Flight Data Records

Flight Plan Processing.


Flight plans received are parsed and processed into Flight Data Records (FDR).

Flight Data Records form the basis of all interaction with aircraft other than directly with uncoupled radar tracks.

When an FDR is first added it is initialised at the first FDR state (Preactive), and will evolve through a series of states until it is no longer needed.

States and Evolution

Abbreviation State Description
PREA Preactive The initial state. Controlling sector is assigned to the first sector entered or as defined in profile dataset, however FDR may be activated or modified by anyone.
COOR Coordinated Initial activation has occurred. Controlling sector is set to the activating sector unless activated by a TWR position. The activation event seeds an initial coordinated estimate for the first point of the route. FDR is now eligible for coupling to radar tracks and may be departed. The FDR may now only be modified by the controlling sector.
HND Handover First Departure time has been recorded and route estimates updated. An initial handover is proposed to the controlling sector. If departure has occurred within the activating sector, this handover is automatically accepted.
CONT Controlled Departed FDR has been accepted and may only be interacted with by the controlling sector.
HND Handover A handover has been proposed between controlling sectors.
UCTL Uncontrolled Departed FDR has been handed to none. In this state, anyone may accept jurisdiction and become the controlling sector.
INHI Inhibited The FDR has been suppressed locally. Processing still occurs, but Strips and Tracks are suppressed from display. In this state, anyone may accept jurisdiction and become the controlling sector.
FIN Finished The final state when a Departed FDR has been cancelled. Radar update over the assigned arrival runway will automatically cancel an FDR. The FDR is no longer usable and must be recreated if recovery is needed.
NACT Inactive Preactive FDR has been cancelled. The FDR will not generate strips or tracks, but may be recovered by reentering ETD.


FDR’s may be activated through the aircraft strip or by accessing the Flight Plan Window.

An initial estimate at the departure point is set of now + 10 minutes, or a manual estimate for any waypoint may be entered in the flight plan window.

Positions that are TWR, GND or DEL, do not alter the assigned controlling sector upon activation.

Non-vatSys controllers may activate FDR’s by momentarily setting the Label Op Data (scratchpad) to TAXI, PUSH or DEPA. In Euroscope, this is done by using the Flight status item of the aircraft list.

Radar / ADS-B Coupling

FDR’s are eligible for automatic coupling to a radar or ADS-B track when state is COOR, HND, CONT, UCTL and INHI.

Automatic coupling is possible when the following conditions are met when the radar / ADS-B track:

  • is squawking assigned code (MODE A/C radar) or
  • has Flight ID (callsign) that matches FDR Callsign (MODE S/ADS-B) and;
  • is within 7NM of FDR route and;
  • has groundspeed of at least defined takeoff speed for aircraft type

FDR’s may be manually coupled or decoupled by using the Flight Plan Window. Manual couplings are local to your client. Manual coupling will disable the auto couple function until re-enabled in the Flight Plan Window.

On initial coupling if no departure time (ATD) is present, a departure time is calculated and entered.

Automatic Position Reporting

Radar / ADS-B coupled FDR’s will periodically update route estimates and overflown waypoint index based on the current surveillance track location. This function is disabled if the track is in RAM (Route adherence monitor) state.

Trajectory Calculation

On FDR creation and modification, a 4D trajectory is calculated along the FDR route.

Aircraft performance data is used to calculate vertical changes (climbs/descent) in combination with flight planned TAS for level segments and GRIB forecast winds and temperatures.

Track state is determined and Strips are “posted” to sectors when the calculated trajectory enters one of the sector’s airspace volumes.

Shared Data

Without a central server acting as Flight Data Processor, each client must attempt to synchronise data contained within each FDR. The majority of FDR fields are shared, including but not limited to:

  • FDR activation
  • Route estimates
  • CFL (including block levels)
  • Assigned SSR code
  • Label Op Data (Scratchpad)
  • Global Op Data

Fields that are not shared:

  • Weather diversion
  • SAR Timer
  • Manual coupling
  • Pilot reported level