When two or more strobes are visible from a location, they must be what?

When two or more strobes are visible from a location, they must be synchronized. This synchronization is crucial for safety in environments like airports, where multiple light signals are used to convey information or warnings to pilots. Synchronization ensures that the signals sent by the strobes do not create confusion among observers. If they were to flash independently, it could lead to misinterpretation of signals, increasing the risk of accidents.

The necessity for synchronization is also rooted in standardization practices within many industries, as it helps in maintaining clear and distinct signals for different purposes, allowing for immediate recognition and understanding. Thus, synchronized strobes provide clarity and help in conveying the correct information effectively.