Army Aircraft Icing
31
c. Typical duration for forecast in-flight icing conditions.
The impact of forecasted in-flight icing on aviation operations in a given
month is dependent on the number of hours for which in-flight icing is predicted
to occur. The same number of "no fly" hours per month could result from a few
in-flight icing forecasts of long duration as from more numerous icing forecasts
of shorter duration. A unit's flight schedule determines which occurrence (many
short-duration icing forecasts vs. fewer long-duration icing forecasts) is more
disruptive to its operations, and so influences the statistics of the flight operations
responses. Units contend with their aircraft's icing restrictions in creative ways
to minimize cancellations in response to forecast in-flight icing. For instance, as
reported on the Aircraft and Ground Maintenance questionnaire, the 34th Avn
Bde of the Minnesota National Guard allows UH-1 aircraft to fly in forecast light
icing only within a 25-km radius of its base of operations. The respondent noted
that "if this rule did not exist, we would cancel a lot of flights in December and
MarchApril timeframe."
The majority of units in Germany receive forecasts of in-flight icing with
duration of at least 24 hours in December, January, and February (Table 11). The
duration of in-flight icing forecasts for most units in Korea falls in the range of
seven to 24 hours, although the 1-52nd Avn Regt (CAB) receives forecasts with
a typical duration of more than 1.5 days throughout the winter (October through
April). At Fort Wainwright, the forecast duration of in-flight icing is 1924 hours
throughout the winter. Fort Drum, Fort Campbell, and Fort Sheridan all are sub-
ject to forecast icing durations of more than 1.5 days.
A worthwhile activity would be the comparison of icing forecast duration
with actual persistence of icing conditions. Such an analysis would indicate
whether Army aircraft at a location spend an inordinate amount of time grounded
because of forecast (vs. actual) icing conditions.
Previous Page
