diff --git a/shared/atc/phases/approach.ts b/shared/atc/phases/approach.ts
new file mode 100644
index 0000000..b67e6fa
--- /dev/null
+++ b/shared/atc/phases/approach.ts
@@ -0,0 +1,67 @@
+import type { Phase } from '../types'
+
+export const approachPhase: Phase = {
+  id: 'approach',
+  name: 'Approach Control',
+  frequency: '119.100',
+  unit: 'APP',
+  nextPhase: 'landing',
+  interactions: [
+    {
+      id: 'contact_approach',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot makes initial contact with approach control',
+      pilotExample: '{callsign}, descending flight level {flight_level}, information {atis_code}',
+      atcResponse: '{callsign}, radar contact. Expect {approach_type} approach runway {arrival_runway}.',
+    },
+    {
+      id: 'descend_instruction',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC instructs pilot to descend to an assigned altitude',
+      atcResponse: '{callsign}, descend altitude {assigned_alt} feet, QNH {qnh}.',
+      readback: {
+        required: ['assigned_alt', 'qnh'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, descend altitude {assigned_alt} feet, QNH {qnh}.',
+      },
+    },
+    {
+      id: 'cleared_approach',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC clears pilot for the instrument approach',
+      atcResponse: '{callsign}, cleared {approach_type} approach runway {arrival_runway}.',
+      readback: {
+        required: ['approach_type', 'arrival_runway'],
+        atcConfirm: 'Correct. Contact tower on {tower_freq}.',
+        atcCorrect: 'Negative, cleared {approach_type} approach runway {arrival_runway}.',
+      },
+      handoff: { toPhase: 'landing', say: 'Contact tower on {tower_freq}.' },
+    },
+    {
+      id: 'request_alternate_approach',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot requests a different approach type than assigned',
+      pilotExample: '{callsign}, request {requested_approach} approach runway {arrival_runway}',
+      atcResponse: '{callsign}, approved, expect {requested_approach} approach runway {arrival_runway}.',
+      updates: { approach_type: '{requested_approach}' },
+    },
+    {
+      id: 'go_around',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot executes a go-around and reports to approach',
+      pilotExample: '{callsign}, going around',
+      atcResponse: '{callsign}, roger, climb altitude {initial_alt} feet, fly runway heading, contact approach on {approach_freq}.',
+    },
+    {
+      id: 'speed_instruction',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC instructs pilot to reduce or maintain a specific speed',
+      atcResponse: '{callsign}, reduce speed {assigned_speed} knots.',
+      readback: {
+        required: ['assigned_speed'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, reduce speed {assigned_speed} knots.',
+      },
+    },
+  ],
+}
diff --git a/shared/atc/phases/clearance.ts b/shared/atc/phases/clearance.ts
new file mode 100644
index 0000000..68301da
--- /dev/null
+++ b/shared/atc/phases/clearance.ts
@@ -0,0 +1,32 @@
+import type { Phase } from '../types'
+
+export const clearancePhase: Phase = {
+  id: 'clearance',
+  name: 'Clearance Delivery',
+  frequency: '121.900',
+  unit: 'DEL',
+  nextPhase: 'ground',
+  interactions: [
+    {
+      id: 'request_clearance',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot requests IFR clearance to destination',
+      pilotExample: '{callsign}, request IFR clearance to {dest}, information {atis_code}',
+      atcResponse: '{callsign}, cleared to {dest} via {sid} departure, runway {runway}, climb initially {initial_alt} feet, expect flight level {flight_level}, squawk {squawk}',
+      readback: {
+        required: ['dest', 'sid', 'runway', 'squawk', 'initial_alt'],
+        atcConfirm: 'Readback correct. Contact ground on {ground_freq}.',
+        atcCorrect: 'Negative, I say again: cleared to {dest} via {sid}, runway {runway}, climb initially {initial_alt} feet, squawk {squawk}.',
+      },
+      updates: { clearance_received: 'true' },
+      handoff: { toPhase: 'ground', say: 'Contact ground on {ground_freq}.' },
+    },
+    {
+      id: 'request_information',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot requests ATIS information or QNH',
+      pilotExample: '{callsign}, request ATIS information',
+      atcResponse: 'Information {atis_code} is current, QNH {qnh}.',
+    },
+  ],
+}
diff --git a/shared/atc/phases/departure.ts b/shared/atc/phases/departure.ts
new file mode 100644
index 0000000..a7ae6b8
--- /dev/null
+++ b/shared/atc/phases/departure.ts
@@ -0,0 +1,61 @@
+import type { Phase } from '../types'
+
+export const departurePhase: Phase = {
+  id: 'departure',
+  name: 'Departure Control',
+  frequency: '125.100',
+  unit: 'DEP',
+  nextPhase: 'enroute',
+  autoAdvance: {
+    parameter: 'altitude_ft',
+    operator: '>=',
+    value: 18000,
+  },
+  interactions: [
+    {
+      id: 'contact_departure',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot makes initial contact with departure after handoff from tower',
+      pilotExample: '{callsign}, passing {altitude} feet, climbing {initial_alt}',
+      atcResponse: '{callsign}, radar contact. Climb flight level {flight_level}.',
+      readback: {
+        required: ['flight_level'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, climb flight level {flight_level}.',
+      },
+    },
+    {
+      id: 'climb_instruction',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC instructs pilot to climb to a new flight level',
+      atcResponse: '{callsign}, climb flight level {assigned_fl}.',
+      readback: {
+        required: ['assigned_fl'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, climb flight level {assigned_fl}.',
+      },
+    },
+    {
+      id: 'turn_instruction',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC instructs pilot to turn to a specific heading',
+      atcResponse: '{callsign}, turn {turn_direction} heading {assigned_heading}.',
+      readback: {
+        required: ['turn_direction', 'assigned_heading'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, turn {turn_direction} heading {assigned_heading}.',
+      },
+    },
+    {
+      id: 'direct_to',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC clears pilot to proceed direct to a waypoint',
+      atcResponse: '{callsign}, proceed direct {waypoint}.',
+      readback: {
+        required: ['waypoint'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, proceed direct {waypoint}.',
+      },
+    },
+  ],
+}
diff --git a/shared/atc/phases/emergency.ts b/shared/atc/phases/emergency.ts
new file mode 100644
index 0000000..3a3778f
--- /dev/null
+++ b/shared/atc/phases/emergency.ts
@@ -0,0 +1,65 @@
+import type { Phase } from '../types'
+
+/**
+ * Emergency phase -- can be activated from ANY other phase.
+ *
+ * When the engine detects a MAYDAY or PAN PAN call it should:
+ *   1. Save `flags.previousPhase` with the current phase id
+ *   2. Set `flags.emergencyActive = true`
+ *   3. Transition to this phase
+ *
+ * When the emergency is cancelled the engine should:
+ *   1. Set `flags.emergencyActive = false`
+ *   2. Restore `currentPhase` to `flags.previousPhase`
+ *   3. Clear `flags.previousPhase`
+ */
+export const emergencyPhase: Phase = {
+  id: 'emergency',
+  name: 'Emergency',
+  frequency: '121.500',
+  unit: 'EMG',
+  nextPhase: null,
+  interactions: [
+    {
+      id: 'declare_mayday',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot declares a MAYDAY emergency (distress)',
+      pilotExample: 'MAYDAY MAYDAY MAYDAY, {callsign}, {emergency_nature}, {pob} persons on board, fuel remaining {fuel_remaining} minutes',
+      atcResponse: '{callsign}, MAYDAY acknowledged. Roger {emergency_nature}. All stations, stop transmitting, MAYDAY in progress. {callsign}, say intentions.',
+      updates: { emergency_type: 'mayday', emergency_active: 'true' },
+    },
+    {
+      id: 'declare_panpan',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot declares a PAN PAN (urgency)',
+      pilotExample: 'PAN PAN PAN PAN PAN PAN, {callsign}, {emergency_nature}',
+      atcResponse: '{callsign}, PAN PAN acknowledged. Roger {emergency_nature}. Say intentions.',
+      updates: { emergency_type: 'panpan', emergency_active: 'true' },
+    },
+    {
+      id: 'cancel_emergency',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot cancels the emergency, situation resolved',
+      pilotExample: '{callsign}, cancel {emergency_type}, situation resolved',
+      atcResponse: '{callsign}, roger, {emergency_type} cancelled. Resume normal operations. Contact {resume_freq}.',
+      updates: { emergency_active: 'false' },
+    },
+    {
+      id: 'emergency_landing',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC provides vectors for an emergency landing',
+      atcResponse: '{callsign}, turn {turn_direction} heading {assigned_heading}, vectors for {arrival_runway}. Cleared {approach_type} approach runway {arrival_runway}, emergency services standing by.',
+      readback: {
+        required: ['assigned_heading', 'arrival_runway'],
+        atcConfirm: 'Correct, emergency services standing by.',
+        atcCorrect: 'Negative, turn {turn_direction} heading {assigned_heading}, vectors for {arrival_runway}.',
+      },
+    },
+    {
+      id: 'souls_on_board',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC requests souls on board and fuel remaining for emergency coordination',
+      atcResponse: '{callsign}, say souls on board and fuel remaining.',
+    },
+  ],
+}
diff --git a/shared/atc/phases/enroute.ts b/shared/atc/phases/enroute.ts
new file mode 100644
index 0000000..b7ec105
--- /dev/null
+++ b/shared/atc/phases/enroute.ts
@@ -0,0 +1,54 @@
+import type { Phase } from '../types'
+
+export const enroutePhase: Phase = {
+  id: 'enroute',
+  name: 'Center / En-Route Control',
+  frequency: '132.600',
+  unit: 'CTR',
+  nextPhase: 'approach',
+  interactions: [
+    {
+      id: 'contact_center',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot makes initial contact with center after handoff from departure',
+      pilotExample: '{callsign}, flight level {flight_level}',
+      atcResponse: '{callsign}, radar contact. Maintain flight level {flight_level}.',
+    },
+    {
+      id: 'maintain_level',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC instructs pilot to maintain current flight level',
+      atcResponse: '{callsign}, maintain flight level {flight_level}.',
+      readback: {
+        required: ['flight_level'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, maintain flight level {flight_level}.',
+      },
+    },
+    {
+      id: 'request_level_change',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot requests a different flight level due to weather or ride comfort',
+      pilotExample: '{callsign}, request flight level {requested_fl}',
+      atcResponse: '{callsign}, climb flight level {requested_fl}.',
+      readback: {
+        required: ['requested_fl'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, climb flight level {requested_fl}.',
+      },
+      alternatives: [
+        {
+          intent: 'Request denied due to traffic',
+          atcResponse: '{callsign}, unable flight level {requested_fl} due traffic. Maintain flight level {flight_level}.',
+        },
+      ],
+    },
+    {
+      id: 'position_report',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot reports current position over a waypoint or fix',
+      pilotExample: '{callsign}, position {waypoint}, flight level {flight_level}, estimating {next_waypoint} at {est_time}',
+      atcResponse: '{callsign}, roger, report {next_waypoint}.',
+    },
+  ],
+}
diff --git a/shared/atc/phases/ground.ts b/shared/atc/phases/ground.ts
new file mode 100644
index 0000000..50d1a3d
--- /dev/null
+++ b/shared/atc/phases/ground.ts
@@ -0,0 +1,59 @@
+import type { Phase } from '../types'
+
+export const groundPhase: Phase = {
+  id: 'ground',
+  name: 'Ground Control',
+  frequency: '121.700',
+  unit: 'GND',
+  nextPhase: 'tower',
+  interactions: [
+    {
+      id: 'request_pushback',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot requests pushback and start-up clearance',
+      pilotExample: '{callsign}, stand {stand}, request pushback and start-up',
+      atcResponse: '{callsign}, pushback approved, face {push_direction}.',
+      readback: {
+        required: ['push_direction'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, pushback approved, face {push_direction}.',
+      },
+      updates: { pushback_approved: 'true' },
+    },
+    {
+      id: 'request_taxi',
+      type: 'pilot_initiates',
+      when: 'vars.pushback_approved',
+      pilotIntent: 'Pilot requests taxi clearance to the runway',
+      pilotExample: '{callsign}, request taxi',
+      atcResponse: '{callsign}, taxi to holding point {runway} via {taxi_route}.',
+      readback: {
+        required: ['runway', 'taxi_route'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, taxi to holding point {runway} via {taxi_route}.',
+      },
+      updates: { taxi_clearance_received: 'true' },
+    },
+    {
+      id: 'report_holding_short',
+      type: 'pilot_initiates',
+      when: 'vars.taxi_clearance_received',
+      pilotIntent: 'Pilot reports holding short of the runway',
+      pilotExample: '{callsign}, holding short runway {runway}',
+      atcResponse: '{callsign}, contact tower on {tower_freq}.',
+      handoff: { toPhase: 'tower', say: 'Contact tower on {tower_freq}.' },
+    },
+    {
+      id: 'request_cross_runway',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot requests permission to cross an active runway',
+      pilotExample: '{callsign}, request cross runway {cross_runway}',
+      atcResponse: '{callsign}, cross runway {cross_runway}, report vacated.',
+      readback: {
+        required: ['cross_runway'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, cross runway {cross_runway}, report vacated.',
+      },
+    },
+  ],
+}
diff --git a/shared/atc/phases/index.ts b/shared/atc/phases/index.ts
new file mode 100644
index 0000000..40a41ca
--- /dev/null
+++ b/shared/atc/phases/index.ts
@@ -0,0 +1,48 @@
+import type { Phase } from '../types'
+import { clearancePhase } from './clearance'
+import { groundPhase } from './ground'
+import { towerPhase } from './tower'
+import { departurePhase } from './departure'
+import { enroutePhase } from './enroute'
+import { approachPhase } from './approach'
+import { landingPhase } from './landing'
+import { taxiInPhase } from './taxiIn'
+import { emergencyPhase } from './emergency'
+
+const phases: Phase[] = [
+  clearancePhase,
+  groundPhase,
+  towerPhase,
+  departurePhase,
+  enroutePhase,
+  approachPhase,
+  landingPhase,
+  taxiInPhase,
+  emergencyPhase,
+]
+
+const phaseMap = new Map<string, Phase>(phases.map(p => [p.id, p]))
+
+export function getPhase(id: string): Phase | undefined {
+  return phaseMap.get(id)
+}
+
+export function getPhaseOrder(): string[] {
+  return phases.filter(p => p.id !== 'emergency').map(p => p.id)
+}
+
+export function getAllPhases(): Phase[] {
+  return [...phases]
+}
+
+export {
+  clearancePhase,
+  groundPhase,
+  towerPhase,
+  departurePhase,
+  enroutePhase,
+  approachPhase,
+  landingPhase,
+  taxiInPhase,
+  emergencyPhase,
+}
diff --git a/shared/atc/phases/landing.ts b/shared/atc/phases/landing.ts
new file mode 100644
index 0000000..a6882e6
--- /dev/null
+++ b/shared/atc/phases/landing.ts
@@ -0,0 +1,45 @@
+import type { Phase } from '../types'
+
+export const landingPhase: Phase = {
+  id: 'landing',
+  name: 'Tower (Landing)',
+  frequency: '118.500',
+  unit: 'TWR',
+  nextPhase: 'taxiIn',
+  autoAdvance: {
+    parameter: 'on_ground',
+    operator: '==',
+    value: 1,
+  },
+  interactions: [
+    {
+      id: 'report_established',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot reports established on the final approach',
+      pilotExample: '{callsign}, established {approach_type} runway {arrival_runway}',
+      atcResponse: '{callsign}, roger, continue approach runway {arrival_runway}.',
+    },
+    {
+      id: 'cleared_land',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC clears pilot to land',
+      atcResponse: '{callsign}, wind {wind}, runway {arrival_runway}, cleared to land.',
+      readback: {
+        required: ['arrival_runway'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, runway {arrival_runway}, cleared to land.',
+      },
+    },
+    {
+      id: 'go_around_instruction',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC instructs pilot to go around due to traffic or runway obstruction',
+      atcResponse: '{callsign}, go around, I say again go around. Climb altitude {go_around_alt} feet, fly runway heading.',
+      readback: {
+        required: ['go_around_alt'],
+        atcConfirm: 'Correct, contact approach on {approach_freq}.',
+        atcCorrect: 'Negative, go around, climb altitude {go_around_alt} feet, fly runway heading.',
+      },
+    },
+  ],
+}
diff --git a/shared/atc/phases/taxiIn.ts b/shared/atc/phases/taxiIn.ts
new file mode 100644
index 0000000..58880e1
--- /dev/null
+++ b/shared/atc/phases/taxiIn.ts
@@ -0,0 +1,42 @@
+import type { Phase } from '../types'
+
+export const taxiInPhase: Phase = {
+  id: 'taxiIn',
+  name: 'Ground Control (Arrival)',
+  frequency: '121.700',
+  unit: 'GND',
+  nextPhase: null,
+  interactions: [
+    {
+      id: 'contact_ground_arrival',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot contacts ground after vacating the runway',
+      pilotExample: '{callsign}, runway {arrival_runway} vacated, request taxi to stand',
+      atcResponse: '{callsign}, taxi to stand {arrival_stand} via {arrival_taxi_route}.',
+      readback: {
+        required: ['arrival_stand', 'arrival_taxi_route'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, taxi to stand {arrival_stand} via {arrival_taxi_route}.',
+      },
+    },
+    {
+      id: 'taxi_to_gate',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC provides taxi instructions to the assigned stand',
+      atcResponse: '{callsign}, taxi to stand {arrival_stand} via {arrival_taxi_route}.',
+      readback: {
+        required: ['arrival_stand', 'arrival_taxi_route'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, taxi to stand {arrival_stand} via {arrival_taxi_route}.',
+      },
+    },
+    {
+      id: 'report_at_gate',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot reports on stand with engines shut down',
+      pilotExample: '{callsign}, on stand {arrival_stand}, engines shut down',
+      atcResponse: '{callsign}, roger, welcome to {dest}. Frequency change approved.',
+      updates: { session_complete: 'true' },
+    },
+  ],
+}
diff --git a/shared/atc/phases/tower.ts b/shared/atc/phases/tower.ts
new file mode 100644
index 0000000..1c7f715
--- /dev/null
+++ b/shared/atc/phases/tower.ts
@@ -0,0 +1,59 @@
+import type { Phase } from '../types'
+
+export const towerPhase: Phase = {
+  id: 'tower',
+  name: 'Tower',
+  frequency: '118.500',
+  unit: 'TWR',
+  nextPhase: 'departure',
+  autoAdvance: {
+    parameter: 'altitude_ft',
+    operator: '>=',
+    value: 1000,
+  },
+  interactions: [
+    {
+      id: 'report_ready_departure',
+      type: 'pilot_initiates',
+      pilotIntent: 'Pilot reports ready for departure',
+      pilotExample: '{callsign}, ready for departure runway {runway}',
+      atcResponse: '{callsign}, hold position, standby.',
+    },
+    {
+      id: 'lineup_and_wait',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC instructs pilot to line up on the runway and wait',
+      atcResponse: '{callsign}, runway {runway}, line up and wait.',
+      readback: {
+        required: ['runway'],
+        atcConfirm: 'Correct.',
+        atcCorrect: 'Negative, runway {runway}, line up and wait.',
+      },
+    },
+    {
+      id: 'cleared_takeoff',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC clears pilot for takeoff',
+      atcResponse: '{callsign}, wind {wind}, runway {runway}, cleared for takeoff.',
+      readback: {
+        required: ['runway'],
+        atcConfirm: 'Correct, contact departure on {departure_freq} when airborne.',
+        atcCorrect: 'Negative, runway {runway}, cleared for takeoff.',
+      },
+      updates: { takeoff_clearance: 'true' },
+      handoff: { toPhase: 'departure', say: 'Contact departure on {departure_freq}.' },
+    },
+    {
+      id: 'cancel_takeoff',
+      type: 'atc_initiates',
+      pilotIntent: 'ATC cancels takeoff clearance',
+      atcResponse: '{callsign}, cancel takeoff, I say again cancel takeoff. Hold position.',
+      readback: {
+        required: [],
+        atcConfirm: 'Correct, hold position.',
+        atcCorrect: 'Negative, cancel takeoff, hold position.',
+      },
+      updates: { takeoff_clearance: 'false' },
+    },
+  ],
+}
diff --git a/shared/atc/telemetryWatcher.ts b/shared/atc/telemetryWatcher.ts
new file mode 100644
index 0000000..cd09dd1
--- /dev/null
+++ b/shared/atc/telemetryWatcher.ts
@@ -0,0 +1,61 @@
+import type { Phase, TelemetryCondition, TelemetryState } from './types'
+
+export interface TelemetryEvent {
+  type: 'phase_advance' | 'atc_interrupt'
+  toPhase?: string
+  interactionId?: string
+  trigger: {
+    parameter: string
+    condition: string
+    value: number | boolean
+  }
+}
+
+/**
+ * Evaluates a single telemetry condition against current telemetry state.
+ * Returns true if the condition is met, false otherwise.
+ */
+export function evaluateCondition(
+  telemetry: TelemetryState,
+  condition: TelemetryCondition
+): boolean {
+  const actual = telemetry[condition.parameter]
+  if (actual === undefined) return false
+
+  const val = condition.value
+  switch (condition.operator) {
+    case '>':  return (actual as number) > val
+    case '>=': return (actual as number) >= val
+    case '<':  return (actual as number) < val
+    case '<=': return (actual as number) <= val
+    case '==': return actual == val  // loose equality for boolean/number comparison (on_ground == 1)
+    case '!=': return actual != val
+    default:   return false
+  }
+}
+
+/**
+ * Evaluates telemetry against the current phase's autoAdvance condition.
+ * If the condition is met and nextPhase is set, returns a phase_advance event.
+ * Otherwise returns null.
+ */
+export function evaluateTelemetry(
+  telemetry: TelemetryState,
+  currentPhase: Phase
+): TelemetryEvent | null {
+  if (currentPhase.autoAdvance && currentPhase.nextPhase) {
+    if (evaluateCondition(telemetry, currentPhase.autoAdvance)) {
+      return {
+        type: 'phase_advance',
+        toPhase: currentPhase.nextPhase,
+        trigger: {
+          parameter: currentPhase.autoAdvance.parameter,
+          condition: `${currentPhase.autoAdvance.parameter} ${currentPhase.autoAdvance.operator} ${currentPhase.autoAdvance.value}`,
+          value: telemetry[currentPhase.autoAdvance.parameter] as number,
+        },
+      }
+    }
+  }
+
+  return null
+}
diff --git a/shared/atc/templateRenderer.ts b/shared/atc/templateRenderer.ts
new file mode 100644
index 0000000..a067b00
--- /dev/null
+++ b/shared/atc/templateRenderer.ts
@@ -0,0 +1,11 @@
+/**
+ * Simple template renderer that replaces {variable} placeholders with values.
+ * Renders a template string like "{callsign}, cleared to {dest} via {sid}"
+ * by replacing {key} placeholders with values from the vars object.
+ * Unreplaced placeholders are left as-is (useful for debugging).
+ */
+export function renderTemplate(template: string, vars: Record<string, string>): string {
+  return template.replace(/\{(\w+)\}/g, (match, key) => {
+    return vars[key] ?? match
+  })
+}
diff --git a/shared/atc/types.ts b/shared/atc/types.ts
new file mode 100644
index 0000000..6a39b64
--- /dev/null
+++ b/shared/atc/types.ts
@@ -0,0 +1,191 @@
+// Phase definition
+export interface Phase {
+  id: string
+  name: string
+  frequency: string
+  unit: string
+  interactions: Interaction[]
+  autoAdvance?: TelemetryCondition
+  nextPhase: string | null
+}
+
+export interface Interaction {
+  id: string
+  type: 'pilot_initiates' | 'atc_initiates' | 'readback_check'
+  when?: string                       // Condition expression
+  pilotIntent: string                 // For LLM prompt
+  pilotExample?: string               // Template with {vars}
+  atcResponse: string                 // Template with {vars}
+  readback?: ReadbackSpec
+  updates?: Record<string, any>
+  handoff?: { toPhase: string; say?: string }
+  alternatives?: AlternativeResponse[]
+}
+
+export interface ReadbackSpec {
+  required: string[]
+  atcConfirm: string
+  atcCorrect: string
+}
+
+export interface AlternativeResponse {
+  intent: string
+  atcResponse: string
+  updates?: Record<string, any>
+}
+
+export interface TelemetryCondition {
+  parameter: string
+  operator: '>' | '>=' | '<' | '<=' | '==' | '!='
+  value: number
+  holdMs?: number
+}
+
+// Flight variables
+export interface FlightVars {
+  callsign: string
+  aircraft: string
+  dep: string
+  dest: string
+  stand: string
+  runway: string
+  sid: string
+  squawk: string
+  atis_code: string
+  initial_alt: string
+  flight_level: string
+  qnh: string
+  taxi_route: string
+  ground_freq: string
+  tower_freq: string
+  departure_freq: string
+  approach_freq: string
+  center_freq: string
+  atis_freq: string
+  wind: string
+  arrival_runway: string
+  arrival_stand: string
+  arrival_taxi_route: string
+  star: string
+  approach_type: string
+  [key: string]: string
+}
+
+// Telemetry from SimBridge
+export interface TelemetryState {
+  altitude_ft: number
+  speed_kts: number
+  groundspeed_kts: number
+  vertical_speed_fpm: number
+  heading_deg: number
+  latitude_deg: number
+  longitude_deg: number
+  on_ground: boolean
+  [key: string]: number | boolean
+}
+
+// Engine state
+export interface EngineState {
+  currentPhase: string
+  currentInteraction: string | null
+  waitingFor: 'pilot' | 'readback' | 'none'
+  vars: FlightVars
+  flags: {
+    inAir: boolean
+    emergencyActive: boolean
+    previousPhase: string | null
+  }
+  telemetry: TelemetryState
+  sessionId: string
+  transmissions: Transmission[]
+}
+
+// Transmission with debug info
+export interface Transmission {
+  id: string
+  timestamp: Date
+  speaker: 'pilot' | 'atc' | 'system'
+  message: string
+  normalized?: string
+  phase: string
+  frequency: string
+  debug: TransmissionDebug
+}
+
+export interface TransmissionDebug {
+  sttRaw?: string
+  llmRequest?: {
+    currentPhase: string
+    currentInteraction: string | null
+    pilotSaid: string
+    candidates: { id: string; intent: string }[]
+    contextSent: Record<string, any>
+  }
+  llmResponse?: {
+    chosenInteraction: string
+    confidence: 'high' | 'medium' | 'low'
+    reason: string
+    tokensUsed: number
+    durationMs: number
+    model: string
+  }
+  engineAction?: {
+    templateUsed: string
+    variablesUpdated: Record<string, any>
+    handoff?: { from: string; to: string }
+    phaseChanged?: { from: string; to: string }
+  }
+  telemetryTrigger?: {
+    parameter: string
+    condition: string
+    value: number
+  }
+  readbackResult?: {
+    complete: boolean
+    missing?: string[]
+  }
+}
+
+// Flight plan input
+export interface FlightPlan {
+  callsign: string
+  aircraft?: string
+  dep: string
+  arr: string
+  route?: string
+  altitude?: string
+  squawk?: string
+  id?: number
+  assignedsquawk?: string
+}
+
+// LLM Router types
+export interface RouteRequest {
+  pilotSaid: string
+  phase: string
+  interaction: string | null
+  waitingFor: 'pilot' | 'readback' | 'none'
+  candidates: RouteCandidate[]
+  vars: Record<string, any>
+  recentTransmissions: string[]
+}
+
+export interface RouteCandidate {
+  id: string
+  intent: string
+  example?: string
+}
+
+export interface RouteResponse {
+  chosen: string
+  reason: string
+  pilotIntent: string
+  confidence: 'high' | 'medium' | 'low'
+  tokensUsed: number
+  durationMs: number
+  model: string
+  readbackResult?: {
+    complete: boolean
+    missing?: string[]
+  }
+}