Calibration is a survey flight around a Direction-Finding station. The twelve 30-degree sectors around the station are calibrated separately, and a calibrated sector removes that station's directional error for every bearing that later arrives from that compass direction. It roughly halves the width of a threat cone and costs nothing but flight time, so it is the cheapest way to make an existing station more precise without upgrading it.

Before the flight. The airfield must already have a built Direction-Finding station; a bare airfield cannot be calibrated. Open the Live Map, switch the CAL layer on and read the twelve rings around the station: bright sectors are calibrated, dim sectors are not. The Calibration group on the sortie board also names every station that is currently deaf in one or more sectors. Sectors that are already calibrated are skipped in flight, so flying the full circle is always safe.

1. Take off and settle on the ring 3 to 6 km from the station airfield at 300 to 900 m above the ground below the aircraft.
2. Hold inside one sector. A steady orbit, a slow arc or a straight leg flown outbound or inbound along the same radial all work.
3. After 20 continuous seconds the message DF calibration sector 5/12 complete at KOBULETI confirms that sector.
4. Continue into the next sector and repeat. There is no required order.
5. When the twelfth sector is done, DF station calibration complete at KOBULETI appears.

The dwell timer restarts at zero whenever the aircraft leaves the distance band, leaves the height band or crosses into another sector. Only the current sector is lost; confirmed sectors stay confirmed. Mountainous terrain is the usual trap, because the height band is measured against the ground directly below the aircraft and not against the airfield elevation.

Orbit speed. A single circle can calibrate all twelve sectors as long as each one is crossed slowly enough. Any speed that leaves at least 20 seconds inside a sector works; above roughly 150 knots on the inner edge of the ring the aircraft crosses a sector too quickly for anything to be recorded, so slow down or move out toward 6 km, where each arc is twice as long.

A sector is the true bearing from the station to the aircraft. Sector 1 begins at north and every following sector is 30 degrees clockwise. The Live Map labels the same sectors by their bearing band.

A calibrated sector improves every bearing the network reports in that compass direction, not only bearings taken by the station airfield itself. Relay sensors assigned to the station use the station's calibration, and the sector that counts is the direction from the sensor to the enemy.

• Narrower cones. A fully calibrated sector roughly halves the daylight cone: Loop from about 86 to 42 degrees, Adcock from 52 to 26 and Watson-Watt from 32 to 16. Full values are on Enemy Detection.
• Better quality grades. An uncalibrated bearing carries a fixed penalty on the A, B or C rating shown in the contact tooltip.
• No effect on the night error. Darkness widens every cone, and calibration cannot remove that part. A survey flight maps the antenna, not the ionosphere.
• No effect on detection range or chance. Calibration only sharpens a bearing that has already been received.

A calibrated sector holds full quality for 180 mission cycles after the flight, then fades linearly to nothing at 365 cycles. One cycle is one server restart and one game day, six of them per real day, so a sector stays perfect for roughly a month of continuous server operation and is gone after about two.

A partly decayed sector still produces a usable bearing and cannot be topped up: as long as any quality remains, the flight skips it and no dwell timer runs. Once it has decayed to zero the sector becomes flyable again and a fresh 20-second dwell restores it to full.

Upgrading a station clears all twelve sectors, because the new antenna has its own directional error. Fly the calibration after an upgrade, never before it.

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