Traffic density and loss-of-separation events, as map layers inside ForeFlight.
Press and hold the blue button — don't just tap it — then choose Open in ForeFlight.
Two map layers, built from the same data behind the rest of this site. See Methodology for how events are detected and rated.
On an iPad or iPhone — press and hold the Install in ForeFlight button above (don't just tap it), then choose Open in ForeFlight. ForeFlight downloads and imports the pack for you. This only works on a device with ForeFlight installed: the button is a handoff to the app, not a web page, so on a computer it just leads to a ForeFlight error page. Use Download .zip there instead.
From a Mac
Other ways
Once imported, the pack appears under More → Custom Content. Its two layers then show up in the Maps layer selector, in the left-hand column — switch them on there. Remove or replace the pack from the same Custom Content screen.
These layers are a historical picture of a fixed date range. They are not live traffic, not a traffic advisory, and no substitute for see-and-avoid or ATC. They will not update in flight. Events are inferred from crowdsourced ADS-B data and any individual one may be a false positive — see Methodology for the known sources of error.