Start here

1. Nothing on this field moves until you tell it to. Every aircraft calls up and then waits.
2. Click any strip carrying a colored tag — those are the ones waiting on you. The line above the command box names whichever has waited longest, which is where to start.
3. Type the command the strip is showing. cleared answers a clearance request; taxi 25L via p n answers a taxi request.
4. Stuck on the route? Type progressive. It prints a legal one you can read straight back.
5. Then watch it. If something changes — an arrival appears, two aircraft converge — amend what you said: hold short 25R, give way to N42ER, or a fresh taxi … via ….
6. When it stops at the runway, contact tower hands it off and the strip clears. That is the whole loop.

Phraseology

cleared issue IFR clearance (CRAFT)
taxi 25L via P N taxi to a runway
taxi ramp via N C taxi an arrival in
cross 16 clear a runway crossing
hold short 25R take a crossing clearance back
give way to N42ER yield, then continue
follow DAL356 sequence in behind
hold position / continue
contact tower hand off at the hold short
progressive show a legal route (hint)

After the clearance

Issuing the route is the smaller half of the job. The rest is watching and intervening. hold short 25R is the inverse of cross — use it when an arrival turns up after you have already cleared somebody across. give way to picks which of two converging aircraft goes first, and the one that yields gets going again on its own once the traffic has passed; follow is the same thing without the ending. Re-issuing taxi … via … amends the route from wherever the aircraft has got to. continue lifts all of it, so nothing you say can leave an aeroplane stuck.

Scenarios

Free play draws its traffic at random. A scenario is a scripted problem instead — the same aircraft doing the same thing at the same times, so an instructor can pose it to every student and pose it again next week. Add ?scenario=late-handoff to the address to run one; the ones that ship are late-handoff, arrival-bank and twy-closed. The brief is read onto the frequency when it starts and the header names it. A scenario may close a taxiway, in which case the ATIS line says so and any clearance naming it is refused. Reload without ?scenario= for free play, and ?seed= repeats a free-play session exactly.

Panels

Drag the bars between the bay, the scope, the transcript and this panel to resize any of them; double-click a bar to put it back, or focus it and use the arrow keys. Sizes are remembered. HELP in the header hides this panel altogether. Every panel scrolls.

Push to talk

Hold ` (backquote, left of the 1) or the MIC button, speak, then release. Say it as you would on the radio — “november four two echo romeo, taxi runway two five left via papa november”. What was heard is echoed into the transcript before it runs, and anything that doesn't parse gets a say again rather than a guess. Chrome and Edge only; everything voice does, the keyboard does.

The pilots talk

AUDIO in the header is the radio, and the lit button is the window you can hear it in. Pilots sound like who they are: an Embry-Riddle student is slow and careful, an airline crew reads a clearance back at half again the speed and half of them lose the first word off the front of the transmission. That is the exercise, not a fault. Every word is still in the transcript above — look out of the window, check the strip, and if you didn't copy it, read it. If several windows are on one session only one of them plays the radio; clicking AUDIO on another moves it there.

Scripted exercises

The same problem, posed to every student, and posed again next week. Each one carries its own seed and its own wind, so two people get the same traffic in the same places — which is what makes their two debriefs comparable. Picking one reloads the page: a scenario is the session, not a mode you switch into halfway through.

Session review

SESSION REVIEW or type debrief

Grades the controller, not the aircraft: runway incursions, losses of separation, how long each aircraft waited on you, which instructions were refused and why, and departures handed off too late to go. It reads the session — nothing on the strips changes and the exercise is neither easier nor harder for it being open. COPY and SAVE write out a plain-text report stamped with the seed, the build and the scenario, which is what makes two students comparable. Every figure it cannot honestly measure — CRAFT completeness for typed input, readback accuracy — is listed on the report as not measured rather than filled in.

Tower view

TOWER swaps the scope for the view out of the cab window, from the surveyed position of the real ATCT. It is a 3D scene and it is fetched the first time you ask for it, so the button says LOADING for a moment. Drag to look around — the scene follows the pointer, the way dragging a photograph does — scroll to zoom, and once the view has keyboard focus the arrow keys look around (hold Shift to swing faster), Home recenters and +/- zoom. A compass ribbon along the top gives the bearing you are facing. Selected traffic is ringed in cyan and a conflict in red, the same as on the scope. LABELS hides the callsign tags, which leaves you identifying traffic by where it is and where you sent it — the selected aircraft keeps its tag.

Notes

Prefix with a callsign to skip selecting: N42ER taxi 25L via p n. Routes are validated against the real taxiway graph — if the taxiways you name don't connect, the pilot will say unable.