The C-21 is a twin turbofan-engine aircraft used for passenger and cargo airlift. The aircraft is the military version of the Learjet 35A business jet. In addition, the aircraft is capable of transporting one litter or five ambulatory patients for aeromedical evacuation operations.

The turbofan engines are pod-mounted on the sides of the rear fuselage. The swept-back wings have hydraulically actuated single-slotted flaps. The aircraft has a retractable tricycle landing gear, single steerable nose gear and multiple-disc hydraulic brakes.

The C-21 can carry eight passengers and 42 cubic feet (1.26 cubic meters) of cargo. Fuel capacity of the C-21 is 931 gallons (3,537.8 liters) with refueling accomplished at ground level through each wingtip tank. Safety and operational capabilities of the C-21 are increased by the autopilot, color weather radar and tactical air navigation system as well as high-frequency, very high-frequency and ultra high-frequency radios.

The aircraft has a crew of two and may be flown from either cockpit seat. It is equipped with an automatic navigation system to enhance crew efficiency.

Delivery of the C-21 fleet began in April 1984 and was completed in October 1985. C-21s stationed outside the continental United States, or CONUS, were assigned to the theater commanders. Air Mobility Command at Scott Air Force Base, Illinois, is the lead command for the aircraft.

In April 1997, the majority of CONUS-based C-21s were consolidated within the 375th Airlift Wing at Scott AFB, while the National Guard Bureau maintained several aircraft at Peterson AFB, Colorado, Air Force Flight Standards Agency maintained several aircraft at Joint Base Andrews, Maryland and Air Education and Training Command maintained several aircraft at Keesler AFB, Mississippi.

In January 2007, Program Budget Decision number 720 reduced C-21 operations to 40 aircraft. AMC dissolved C-21 operations at Wright-Patterson AFB, Ohio. U.S. Air Forces in Europe was reduced from 13 to 10, Pacific Air Forces from four to three and AETC from five to three.

The NGB picked up 19 aircraft for ‘bridge’ missions at Fargo, North Dakota, Battle Creek, Michigan, and Bradley Air National Guard Base, Connecticut, until they received C-27 aircraft. Base Realignment and Closure actions moved the AFFSA C-21s from Joint Base Andrews to Will Rogers World Airport, Oklahoma City, Oklahoma. In June 2007, Pacific Air Forces divested itself of its three C-21s, the NGB gaining them.

In 2010, Resource Management Decision 700, or RMD 700, cut the number of C-21 aircraft from 56 to 28. Also in line with RMD 700, AETC closed the flight training unit located at Keesler AFB, Mississippi.

Beginning in 2018, the C-21 fleet in the United States began further consolidation efforts from Peterson AFB, Joint Base Andrews, moving all CONUS-based C-21s to Scott AFB’s 458th Airlift Squadron via the National Defense Authorization Acts of fiscal year 2018 and fiscal 2019.

These consolidation efforts leave Scott AFB’s 458th Airlift Squadron (AMC) and Ramstein Air Base, Germany’s 76th Airlift Squadron (USAFE) as the remaining force of C-21s. In addition, the first major upgrade in the fleet’s history is a $38 million “Avionics Upgrade Program” to modify all aircraft to a ‘glass cockpit’ configuration and meet 2020 global airspace equipment requirements.

General Characteristics
Primary Function: Passenger and cargo airlift
Contractor: Learjet, Inc.
Power Plant: Two Garrett TFE-731-2-2B turbofan engines
Thrust: 3,500 pounds each engine
Maximum Takeoff Weight: 18,300 pounds (8,235 kilograms)
Length: 48 feet, 7 inches (14.71 meters)
Height: 12 feet, 3 inches (3.71 meters)
Wingspan: 39 feet, 6 inches (11.97 meters)
Fuel Capability: 931 gallons (3,537.8 liters) [1,120 gallons (4,256 liters) with ferry tanks]
Speed: 530 mph (Mach 0.81, 461 knots at 41,000 feet (12,496.8 meters)
Range: 2,306 miles (3,689.6 kilometers)
Ceiling: 45,000 feet (13,716 meters)
Maximum Load: Eight passengers and 3,153 pounds (1,433 kilograms) of cargo, or one litter patient or five ambulatory patients.
Crew: Two (pilot and copilot); aeromedical evacuation adds medical crew of three (one flight nurse and two medical technicians). Minimal medical crew may be one flight nurse and one medical technician as required
Unit Cost: $3.1 million (Fiscal 1996 constant dollars)
Initial Operating Capability: April 1984
Current Inventory: Active Duty: 19; ANG: 0; AFRC: 0.

(Current as of March 2019)