The data block shown at left indicates the aircraft call sign (N20439), the transponder-reported altitude (029 - 2,900 feet) and the computer-determined ground speed (11V - 110 knots) - the 'V' indicates the flight is VFR The "splat" or asterisk to the right of the call sign indicates that low-altitude alerting functions for this aircraft are suppressed. In the upper left corner of the picture is an untracked target, meaning the flight is not talking to a controller. The transponder-reported altitude (036) is 3,600 feet. The information contained in the bottom half of the data block timeshares, meaning flight plan and tracking data are alternately displayed in the data block. Look below to see what is displayed in the second half of the timeshare.

The data block shown at left again indicates the aircraft call sign (N20439), but the bottom line (timesharing) now shows aircraft destination or intentions (in this case landing at Santa Rosa) and the type of aircraft (here a C172 - Cessna Skyhawk). The "splat" or asterisk to the right of the call sign still indicates that low-altitude alerting functions for this aircraft are suppressed. Notice the letter "O" below the data block. This is a control symbol, indicating which ARTS position has control over the data block (and hence is most-likely talking to the pilot). In this case, the letter "O" indicates the Oakland South Tower - Local 1 position. Below is a list of common data block symbology.

Control Symbols: A: Oakland North Tower - Local Two B: NCT - Boulder Sector C: Center - the aircraft has been handed off to the Oakland Air Route Traffic Control Center (ARTCC) in Fremont D: NCT - Diablo Sector F: NCT - Foster Sector (typically SFO runway 28R arrivals) G: NCT - Grove Sector (typically OAK runway 27 arrivals) H: NCT - Hooks Sector J: San Jose Tower M: NCT - Mulford Sector (takes work from Grove when it gets too busy) O: Oakland South Tower - Local One N: NCT - Niles Sector (feeder sector for OAK and SFO arrivals from the east/south) R: NCT - Richmond Sector (OAK and SFO departures north and east) S: NCT - South Feeder Sector (feeder sector for OAK and SFO arrivals from the north/west) T: NCT - Tioga Sector U: NCT - Sutro Sector (OAK and SFO departures to the west and south) V: SFO Tower W: NCT - Woodside Sector (typically SFO 28L arrivals)

Common Destination/Intention Indicators: DPA - Diablo Practice Area SPB - San Pablo Bay Practice Area 2ER - Bay tour T/G - Touch and Goes ILS - ILS approach GPS - GPS approach NDB - NDB approach VRA - VOR Alpha approach at HWD LOC - LOC/DME approach at HWD VOR - VOR 27L approach at OAK VA - Visual Approach III - Category Three ILS approach NOS - Gnoss Field BYR - Byron RIC - Richmond Area BRK - Berkeley Area SMB - San Mateo Bridge BBR - Bay Bridge GGB - Golden Gate Bridge BNR - Banner-tow PCB/PAC - PacBell Ballpark P # # - Landing at Pier-number CTY - City of San Francisco RB - on a right base for 27 AIS - airport in sight STK - Candlestick Park

Letter Indicators (next to aircraft speed in timeshare): A or V: VFR flight No letter: IFR flight R: Practice Approach