Laydown delivery is a mode of delivery found in some nuclear gravity bombs: the bomb's descent to the target is slowed by parachute so that it lands on the ground without detonating. The bomb then detonates by timer some time later. Laydown delivery requires the weapon to be reinforced so that it can survive the force of impact.

Laydown modes are used to make weapon delivery survivable by aircraft flying at low level. Low-altitude delivery helps hide the aircraft from surface-to-air missiles. The ground burst detonation of a laydown delivered weapon is used to increase the effect of the weapon's blast on built-up targets such as submarine pens, or to transmit a shock wave through the ground to attack deeply-buried targets. An attack of this type produces large amounts of radioactive fallout.

The issue of aircraft survivability led to laydown being selected for the Vickers Valiant bomber of the Royal Air Force, as the design became increasingly vulnerable to Soviet weapons, especially the SA-2 missile. The low-level laydown delivery was referred to as "Equipment 2 Foxtrot" in RAF parlance; alternatives included "2 Echo" toss bombing and "2 Hotel", a particular climbing delivery method used by the Avro Vulcan.