Geiger was a Cadet at the United States Military Academy June 16, 1904 to February 14, 1908, when he was graduated as an Army Second Lieutenant in the Coast Artillery Corps. He was promoted to First Lieutenant November 8, 1908.
As a lieutenant, Geiger commanded the aviation assets of the United States Army Signal Corps in the Hawaiian Islands. The first Army airplanes, pilots and crews arrived in Oahu in July 1913. The planes were based at Fort Kamehameha, near present-day Hickam Air Force Base.
Lieutenant Geiger arrived in Oahu with two Curtiss Aeroplane and Motor Company float planes, 1 mechanic, 12 enlisted men, and other equipment. However, Geiger’s aircraft were in poor shape. His flights were limited to short flights in Pearl Harbor and a longer flight to Diamond Head, Hawaii and back to Fort Kamehameha.
Geiger was ordered to cease all flying operations in late 1913, because of too strong trade winds. The planes were sold locally, and the engines were sent back to the North Island Flying School. The Hawaiian Islands wouldn’t see any more Army aviation activity until 1917.
Geiger was a World War I veteran who served as a Lieutenant Colonel in France.
Geiger completed courses at the U.S. Army Balloon School in April 1917, and later served overseas with the Army's Balloon Section Headquarters. He completed dirigible studies in France and Italy. He had been attached later to the Ambassador's staff in Berlin. While in Germany, Major Geiger sent reports to the Chief of the United States Army Air Service on the construction of the dirigible USS Los Angeles (ZR-3), and repeatedly urged that the craft, which was later taken over by the Navy, be purchased by the Army. He was on the ZR-3 on its transatlantic flight.
Geiger also commanded the Army Balloon School at Ross Field, Arcadia, California.
By 1927, Geiger was commandant of Phillips Air Field at Aberdeen, Maryland.
On May 17, 1927, Geiger died in the crash of his Airco DH.4 de Havilland plane. Six mechanics and officers at the Middleton Air Station, at Olmstead Field, Pennsylvania told The New York Times Geiger's plane took a 50-foot nose dive. Geiger managed to jump out just as the plane struck and burst into flames. He made desperate efforts to get clear of the wreckage and, according to the onlookers, half crawled and ran as far as the tail of the machine before he was overcome. There he dropped and the flames prevented the watchers from getting near enough to rescue him.''.
In 1941, the United States Department of Defense purchased the area then known as Sunset Field from Spokane County, Washington as a World War II training facility for pilots of the B-17 Flying Fortress and the C-47 Skytrain. Following the acquisition, they renamed the facility Geiger Field in honor of Major Geiger. In 1946, a portion of the airfield was designated a municipal airport, and commercial airline operations were moved from Felts Field to Geiger Field. In 1960, the facility was renamed Spokane International Airport.