Why In The World Did The Boeing 777X Fly To Mexico?

In 2024, Mexico’s Toluca International Airport (TLC) was seen hosting Boeing 777X test flights. While the Boeing 777X was not the first aircraft to conduct flight testing at Toluca, it does appear to be uncommon for Boeing to test its aircraft there. The Boeing 777X has been flying for five years now, having first flown in 2020. Boeing had planned for it to already be in service, but the aircraft has experienced FAA certification delays.

The delays have been aggravated by a collapse in confidence in Boeing’s quality assurance and transparency after it misled the FAA about the Maneuvering Characteristics Augmentation System (MCAS) software on its 737 MAX aircraft. New technologies like the 777X’s folding wingtips are also likely delaying its certification, requiring extensive testing. Here is what to know about why the 777X was tested in Mexico and why it needs to be tested outside of the United States.

What To Know About Mexico’s High-Altitude Toluca Airport

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Toluca International Airport (officially Aeropuerto Internacional Licenciado Adolfo López Mateos) serves the city of Toluca, not far from Mexico City. It also functions as a secondary airport for the Greater Mexico City area and is the fifth-busiest city in Mexico. In 2024, the airport served around 1.7 million passengers and hosts cargo, scheduled passenger, charter, and other operations.

While designated as an international airport, the only scheduled passenger airlines operating there are Viva and Volaris. These airlines operate flights to other domestic Mexican destinations like Cancun, Puerto Vallarta, Monterrey, San Jose del Cabo, and Tijuana. Notably for Boeing, Toluca is also located at an altitude of around 8,465 feet and has a 13,800-foot runway.

This makes it a great destination for testing aircraft in hot weather and at high altitude. These tests assess an aircraft’s performance operating in these environments. Here, the warm air is less dense, reducing the lift generated by the wings and the thrust generated by the engines. The tests determine the aircraft’s maximum takeoff weight (MTOW) at higher altitudes and the aircraft’s pressurization. This is all feeds into what is published in the aircraft’s operations manual.

Boeing’s 777X Tests In Toluca

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A year ago, in August 2024, Boeing conducted “Hot & High” testing with a Boeing 777X (specifically 777-9), WH003/N779XY aircraft in Toluca. While there, Boeing tested the 777X’s engine, aerodynamic, and overall handling performance. This was part of the (still ongoing) FAA certification process. After the Boeing 737 MAX crashes in 2018 and 2019, the FAA’s confidence in Boeing was shaken. The FAA is still withholding type certificates for the MAX 7, MAX 10, and 777X.

Toluca is not a primary testing site for Boeing, with Boeing Field in Seattle and Colorado Springs being more prominent test sites. However, it can be used for high-altitude testing thanks to its elevation and challenging conditions. Toluca is not a regular testing hub for Boeing, but has been utilized on occasion for specific programs like the 777X.

This suggests that Boeing’s choice of Toluca is not a routine decision, and it’s unclear why Boeing chose it in 2024. These high-altitude tests more commonly take place at the more extreme El Alto International Airport in La Paz, Bolivia. It is unclear what circumstances made Boeing select Toluca in 2024. There appear to be no open records of Boeing testing other aircraft, such as the Boeing 737 Next Generation, 737 MAX, 757, or 787 Dreamliner, at Toluca.

Airbus Testing The A330-900neo In Toluca

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Boeing is not alone in testing aircraft in Toluca. In March 2024, Airbus conducted similar “Hot & High” flight testing with its A330-900neo aircraft registered F-WTTN. This was part of a broader test program for the A330neo that included tests in La Paz. The tests allowed the A330neo to be certified to operate at airports up to 12,500 feet in elevation.

Like the 777X, the A330neo is a modernization of an older 1990s-era widebody aircraft. Both of these aircraft have received new wings for better aerodynamic performance and new engines. The A330neo’s new lengthened wing replaced the suboptimal wing it shared with the related A340 quad-engine. Being designed for both a twin and quad-engined aircraft, the old wing was suboptimal for both. Meanwhile, the 777X’s wing is notable for having folding wingtips, allowing it to have better aerodynamic performance and remain within airport Code E regulations.

The 777X is exclusively powered by the massive GE Aerospace GE9X turbofan. This is the largest commercial engine ever made. The A330neo is exclusively powered by the Rolls-Royce Trent 7000. The 777X has so far attracted around 551 firm orders, all of which are from international customers, with more than half being from Emirates and Qatar Airways. The A330neo has attracted fewer orders, although its orders have gained traction in 2025 as Vietjet, Malaysia Airlines, and aircraft lessor Avolon placed significant orders.

Aircraft Testing At El Alto International Airport

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La Paz is famously the highest capital city in the world, and at 13,325 feet, El Alto International Airport is the world’s highest international airport. This makes it a great destination for aircraft manufacturers like Boeing and Airbus to conduct high-altitude flight testing. High-altitude conditions at large commercial airports don’t get much more extreme than those at La Paz.

Boeing has tested the Boeing 737 MAX 8, Boeing 787-8 Dreamliner, and several other aircraft. Although it’s unclear if Boeing has tested all its aircraft, like the 757 and earlier 777s, there. Airbus has tested the A330-900, the A350-1000, and other aircraft there. It’s unclear if all Airbus aircraft, like the A320 or A380, were tested at El Alto. Bombardier also tested some of its aircraft there, although it’s unclear if Embraer has used the airport for testing.

El Alto’s thin air limits the payload capacity of some widebody aircraft like the Boeing 747 and A330. The airport has seen issues in the past, e.g., the Eastern Air Lines Boeing 727 crash of 1985. In 2019, FlightGlobal reported that Bolivian authorities even temporarily suspended operations of Boeing 737 Classics at the airport due to landing gear failures. In 2018, the BBC reported a Peruvian 737-300 skidded off the runway, although it’s unclear if these incidents were related to the airport’s altitude.

Testing In The United States

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Boeing conducts many of its tests at Boeing Field, otherwise known as King County International Airport (BFI) in Seattle. It was the primary airport serving Seattle until Seattle-Tacoma opened in 1944. However, the airport is only set at 21 feet above sea level. By contrast, a large number of tests are conducted at Colorado Springs Airport (COS), which sits at 6,187 feet above sea level.

Boeing has tested the Boeing 777X, 787 Dreamliner, and other aircraft at Colorado Springs. But while it has a high elevation by US airport standards and is considered challenging conditions for aircraft, it is far lower than El Alto and even Mexico’s Toluca. It’s unclear if Airbus has tested aircraft at Colorado Springs. One of the 777X prototypes, registered as N779XX, conducted high-elevation testing at Colorado Springs Airport in February 2024.

At the time, the 777X operated under the callsign “Boeing 002 Heavy,” and it performed eight takeoffs and landings using Colorado Springs’ Runway 17L. After that, Boeing moved on to testing the 777X at Mexico’s higher Toluca airport. It’s unclear if the 777X then moved onto El Alto or not. While Boeing can conduct most flight testing in the US, it lacks the high-altitude airports of other countries where these aircraft are expected to operate.

Clearing The Way For The 777X Introduction

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FAA certification for the Boeing 777X is still expected to be granted later in 2025, and the aircraft is expected to enter service in 2026. That said, it is not guaranteed that the FAA will award the type certificate for the 777X (or MAX 7 and MAX 10) in the coming months. After the tests in early and mid-2024, Boeing resumed test flights on its 777X in 2025.

The Boeing 777X has failed to attract a single order in either North or South America. The 777X is seen as too big for giant airlines like United Airlines, which operate around half a dozen dispersed hubs. However, it is well-suited for long-haul carriers like Qatar Airways and Emirates that operate a massive, singular hub.

In 2025, Boeing is only delivering Boeing 737s (specifically MAX 8s and MAX 9s) and Boeing 787s as passenger aircraft. This is because the Boeing 767 is only produced as a freighter and military aircraft, and the final passenger orders for the previous-generation 777-300ER have been delivered, except for a few questionable Pakistan International Airlines orders still on the books. In 2025, Boeing is only delivering freighter 777s as it readies the 777X for service in 2026.