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  • Squawk changing Radar

    I noticed that if an aircraft shows on Radar T-OLDS the squawk code changes to an Alpha Numeric code, this not a major issue and is probably due to it running old Feeder Software.

    At first i thought this to with Turkish airspace, so i checked if this was new, but they use the same as the rest of the world.

    Here's some examples of the codes:

    Airline: Nouvelair Tunisie
    Flight: LN192
    From: Tripoli, Tripoli (TIP)
    To: Istanbul, Ataturk (IST)
    Reg: TS-INN
    Squawk: 07EB
    Radar: T-OLDS

    Airline: Turkish Airlines
    Flight: TK2916
    From: Izmir, Adnan Menderes (ADB)
    To: Istanbul, Sabiha Gokcen (SAW)
    Reg: TC-JGC
    Squawk: 01E9
    Radar: T-OLDS

    This is the same aircraft on T-F4V and then the squawk changes when it is picked up by T-OLDS.

    Airline: Austrian Airlines
    Flight: OS831
    From: Vienna, Schwechat (VIE)
    To: Larnaca, Larnaca (LCA)
    Reg: OE-LBB
    Squawk: 0341
    Radar: T-F4V


    Airline: Austrian Airlines
    Flight: OS831
    From: Vienna, Schwechat (VIE)
    To: Larnaca, Larnaca (LCA)
    Reg: OE-LBB
    Squawk: 00E1
    Radar: T-OLDS
    AMS Daily Fight Information: http://schiphol.dutchplanespotters.nl/

  • #2
    Numeral System

    Hi,

    the SSR Code used for Mode A is coded in 4 digits within the so called "Octal" Numeral System (Usage of the digits 0 to 7).

    The codes shown in your post are Hexadecimal (base 16 numeral system)

    T-OLDS is obviously only using Hexadecimal in their system.
    Today (25 AUG 2012 1632UTC) I watched TP77, enroute from LIS to GIG change from N-GCLP1 to T-OLDS south of the Canaries. The Squawk entry changed from 3352 to 06EI - that is the same - Octal to HEX.

    HEX to Octal
    07EB = 3753
    O1E9 = 751 (with a leading 0 omitted) - so setting on the transponder is 0751
    O1E1 = 741 (with a leading 0 omitted) - so setting on the transponder is 0741

    A change of the code is performed only if ATC is not connected automatically to a central database issuing these codes (in Europe the Central Flow Management Unit or CFMU).

    In case of the same code in the next ATC sector the identification by the controller is done by using the SSR Mode A ident function or a verbal change over - in other cases by changing to a newly assigned code. To so so each ATC unit and resp. Sector has a set of codes for its special use.

    The mode S identification is given by the ICAO and consits of 3 Hexadecimal values.

    As the setting of flight numbers is not a requirement and not all Mode S transponders are capable of doing so the correalation of Flight to Radar Target is still done using Mode A - and - Mode A has the Altitude (Mode C) atomatically attached. (not Mode S!)

    Greetings

    Andreas


    SSR = Secondary Surveillance Radar = the system
    Transponder the airborne / aircraft part
    Mode A, C and S mandatory in Europe
    ADSB capability on almost all Mode S transponders given.
    Even if equipped with GNSS RNAV / BRNAV systems like GPS, the data is not always transfered to the Mode S - transponder due to other inputs that are mandatory but missing in that specific aircraft.

    Comment


    • #3
      Originally posted by andbur View Post
      A change of the code is performed only if ATC is not connected automatically to a central database issuing these codes (in Europe the Central Flow Management Unit or CFMU).
      There is no central squawk database in Europe, except for a few countries that participate in CCAMS (Bulgaria, Norway, Ukraine and Ireland http://atwonline.com/aircraft-engine...nal-ccams-0828). Today other countries and in future the vast majority of countries will remain the ORCAM assignment method, which divides Europe in different regions. Within each region a code is assigned per a particular table. The code may be retained within an adjacent region if it is not used there.
      http://www.eurocontrol.int/working_a.../icao_oug.html

      Originally posted by andbur View Post
      As the setting of flight numbers is not a requirement and not all Mode S transponders are capable of doing so the correalation of Flight to Radar Target is still done using Mode A - and - Mode A has the Altitude (Mode C) atomatically attached. (not Mode S!)
      It is an requirement throughout Europe that the Flight ID is programmed. Where squawk A1000 is used this is the sole means of identification. Mode A and C are different packets. Mode-S DF4 and 20 (ground interrogated) have the altitude in it, also DF17 (ADS-B)

      Comment

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