Pilot/Controller Glossary 

4/20/23 

UNMANNED AIRCRAFT (UA)- A device used or intended to be used for flight that has no onboard pilot.  This 

device can be any type of airplane, helicopter, airship, or powered-lift aircraft. Unmanned free balloons, moored 

balloons, tethered aircraft, gliders, and unmanned rockets are not considered to be a UA. 
UNMANNED AIRCRAFT SYSTEM (UAS)- An unmanned aircraft and its associated elements related to safe 

operations, which may include control stations (ground, ship, or air based), control links, support equipment, 

payloads, flight termination systems, and launch/recovery equipment.  It consists of three elements: unmanned 

aircraft, control station, and data link. 
UNPUBLISHED ROUTE

−

 A route for which no minimum altitude is published or charted for pilot use. It may 

include a direct route between NAVAIDs, a radial, a radar vector, or a final approach course beyond the segments 

of an instrument approach procedure. 

(See PUBLISHED ROUTE.) 
(See ROUTE.) 

UNRELIABLE (GPS/WAAS)

−

 An advisory to pilots indicating the expected level of service of the GPS and/or 

WAAS may not be available. Pilots must then determine the adequacy of the signal for desired use. 
UNSERVICEABLE (U/S) 

(See OUT OF SERVICE/UNSERVICEABLE.) 

UPWIND LEG

−

 

(See TRAFFIC PATTERN.) 

URBAN AIR MOBILITY (UAM)

−

 A subset of Advanced Air Mobility (AAM), referring to an air transportation 

system utilizing highly automated aircraft to transport passengers or cargo in urban/suburban areas. 
URGENCY

−

 A condition of being concerned about safety and of requiring timely but not immediate assistance; 

a potential distress condition. 

(See ICAO term URGENCY.) 

URGENCY [ICAO]

−

 A condition concerning the safety of an aircraft or other vehicle, or of person on board 

or in sight, but which does not require immediate assistance. 
USAFIB

−

 

(See ARMY AVIATION FLIGHT INFORMATION BULLETIN.) 

UTM

−

 

(See UAS TRAFFIC MANAGEMENT.) 

PCG U

−

2