WEATHER OBSERVATIONS

Field skiway and Pegasus, which operate concur-

WEATHER OBSERVATIONS

rently during January and February. At times,

The weather present at the glacial ice runway

there have been seven flights per day operating

site during the period of air operations will dic-

from Pegasus and, occasionally, there is a plane

tate the quality and quantity of weather data re-

on the runway while another plane circles over-

quired. Requirements will also be driven by the

head awaiting its departure. The Pegasus runway

nature of the aircraft used (on-board navigation

has never had two aircraft on deck at the same

aids), availability of nearby alternate landing sites,

time, but there is ample room on the runway and

flight origination point, and the standard operat-

"ramp" area to accommodate two aircraft. We

ing procedures of the pilots and air crews. Many

recommend that Pegasus have its own air traffic

of the flights to Pegasus originate in New Zea-

controller if two planes will be on the runway

land in (L)C-130 aircraft. The fuel capacity of the

at once or if concentrations of flights become a

aircraft is such that the point of safe return (PSR),

regular occurrence.

or point at which a decision as to whether to turn

Ground control is a critical issue. Once the

back or continue based on fuel remaining, is ap-

Pegasus runway became operational, we found

proximately 12 hours short of the runway. There-

that it was difficult to immediately make the tran-

fore, flight managers and ground personnel

sition from viewing the site as a construction zone

should have available adequate weather informa-

to a restricted area. Personnel briefings and writ-

tion to make accurate forecasts for several hours

ten guidelines for anyone preparing to work out

to assist the incoming flight crew in making this

of a camp using a glacial ice runway should in-

decision. To avoid wasted flight time, adequate

clude a clear indication of the restricted area

weather forecasts are required for the time period

around the runway and explain proper proce-

extending from pre-launch to estimated time of

dures for approaching the runway.

arrival. Fortunately, McMurdo has a sophisticated

At Pegasus, a single access road leading to one

weather center, using data from satellite imagery

end of the runway makes it relatively easy to

and numerous automatic weather stations around

control access. A single ground controller is re-

the continent, which makes forecasting possible.

quired, having radio contact with anyone who

Based on the forecasts, decisions are made whether

will have business on or in the immediate vicinity

to launch flights from New Zealand, thus mini-

of the runway when aircraft are in the area. The

mizing "boomerang" flights.

ground controller must also be in constant con-

Localized variations in weather should be noted

tact with, and be the only person on the ground

over time by an on-site weather observer as a

communicating with, the air traffic controller.

function of specific occurrences. For example, dur-

Guidelines for both the ground controller and

ing the austral spring and autumn it is common

for persons needing access to the runway can

for the Pegasus site to have adequate visibility for

be found in a document published by the Fed-

air operations when virtual white-out conditions

eral Aviation Administration (1990). Such guide-

are present at Williams Field. At other times, there

lines can be obtained and customized as necessary

can be a very strong southerly wind with active

for each specific glacial ice runway by the run-

snow movement at ground level at the Pegasus

way manager and assigned ground controller.

runway while Williams Field has calm conditions.

At Pegasus, the crash/fire chief often acts as

The combination of large scale weather data (e.g.,

the ground controller.

from McMurdo Center) and a good understand-

Ground control will obviously include coordi-

ing of local variations will provide the necessary

nation of vehicles and persons on the runway and

information for flight planning and decision mak-

approaching aircraft. Since it will not be reason-

ing at critical times.

able to establish physical security around a gla-

cial ice runway to limit access, the ground con-

troller will also need to inspect for foreign objects

(e.g., people, seals, penguins, bears, or debris) on

AIR AND GROUND CONTROL

the runway immediately prior to landings and

At the Pegasus runway we used the tower at

takeoffs. This can be achieved rapidly using a

nearby Williams Field for air traffic control. This

snowmobile, a rubber-tired all-terrain vehicle

ensures traffic coordination between the Williams

(ATV) or a pickup truck for transportation.