Pilot/Controller Glossary

UAM-
(See URBAN AIR MOBILITY.)
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 3,000 MHz. The bank of radio
frequencies used for military air/ground voice communications. In some instances this may go as low as
225 MHz 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 14 CFR Part 103.)

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 14 CFR Part 91.)

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 U.S.)
(Refer to AIM.)