When the weather is favorable, we stand out on the field eight hours a day waiting our turn to fly; that is a strain. Usually we fly a half hour a day, but at times, one may go three or four days without a flight, but no matter how long you wait, a single half hour in the air satisfies all desire for action, excitement, and exercise for the time being. That is one of the strange things about aviation. Though a man is strapped in his seat and moves no part of his body more than three inches, an hour in the air will keep him in excellent physical condition, provided he is nervously fitted for the work. And the mind and eyes are equally fatigued. Absolute concentration is necessary. The more I see of the game, the more I believe that nine-tenths of the accidents and deaths are due to the inability of the pilot to concentrate or to recognize that concentration is necessary. We are using the best and fastest fighting plane now, the Spad, Guynemer’s plane. In starting, one must immediately throw every nerve into stress to keep the machine in its given course; not doing so means a quick turn, a crushing of the running gear, and a broken wing. This is an inexcusable accident with a trained pilot; yet it happens about once a day because someone is only three-fourths on the job. In gaining speed, the machine must be brought to its line of flight, the danger here being to tip it too far forward and break the propeller on the ground. This is easy to prevent, and so is inexcusable, yet it happens once a week because someone forgets himself. There is danger in leaving the ground too soon, and danger in mounting too quickly. About one pilot a month is killed at the Front by attempting to mount too quickly while close to the ground. At a height of twenty feet, one must be all alert for sharp heat waves that are liable to get under one wing. When one comes to make the first turn, there is danger of too great a bank allowing the head-on wind to get under the high wing and slide you down, yet this almost never happens because by the time the pilot is up there he is all present. All this time he must have been alert for arriving and departing machines which are dangerous, not only because of collision, but because of the turbulent current of air they leave in their wake. One machine passing through the wake of another acts like a wild goose frightened by a passing bullet.