Index   484 -- Page 485 -- 486

5/26/16
12/10/15                                                                                                                     AIM


EXAMPLE-                                                            2. Clear ice. A glossy, clear, or translucent ice formed by
Pilot report: give aircraft identification, location,               the relatively slow freezing of large supercooled water
time (UTC), intensity of type, altitude/FL, aircraft                droplets.
type, indicated air speed (IAS), and outside air                    3. The OAT should be requested by the FSS or ATC if not
temperature (OAT).                                                  included in the PIREP.
NOTE-                                                               7-1-21. Definitions of Inflight Icing Terms
1. Rime ice. Rough, milky, opaque ice formed by the
instantaneous freezing of small supercooled water                   See TBL 7-1-8, Icing Types, and TBL 7-1-9, Icing
droplets.                                                           Conditions.


                                                            TBL 7-1-8
                                                         Icing Types
        Clear Ice             See Glaze Ice.
        Glaze Ice             Ice, sometimes clear and smooth, but usually containing some air pockets, which results in a
                              lumpy translucent appearance. Glaze ice results from supercooled drops/droplets striking a
                              surface but not freezing rapidly on contact. Glaze ice is denser, harder, and sometimes more
                              transparent than rime ice. Factors, which favor glaze formation, are those that favor slow
                              dissipation of the heat of fusion (i.e., slight supercooling and rapid accretion). With larger
                              accretions, the ice shape typically includes "horns" protruding from unprotected leading edge
                              surfaces. It is the ice shape, rather than the clarity or color of the ice, which is most likely to
                              be accurately assessed from the cockpit. The terms "clear" and "glaze" have been used for
                              essentially the same type of ice accretion, although some reserve "clear" for thinner accretions
                              which lack horns and conform to the airfoil.
      Intercycle Ice          Ice which accumulates on a protected surface between actuation cycles of a deicing system.
 Known or Observed or Actual ice observed visually to be on the aircraft by the flight crew or identified by on-board
 Detected Ice Accretion sensors.
        Mixed Ice             Simultaneous appearance or a combination of rime and glaze ice characteristics. Since the
                              clarity, color, and shape of the ice will be a mixture of rime and glaze characteristics, accurate
                              identification of mixed ice from the cockpit may be difficult.
       Residual Ice           Ice which remains on a protected surface immediately after the actuation of a deicing system.
        Rime Ice              A rough, milky, opaque ice formed by the rapid freezing of supercooled drops/droplets after
                              they strike the aircraft. The rapid freezing results in air being trapped, giving the ice its opaque
                              appearance and making it porous and brittle. Rime ice typically accretes along the stagnation
                              line of an airfoil and is more regular in shape and conformal to the airfoil than glaze ice. It is
                              the ice shape, rather than the clarity or color of the ice, which is most likely to be accurately
                              assessed from the cockpit.
       Runback Ice            Ice which forms from the freezing or refreezing of water leaving protected surfaces and
                              running back to unprotected surfaces.
Note-
Ice types are difficult for the pilot to discern and have uncertain effects on an airplane in flight. Ice type definitions will
be included in the AIM for use in the "Remarks" section of the PIREP and for use in forecasting.




Meteorology                                                                                                               7-1-41