UAM-

(See URBAN AIR MOBILITY.)

UAP-

(See UNIDENTIFIED ANOMALOUS PHENOMENA.)

UAS FACILITY MAP (UASFM)- Defined grid squares showing maximum altitudes around airports where the ­FAA may authorize part 107 sUAS operations without additional safety analysis. The maps should be consulted ­prior to conducting UAS operations (part 91, part 107 or section 44809) in controlled airspace. The UASFM ­will aid in determining if the airspace authorization or waivers are necessary. UASFM(s) are charted on the UAS ­Data Delivery System (UDDS) at the following website address:
https://faa.maps.arcgis.com/apps/webappviewer/index.html?id=9c2e4406710048e19806ebf6a06754ad.

UAS TEST SITE- Independently owned UAS test & research sites, recognized by the FAA.

UAS TRAFFIC MANAGEMENT (UTM)-The unmanned aircraft traffic management ecosystem that will ­allow multiple low altitude BVLOS operations and which is separate from, but complementary to, FAA's Air ­Traffic Control System.

UASFM-

(See UAS FACILITY MAP.)

UHF-

(See ULTRAHIGH FREQUENCY.)

ULTRAHIGH FREQUENCY (UHF)- The frequency band between 300 and 3,000MHz. The bank of radio ­frequencies used for military air/ground voice communications. In some instances this may go as low as ­225MHz and still be referred to as UHF.

ULTRALIGHT VEHICLE- A single‐occupant aeronautical vehicle operated for sport or recreational purposes ­which does not require FAA registration, an airworthiness certificate, or pilot certification. Operation of an ­ultralight vehicle in certain airspace requires authorization from ATC.

(Refer to 14CFR part103.)

UNABLE- Indicates inability to comply with a specific instruction, request, or clearance.

UNASSOCIATED- A radar target that does not display a data block with flight identification and altitude ­information.

(See ASSOCIATED.)

UNCONTROLLED AIRSPACE- Airspace in which aircraft are not subject to controlled airspace (Class A, B, ­C, D, or E) separation criteria.

UNDER THE HOOD- Indicates that the pilot is using a hood to restrict visibility outside the cockpit while ­simulating instrument flight. An appropriately rated pilot is required in the other control seat while this operation ­is being conducted.

(Refer to 14CFR part91.)

UNFROZEN- The Scheduled Time of Arrival (STA) tags, which are still being rescheduled by the time-based ­flow management (TBFM) calculations. The aircraft will remain unfrozen until the time the corresponding ­estimated time of arrival (ETA) tag passes the preset freeze horizon for that aircraft's stream class. At this point ­the automatic rescheduling will stop, and the STA becomes “frozen.”

UNICOM- A nongovernment communication facility which may provide airport information at certain airports. ­Locations and frequencies of UNICOMs are shown on aeronautical charts and publications.

(See Chart Supplement.)

(Refer to AIM.)

UNIDENTIFIED ANOMALOUS PHENOMENA (UAP)– For aviation reporting purposes, a UAP may be ­airborne objects or other detected/observed objects that are not immediately identifiable, such as balloons, ­aircraft, or natural known phenomena, that demonstrate behaviors that are not readily understood by sensors or ­observers. A UAP may consist of one or more unidentified anomalous objects and may persist over an extended ­period of time. The full definition of UAP may be found on the All‐Domain Anomaly Resolution Office (AARO) ­website at https://www.aaro.mil.

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.)

UPLINK– CPDLC message sent from ATC to the flight deck.

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.)