SWIM → vICE

Record a live traffic feed in your browser, boil it down to a vice timetable, and fly the traffic that was really there. vice does not replay radar — it flies aircraft itself from flight plans — so what a recording has to become is one row per flight, plus the routes they filed.

1 Open the feed and start the recorder

Open the page that shows the live traffic — for example the SWIM ERAM scope — and let it connect until you can see aircraft moving.
Open the browser console: F12 (or Cmd+Option+I on a Mac), then click the Console tab.
If the console asks you to type allow pasting before it will accept pasted code, type that first and press Enter.
Paste the whole block below and press Enter. A small amber panel appears in the bottom-right corner counting frames.

loading…

If the counter stays at zero, the page opened its connection before the recorder was watching. Reload the page and paste again straight away — or, in DevTools, switch the Network tab to Offline for two seconds and back to Online, which makes the page reconnect through the recorder.

2 Leave it running

Keep the tab open and the screen awake. The recorder saves a numbered part file every 20 MB so a long session cannot fill up memory; your browser may ask once whether to allow multiple downloads — say yes. When you are done, press Stop on the panel (or run swimRecorder.stop()), which downloads whatever is left.

The recorder only reads. It never sends anything anywhere, and swimRecorder.stop() puts the page back exactly as it was.

3 How long to record

Record for at least as long as you intend to fly, plus about 30 minutes. A timetable contains only the flights you captured: when your recording runs out, the scope goes quiet, however long the sim keeps running.

45–60 minutes — the practical minimum. Enough for one short session, with no room to choose a start time.
2–3 hours — the sweet spot. Covers a full arrival or departure bank with a build-up and a taper, and lets you start the sim anywhere in the middle.
6+ hours, or a whole day — a timetable you can launch at any hour, with the real overnight lull and morning push in it.

Record a busy period on purpose. An hour of a major airport is roughly 60–110 movements; an hour of a quiet field may be five, which will not feel like much once vice splits it into arrivals and departures. Note the local time you started — you will want to start the sim near it.

1 Load your recording

Drop your .ndjson part files here, or click to choose them.
All parts at once is fine — they are stitched back together in order.

Four hours of made-up Denver traffic, to try the tool without capturing anything.

3 Match up the fields

These are guesses from the keys your feed actually uses. Check them against the example values and fix any that are wrong — the sample column is usually enough to tell.

vice needs	Field in your recording	Example values

5 Review

Flights per local hour. Empty hours are hours of empty scope — start the sim inside the busy part.

First 60 rows

callsign	origin	destination	aircraft_type	time	cargo	op	seen

1 Put the CSV where vice looks

Timetables live in a folder named after the airport, and vice finds them on its own — no rebuilding, no editing anything else:

<vice resources>/traffic/timetables/<ICAO>/<Your Name>.csv

Where <vice resources> is:

Windows — %AppData%\Vice\resources (paste that into the Explorer address bar)
macOS — ~/Library/Application Support/Vice/resources (Finder → Go → Go to Folder)
Linux — ~/.config/Vice/resources
Running vice from a source checkout — the resources/ folder in the checkout itself

So a Denver timetable ends up at %AppData%\Vice\resources\traffic\timetables\KDEN\Tuesday Evening Push.csv Create the KDEN folder if it is not there. The file name is the name vice shows you, so name it something you will recognise.

Keep the CSV somewhere of your own as well. A vice update that refreshes its resources can take anything extra in that folder with it.

2 Fly it

Start vice and pick a scenario that includes your airport. If no scenario there exists yet, that is its own project — building a facility is much more work than this was.
In the new-sim window, find the traffic source setting and change it from Scenario to Timetable. Your timetable is in the list beside it. If neither appears, vice did not find the file: check the folder name is the ICAO code and the file ends in .csv.
Set the sim's start time to a time your recording covers — the busy hours from the histogram in step 2. Start it at 0300 local and you will get an empty scope, correctly.
Launch. The callsigns, types and city pairs on the scope are the ones that were really flying.

3 Optional: the real routes

A timetable records where each flight went, not how it got there, so vice works out a route for every flight from its own databases. If your feed carried filed routes, this page will have built a traffic_routes block from them — the routes your traffic actually flew.

Open the scenario's JSON file (in <vice resources>/scenarios/), find the airport's object, and paste the "traffic_routes" member into it alongside the members already there. Then start vice with that file:

vice -scenario "C:\path\to\your-scenario.json"

vice checks its own scenario routes first, then its database of recently filed routes, then the FAA's preferred routes — so this only overrides what it would otherwise guess.

When something is wrong

vice refuses to start, naming a row — the CSV was edited after export, or this page's checks were overridden. Re-export and use the file as it comes.
Timetable is not offered — wrong folder, or the scenario does not include that airport. The folder must be the ICAO code exactly: KDEN, not DEN or kden.
Traffic dries up mid-session — you reached the end of what you recorded. Record longer, or start the sim earlier in the window.
Aircraft appear with strange routes — expected without a traffic_routes block; vice is guessing. See step 3.
Everything is an arrival, or everything is a departure — the origin and destination fields are swapped in the mapping. Go back and switch them.