Signal area (ICAO Annex 2 Appendix 1)

General (ICAO)

The signal area is a level square surface (minimum 9 m × 9 m) on the aerodrome where ground signals are laid out for pilots — governed by ICAO Annex 14 Vol I, §5.5 and the signal definitions in ICAO Annex 2 Appendix 1, Section 5.

Visible to aircraft in flight from 300 m (1 000 ft) altitude, normally white-bordered. Ground signals supplement or replace radio signals at aerodromes without communication or in case of radio failure.

Key ground signals (Annex 2 Appendix 1, §5):

Landing prohibited

• Red square with two diagonal yellow stripes = landing prohibited, likely to be of long duration.

Special precautions when approaching or landing

• Red square with one yellow diagonal stripe = due to poor condition of the movement area or other reasons, caution required.

Runways and taxiways unfit for use

• White or yellow crosses on a runway / taxiway / runway portion = not to be used.

Direction for landing and take-off

• White or orange landing "T" = longitudinal axis of the "T" indicates landing/take-off direction.
• Vertical two-digit number in black on a yellow background at the tower → runway designator of the runway in use (hundreds digit dropped, e.g. "27" for magnetic 270°).

Right-hand traffic mandatory

• Conspicuous right-angled arrow pointing right in the signal area or horizontally at the runway threshold = circuits and approaches are to be flown to the right.

Reporting station

• Letter "C" in black on yellow in a vertical position → pilots must report to the aerodrome operator ("C" = Communication/Reporting).

Glider operations in progress

• White double-cross in the signal area or horizontally at the runway threshold = glider operations in progress, powered aircraft must expect glider traffic.

Dumbbell signal

• Dumbbell with horizontal connecting bars = taxiing, take-off and landing only on runways and taxiways.
• Dumbbell with vertical connecting bars (or closed bars toward the dumbbell) = take-off and landing only on runways; taxiing also allowed off taxiways.

Europe (EASA / EU)

Signal definitions are made EU-wide binding via SERA Appendix 1 (annex to Regulation (EU) 923/2012) — identical with Annex 2 Appendix 1, Section 5.

Annex 14 applied EU-wide via Regulation (EU) 139/2014 / Part-ADR.

Germany (national)

EU law. A signal area is found on many German VFR aerodromes; the "C" signal and double cross for glider activity are common. Exact location and signals are published per aerodrome in AIP VFR Germany.