U.S. Military UAV tier system

The modern concept of United States Department of Defense UAVs (unmanned aerial vehicles) is to have the various aircraft systems work together in support of personnel on the ground. The integration scheme is described in terms of a "Tier" system, and is used by military planners to designate the various individual aircraft elements in an overall usage plan for integrated operations. The Tiers do not refer to specific models of aircraft, but rather roles the aircraft must fill. Periodically the models that fill each role become outdated. The roles are also periodically expanded to encompass more functionality. In these cases, several different aircraft designers such as Boeing and Lockheed Martin write design proposals. These proposals are compared, and the best design is then put into production as the next aircraft to fill the given role. The U.S. Air Force and the U.S. Marine Corps each has its own tier system, and the two systems are themselves not integrated.

US Air Force tiers

 * Tier N/A: Small/Micro UAV. Role filled by BATMAV (Wasp Block III).
 * Tier I: Low altitude, long endurance. Role filled by the Gnat 750.
 * Tier II: Medium altitude, long endurance (MALE). Role currently filled by the MQ-1 Predator and MQ-9 Reaper.
 * Tier II+: High altitude, long endurance conventional UAV (or HALE UAV). Altitude: 60,000 to 65000 ft, less than 300 kn airspeed, 3000 nmi radius, 24 hour time-on-station capability. Complementary to the Tier III- aircraft. Role currently filled by the RQ-4 Global Hawk.
 * Tier III-: High altitude, long endurance low-observable UAV. Same parameters as, and complementary to, the Tier II+ aircraft. The RQ-3 DarkStar was originally intended to fulfill this role before it was "terminated."

US Marine Corps tiers

 * Tier N/A: Micro UAV. Wasp is targeted for this role, now more so given commonality with USAF BATMAV.
 * Tier I: Role currently filled by the Dragon Eye but transitioning to the RQ-11B Raven B.
 * Tier II: Role currently filled by the Scan Eagle and, to some extent, the RQ-2 Pioneer.
 * Tier III: Role currently filled by the Pioneer, although USMC planners do not view this aircraft as meeting future Tier III requirements.

US Army tiers

 * Tier I: Small UAV. Role filled by the RQ-11A/B Raven.
 * Tier II: Short Range Tactical UAV. Role filled by the RQ-7A/B Shadow 200.
 * Tier III: Medium Range Tactical UAV. Role currently filled by the RQ-5A / MQ-5A/B Hunter and i-Gnat, but transitioning to the Extended Range Multi-Purpose (ERMP) MQ-1C Warrior.

Future Combat Systems (FCS) (US Army) classes

 * Class I: For small units. Role to be filled by all new UAV with some similarity to Micro Air Vehicle.
 * Class II: For companies. (cancelled.)
 * Class III: For battalions. (cancelled.)
 * Class IV: For brigades. Role to be filled by the RQ-8A/B / MQ-8B Fire Scout.