The U-550 Sky Warden is a Utility Aircraft, based of the Learjet 31, primarily used by the Nihon Air Self-Defense Force. The U-550 can do roles like Air Calibration, Flight Inspection, ISR (Intelligence, Surveillance Surveillance, and Reconnaissance), Target Towing, Jamming, and Utility. The U-550 was first developed in 1993 by LearJet and Kawasaki Aerospace under the U-X Program aiming for a new Utility Aircraft to replace the aging NACA YS-11EA/EB. It met competition with the Raytheon U-125A and the Cessna U-680A but all 3 were put into service. The U-550 first saw use in the Flight Check Squadron of the NASDF. They used the U-550 for Flight Inspection and sometimes ISR missions. As of 2023, 2 have been lost in accidents. The Nordinia Air Defense Force purchased 3 aircraft for ISR missions.

Design Group: LearJet, Kawasaki Aerospace, and Relocan Systems.

Aircraft Type: Utility Aircraft

Variants:
Learjet 31 (Predecessor)
Learjet U-550 (This version, In production and service)
Learjet UC-50 (Nordinia Air Defense Force Designation)

Years of Development: 1993-1995 (U-550)

Year of Rollout: 1997 (U-550)

Armament: Chaff and Flayers

Status: Operational, In production

Crew: 2x pilots, 4x System Operators

Maximum Cruise Ceiling: 45,000ft

Price: 183,653,000 USD

Number Built: 32

Main Operators: Nihon Air Self-Defense Force (29), Nordinia Air Defense Force (3), Cabo Verdean Coast Guard (1 placed on order)

Livery: Nihon Air Self-Defense Force Flight Check Squadron

Squadron: Flight Check Squadron

Controls: Normal, AG-8: Enable/Disable Lights