5-101. Combat engineering in support of aviation operations includes requirements for the hasty construction or rehabilitation of aviation facilities that support fixed- and rotary-wing aircraft as well as UASs. It includes the requirements to improve drop zones and extraction zones for airborne insertions and aerial (airdrop) delivery. The considerations associated with performing forward aviation combat engineering are similar to those associated with the construction of combat roads and trails. Both are based on expedient horizontal construction techniques and are considered combat engineering missions, although they can be conducted by units that are designed to perform general engineering tasks.