Agility and strength are sharpened during the naval aviation cadet's pre-flight course. One way it's done is hand-over-hand work along ropes. There is a practical side, as well, in that some day he may be called upon to work his way through tropical jungles after a forced landing, or utilize his training on vines or ropes in crossing rivers or dangerous patches of jungle growth. But it is strenuous exercise and subject to slips--as witness the cadet tumbling into the net below.