ONE of the most serious hazards that an aircraft must contend with, and one which, has been the cause of many disasters down the years, is the accumulation of ice upon the airframe. The worst culprit is "glazed ice", which occurs when water lands on a surface the temperature of which is well below freezing point, and spreads outwards from the, area of impact to form a solid, coating that is difficult to dislodge.
The same phenomenon, however, can result in tragedies at sea. It is particularly common in the waters between Scotland and Iceland in the depths of winter, when an easterly airflow may bring freezing Siberian air over, waters kept relatively warm by the benign influence of the North Atlantic Drift. A case in point was that of the Hull trawler Ross Cleveland which sank with all hands 28 years ago yesterday, on February 4th 1968.
The Ross Cleveland that morning was near the coast of Iceland, battered by storm force easterly winds in conditions where the air temperature was minus 10 to 12 degrees. The gales and mountainous seas were serious enough, but it was ice accretion that sealed the vessel's fate. The upper parts of the ship took their temperature from the air stream, 59 that spray froze immediately on contact with the superstructure.
Ice accumulated on the Ross Cleveland during the morning at a rate subsequently estimated to have been about 10 tons every hour. Had all this formed only on the deck, it might have been a tolerable load, but the rigging and the clutter of equipment high above provided endless nooks and crannies in which the ice could gain a hold. By gradually altering the centre of gravity of the vessel, the build up soon induced a tragic instability.
The crew worked hard, hacking at the ice with axes to try to save the ship. But theirs was a losing battle, and in any case it was impossible to get at accumulations high above the deck, where it mattered most. More lover, the large areas of ice presented to the wind made it more and more difficult to hold the ship at a bearing where the wind was aft, thereby preventing the spray from coming inboard in such very large amounts.
Towards noon, other trawlers of the fleet received a radio message from the master of the Ross Cleveland. "I am going over. We are laying over. Help me Within minutes the ship was on its port side, and it sank eight seconds later. There was only one survivor.