To keep its aircraft in operation throughout the winter, the RCAF has developed standard instructions to meet the snow problem at all fields, in this way being able to maintain the vast training problem of the British Commonwealth Air Training Plan. Little time is lost through snowfalls. with aircraft using cleared or compacted runways a few hours after a storm.
Methods are dependent on whether the airfield is in the heavy snow belt or in more southern sections where snow does not lie throughout the winter. In heavy snowfall areas. compacting does the trick, each fall of snow being rolled into the previous layer, 1 ft of snow being packed down to 3 in. In light precipitation areas, snow is removed entirely from the runways. In both cases, wheeled aircraft can now be used the year 'round.
Where complete or partial snow removal is carried out, one-way snow plows are used as soon as 1" - 2" of snow has fallen. The starting swath is down the center of the runways, then there is continuous working of the snow to each side. An early start often eliminates the use of a snowblower. To save burying marker lights, one or two trips are made on the outer edge of the runway, forcing the snow towards the center.
When blowers are used, the RCAF recommends that snow be blown at least 100' from the runway and that rollers be used to consolidate it enough to support an airplane. Snow banking up along the edge of the runway must be cut down to remove a hazard to wing tips.
Basic idea in compacting snow by rolling and dragging is to build a paving of snow which may eventually become ice on which planes can land and take off readily. It is recommended only when average temperatures are low enough to insure that occasional thaws will not cause disintegration. This method has increased flying by as much as 400% at some fields.
The initial packing is by far the most important step in obtaining a satisfactory runway, since this forms a foundation for future surfaces by cementing the snow firmly to the ground. It should be started as soon as 2" - 3" of snow has fallen and continued until the storm has stopped. The field should only be rolled once after each snowfall. Further rolling has a tendency to pulverize not only the new snow but the former surface as well.
Heavy snowfalls usually have to be rolled and dragged after the first rolling has frozen. Uneven surfaces can be leveled off by using a drag ahead of the rollers to shave off high spots and fill low ones. A drag also helps to press air out of light fluffy snow.
When a rise in temperature softens the surface, the airfield must also be rolled to compact the snow, starting late in the day when the temperature is falling. A properly compacted surface usually does not honeycomb like ice on a lake, during the spring thaw, if rolling is continued. In the spring breakup, as much as possible of the compacted snow should be removed. When the surface goes completely rotten, all snow may be removed with snow blowing equipment. Slush should be blown far from runways because a sudden freeze would make a mass of ice which would be very hazardous prior to another thaw.
Corrugated gang rollers are used by the RCAF in sets of three. They are fitted with adjustable blades to level off drifts after severe storms. A stop is provided so these leveling bars may not be lowered to the surface and used instead of the drag. If this bar is set too low it will gouge out sections of the surface due to rocking of the rollers. Adjustable angle-iron drags scarify the surface, reduce the compacted snow, and remove ruts. Scarifier teeth on the drags rip up the snow at spring breakup, at which time the crew must give particular attention to temperature forecasts. Sometimes no freezing takes place in the spring, and then no rolling should be undertaken.
During the entire winter the snow-clearing crew must be in close touch with the flight control officer, both to time rolling operations and to keep him informed on the condition of the field.
RCAF has also made use of a combination method of rolling and blowing by which snow is packed 4" - 5" deep on the runway. Subsequent snow is all blown off the runway, which never has more than the original depth. When the spring breakup commences, the snow runway is left to disintegrate normally. If a wheel should break through it would make contact with the hard surface beneath. When the snow becomes completely rotten, it is only necessary to scrape it up and blow it off of the runway.
Compacting wet snow during a snowstorm presents special difficulties, because moist snow sticks to the rollers and tractor cleats. To overcome this and insure against interrupted rolling during the snowstorm, a method has been developed using cocoanut matting and a salt solution. Cocoanut matting is nailed to a wooden crossbar overhanging the roller. The matting is soaked with hot salt water mixed in the proportion of 7 lb of salt to 5 gal of water, which will keep a roller in operation for 20 hr.
This method is cheap and easy. It makes possible the complete rolling of an airfield during a snowstorm when the temperature is no lower than 27° making the airfield available for flying immediately after the storm. For keeping roads in good condition in late winter and spring, the RCAF recommends loosening snow on roads by disking, digging holes in snow drifts to hasten thawing, and using a grader to clear road surfaces and open ditches.
This article was originally published in the November, 1944, issue of Aviation magazine, vol 43, no 11, pp 164-165, 293, 295.
The original article includes 5 photos.
Photos credited to RCAF.