nature, the result was a usable runway. While we
Snowdrifting
Earlier we discussed the critical nature of snow
would do a few things differently if we were to
control at some sites where a glacial ice runway
start over today, the current Pegasus runway is
might exist. In polar regions where snow is not
robust and has the potential for a long life in its
completely lost during the summer, a small drift
current form with proper attention paid to main-
problem will nearly always eventually become a
tenance.
big problem if left unattended. Construction ac-
tivities and topographic rearrangement will likely
encourage drifting. If a effective plan for drift
DEMONSTRATED UTILITY
control is not determined and pursued the site
may collect additional amounts of snow each sea-
We have shown the usefulness of the Pegasus
son until it is inundated and unmanageable. Rarely
runway for late season (mid-January to the end of
will mechanical means be adequate to overcome
February) use by LC-130s delivering cargo to
a snowdrift problem in polar regions.
South Pole Station (Fig. 65) and for redeployment
We originally thought that the Pegasus site
of personnel to Christchurch using either C-130s
would be very prone to snowdrift buildup with
(Fig. 84) or C-141s (Fig. 67). Continued reliance
slight perturbations to the natural topography.
on the Pegasus runway for these uses alone justi-
Our experience over the past three austral sum-
fies its maintenance. We can also cite many indi-
mer seasons suggests that the site is not as sensi-
rect advantages including reduced wear and tear
tive to this problem as initially imagined. How-
on airframes, more efficient use of aircraft and
ever, we do not yet have enough data to know
flight crews, less wasted time by science and sup-
precisely how much drift snow will be trapped in
port personnel waiting for transport on outbound
the long-term by the berms that were created dur-
aircraft (Pegasus provides a reliable number of
ing construction and the first several years of op-
seats for each flight), enhanced morale (program
eration. The survey data in Appendix C are en-
participants now have confidence in their rede-
couraging. We have taken care to ensure that any
ployment date), assurance of stocking South Pole
large snow piles have a gentle slope (1 in 7 or
before station close, increased efficiency for cargo
greater) in the lee and windward sides which
handlers at South Pole, and timely station close-
appears to significantly reduce snow trapping.
out despite late vessel arrival or storms.
We are also studying natural methods to encour-
From a quantitative standpoint, we can com-
age selective accelerated snow loss. The berms
pare maximum takeoff weights and show that
created during construction have now become
two flights from the Pegasus runway (wheels) are
firn, making them more difficult to obliterate.
equal to three from Williams Field (skis). In 1993,
23 flights operated from Pegasus and more than
55 flights departed the runway in each year from
Climatic effects
A glacial ice runway site selected on the fringe
1994 to 1997. Thus, at least 122 flights were saved.
of a glacialogical zone, such as the Pegasus site,
If we assumed that half of these would have gone
may be sensitive to slight perturbations in cli-
to the South Pole (6-hr round-trip) and half to
matic conditions. For example, if a series of ab-
Christchurch (16-hr round-trip), 1342 flight-hours
normally warm summers occur for one or more
were saved. An accepted cost for the Hercules
years, runway preservation efforts may become
(including fuel) is ,000 per hour, which results
immense. It may not be possible to maintain run-
in a cost savings of more than million to the
USAP. At the beginning of the 1996-97 and 1997
way ice integrity.
Anything that changes the solar intensity im-
98 seasons, the Pegasus runway was used in late
pinging on the site will also change the runway's
August for WINFLY (winter fly-in). This set-up
heat balance. An increase in intensity, for example
operation is usually done using LC-130 aircraft,
due to depleted ozone, may shift the boundary
requiring a separate deployment from California.
between chronic melt pool regions and protected
By using Air Force C-141 aircraft that are rou-
ice areas.
tinely passing through Christchurch, New
Zealand, the USAP saved about 0,000 on the
cost of WINFLY each season.
Future of the Pegasus runway
Although the project that spawned the Pegasus
These cost savings compare very favorably with
glacial ice runway was a research program and
the estimated cost of the runway,
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.65 million
the construction performed was experimental in
over the five-year development, which included
90
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