as ice pellets imbedded in the fluid. Therefore under the
term holdover time the fluid would have failed from the time the
first ice pellet hit the fluid and the holdover time would have been
zero.
– Additionally with a holdover time a pre-takeoff contamination
check could be conducted after the expiration of the holdover
time and if the fluid has not failed a takeoff could still be
conducted. This is not the case with ice pellets.
Federal Aviation 10 10
Administration
FAA Icing Program Update
September 26, 2007
Why not a pre-takeoff
contamination check?
Ice Pellets Are Different!
Two Concerns
• Are they adhering to the aircraft surface?
– No way to make this determination with a visual check
– Could probably make this assessment with a tactile check, but
• Will the now thickened fluid with the imbedded ice
pellets still shear off the wing prior to liftoff?
– There is no way to make this determination (visually or tactilely)
Federal Aviation 11 11
Administration
FAA Icing Program Update
September 26, 2007
Problems with 25 Minute
Allowance Time
• Light Ice Pellets alone, not mixed with other
forms of precipitation, only occur about
30% of the time that ice pellets are present
• Provided no relief for moderate ice pellets
• Insufficient time for long duration ice pellet
events at major airports
Federal Aviation 12 12
Administration
FAA Icing Program Update
September 26, 2007
Some Of The Most Extensive Antiicing
Fluid Testing Ever Conducted
Winter 2006-2007
Wind Tunnel
– High speed photo analysis of fluid shear qualities
– Lift loss measurements
Live Aircraft Testing
– Supportive photo analysis of wind tunnel testing
Deicing Fluid Flat Plate Testing
– Supportive shear quality testing of wind tunnel
testing
– Determining the effects of ageing anti-icing fluid with
imbedded ice pellets
Federal Aviation 13 13
Administration
FAA Icing Program Update
September 26, 2007
So Where Did All This
Testing Get Us for Winter
2007-2008?
Federal Aviation 14 14
Administration
FAA Icing Program Update
September 26, 2007
Ice Pellet Allowance Times
2007-2008
Currently Posted on AFS-200
Web Site
http://www.faa.gov/about/office_org/headqu
arters_offices/avs/
offices/afs/afs200/
Signed Notice Last Thursday
Federal Aviation 15 15
Administration
FAA Icing Program Update
September 26, 2007
OAT -50 C
or Warmer
OAT Colder
Than -50 C
Light Ice Pellets 50 Minutes 30 Minutes
Moderate Ice Pellets 25 Minutes 10 Minutes
Light Ice Pellets Mixed
with Light or Moderate
Snow
25 Minutes Operations
Not
Authorized
Light Ice Pellets Mixed
with Light or Moderate
Freezing Drizzle, or
Light Freezing Rain
(Operations Not
Authorized below -10C
OAT)
25 Minutes 10 Minutes
(Operations
Not
Authorized
below -10C
OAT)
　
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