Flight training consisted of about 60 hours of flying time and stressed such procedures as short field landings and takeoffs over obstacles, low altitude navigation, first aid, day and night reconnaissance, aerial photography, and aircraft maintenance. Unarmored and unarmed—except perhaps for a .45 pistol or .30 carbine—these men in 28 different squadrons flew low and slow with wheels, skis, or floats. They flew varied and often hazardous missions in nearly every theater—medical evacuation from forward areas; delivering munitions, blood plasma, mail, and other supplies to front lines; ferrying personnel; flying photographic or intelligence missions; serving as air observers for fighters or bombers; and other critical yet often unpublicized missions. During the campaign to recapture the Philippines, pilots of the 25th Liaison Squadron flew a dozen Stinson L-5 Sentinel aircraft in short 30-minute flights (December 10–25, 1944) delivering supplies (including a 300-bed hospital) to the 6,000 men of the 11th Airborne Division isolated in the mountains of Leyte. In another mission, an Army officer wounded in the chest in New Guinea was evacuated in a liaison aircraft as the pilot pumped a portable respirator with one hand while he flew the aircraft with the other. In the northwestern U.S., some liaison pilots flew forest patrols (Project Firefly) watching for fires ignited by incendiary bombs carried across the Pacific beneath unmanned Japanese high altitude balloons. Kingsley Davis  Kingsley Davis (August 20, 1908 – February 27, 1997) was an internationally recognized American sociologist and demographer. He was identified by the American Philosophical Society as one of the most outstanding social scientists of the twentieth century, and was a Hoover Institution senior research fellow. Davis received his Ph.D. from Harvard University and taught at Smith College, Clark University, Pennsylvania State University, Princeton University, Columbia University, the University of California at Berkeley and the University of Southern California. Among his other accomplishments, Davis  Davis won the Irene B. Taeuber Award for outstanding research in demography (1978), the Common Wealth Award for distinguished work in sociology (1979), and the Career of Distinguished Scholarship Award from the American Sociological Association (1982). In 1953 he was elected as a Fellow of the American Statistical Association. Davis led and conducted major studies of societies in Europe, South America, Africa and Asia, coined the term "population explosion,", and played a major role in the naming and development of the demographic transition model. He was also one of the original scholars in the development of the theory of overurbanization.