The Aircrew Survival Egress Knife or ASEK is a U.S. Army aircrew survival knife, designed and initially manufactured by the Ontario Knife Company, and entered service in 2003.

The ASEK has a number of features set by the United States Army Aviation Branch that aid in escaping an aircraft, such as the ability to be used as a hammer to break acrylic glass cockpit windows and cut through an aircraft's aluminium skin. It may also be used as a screwdriver or precision edge marker.

The ASEK includes a crushed diamond disk sharpener and a separate blade for cutting through seatbelt webbing. The knife is 10.25 inches (26.0 cm) in length, the blade is 5 inches (13 cm) in length, .1875 inches (4.76 mm) thick and constructed from 1095 carbon steel.

Required features included:

During the initial evaluation, an electrically insulated handle was considered to be desirable but not mandatory.

The United States Army Aeromedical Research Lab (USAARL) considered the lack of insulated handle of the Ontario knife to be a catastrophic failure of the standard, and Ontario is redesigning their ASEK to meet this requirement.

In May 2005, Gerber Legendary Blades introduced its own ASEK-compliant knife (available commercially under the name LMF II) to the military for evaluation.

The Gerber ASEK met all requirements, and outperformed the Ontario model in the area of electrical insulation.