Unlike many airports in Europe, Asia, and (some) in the USA, transiting between an international flight and a domestic one in Mexico can, at times, be a real hassle. Transportation between terminals in case of a switch of airline is often problematic, and separate transit passenger security lines are often unmanned. If transiting from an international flight, you always have to pass through customs and repass through security. Rarely are separate terminals connected via a walkway or airport train.
Please note that foreign travelers are sometimes targeted by the police both at the Mexico City and Cancun airports for bribe money. Official reason used is to accuse them of petty crimes in order to demand immediate payment.
Mexico City:
By far the largest airport in Mexico, with the most international arrivals/departures in the country. Two separate terminals exist, which are actually 3 km apart. Terminal 2, a modern terminal which services AeroMexico and SkyTeam partners Delta and Copa airlines, as well as LAN and low cost carrier Aeromar. All other carriers use older Terminal 1, which is one long terminal that often involves quite a bit of walking between gates.
To get from T2 to T1 (or vice versa) can be a journey in itself. Please note: the area between the two terminals is NOT SAFE to walk, even in the daytime.
The easiest (and fastest) way is to use the Aerotrain that connects the two terminals. It is a 7 minute trip, with trains leaving every 15 minutes. However, please note that you need a valid boarding pass for an UPCOMING trip for that day on an airline using the terminal you are transiting to. In addition, many times the security officer will not accept a mobile boarding pass, only a printed one. Please also note that the Aerotrain is not 24 hours, and often shuts down around 10 pm. The Aerotrain can be accessed in T1 via Puente Pilotos bridge in the middle of the terminal, up the D escalators. In T2, it is located at Gate M.
If you are unable to board the Aerotrain, then a public bus does exist that transports passengers between the terminals. The cost of the red bus is now 14 pesos, which you pay directly to the driver, and it runs from 5 am to 1 am. This inter-terminal bus can be accessed via gate 6 in T1 and gate 4 in T2. As this is a public bus that transits an unsafe area, there have been incidences of theft aboard the bus, especially at night.
You can try to use Uber between the terminals. However, be advised that while using Uber to get to the airport is fine, Uber drivers picking up passengers at each of the terminals in Mexico City have occasionally run into problems with the authorities, with both driver and passengers paying a large fine to continue their voyage.
Cancun:
Mexico’s second largest airport in terms of international passenger traffic, Cancun has three terminals, although Terminal 1 is almost exclusively now freight and private jet traffic. Terminal 2 houses all domestic traffic as well as international flights. Terminal 3 is primarily used for international flights. There is a free inter-terminal shuttle between T2 and T3 that is supposed to run every 20 minutes. Oftentimes, however, wait times of 45 minutes or more are not uncommon. The walk, while safe, can take up to 15 minutes.
Complicating factors for transiting passengers is that many airlines share both T2 and T3 at Cancun, so it is crucial to check beforehand both arriving and departing terminals. While cartels do not operate much in Cancun, local law enforcement acts as the resident bribe mongers. It is advisable NOT to ask LE questions, or be prepared to provide some funds to a local endeavor.
Guadalajara:
The third largest international airport in Mexico by international passenger volume, Guadalajara is by far (along with Monterrey) the easiest major airport to transit in for passengers arriving in Mexico. Modern Terminal 1 houses all international flights, with close by and walkable Terminal 2 only servicing regional jet domestic service for AeroMexico and low cost carrier VivaAerobus. Please be aware that AeroMexico check-in lines in T1 can occasionally get very long, as this is a major hub for them.
Monterrey:
Monterrey airport serves the industrial hub city of Mexico, and has three separate terminals. Modern Terminal B is used by AeroMexico and Delta airlines, while Terminal C is exclusively used by VivaAerobus. All other airlines use Terminal A, which is next to Terminal B and walkable.
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