Use REL and THL

Before first use, check EuroScope settings.

Start with REL at runway entrances. Then use THL for aircraft lined up to depart. Both work automatically once you claim them.

Runway Entrance Lights (REL)

REL protects traffic entering a runway. It draws a red row from each holding position to the runway edge, lit while traffic makes that entrance unsafe. You never switch a row. You claim REL on a runway, and the monitor drives every row on it.

Turn it on

1. Expand the airport’s + ICAO header.
2. Each runway row carries three boxes: BAR · THL · REL. Tick REL.

The rows light and clear themselves from live traffic.

• REL is claimed per runway and independently of BAR and THL.
• It is a claim: one controller per runway, following the same eligibility, heartbeat and expiry rules - see who can claim what.
• A runway with no published REL geometry can be ticked, but nothing will run there. The server refuses the empty claim, and the plugin warns you in chat.
• When the claim dies, the server forces that runway’s rows dark.

Tune the timing in the menu’s REL section (see Settings). On the scope, a lit row draws along its published line. Prefer them out of the picture? Turn Show REL indicators off.

Controller requirement

REL is EuroScope-only, like Follow the Greens.

Further reading - RWSL in the real world

XPGuard’s THL and REL follow the Runway Status Lights (RWSL) system. RWSL is an ICAO-recognized runway-safety concept operated in the real world by EUROCONTROL and the FAA:

• FAA - Runway Status Lights
• EUROCONTROL - Runway Status Lights
• SKYbrary - Runway Status Lights (RWSL)

Takeoff Hold Lights (THL)

XPGuard’s automatic runway-conflict warning. A double row of red lights runs down the runway for an aircraft lined up to depart, whenever the runway ahead is occupied or about to be crossed. You do not switch it bar by bar. You enable it on a runway, and the monitor drives the lights.

THL Warning with anticipation;

THL Warning for multiple lineup;

Turn it on

1. Expand the airport’s + ICAO header.
2. Tick THL on a runway (the right-hand box). It fills red. Untick to stop.

That is all. When an aircraft lines up and the runway ahead is unsafe, the lights turn red in the sim. They go dark when it clears.

• THL is armed per runway and independently of its BAR claim.
• Arming THL is a claim: one controller per runway. A runway armed by someone else shows as taken and refuses the click. It follows the same eligibility, heartbeat and expiry rules as a BAR claim - see who can claim what.
• When the claim dies, the server forces that runway’s THL off.

On the radar, an armed runway shows the red double row and labels the protected aircraft THL <runway>.

How the warning responds to traffic

• THL runs on anticipation, not only on the present.
• It predicts each target’s path from its motion, so a crossing aircraft lights the runway before it arrives. The lights clear the moment the conflict is predicted to resolve.
• It uses your EuroScope ground radar. An active controller is required.
• The conflict logic follows the FAA RWSL model - MIT Lincoln Laboratory ATC-206.

Safety

THL never replaces a verbal clearance. It is an advisory aid; the lights going dark is not a takeoff clearance. Keep clearing takeoffs verbally.

Next: Set up FTG list controls.