diff --git a/game/ato/flight.py b/game/ato/flight.py
index 978079c0..462360c3 100644
--- a/game/ato/flight.py
+++ b/game/ato/flight.py
@@ -10,6 +10,7 @@ from .flightstate import Uninitialized, FlightState
 
 if TYPE_CHECKING:
     from game.dcs.aircrafttype import AircraftType
+    from game.sim.aircraftengagementzones import AircraftEngagementZones
     from game.squadrons import Squadron, Pilot
     from game.theater import ControlPoint, MissionTarget
     from game.transfers import TransferOrder
@@ -137,5 +138,5 @@ class Flight:
     def on_game_tick(self, time: datetime, duration: timedelta) -> None:
         self.state.on_game_tick(time, duration)
 
-    def should_halt_sim(self) -> bool:
-        return self.state.should_halt_sim()
+    def should_halt_sim(self, enemy_aircraft_coverage: AircraftEngagementZones) -> bool:
+        return self.state.should_halt_sim(enemy_aircraft_coverage)
diff --git a/game/ato/flightstate/flightstate.py b/game/ato/flightstate/flightstate.py
index b4bf8988..a07714cf 100644
--- a/game/ato/flightstate/flightstate.py
+++ b/game/ato/flightstate/flightstate.py
@@ -2,13 +2,15 @@ from __future__ import annotations
 
 from abc import ABC, abstractmethod
 from datetime import datetime, timedelta
-from typing import TYPE_CHECKING
+from typing import Optional, TYPE_CHECKING
 
 from game.ato.starttype import StartType
 
 if TYPE_CHECKING:
     from game.ato.flight import Flight
     from game.settings import Settings
+    from game.sim.aircraftengagementzones import AircraftEngagementZones
+    from game.threatzones import ThreatPoly
 
 
 class FlightState(ABC):
@@ -20,7 +22,7 @@ class FlightState(ABC):
     def on_game_tick(self, time: datetime, duration: timedelta) -> None:
         ...
 
-    def should_halt_sim(self) -> bool:
+    def should_halt_sim(self, enemy_aircraft_coverage: AircraftEngagementZones) -> bool:
         return False
 
     @property
@@ -32,3 +34,6 @@ class FlightState(ABC):
     @abstractmethod
     def spawn_type(self) -> StartType:
         ...
+
+    def a2a_commit_region(self) -> Optional[ThreatPoly]:
+        return None
diff --git a/game/ato/flightstate/inflight.py b/game/ato/flightstate/inflight.py
index 0b543364..d8371eb9 100644
--- a/game/ato/flightstate/inflight.py
+++ b/game/ato/flightstate/inflight.py
@@ -8,14 +8,16 @@ from dcs import Point
 
 from game.ato.flightstate import Completed
 from game.ato.flightstate.flightstate import FlightState
+from game.ato.flightwaypoint import FlightWaypoint
 from game.ato.flightwaypointtype import FlightWaypointType
 from game.ato.starttype import StartType
 from game.utils import Distance, Speed, meters
-from gen.flights.flightplan import LoiterFlightPlan, PatrollingFlightPlan
+from gen.flights.flightplan import LoiterFlightPlan
 
 if TYPE_CHECKING:
     from game.ato.flight import Flight
     from game.settings import Settings
+    from game.sim.aircraftengagementzones import AircraftEngagementZones
 
 
 def lerp(v0: float, v1: float, t: float) -> float:
@@ -23,27 +25,32 @@ def lerp(v0: float, v1: float, t: float) -> float:
 
 
 class InFlight(FlightState):
-    def __init__(self, flight: Flight, settings: Settings) -> None:
+    def __init__(self, flight: Flight, settings: Settings, waypoint_index: int) -> None:
         super().__init__(flight, settings)
-        self.waypoints = flight.flight_plan.iter_waypoints()
-        # TODO: Error checking for stupid flight plans with fewer than two waypoints.
-        self.current_waypoint = next(self.waypoints)
-        self.next_waypoint = next(self.waypoints)
-        self.passed_waypoints = {self.current_waypoint}
-        self.total_time_to_next_waypoint = self._total_time()
+        waypoints = self.flight.flight_plan.waypoints
+        self.waypoint_index = waypoint_index
+        self.current_waypoint = waypoints[self.waypoint_index]
+        # TODO: Error checking for flight plans without landing waypoints.
+        self.next_waypoint = waypoints[self.waypoint_index + 1]
+        self.total_time_to_next_waypoint = self.travel_time_between_waypoints()
         self.elapsed_time = timedelta()
 
-    def _total_time(self) -> timedelta:
-        if isinstance(self.flight.flight_plan, PatrollingFlightPlan):
-            # Racetracks should remain at the first waypoint until the patrol ends so
-            # that the waypoint generation doesn't need to reverse the orbit direction.
-            if self.current_waypoint == self.flight.flight_plan.patrol_start:
-                return self.flight.flight_plan.patrol_duration
+    def has_passed_waypoint(self, waypoint: FlightWaypoint) -> bool:
+        index = self.flight.flight_plan.waypoints.index(waypoint)
+        return index <= self.waypoint_index
 
-        # Loiter time is already built into travel_time_between_waypoints.
-        return self.flight.flight_plan.travel_time_between_waypoints(
+    def travel_time_between_waypoints(self) -> timedelta:
+        travel_time = self.flight.flight_plan.travel_time_between_waypoints(
             self.current_waypoint, self.next_waypoint
         )
+        if self.current_waypoint.waypoint_type is FlightWaypointType.LOITER:
+            # Loiter time is already built into travel_time_between_waypoints. If we're
+            # at a loiter point but still a regular InFlight (Loiter overrides this
+            # method) that means we're traveling from the loiter point but no longer
+            # loitering.
+            assert isinstance(self.flight.flight_plan, LoiterFlightPlan)
+            travel_time -= self.flight.flight_plan.hold_duration
+        return travel_time
 
     def progress(self) -> float:
         return (
@@ -52,19 +59,6 @@ class InFlight(FlightState):
         )
 
     def estimate_position(self) -> Point:
-        # TODO: Make Loiter and RaceTrack distinct FlightStates.
-        if isinstance(self.flight.flight_plan, PatrollingFlightPlan):
-            # Prevent spawning racetracks in the middle of a leg. For simplicity we
-            # always start the aircraft at the beginning of the racetrack.
-            if self.current_waypoint == self.flight.flight_plan.patrol_start:
-                return self.current_waypoint.position
-        elif isinstance(self.flight.flight_plan, LoiterFlightPlan):
-            if (
-                self.current_waypoint == self.flight.flight_plan.hold
-                and self.elapsed_time < self.flight.flight_plan.hold_duration
-            ):
-                return self.current_waypoint.position
-
         x0 = self.current_waypoint.position.x
         y0 = self.current_waypoint.position.y
         x1 = self.next_waypoint.position.x
@@ -73,7 +67,6 @@ class InFlight(FlightState):
         return Point(lerp(x0, x1, progress), lerp(y0, y1, progress))
 
     def estimate_altitude(self) -> tuple[Distance, str]:
-        # TODO: Should count progress as 0 until departing a hold.
         return (
             meters(
                 lerp(
@@ -86,27 +79,32 @@ class InFlight(FlightState):
         )
 
     def estimate_speed(self) -> Speed:
-        # TODO: Patrol/loiter speeds may be different.
         return self.flight.flight_plan.speed_between_waypoints(
             self.current_waypoint, self.next_waypoint
         )
 
-    def update_waypoints(self) -> None:
-        self.current_waypoint = self.next_waypoint
-        self.passed_waypoints.add(self.current_waypoint)
-        try:
-            self.next_waypoint = next(self.waypoints)
-        except StopIteration:
-            self.flight.set_state(Completed(self.flight, self.settings))
-        self.total_time_to_next_waypoint = self._total_time()
-        self.elapsed_time = timedelta()
+    def next_waypoint_state(self) -> FlightState:
+        from game.ato.flightstate.loiter import Loiter
+        from game.ato.flightstate.racetrack import RaceTrack
+
+        new_index = self.waypoint_index + 1
+        if self.next_waypoint.waypoint_type is FlightWaypointType.LANDING_POINT:
+            return Completed(self.flight, self.settings)
+        if self.next_waypoint.waypoint_type is FlightWaypointType.PATROL_TRACK:
+            return RaceTrack(self.flight, self.settings, new_index)
+        if self.next_waypoint.waypoint_type is FlightWaypointType.LOITER:
+            return Loiter(self.flight, self.settings, new_index)
+        return InFlight(self.flight, self.settings, new_index)
+
+    def advance_to_next_waypoint(self) -> None:
+        self.flight.set_state(self.next_waypoint_state())
 
     def on_game_tick(self, time: datetime, duration: timedelta) -> None:
         self.elapsed_time += duration
         if self.elapsed_time > self.total_time_to_next_waypoint:
-            self.update_waypoints()
+            self.advance_to_next_waypoint()
 
-    def should_halt_sim(self) -> bool:
+    def should_halt_sim(self, enemy_aircraft_coverage: AircraftEngagementZones) -> bool:
         contact_types = {
             FlightWaypointType.INGRESS_BAI,
             FlightWaypointType.INGRESS_CAS,
@@ -116,7 +114,7 @@ class InFlight(FlightState):
             FlightWaypointType.INGRESS_SEAD,
             FlightWaypointType.INGRESS_STRIKE,
         }
-        # TODO: Check against enemy threats.
+
         if self.current_waypoint.waypoint_type in contact_types:
             logging.info(
                 f"Interrupting simulation because {self.flight} has reached its "
@@ -132,6 +130,13 @@ class InFlight(FlightState):
             )
             return True
 
+        if enemy_aircraft_coverage.covers(self.estimate_position()):
+            logging.info(
+                f"Interrupting simulation because {self.flight} has encountered enemy "
+                "air-to-air patrol"
+            )
+            return True
+
         return False
 
     @property
diff --git a/game/ato/flightstate/loiter.py b/game/ato/flightstate/loiter.py
new file mode 100644
index 00000000..7adbd2c9
--- /dev/null
+++ b/game/ato/flightstate/loiter.py
@@ -0,0 +1,38 @@
+from __future__ import annotations
+
+from datetime import timedelta
+from typing import TYPE_CHECKING
+
+from dcs import Point
+
+from game.ato.flightstate import FlightState, InFlight
+from game.utils import Distance, Speed
+from gen.flights.flightplan import LoiterFlightPlan
+
+if TYPE_CHECKING:
+    from game.ato.flight import Flight
+    from game.settings import Settings
+
+
+class Loiter(InFlight):
+    def __init__(self, flight: Flight, settings: Settings, waypoint_index: int) -> None:
+        assert isinstance(flight.flight_plan, LoiterFlightPlan)
+        self.hold_duration = flight.flight_plan.hold_duration
+        super().__init__(flight, settings, waypoint_index)
+
+    def estimate_position(self) -> Point:
+        return self.current_waypoint.position
+
+    def estimate_altitude(self) -> tuple[Distance, str]:
+        return self.current_waypoint.alt, self.current_waypoint.alt_type
+
+    def estimate_speed(self) -> Speed:
+        return self.flight.unit_type.preferred_patrol_speed(self.estimate_altitude()[0])
+
+    def next_waypoint_state(self) -> FlightState:
+        # Do not automatically advance to the next waypoint. Just proceed from the
+        # current one with the normal flying state.
+        return InFlight(self.flight, self.settings, self.waypoint_index)
+
+    def travel_time_between_waypoints(self) -> timedelta:
+        return self.hold_duration
diff --git a/game/ato/flightstate/racetrack.py b/game/ato/flightstate/racetrack.py
new file mode 100644
index 00000000..7309a04e
--- /dev/null
+++ b/game/ato/flightstate/racetrack.py
@@ -0,0 +1,49 @@
+from __future__ import annotations
+
+from datetime import timedelta
+from typing import Optional, TYPE_CHECKING
+
+from dcs import Point
+from shapely.geometry import LineString, Point as ShapelyPoint
+
+from game.ato import FlightType
+from game.ato.flightstate import InFlight
+from game.threatzones import ThreatPoly
+from game.utils import Distance, Speed
+from gen.flights.flightplan import PatrollingFlightPlan
+
+if TYPE_CHECKING:
+    from game.ato.flight import Flight
+    from game.settings import Settings
+
+
+class RaceTrack(InFlight):
+    def __init__(self, flight: Flight, settings: Settings, waypoint_index: int) -> None:
+        assert isinstance(flight.flight_plan, PatrollingFlightPlan)
+        self.patrol_duration = flight.flight_plan.patrol_duration
+        super().__init__(flight, settings, waypoint_index)
+        self.commit_region = LineString(
+            [
+                ShapelyPoint(self.current_waypoint.x, self.current_waypoint.y),
+                ShapelyPoint(self.next_waypoint.x, self.next_waypoint.y),
+            ]
+        ).buffer(flight.flight_plan.engagement_distance.meters)
+
+    def estimate_position(self) -> Point:
+        # Prevent spawning racetracks in the middle of a leg. For simplicity we
+        # always start the aircraft at the beginning of the racetrack.
+        return self.current_waypoint.position
+
+    def estimate_altitude(self) -> tuple[Distance, str]:
+        return self.current_waypoint.alt, self.current_waypoint.alt_type
+
+    def estimate_speed(self) -> Speed:
+        return self.flight.unit_type.preferred_patrol_speed(self.estimate_altitude()[0])
+
+    def travel_time_between_waypoints(self) -> timedelta:
+        return self.patrol_duration
+
+    def a2a_commit_region(self) -> Optional[ThreatPoly]:
+        if self.flight.flight_type in {FlightType.BARCAP, FlightType.TARCAP}:
+            return self.commit_region
+        return None
diff --git a/game/ato/flightstate/startup.py b/game/ato/flightstate/startup.py
index 9435a734..df94aef0 100644
--- a/game/ato/flightstate/startup.py
+++ b/game/ato/flightstate/startup.py
@@ -11,6 +11,7 @@ from ..starttype import StartType
 if TYPE_CHECKING:
     from game.ato.flight import Flight
     from game.settings import Settings
+    from game.sim.aircraftengagementzones import AircraftEngagementZones
 
 
 class StartUp(FlightState):
@@ -31,7 +32,7 @@ class StartUp(FlightState):
     def spawn_type(self) -> StartType:
         return StartType.COLD
 
-    def should_halt_sim(self) -> bool:
+    def should_halt_sim(self, enemy_aircraft_coverage: AircraftEngagementZones) -> bool:
         if (
             self.flight.client_count > 0
             and self.settings.player_mission_interrupts_sim_at is StartType.COLD
diff --git a/game/ato/flightstate/takeoff.py b/game/ato/flightstate/takeoff.py
index f67a58a6..fb82131c 100644
--- a/game/ato/flightstate/takeoff.py
+++ b/game/ato/flightstate/takeoff.py
@@ -11,6 +11,7 @@ from ..starttype import StartType
 if TYPE_CHECKING:
     from game.ato.flight import Flight
     from game.settings import Settings
+    from game.sim.aircraftengagementzones import AircraftEngagementZones
 
 
 class Takeoff(FlightState):
@@ -22,7 +23,7 @@ class Takeoff(FlightState):
     def on_game_tick(self, time: datetime, duration: timedelta) -> None:
         if time < self.completion_time:
             return
-        self.flight.set_state(InFlight(self.flight, self.settings))
+        self.flight.set_state(InFlight(self.flight, self.settings, waypoint_index=0))
 
     @property
     def is_waiting_for_start(self) -> bool:
@@ -32,7 +33,7 @@ class Takeoff(FlightState):
     def spawn_type(self) -> StartType:
         return StartType.RUNWAY
 
-    def should_halt_sim(self) -> bool:
+    def should_halt_sim(self, enemy_aircraft_coverage: AircraftEngagementZones) -> bool:
         if (
             self.flight.client_count > 0
             and self.settings.player_mission_interrupts_sim_at is StartType.RUNWAY
diff --git a/game/ato/flightstate/taxi.py b/game/ato/flightstate/taxi.py
index e8ccdc76..e5d29abf 100644
--- a/game/ato/flightstate/taxi.py
+++ b/game/ato/flightstate/taxi.py
@@ -11,6 +11,7 @@ from ..starttype import StartType
 if TYPE_CHECKING:
     from game.ato.flight import Flight
     from game.settings import Settings
+    from game.sim.aircraftengagementzones import AircraftEngagementZones
 
 
 class Taxi(FlightState):
@@ -31,7 +32,7 @@ class Taxi(FlightState):
     def spawn_type(self) -> StartType:
         return StartType.WARM
 
-    def should_halt_sim(self) -> bool:
+    def should_halt_sim(self, enemy_aircraft_coverage: AircraftEngagementZones) -> bool:
         if (
             self.flight.client_count > 0
             and self.settings.player_mission_interrupts_sim_at is StartType.WARM
diff --git a/game/ato/flightstate/waitingforstart.py b/game/ato/flightstate/waitingforstart.py
index bc236305..b748d31e 100644
--- a/game/ato/flightstate/waitingforstart.py
+++ b/game/ato/flightstate/waitingforstart.py
@@ -41,7 +41,7 @@ class WaitingForStart(FlightState):
         elif self.start_type is StartType.RUNWAY:
             new_state = Takeoff(self.flight, self.settings, time)
         else:
-            new_state = InFlight(self.flight, self.settings)
+            new_state = InFlight(self.flight, self.settings, waypoint_index=0)
         self.flight.set_state(new_state)
 
     @property
diff --git a/game/missiongenerator/aircraft/waypoints/waypointgenerator.py b/game/missiongenerator/aircraft/waypoints/waypointgenerator.py
index dea9e4b9..79c41a36 100644
--- a/game/missiongenerator/aircraft/waypoints/waypointgenerator.py
+++ b/game/missiongenerator/aircraft/waypoints/waypointgenerator.py
@@ -74,7 +74,7 @@ class WaypointGenerator:
                     # mission aircraft starting at a waypoint with tasks behave
                     # correctly.
                     self.builder_for_waypoint(point).add_tasks(self.group.points[0])
-                if point not in self.flight.state.passed_waypoints:
+                if not self.flight.state.has_passed_waypoint(point):
                     filtered_points.append(point)
             else:
                 filtered_points.append(point)
diff --git a/game/settings/settings.py b/game/settings/settings.py
index 7189755a..ce86513a 100644
--- a/game/settings/settings.py
+++ b/game/settings/settings.py
@@ -290,7 +290,7 @@ class Settings:
         "Fast forward mission to first contact (WIP)",
         page=MISSION_GENERATOR_PAGE,
         section=GAMEPLAY_SECTION,
-        default=False,
+        default=True,
         detail=(
             "If enabled, the mission will be generated at the point of first contact."
         ),
diff --git a/game/sim/aircraftengagementzones.py b/game/sim/aircraftengagementzones.py
new file mode 100644
index 00000000..6501cc84
--- /dev/null
+++ b/game/sim/aircraftengagementzones.py
@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+from typing import Optional, TYPE_CHECKING
+
+from dcs import Point
+from shapely.geometry import Point as ShapelyPoint
+from shapely.ops import unary_union
+
+from game.ato.flightstate import InFlight
+
+if TYPE_CHECKING:
+    from game.ato import Flight
+    from game.ato.airtaaskingorder import AirTaskingOrder
+    from game.threatzones import ThreatPoly
+
+
+class AircraftEngagementZones:
+    def __init__(self, threat_zones: ThreatPoly) -> None:
+        self.threat_zones = threat_zones
+
+    def covers(self, position: Point) -> bool:
+        return self.threat_zones.intersects(ShapelyPoint(position.x, position.y))
+
+    @classmethod
+    def from_ato(cls, ato: AirTaskingOrder) -> AircraftEngagementZones:
+        commit_regions = []
+        for package in ato.packages:
+            for flight in package.flights:
+                if (region := cls.commit_region(flight)) is not None:
+                    commit_regions.append(region)
+        return AircraftEngagementZones(unary_union(commit_regions))
+
+    @classmethod
+    def commit_region(cls, flight: Flight) -> Optional[ThreatPoly]:
+        if isinstance(flight.state, InFlight):
+            return flight.state.a2a_commit_region()
+        return None
diff --git a/game/sim/aircraftsimulation.py b/game/sim/aircraftsimulation.py
index e7b17b2d..3f844b99 100644
--- a/game/sim/aircraftsimulation.py
+++ b/game/sim/aircraftsimulation.py
@@ -17,6 +17,7 @@ from game.ato.flightstate import (
     WaitingForStart,
 )
 from game.ato.starttype import StartType
+from game.sim.aircraftengagementzones import AircraftEngagementZones
 from gen.flights.traveltime import TotEstimator
 
 if TYPE_CHECKING:
@@ -45,18 +46,17 @@ class AircraftSimulation:
                 return
 
     def tick(self) -> bool:
-        interrupt_sim = False
         for flight in self.iter_flights():
             flight.on_game_tick(self.time, TICK)
-            if flight.should_halt_sim():
-                interrupt_sim = True
 
-        # TODO: Check for SAM or A2A contact.
-        # Generate an engagement poly for all active air-to-air aircraft per-coalition
-        # and compare those against aircraft positions. If any aircraft intersects an
-        # enemy air-threat region, generate the mission. Also check against enemy SAM
-        # zones.
-        return interrupt_sim
+        # Finish updating all flights before computing engagement zones so that the new
+        # positions are used.
+        blue_a2a = AircraftEngagementZones.from_ato(self.game.blue.ato)
+        red_a2a = AircraftEngagementZones.from_ato(self.game.red.ato)
+        for flight in self.iter_flights():
+            if flight.should_halt_sim(red_a2a if flight.squadron.player else blue_a2a):
+                return True
+        return False
 
     def set_initial_flight_states(self) -> None:
         now = self.game.conditions.start_time
@@ -78,7 +78,7 @@ class AircraftSimulation:
         elif flight.start_type is StartType.RUNWAY:
             flight.set_state(Takeoff(flight, self.game.settings, now))
         elif flight.start_type is StartType.IN_FLIGHT:
-            flight.set_state(InFlight(flight, self.game.settings))
+            flight.set_state(InFlight(flight, self.game.settings, waypoint_index=0))
         else:
             raise ValueError(f"Unknown start type {flight.start_type} for {flight}")