During the hours after midnight on Saturday, June 17, 1961, several jeep teams composed of Patrol Inspectors from Calexico, California, tracked two illegal aliens to an alfalfa field located approximately three miles north of the Mount Signal School and approximately nine miles southwest of El Centro, California. Personnel of the jeep patrol encircled the field and prevented possible egress of the aliens. At dawn on June 18, officers at the scene initiated a radio message to Sector Headquarters for aerial patrol assistance in spotting the aliens.

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Pilot Kenneth L. Carl was airborne at approximately 5:30 a.m. in Piper Supercub N8574D and proceeded to rendezvous with the jeep patrol. At the field he immediately initiated low observation passes over the field. In a short time one of the illegal aliens raised his head above the level of the alfalfa and was spotted by the pilot and ground units. When the first capture had been accomplished, the Patrol Inspectors ascertained the description, dress, and name of the second alien and radioed that information to Pilot Carl. The pilot then made repeated passes over the alfalfa field, as well as over an adjoining maize field, searching for the second alien, calling his name over the loud-speaker system, directing him to give up and surrender himself.

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The pilot was reported to have been flying at reduced air speed and very close to the ground. After circling the search area, the pilot flew to mid-field and then commenced a left bank which steepened rapidly to a near vertical angle. The aircraft was observed to climb to an altitude of approximately 40 feet above the ground and then to stall. The aircraft struck the ground in a flight path angle of approximately 40 degrees and stopped immediately upon impact with the soft muddy soil.

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Pilot Carl was pronounced dead prior to being removed from the scene of the accident. It was later ascertained that his heart had been crushed within the rib cage on impact with the instrument panel.