Houston George Bush Intercontinental (IAH) Airport Terminal Transfer Guide: Terminals A, B, C, D, and E Skyway Train, Subway, Minimum Connection Times, and Baggage Rules (2026)

Quick Summary

• Primary Update: Houston George Bush Intercontinental Airport (IAH) links five passenger terminals—Terminals A, B, C, D, and E—using the post-security elevated Skyway automated people mover and the pre-security underground Subway train.
• Transit Impact: The airside Skyway operates 24/7 on Level 4 inside the Transportation Security Administration (TSA) sterile perimeter, departing every 2 minutes with a 1-to-2 minute transit time between terminals, allowing domestic and international departing passengers to transfer without clearing security again.
• Traveler Advice: Single-ticket domestic flight transfers require an operational minimum of 45 to 50 minutes, whereas inbound international travelers landing at Terminals D or E must complete U.S. Customs and Border Protection (CBP) border checks, claim checked luggage, drop bags onto airline re-check belts, and clear TSA screening, requiring an operational layover window of 90 to 120 minutes.

Houston George Bush Intercontinental Airport (IAH) serves as the primary international gateway to Texas and the southern United States, handling tens of millions of passengers annually. As the premier Latin American gateway and premier secondary transatlantic hub for United Airlines, alongside long-haul operations from major European, Middle Eastern, and Asian carriers, IAH manages heavy connection traffic across five distinct terminals: Terminals A, B, C, D, and E.

Navigating between terminals efficiently requires understanding the airport's dual transit networks: an elevated, post-security people mover train system (Skyway) and a subterranean, landside automated train (Subway). Passengers transferring between domestic flights, or departing internationally on a connected ticket, can move throughout the terminal complex without leaving the secure zone. Conversely, travelers arriving on inbound international services must exit the secure area through federal inspection and undergo secondary security screening before proceeding to onward domestic flights.

 [ TERMINAL A ]             [ TERMINAL B ]             [ TERMINAL C ]             [ TERMINAL D ]             [ TERMINAL E ]
Non-United Domestic        United Express             United Domestic            Mickey Leland Int'l        United Int'l
Mainline & Regional        Regional Jets              Mainline Operations        Foreign Flag Carriers      Hub Operations
Gates A1 - A30             Gates B1 - B88             Gates C14 - C45            Gates D1 - D16             Gates E1 - E24
(Skyway Level 4)           (Skyway Level 4)           (Skyway Level 4)           (Skyway Level 4)           (Skyway Level 4)
       ^                          ^                          ^                          ^                          ^
       |                          |                          |                          |                          |
       +==========================+==========================+==========================+==========================+
       |                  AIRSIDE SKYWAY APM TRAIN (POST-SECURITY / ELEVATED LEVEL 4)                              |
       |                  *Departs every 2 min | 1-2 min per leg | Continuous airside sterile loop*                |
       |                                                                                                           |
       |                          +--------------------------+--------------------------+--------------------------+
       |                          |      AIRSIDE PEDESTRIAN WALKWAYS (POST-SECURITY CONCOURSE CONNECTORS)          |
       |                          |      *Walk between Terminals B, C, D, and E on Levels 2 & 3 without train*     |

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

===================== UNDERGROUND SUBWAY APM TRAIN (LANDSIDE / PRE-SECURITY BASEMENT LEVEL LL) =====================
[ Terminal A ] <-----> [ Terminal B ] <-----> [ Terminal C ] <-----> [ Marriott Hotel ] <-----> [ Terminals D & E ]
*Departs every 3 min (03:30 - 00:30) | Landside only | Exiting requires complete TSA screening to re-enter airside*

Terminal Assignments Across Houston IAH

IAH distributes flights across five terminals, configured alphabetically from west to east:

• Terminal A (Gates A1 to A30): Operates as the central facility for all non-United domestic carriers. Participating airlines include American Airlines, Delta Air Lines, Southwest Airlines, Spirit Airlines, Frontier Airlines, JetBlue Airways, and Alaska Airlines. Terminal A features north (Gates A1–A15) and south (Gates A17–A30) concourses, alongside an American Airlines Admirals Club (near Gate A25) and a United Club (near Gate A9). Terminal A is separated from other concourses by airfield apron ramps, meaning post-security transit to Terminals B, C, D, or E requires boarding the elevated Skyway train.
• Terminal B (Gates B1 to B88): Dedicated exclusively to United Express regional flight operations. The modernized South Concourse (Gates B1–B31) provides spacious boarding lounges for regional jet departures, while the North Concourse handles commuter feeder routes. A United Club is located on the mezzanine level.
• Terminal C (Gates C14 to C45): Serves as United Airlines' domestic mainline operations center. The facility is split into Terminal C North (Gates C14–C27) and Terminal C South (Gates C33–C45), hosting two large United Club lounges. Broad airside corridors link Terminal C directly to Terminals D and E on foot.
• Terminal D (Gates D1 to D16): Houses the Mickey Leland International Terminal, accommodating foreign flag carriers alongside international arrivals requiring U.S. border processing. Operating airlines include Emirates, Qatar Airways, British Airways, Lufthansa, Air France, KLM, Turkish Airlines, All Nippon Airways (ANA), Singapore Airlines, EVA Air, Aeromexico, Volaris, VivaAerobus, and Avianca. Terminal D houses diverse airline lounges, including the British Airways Lounge, KLM Crown Lounge, Air France Lounge, and an American Express Centurion Lounge.
• Terminal E (Gates E1 to E24): United Airlines' dedicated international long-haul terminal and premium transcontinental domestic facility. All international arrivals on United disembark here or in Terminal D to access the Federal Inspection Services (FIS) customs hall. Terminal E features United's multi-level flagship United Polaris Lounge (near Gate E12) and a United Club.

Inter-Terminal Transit Systems: Skyway vs. Subway

Houston IAH provides two separate automated train networks. Choosing the correct system depends on whether you have cleared TSA security, hold an onward boarding pass, and have luggage checked through to your final airport.

1. Skyway Automated People Mover (Airside / Inside Security)

The Skyway is an elevated automated people mover (APM) running along the roofline (Level 4) of the terminal complex, offering clear views across the active taxiways. It operates entirely within the TSA sterile perimeter.

• Operating Hours: Operates 24 hours a day, 365 days a year.
• Frequency: Trains depart every 2 minutes throughout the day and evening.
• Station Locations: Stations are situated on Level 4 in each terminal:
  • Terminal A: Station located above the central connector between North and South concourses.
  • Terminal B: Station located near Gate B85.
  • Terminal C: Station located near Gate C24.
  • Terminal D & E: Joint station accessible via the wide indoor corridor linking Terminal D (near Gate D8) and Terminal E (near Gate E10).
• Transit Duration: Transit between adjacent stations takes 1 to 2 minutes. A complete journey from Terminal A to the Terminal D/E complex takes roughly 4 to 5 minutes.
• Security Exemption: Travelers connecting between domestic gates, or from domestic flights to international departures, do not exit security and do not undergo secondary TSA screening when using the Skyway.

2. Underground Subway People Mover (Landside / Outside Security)

The Subway is a subterranean automated guideway transit system located on the basement level (Level LL), beneath the baggage claim and ticket counters. It links all five passenger terminals and the on-airport hotel outside the security perimeter.

• Operating Hours: Operates daily from 03:30 to 00:30 (12:30 AM).
• Frequency: Trains depart every 3 minutes.
• Station Locations: Basement level escalators and elevators lead directly to Subway platforms at:
  • Terminal A (Level LL)
  • Terminal B (Level LL)
  • Terminal C (Level LL)
  • Houston Airport Marriott Hotel (Central Lobby Station)
  • Terminals D & E (Joint Station at Level LL)
• Operational Requirement: Because the Subway is situated entirely in the public landside zone, any passenger using it must clear standard TSA security checkpoint lanes to access boarding gates in their departure terminal.

3. Airside Pedestrian Walkways

Passengers traveling between United-operated concourses can also transfer on foot without riding the train. Indoor, climate-controlled pedestrian corridors with moving walkways connect Terminals B, C, D, and E post-security:

• Terminal B to Terminal C: Connected via a ground-level airside walking path (approximately 6 to 9 minutes on foot).
• Terminal C to Terminal D/E: Connected via broad concourse-level skybridges (approximately 5 to 8 minutes on foot).
• Terminal D to Terminal E: Directly contiguous; passengers walk freely between concourses in 3 to 5 minutes.
• Terminal A Access: Terminal A is physically isolated from the other four terminals by tarmac; walking to or from Terminal A post-security is impossible. All post-security transfers involving Terminal A must utilize the Skyway.

Minimum Connection Times (MCT) at Houston IAH

Airlines program Minimum Connection Times into ticketing reservation systems to enforce legal flight pairings. The schedule below details standard minimum parameters alongside real-world recommended buffers:

International Arrival Formalities & Baggage Re-Check at Terminals D and E

The United States does not provide sterile international transit areas. Every passenger arriving on an international flight at IAH must disembark through secured corridors leading to the central Federal Inspection Services (FIS) facility located between Terminals D and E.

Baggage Re-Check Guidelines

• Single Through-Tickets (Protected Bookings): When traveling on a single ticket (for instance, flying Qatar Airways from Doha to Houston and connecting to United Airlines to New Orleans), your checked bags are tagged through to your final airport code. However, federal law mandates that you claim those bags from the IAH customs carousel. After walking through customs inspection, turn immediately toward the dedicated baggage drop counters staffed by United and airline handlers. Drop your bags onto the conveyor. You do not need to pay additional bag fees or visit the public ticketing hall.
• Separate Unlinked Tickets (Self-Transfers): If your journey involves two separate ticket confirmations on airlines that do not maintain an interline baggage agreement (for instance, flying Turkish Airlines into IAH and separately booking a Southwest Airlines flight from Terminal A), you cannot use the transit re-check belts. You must claim your luggage, exit customs into the public landside arrivals lobby, proceed downstairs to the underground Subway train, ride to Terminal A, ascend to the ticket lobby, and check your luggage before the airline's checked bag cut-off deadline (typically 45 to 60 minutes prior to departure).

Traveler Logistics Guide

Follow these sequential steps to ensure smooth flight transfers across Houston IAH:

Domestic-to-Domestic Connection Walkthrough (Airside via Skyway)

1. Verify Your Departure Gate: Upon stepping off the aircraft, check airport flight information displays or your airline mobile app. Terminal letters dictate your route (e.g., Gate A22 is Terminal A; Gate C35 is Terminal C; Gate E14 is Terminal E).
2. Determine Walking vs. Skyway Route: If your connecting flight departs from the same terminal, walk directly to your gate. If connecting between Terminals C, D, and E, you can walk along the wide concourse connectors. If connecting to or from Terminal A or B, follow illuminated overhead signs toward the "Skyway Train."
3. Ascend to Level 4: Take the designated elevators or escalators up to the Skyway platform on Level 4.
4. Board the Skyway: Trains arrive every 2 minutes. Monitor platform display monitors for train direction and board the automated car.
5. Descend at Your Departure Terminal: Exit at your destination terminal, take the escalator down to the secure departures concourse, and walk straight to your gate without clearing security.

International-to-Domestic Connection Walkthrough (Terminals D & E)

1. Prepare Entry Credentials: Have your passport, valid U.S. visa or approved ESTA, and Mobile Passport Control (MPC) digital confirmation ready upon deplaning.
2. Complete CBP Border Processing: Proceed through passport inspection lines in the FIS hall. Global Entry cardholders and MPC app users should utilize their dedicated express lanes to bypass standard visitor queues.
3. Retrieve Checked Baggage: Proceed to the baggage claim carousels inside the FIS hall. Locate your inbound flight number on monitors and collect all checked suitcases.
4. Clear Customs Inspection: Proceed through the customs exit doors.
5. Deposit Luggage on Connecting Belts: If your bags are tagged to your final destination, hand them immediately to the airline transfer agents at the connecting baggage drop belts located right outside customs.
6. Pass TSA Transit Security: Enter the dedicated connecting flight TSA security checkpoint. Complete standard security screening.
7. Access Departure Gates: Once cleared, take the escalator up to the Level 4 Skyway station (for Terminals A or B) or walk down the concourse (for Terminals C, D, or E) to reach your departure gate.

Frequently Asked Questions

Can I transfer between terminals at Houston IAH without clearing TSA security again?

Yes, as long as you are transferring between domestic flights or connecting from a domestic flight to an outbound international flight. The elevated Skyway automated people mover operates 24/7 on Level 4 completely inside the post-security sterile perimeter. You can move freely among Terminals A, B, C, D, and E without re-screening. However, if you leave the secure area or take the underground Subway train (which runs landside on Level LL), you must pass through TSA security checkpoint screening to re-enter.

Do international connecting passengers at IAH have to collect their checked bags?

Yes. Under United States federal regulations, all travelers arriving on international flights must retrieve their checked bags from the carousel at the Terminals D/E Federal Inspection Services (FIS) customs hall, even if their luggage tags display an onward domestic city code. After walking past the customs officer, passengers on single through-tickets place their bags on the connecting luggage drop belt located immediately outside the customs exit doors before clearing TSA screening.

What is the difference between the Skyway and the Subway at Houston Airport?

The Skyway is an elevated, airside automated people mover on Level 4 operating inside the TSA security perimeter, designed for ticketed passengers moving between gates across all five terminals without clearing security. The Subway is an underground, landside automated train on the basement level (Level LL) outside security, connecting all five terminals and the Houston Airport Marriott Hotel for non-ticketed visitors, arriving passengers meeting family, or travelers transferring before check-in.

Do international travelers transiting through Houston to another country need a U.S. visa?

Yes. The United States does not have sterile international transit zones. Every foreign national transferring through Houston IAH onward to another country (such as Mexico, Costa Rica, or Europe) must clear U.S. border inspection and must hold either an approved ESTA (if eligible under the Visa Waiver Program) or a valid U.S. transit (C-1) or visitor (B1/B2) visa. Airlines will deny boarding at origin if valid U.S. entry clearance is not present.