Figure 10. Three-dimensional contour map of natural ice surface at the site
chosen for the Pegasus runway. Relative elevations given in feet referenced to
assigned value of 100 ft for the base of the "Pegasus North"automatic weather
station (AWS).
(in)
(mm)
50
1200
ay
Runw
pared
Unpre
for
Limit
40
1000
y
wa
n
Ru
800
d
30
ve
ro
mp
i-i
m
Se
600
r
t fo
i
20
Lim
400
ite
Centerline of Pegasus Runway S
(natural glacial ice surface)
10
200
way
aved Run
Limit for P
0
200
400
600
800
1000 (ft)
0
0
200
300 (m)
100
Figure 11. Bump analysis results for natural ice surface compared to military specifica-
tions for allowable bumps on runways.
A-8863B(AS) (Military Specification 1987) for al-
cial ice runway. Anything more than about a meter
lowable bumps, with the result that surprisingly
of snow present on and around the site of the
little surface preparation would be necessary to
glacial ice runway will be problematic (princi-
meet open field requirements (Fig. 11). Our goal
pally from snowdrifting). Ideally, the site chosen
was to meet the most stringent bump guidelines
should have no net snow depth change from year
to provide a safe, comfortable, and nondestruc-
to year, although a process may be occurring
tive (to aircraft) surface, and to immediately in-
whereby fresh snow is added at the top and bal-
still confidence in pilots upon their first arrival.
anced by some of the snowpack experiencing
ablation or melting with subsequent evaporation
or percolation and refreezing. A survey of the
Snow depth,
average snow cover over the ice (if any) will re-
accumulation, and ablation
veal if snow accumulation is a problem. As much
Little or no permanent snow cover is a prereq-
as possible, the seasonal fluctuation in snow cover
uisite to a suitable site for a semipermanent gla-
10
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