Even small airports will always have a representative of management available to observe and protect the aircraft. An established airport security program doesn't relieve airport users of responsibility for their own protection. All unusual or suspicious persons and activities and violations of airport rules must be immediately reported. By getting to know their airport neighbors, pilots can more readily recognize persons who don't belong. Just knowing that airport management and users are alert and willing to get involved is enough to deter most criminals.
Target hardening can protect aircraft just as it protects buildings.
Aircraft should always be locked and other security devices and alarm systems should be considered. Self-contained alarm systems can be effective deterrents, but only if someone hears them. Alarms used in conjunction with active security patrol can be highly effective. Sun shields installed on aircraft windows block prying eyes as well as solar rays. A thief is more likely to break into an aircraft when valuable components are clearly visible from outside.