Flying is perhaps one of the most freeing activities humans can undertake, as it provides us with the ability to experience the furthest reaches of the world in person, in relatively little time. However, while the experience is tremendously liberating, the rules and regulations governing an aircraft’s ability to take to the sky are strictly regulated. Although flying on a commercial aircraft has become commonplace, it is always worth taking some time to consider much work goes into preparing an aircraft for entry into service. So, let’s examine one of the many aspects of aircraft readiness: flight tests.
In order to ensure safety and efficiency, most airspace around the world is carefully monitored and regulated, with variations depending on the level of congestion and demand for a given airspace. This applies to all flights in controlled airspace, including the test flights that are crucial to the development of new aircraft. As such, each aircraft manufacturer must abide by the respective rules and regulations governing their airspace in order to complete the flight test and certification process for their aircraft. And for some, airspace restrictions can present a considerable obstacle, resulting in the need for creative solutions. COMAC provides a prime example of overcoming unique airspace challenges in order to complete flight test programs.
First, simply flying in China is not an easy task; although commercial aviation has grown exponentially in China over the last few decades, the industry still faces major hurdles due to airspace restrictions when compared to conditions in other countries. For example, in the United States, roughly 80% of airspace is open to civilian use while 20% is reserved for military operations. When combined with additional joint-use airspace zones, where civilian aircraft are permitted to fly through certain military airspace while not in use, there is relatively little conflict between civilian aircraft operators and the military. However, in China the opposite is true, as roughly 20% of airspace is reserved for civilian and 80% designated for military use. Moreover, even the designated civilian airspace is prone to closure by the military for exercises at short notice, causing traffic jams and delays in already congested airspace.
Further complicating the issue is the crowding of available airspace. COMAC’s C919 Assembly Center is located on the grounds of the Shanghai Pudong Airport, which happens to be the ninth busiest airport in the world and the second busiest in China. Transporting over 100 million passengers in 2016, Pudong Airport is an important hub connecting China with the world. As a Shanghai-based corporation, the final assembly center of COMAC’s C919 is located on the grounds of this airport; the first flight of the C919 took place here in May 2017, followed by the first flight of the second C919 and subsequent airframes in the future. However, in order to conduct a complete test flight program, which requires a demanding schedule full of complex maneuvers and varied routes, having to regularly secure slots in some of the busiest airspace in China isn’t ideal. As a result, COMAC found a simple solution by making a move to the countryside!
Once a C919 has completed its first few test flights and has been cleared for cross-country flights, it leaves the hectic Shanghai city life behind and heads to its new home in Yanliang, a rural district of Xi’an in Shanxi Province. There, the C919 enjoys far less airspace congestion and is free to practice test flight maneuvers away from densely populated areas. This is not the first time COMAC has employed this strategy; many of the test flights carried out by the ARJ21 throughout its development, and even today, occur in China’s furthest reaches, often in search of ideal weather conditions but also positioned away from crowded airspace that would complicate its missions.
Another hurdle for flight tests in China is weather, or sometimes the lack thereof. While China is a large and geographically diverse country, the specific weather patterns required to carry out certain tests are not always available. Strict certification requirements call for test aircraft to be subjected to weather conditions that simply cannot be found domestically. For example, while conducting flight tests on the ARJ21 the need for specific weather patterns presented serious problems on two fronts which required creative solutions to overcome.
While the majority of operations progressed steadily during the initial certification test flights of the ARJ21, one area of testing continuously evaded the test flight team – the flight characteristics found in natural icing conditions. China holds a notably diverse array of climates, from the tropical beaches of Hainan, to the bare deserts in the country’s Western regions, to the frigid winter temperatures of the Northeast. Given this, one would expect to find ideal conditions for icing tests. However, after numerous attempts it soon became apparent that the strict weather parameters required by certification bodies could not be found in China. After careful research a suitable location was identified; the only problem – it was in Canada.
With that, the ARJ21 made its first trip abroad to Windsor, Canada in April 2014. After traveling across the world, including a brief European tour, the mission was completed after the right conditions to execute icing tests and satisfy certification requirements were found over the Great Lakes. In the meantime, North America and Europe got a rare glimpse of a Chinese-built airliner in their backyards! Building upon the experience gained from solving this problem, just a few years later in 2018 COMAC once again sent an ARJ21 abroad, this time to Keflavik Airport in Iceland where the unique weather conditions and the airport’s perpendicular runway layout presented the perfect location to conduct the crosswind testing needed for additional certification. After repeated landings in crosswinds reaching 35 kt and gusts as high as 48 kt, the ARJ21 proved it could more than satisfy the minimum 25 kt crosswind capability required by the CAAC. Just like the North American icing tests, this ARJ returned to China from an adventure abroad having triumphantly completed its mission and proving once again that COMAC will go to incredible lengths to ensure that flight testing is carried out as safely and as thoroughly as possible.
As we can see, flight testing any aircraft is no easy task, but when you add the unique challenges of testing a large passenger aircraft in China, the accomplishment becomes that much more impressive. So, the next time you take a commercial flight, whether in China or anywhere else in the world, be sure to consider the years of work and the creative solutions that went into ensuring your aircraft was a part of the safest means of transportation available today.