TM 1-1510-223-10 SRU Shop replaceable unit STBY Standby STO Store SV Space vehicle SYNC Synchronization SYS System TACAN Tactical air navigation TBO Time between overhauls TCN Tactical air navigation TCS Touch control steering TDOA Time difference of arrival TEL Telephone TEMP Temperature TFOM Time figure of merit TGT Target THRT Threat TOD Time of day T/R Transmit and receive T/R+G Transmit/receive +guard TRK Track TRK ERR Track error TRU HDG True heading TS Test set TSEC Transec TST Test TTG Time to go TTL Tuned to localizer TX Transmit UHF Ultra high frequency UNVER Unverified USB Upper sideband UIIL Utility UTM Universal transverse mercator VAPP VOR approach VAR Variation VBS Vertical beam sensor VER Verified VERT Vertical VFR Visual flight rules VG Vertical gyro VHF Very high frequency VIP Video integrated processor VLD Valid VOL Volume VOR VHF omni range VORTAC Collocated VOR and TACAN station VOW Voice order wire VRT Vertical VS Vertical speed VSI Vertical speed indicator W West WARN Warning WOD Word of the day WPT Waypoint WR Weather radar WX Weather radar XFR, XFER Transfer XM1T Transmit XMTR Transmitter XTRK DEV Cross track deviation YD, Y/D Yaw damper B-9 / (B-10 blank)