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T he U.S. Air Force's aircraft inventory is old and getting older. Aircraft, such as the B-52 and KC-135, were designed and manufactured more than 60 years ago but remain critical elements of the Air Force's force structure. At the same time, newer aircraft, such as the F-22 and RQ-4, rely on more-complex technologies, materials, and software, potentially creating new operational and sustainment challenges. The aging of certain fleets and increasing complexity of newer military aircraft, coupled with continued overseas operations and a fluctuating budget environment, have led some to worry that the Air Force's inventory is likely to be more prone to incidents that result in a loss of aircraft or, worse, life.These concerns were elevated following a March 15, 2018, HH-60 loss in Iraq that resulted in seven fatalities and a May 2, 2018, WC-130 loss in Savannah, Georgia, that resulted in nine fatalities and contributed to Congress establishing the National Commission on Military Aviation Safety as part of the 2019 National Defense Authorization Act. 1 To investigate concerns over mishaps and support the commission, we assembled and analyzed mishap data from the Air Force Safety Center for 55 different aircraft types in operation since 1950. 2 A mishap is an "unplanned event or series of events resulting in death, injury, occupational illness, or damage to or loss of equipment or property, or damage to the environment." 3 Our analysis focuses on three types of mishap events, defined as follows: 4

This paper presents a method for installing structural casing from floating drilling vessels in a manner such that the casing is proof loaded and will not settle when other casing is landed later. The method borrows from geotechnical principles and pile installation observations. In addition to structural casing installation, this method can be used to install lightly loaded piles (e.g., anchor piles) in clay soils.