T-34C INSTRUMENT NAVIGATION WORKBOOK
CORRECTION - An error has been made in the transmission, and the correct version follows.
CROSS (FIX) AT (ALTITUDE) - Used by ATC when a specific altitude restriction at a
specific fix is required.
CROSS (FIX) AT OR ABOVE (ALTITUDE) - Used by ATC when an altitude restriction at a
specified fix is required. It does not prohibit the aircraft from crossing the fix at a higher altitude
than specified; however, the higher altitude may not be one that will violate a succeeding altitude
restriction or altitude assignment.
CROSS (FIX) AT OR BELOW (ALTITUDE) - Used by ATC when a maximum crossing
altitude at a specific fix is required. It does not prohibit the aircraft from crossing the fix at a
lower altitude; however, the aircraft must remain at or above the minimum IFR altitude.
DISCRETE FREQUENCY - A separate radio frequency for use in direct aircrew-controller
operating on a particular frequency at one time. Discrete frequencies are normally designated for
each control sector in enroute/terminal ATC facilities. Discrete frequencies are listed in the
Airport/Facility Directory and IFR Enroute Supplement.
DISREGARD - Cancel my last message.
EXECUTE MISSED APPROACH - Instructions issued to an aircrew making an instrument
approach that mean continue inbound to the missed approach point and execute the missed
approach procedure as described on the Instrument Approach Procedure Chart, or as previously
assigned by ATC. The aircrew may climb immediately to the altitude specified in the missed
approach procedure upon making a missed approach. No turns should be initiated prior to
reaching the missed approach point. When conducting an ASR or PAR approach, execute the
assigned missed approach procedures immediately upon receiving instruction to "execute missed
EXPECT (ALTITUDE) AT (TIME) OR (FIX) - Used under certain conditions to provide the
aircrew with an altitude to be used in the event of two-way communications failure. It also
provides altitude information to assist the aircrew in planning.
EXPECT FURTHER CLEARANCE (TIME)/EFC - The time an aircrew can expect to
receive clearance beyond a clearance limit.
EXPEDITE - Used by ATC when prompt compliance is required to avoid development of an
FIX - A geographical position determined by a visual reference to the surface, by reference to
one or more radio NAVAIDs, by celestial plotting, or by another navigational device.
A-2 GLOSSARY OF COMMUNICATION TERMS