Geology Reference
In-Depth Information
transportation, frozen lakes and fjords provide ideal
locations for landings and takeoff. Usually first‐year sea
ice sheets in fjords are relatively free from ridges and rub-
ble fields. This is particularly the situations where there
are mountains or hilly areas on both sides and thereby
protected from severe wind effects. For the Arctic and the
Antarctic, sea ice in refrozen leads within the pack ice
also provides ready‐made sites for emergency operations
for SAR, especially with short takeoff and landing
(STOL) aircraft like Canada's famous
Twin Otters
. Once
landed using the light STOL aircraft, measurements on
the ice conditions can be performed and evaluated for
operations of larger airplanes [
Sinha et al.
, 1996].
Figure 1.12 illustrates a set of plots for weight versus ice
thickness, as functions of flexural strength of ice, recom-
mended for operations of aircraft.
The bearing capacity of an ice sheet can be affected
more by ice quality than by ice thickness. Safe estimates
of strength values can be made by experienced ice spe-
cialists through observations of the type, quality, tem-
perature, and uniformity of the ice, which may be
supplemented by field measurements of ice bending
strength described in details in Appendix A of
Sinha et al.
[1996]. These estimates can then provide the basis for
decisions concerning use of the airstrip for unlimited
movements, or allowing loads in excess of the maximum
recommended for limited use. It is emphasized that an
engineering analysis, including a detailed survey and
investigations of the ice cover, should be made by a quali-
fied ice specialists to approve a runway for an unlimited
number of landings.
For practice, simulated emergency landing by an SAR
aircraft of the Canadian Armed Forces were made in
many areas of the High Arctic. An example of landing
made on a refrozen lead in first‐year sea ice is shown in
Figure 1.13.
Based on the charts in Figure 1.12, history was made
by a Canadian airline, First Air, by landing a fully loaded
(64,640 kg) Boeing B727 jet aircraft on first‐year sea ice in
Frederick Hyde Fjord in northern Greenland at about
83°11′ N, 29°50′ W [
Pole
, 1995]. The landing location was
29°50′ W, but at that high latitude, the longitudes cover
significantly less distances. The longitude of the 30 km
long fjord was between 28°W and 32°W. Also, it was the
most northerly point on sea ice cover that a B727 jet air-
craft had ever landed and operated on a commercial
basis. In all, 16 landings were made in 7 days from 19
May to 25 May, 1994 [
Sinha
,1995].
The ice strip was 100 m wide and 2.5 km long. The ice
thickness varied from 2.24 m at one end to 2.41 m at the
other end of the runway. The ice was thus extremely uni-
form, and about 50% of the surface was absolutely snow
free. Actually, even the snow‐covered areas had very little
snow. Consequently, from the air the entire fjord was
Figure 1.11
Notch in second‐year sea ice floe made by ice
breaking bulk carrier,
MV Arctic
, with CCGS icebreaker,
Louis
S. St‐Laurent
in the background, Baffin Bay North, June 1984
(photo by N. K. Sinha, unpublished).
S. St‐Laurent,
also participated in this expedition. Soon
after these ice breaking trials,
Louis S. St‐Laurent
joined
USCGC
Polar Sea
to become the first North American
surface vessels to reach the North Pole on 22 August
1994.
Louis S. St‐Laurent
was launched in June 1966 and
joined the
SS Manhattan
expedition in the Northwest
Passage during the 2 weeks, 8-22 September 1969,
together with two other icebreakers USCGC
Northwind
and
Staten Island
.
Louis S. St‐Laurent
is classed as a
heavy Arctic icebreaker and is the largest icebreaker and
flagship of the CCG.
There are a number of excellent topics on ice‐structure
interactions and ice engineering, e.g.,
Cammaert and
Muggeridge
[1988],
Sanderson
[1988], and
Jones et al.
[1991]. Up to date information in the areas of ice‐structure
interactions and related field can be found in the journal
Cold Regions Science and Technology
(CRST). Moreover,
the conferences of the Offshore Mechanics and Arctic
Engineering (OMAE) of the American Society of
Mechanical Engineering (ASME) and the Port and
Oceans under Arctic Conditions (POAC) provide current
status of developments in ice engineering. These confer-
ences also provide platforms for disseminating research
results, new developments, and novel concepts in the
multidisciplinary field of polar science and technology.
1.4.8. Sea Ice for Search and Rescue
and Transportation
During the long winters in many cold regions of Earth,
there are more possibilities for finding relatively flat lake
or sea ice surfaces than land‐based areas for aircraft
operations with little or no preparations. For search and
rescue (SAR) operations and temporary winter air
