Airport Simulation with SimPy: From Check-In to Takeoff

Published on February 20, 2026

Airports are complex systems under constant pressure. Passengers flow through multiple touchpoints. Delays cascade. Simulation helps you see where things go wrong before they do. <h2 id="the-airport-model">The Airport Model</h2> Components: - Passengers - Arrive for flights - Check-in - Desks and kiosks - Security - Screening queues - Gates - Boarding areas - Aircraft - Arrivals and departures <h2 id="basic-passenger-flow">Basic Passenger Flow</h2> <div class="code-block"><pre><code>import simpy import random class Airport: def __init__(self, env, config): self.env = env self.check_in_desks = simpy.Resource(env, capacity=config['check_in_desks']) self.security_lanes = simpy.Resource(env, capacity=config['security_lanes']) self.gates = simpy.Resource(env, capacity=config['gates']) self.stats = [] def passenger(self, passenger_id, flight_time): arrival = self.env.now record = {'id': passenger_id, 'arrival': arrival, 'flight': flight_time} # Check-in with self.check_in_desks.request() as req: yield req yield self.env.timeout(random.uniform(2, 5)) record['checked_in'] = self.env.now # Security with self.security_lanes.request() as req: yield req yield self.env.timeout(random.uniform(3, 10)) record['cleared_security'] = self.env.now # Wait at gate (until boarding) boarding_time = flight_time - 30 # Board 30 mins before if self.env.now < boarding_time: yield self.env.timeout(boarding_time - self.env.now) # Board record['boarded'] = self.env.now record['made_flight'] = self.env.now < flight_time self.stats.append(record) def passenger_arrivals(env, airport, flight_schedule): """Generate passengers for scheduled flights.""" passenger_id = 0 for flight_time, num_passengers in flight_schedule: # Passengers arrive 1-3 hours before flight for _ in range(num_passengers): arrival_offset = random.uniform(60, 180) arrival_time = flight_time - arrival_offset if arrival_time > env.now: yield env.timeout(arrival_time - env.now) env.process(airport.passenger(passenger_id, flight_time)) passenger_id += 1 # Run env = simpy.Environment() airport = Airport(env, {'check_in_desks': 10, 'security_lanes': 4, 'gates': 20}) # Flight schedule: (departure_time, passengers) flights = [(60, 150), (120, 200), (180, 180), (240, 220)] env.process(passenger_arrivals(env, airport, flights)) env.run(until=300) </code></pre></div> <h2 id="security-with-different-lanes">Security with Different Lanes</h2> <div class="code-block"><pre><code>class SecurityCheckpoint: def __init__(self, env, regular_lanes, priority_lanes): self.env = env self.regular = simpy.Resource(env, capacity=regular_lanes) self.priority = simpy.Resource(env, capacity=priority_lanes) def screen_passenger(self, passenger_type): if passenger_type in ['business', 'frequent_flyer']: lane = self.priority process_time = random.uniform(2, 5) else: lane = self.regular process_time = random.uniform(4, 12) with lane.request() as req: yield req yield self.env.timeout(process_time) </code></pre></div> <h2 id="aircraft-turnaround">Aircraft Turnaround</h2> <div class="code-block"><pre><code>class Aircraft: def __init__(self, env, flight_id, aircraft_type): self.env = env self.flight_id = flight_id self.type = aircraft_type def turnaround(self, gate, ground_crew, fuel_truck, catering): """Complete turnaround between arrival and departure.""" # Request gate with gate.request() as gate_req: yield gate_req # Parallel activities disembark = self.env.process(self.disembark()) clean = self.env.process(self.clean()) yield disembark yield clean # Sequential activities requiring resources with ground_crew.request() as crew: yield crew yield self.env.timeout(random.uniform(10, 20)) # Baggage with fuel_truck.request() as fuel: yield fuel yield self.env.timeout(random.uniform(15, 25)) with catering.request() as cater: yield cater yield self.env.timeout(random.uniform(10, 15)) # Board yield from self.board() def disembark(self): passengers = random.randint(100, 180) yield self.env.timeout(passengers * 0.1) def clean(self): yield self.env.timeout(random.uniform(15, 25)) def board(self): passengers = random.randint(100, 180) yield self.env.timeout(passengers * 0.15) </code></pre></div> <h2 id="baggage-handling">Baggage Handling</h2> <div class="code-block"><pre><code>class BaggageSystem: def __init__(self, env, num_carousels, num_handlers): self.env = env self.carousels = simpy.Resource(env, capacity=num_carousels) self.handlers = simpy.Resource(env, capacity=num_handlers) self.bags_processed = 0 def process_flight_bags(self, flight_id, num_bags): """Process bags from check-in to aircraft.""" bags_loaded = 0 with self.carousels.request() as carousel: yield carousel while bags_loaded < num_bags: # Handler picks up bags with self.handlers.request() as handler: yield handler batch = min(5, num_bags - bags_loaded) yield self.env.timeout(batch * 0.5) bags_loaded += batch self.bags_processed += num_bags </code></pre></div> <h2 id="complete-airport-simulation">Complete Airport Simulation</h2> <div class="code-block"><pre><code>import simpy import random import numpy as np class AirportSimulation: def __init__(self, env, config): self.env = env self.config = config # Resources self.check_in = simpy.Resource(env, capacity=config['check_in_desks']) self.kiosks = simpy.Resource(env, capacity=config['kiosks']) self.bag_drop = simpy.Resource(env, capacity=config['bag_drops']) self.security = simpy.Resource(env, capacity=config['security_lanes']) self.passport_control = simpy.Resource(env, capacity=config['passport_booths']) self.gates = simpy.Resource(env, capacity=config['gates']) # Stats self.passenger_stats = [] self.missed_flights = 0 def passenger(self, pax_id, flight_time, has_bags, is_international): arrival = self.env.now record = { 'id': pax_id, 'arrival': arrival, 'flight_time': flight_time } # Check-in (desk or kiosk) if random.random() < 0.7: # 70% use kiosk with self.kiosks.request() as req: yield req yield self.env.timeout(random.uniform(1, 3)) else: with self.check_in.request() as req: yield req yield self.env.timeout(random.uniform(3, 7)) # Bag drop if needed if has_bags: with self.bag_drop.request() as req: yield req yield self.env.timeout(random.uniform(2, 5)) record['check_in_complete'] = self.env.now # Security with self.security.request() as req: yield req yield self.env.timeout(random.triangular(3, 15, 6)) record['security_complete'] = self.env.now # Passport control for international if is_international: with self.passport_control.request() as req: yield req yield self.env.timeout(random.uniform(1, 3)) record['airside'] = self.env.now # Check if made it in time for boarding boarding_time = flight_time - 30 if self.env.now > boarding_time: self.missed_flights += 1 record['made_flight'] = False else: record['made_flight'] = True # Wait for boarding if self.env.now < boarding_time: yield self.env.timeout(boarding_time - self.env.now) record['total_time'] = self.env.now - arrival self.passenger_stats.append(record) def flight_passengers(self, flight_time, num_pax, is_international): """Generate passengers for a flight.""" for i in range(num_pax): # Arrival distribution: 60-180 mins before flight advance = random.triangular(60, 180, 120) arrival_time = max(0, flight_time - advance) # Wait until arrival time if arrival_time > self.env.now: yield self.env.timeout(arrival_time - self.env.now) has_bags = random.random() < 0.7 self.env.process(self.passenger( f"{flight_time}_{i}", flight_time, has_bags, is_international )) # Small gap between passenger arrivals yield self.env.timeout(random.uniform(0.1, 0.5)) def run(self, flight_schedule): """Run simulation with flight schedule.""" for flight_time, num_pax, is_intl in flight_schedule: self.env.process(self.flight_passengers(flight_time, num_pax, is_intl)) # Run until last flight + buffer last_flight = max(f[0] for f in flight_schedule) self.env.run(until=last_flight + 60) def report(self): pax = self.passenger_stats made_it = [p for p in pax if p['made_flight']] print("\n=== Airport Simulation Report ===") print(f"Total passengers: {len(pax)}") print(f"Made flight: {len(made_it)} ({len(made_it)/len(pax):.1%})") print(f"Missed flight: {self.missed_flights}") if made_it: total_times = [p['total_time'] for p in made_it] security_times = [p['security_complete'] - p['check_in_complete'] for p in made_it if 'security_complete' in p] print(f"\nTotal journey time (check-in to gate):") print(f" Mean: {np.mean(total_times):.1f} min") print(f" 90th pct: {np.percentile(total_times, 90):.1f} min") print(f"\nSecurity wait + process:") print(f" Mean: {np.mean(security_times):.1f} min") # Config config = { 'check_in_desks': 15, 'kiosks': 20, 'bag_drops': 10, 'security_lanes': 8, 'passport_booths': 6, 'gates': 30 } # Flight schedule: (departure_time, passengers, is_international) schedule = [ (60, 180, True), (90, 150, False), (120, 200, True), (150, 160, False), (180, 220, True), (210, 190, False), (240, 175, True), ] random.seed(42) env = simpy.Environment() sim = AirportSimulation(env, config) sim.run(schedule) sim.report() </code></pre></div> <h2 id="summary">Summary</h2> Airport simulation captures: - Multi-stage passenger journey - Parallel and sequential processes - Time-critical deadlines - Resource contention at bottlenecks - Flight schedule dependencies Every airport is a system. Simulate to optimise. <h2 id="next-steps">Next Steps</h2> <ul> <li><a href="/blog_posts/simpy-hospital-simulation.html">Hospital Simulation</a></li> <li><a href="/blog_posts/simpy-call-center-simulation.html">Call Centre Simulation</a></li> <li><a href="/blog_posts/simpy-queue-model.html">Queue Modelling</a></li> </ul>

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