Airfield Lighting and ATC Procedures
Runway and approach lighting
Runway edge lights are white, with the last 600 m or half of the runway (whichever is less) coloured amber/yellow to warn of the end. Threshold lights are green, runway end lights red, and centreline lights white. Approach lighting leads to the threshold; PAPI shows two white/two red on slope, more red below and more white above. REIL helps identify the threshold. Taxiway edge lights are blue and centreline lights green.
Aerodrome and obstacle lighting
The aerodrome beacon flashes white or alternating white and green at civil aerodromes. Obstacles carry red lights, often flashing. If you see a red light where none is charted, treat it as an obstacle until identified.
ATC and light signals
Night clearances and position reports follow the same rules as day, but request the type of approach and the lighting service you need. If radio fails, squawk 7600, continue according to the last clearance and watch for light signals: steady green = cleared to land or taxi; steady red = stop; flashing red = taxi clear of the runway; flashing white = return to starting point.
Worked example
On final you see a steady red light from the tower. Reasoning: steady red means stop/do not land, so go around and re-establish communication or receive a new signal. Do not continue because you are already on final.
Traps
Confusing amber edge lights with threshold lights; ignoring a red light; assuming PAPI is serviceable; and not knowing the light signals for radio failure.