Advance airfield and forward airfield are military terms for a relatively primitive ad-hoc airfield used for refueling and re-arming air units as part of forward operations near the enemy. Also called advanced airfield for its advanced position, not advanced facilities, such an airfield typically does not carry full aircraft maintenance and service units, and lacks the comfort and security of a major air base. Advance airfields may be subject to enemy observation and attack. They may be expected to change hands after a battle.