Color and type of signal

For aircraft on the surface

For aircraft in flight

Steady green

Cleared for take off.

Cleared to land.

Flashing green

Cleared to taxi.

Return for landing (to

be followed by steady green

at proper time)

Steady red

Stop

Give way to other aircraft and

continue circling.

Flashing red

Taxi clear of runway in use.

Airport unsafe—do not land.

Flashing white

Return to starting point on

Not applicable.

airport.

Alternating red and green

Exercise extreme caution.

Exercise extreme caution.