US Tri-Service Designation System

MDS (Mission - Design - Series)

A = Attack (Standard Designations)

• Fairchild-Republic A-10 Thunderbolt II: First flight 10 May 1972, still in service and the only standard, in-service aircraft in the Attack Mission series.

• A-11: Reserved at some point, but apparently never assigned to any aircraft. Source: Designation-Systems.net

• McDonnell Douglas - General Dynamics A-12 Avenger II: Only a mock-up, cancelled in 1991.

• A-13: Designation skipped for superstitious reasons. Source: Designation-Systems.net

• A-14: Briefly reserved for an EMBRAER EMB-314B Super Tucano that was evaluated by the US Navy. Instead, assigned the non-sequential designation A-29B, which duplicates the Brazilian Air Force designation. It does not seem likely that A-14 will ever be assigned to another aircraft. Source: Designation-Systems.net

• A-15: Next available designation, in standard numerical sequence. Source: Designation-Systems.net

A = Attack (Non-standard, Out-of-Sequence Designations)

• EMBRAER A-29: As noted above, initially assigned to a single aircraft evaluated by the US Navy. Subsequently used for aircraft supplied to Afghanistan under the USA Light Air Support program, as well as several acquired by US Air Force Special Operations Command.

• Air Tractor A-1 Sky Warden: Perhaps the most bizarre mis-application of the MDS system in recent history. This designation (in full, OA-1K), is apparently both an homage to and a continuation of the A-1 Skyraider designation. It probably should have been assigned the A-15 designation instead.

B = Bomber (Standard Designations)

• Rockwell International B-1 Lancer: Still active, but retirement is looming.

• Northrop B-2 Spirit: The first stealth bomber should be around for a while longer.

• B-3: This designation was associated with some projects, including the Future Strike Aircraft, but was never assigned to an aircraft. Technically, still the next available designation, in standard numerical sequence. This would have been the correct designation for the B-21 Raider.

B = Bomber (Non-standard, Out-of-Sequence Designations)

• Northrop Grumman B-21 Raider: This designation was assigned to the Long Range Strike Bomber because it is the "first bomber of the 21st century." Hilarious.

C = Transport (Standard Designations)

• Boeing C-40 Clipper: Several Boeing 737-700 types acquired by the US Navy and USAF.

• CASA C-41: Several C-212 acquired by the USAF and US Army.

• C-42: Skipped, apparently to avoid using the same number as the Ikarus C42. Source: Designation-Systems.net

• C-43: Skipped to avoid confusion with Boeing T-43. Source: Designation-Systems.net

• C-44: Skipped to avoid confusion with Beech T-44 Pegasus. Source: Designation-Systems.net

• EADS / Northrop Grumman KC-45: Losing contender in USAF KC-X program.

• Boeing KC-46 Pegasus: Winning contender in USAF KC-X program.

• C-47: Next available designation, in standard numerical sequence (at least in theory - might conflict with Douglas C-47T). Source: Designation-Systems.net

C = Transport (Non-standard, Out-of-Sequence Designations)

• Bombardier C-143: A single Challenger 604 was acquired by the US Coast Guard. At the time, the next available designation would have been C-42, but apparently there was some confusion around whether or not this could be used (see above). Instead of just skipping a few designations, it was decided to continue the pre-1962 USAF Transport numerical sequence. Source: Designation-Systems.net

• EADS CASA HC-144 Ocean Sentry: Continuing on from C-143, this designation was assigned to several CN-235 acquired by the US Coast Guard.

• PZL Mielec C-145: Continuing on from C-143, this designation was assigned to several M28 Skytrucks acquired by the USAF.

• Dornier C-146 Wolfhound: Continuing on from C-143, this designation was assigned to several Do 328 acquired by the USAF.

• Bombardier C-147: Continuing on from C-143, this designation was assigned to two DHC-8-315 acquired by the US Army for the Golden Knights parachute team.

• C-148: This would be the next available designation if this old numerical sequence is continued.

E = Special Electronic Mission (Standard Designations)

• de Havilland Canada E-9 Widget: This designation was assigned to two DHC-8-100 acquired by the USAF for use as range control aircraft.

• Northrop Grumman E-10: Cancelled MC2A aircraft, intended to replace the E-3 Sentry, E-4, E-8 Joint-STARS, and RC-135 Rivet Joint.

• Northrop Grumman E-11: Several modified Bombardier Global Express acquired by the USAF for use as Battlefield Airborne Communications Nodes.

• E-12: Next available numerical designation, in standard numerical sequence. Source: Designation-Systems.net A potential aircraft that could be assigned this designation would be the Boeing 737 AEW&C, which the USAF is planning to procure as a replacement for the E-3 Sentry. However, the Australian version is designated E-7 Wedgetail, and this designation is somewhat confusingly referenced in relation to the planned USAF version. The E-7 designation was originally reserved for a version of the Boeing C-137 Stratoliner that was instead designated EC-18.

F = Fighter (Standard Designations)

• Lockheed F-22 Raptor: Winning contender in the USAF ATF program.

• Northrop F-23: Losing contender in the USAF ATF program.

• F-24: Next available numerical designation, in standard numerical sequence (in theory). This designation probably should have been assigned to the winning JSF contender selected for production (either the Boeing X-32 or Lockheed Martin X-35, see F-35 below). It could also have potentially been used for the F/A-18 Super Hornet, which is different enough from the F/A-18 Hornet that a new designation could be justified. There has also apparently been a semi-official designation of YF-24 used for an unknown secret aircraft prototype. It is unclear if the next fighter designation to be assigned would use F-24, F-25, or F-36 (or perhaps something completely different). Source: Designation-Systems.net These include the upcoming NGAD F-X, intended to replace the USAF F-22 Raptor, and the F/A-XX, intended to replace the USN F/A-18 Super Hornet.

F = Fighter (Non-standard, Out-of-Sequence Designations)

• Lockheed Martin F-35 Lightning II: Very well documented mis-designation of the X-35 JSF when it was selected for production. The designation should probably have been F-24 (apparently even Lockheed was expecting it). Source: Designation-Systems.net. It is unclear if the next fighter designation would continue on from here as F-36, or perhaps just be some other random number that is derived from some feel-good marketing language.