The HC-144A is based on the Airbus CN235 tactical airlifter and will be delivered by prime contractor EADS North America.
"The HC-144A is becoming the Coast Guard's primary maritime patrol aircraft and we're proud of the central role it is playing in executing the service's increasingly demanding mission," said Antonio Rodriguez-Barberan, Airbus Military senior vice president for its commercial unit.
The order for an 18th FC-144A comes through the exercise of an option in a 2010 contract. Under the overall contract, EADS North America has delivered three aircraft -- the 12th, 13th, and 14th HC-144As operated by the Coast Guard.
Planes 15-17 are to be delivered early next year.
The H-144A can remain airborne for more than 10 hours and is used by the Coast Guard for maritime patrol, drug and migrant interdiction, disaster response and search and rescue. The aircraft are equipped with search radar, electro-optical and infrared cameras, and an Automatic Identification System for data collection from vessels at sea.