The Twin Otter's rugged design and versatility provided by multiple landing gear options (wheels, skis, and amphibious floats) make it an ideal aircraft for a variety of special mission applications.
Field Aerospace has modified Twin Otters for a variety of operators throughout the world. Most recently the Twin Otter Guardian 400 has been developed and built by Field Aerospace in partnership with Viking Aircraft for a Multi Role Surveillance Aircraft (MRSA). The MRSA modifications using a Field Aerospace fully redesigned nose section which includes a 360 º search radar and a retractable EO/IR turret will allow the Guardian 400 to perform seamlessly in a variety of roles whether on wheels, skis or floats. This modification includes a missionized interior and a mission management system for on board data integration. The interior can be customized to support a combination of variety of missions (i.e. surveillance & medevac, surveillance & transport). Noted certified operational modifications have or can be easily integrated to other ruggedized turboprop such as the Do228.