What do white crosses or markings indicate at an aerodrome?

White crosses or markings at an aerodrome are specifically used to indicate an area that is unsafe for operations. These markings serve as a visual warning to pilots and crew that they should avoid landing or taking off in that vicinity. The use of white crosses is a standardized practice to ensure safety at airports, signaling that there may be obstacles, maintenance activities, or other hazardous conditions present.

While other markings at an aerodrome may signify operational areas, runway lengths, or designated parking spots, the white crosses are solely associated with warning against unsafe areas. This system helps maintain situational awareness for pilots and directs them to adhere to safe operational practices while on the ground.