Applying the criterion that cancellation of more than 10% of scheduled
flights in a given month is a severe impact on operations, while cancellation of
110% is a moderate impact, the majority of units in Korea and Germany and at
Fort Campbell experience at least a moderate impact on mission as a result of
actual or forecast icing. Units in Belgium and Illinois and at Fort Wainwright
also experience a moderate impact on mission. Severely affected units are in
Germany, Indiana, and Minnesota, and at Forts Drum and Eustis.
The flight operations respondent for the 3-17th Cavalry Squadron of the 10th
Aviation Brigade at Fort Drum commented that if icing is forecast the flights are
always cancelled prior to departure if icing will affect the profile to be flown; this
is because their aircraft, the Kiowa, is restricted to VFR. From the 11th Aviation
Regiment in Illesheim, Germany, the comment is that only a minimal number of
flights are canceled; rather, missions and mission times are adjusted. This differ-
ence in the way in which units react to icing in the flight profile (cancel vs.
delay) indicates that the reported number of cancelled flights due to actual or
forecast in-flight icing does not fully represent the difficulty of fulfilling missions
in icing conditions. The mission ultimately may be accomplished in spite of in-
flight icing, but on a schedule imposed by the presence or absence of icing
c. Flights disrupted due to unexpected in-flight icing.
Flights aborted or redirected are examples of disruptions. The occurrence
of flight disruptions is a severe problem (more than 10% of scheduled flights
affected) only for the 2-1st Avn Regt (GSAB), whose home station is at Katter-
back, Germany (Table 7). In December, January, and February, 1125% of this
unit's flights are disrupted as a result of unexpected in-flight icing. Flight
cancellations due to ground icing or due to actual/forecast icing in the flight
profile also severely affect this unit; 2650% of scheduled flights are cancelled
because of ground icing, with the same percentage of cancellations reported as a
result of actual or forecast icing conditions. The unit commander, however,
indicated in his questionnaire that forecasted icing conditions in the mission
flight path have a low impact on mission accomplishment.
For the majority of units (62%), more flights are cancelled in midwinter as a
result of actual or forecast icing than are disrupted by in-flight icing. This may
reflect effective forecasting, such that pilots do not frequently encounter unex-
pected in-flight icing. Or, it may reflect conservative decisions with regard to
canceling flights, i.e., flights are cancelled if there is even a small likelihood that
icing would be encountered.