What is the difference between 'on scene' and 'arrived' in 900 codes?

• A. 'On scene' means you are approaching; arrived means you have reached the location
• B. 'On scene' means you are nearby; arrived means you are far away
• C. 'On scene' means you finished; arrived means you start
• D. They are interchangeable

Answer: (A)

The main idea here is how officers communicate their location status as they respond to an incident. In this 900-code usage, you move from approaching to being at the scene.

On scene is spoken while you are en route and nearing the incident—you're approaching the location and may be preparing to enter or establish command. Arrived is spoken once you have actually reached the location and are standing by on the scene, ready to act or begin your assignment. This distinction helps the incident commander know who is still coming and who is already on-site and ready to proceed.

For example, you might say you’re on scene as you turn onto the street or as you near the address, and then say arrived when you reach the doorway or perimeter and officially are at the scene. If you were to say you’re on scene when you’re far away or say arrived before you’ve reached the location, it would blur your real-time status and could delay coordinated response. Saying they’re interchangeable would remove that important cue about proximity and readiness.

So the best explanation is that on scene indicates you’re approaching, and arrived indicates you have reached the location and are on the scene.