Imagine that you are building an airport. What are the key elements to include?
Of course, one of the most important considerations is the runway (or runways, depending on the scale of the project). Runways come in different sizes, depending on the type of aircraft the airport intends to accommodate. The bigger the planes, the longer the runway.
With this in mind, how long should a new runway be to accommodate the Antonov An-225 Mriya, the heaviest, and arguably the largest, aircraft in the world?
The current flagship of Antonov Airlines was built in the 1980s to carry components of the Soviet space program. It has since been repurposed as a cargo aircraft and, as a singular specimen of its species, as well as a marvellous object overall, has attracted a significant cult following among aviation enthusiasts.
Mriya’s wingspan is 88.4 meters (290 feet), second only to the Scaled Composites Stratolaunch; the length of Antonov’s giant, 84 meters (over 275 feet), is second to no other heavier-than-air flying object in history, except maybe for the International Space Station. The track of the An-225, the distance between its main landing gear assemblies, is over eight meters (26 feet), more than the width of some taxiways.
Its sheer size means that some airports are too small to accommodate this aviation behemoth. But the physical dimensions are not the greatest limiting factor of the An-225. Its weight is.
Fully fueled and loaded with cargo, the Mriya can weigh up to 640,000 kilograms (1.4 million pounds), and still take off. That is twice the maximum take-off weight (MTOW) of smaller variants of the Boeing 777, and the equivalent of almost 10 fully-loaded Boeing 737s.
This creates two issues. One of them is that the surface of the runway may not be able to support the aircraft. Fortunately, the An-225 does not have to worry about that: with 32 wheels in its landing gear, the mass is well dispersed and the weight-per-wheel is actually smaller than on many wide-body aircraft, including the Boeing 777.
Then there is the aircraft’s movement. Even with powerful engines and brakes, accelerating and decelerating such a heavy aircraft takes a lot of time. This is the main reason why the Mriya requires one of the longest runways in the world.
The short answer
According to data that was, until recently (it has since been removed but can be found elsewhere on the internet), available on the Antonov website, the runway length requirement for the An-225 is 3,500 meters, or 11,483 feet.
But that is just part of the story. Some 3.5 kilometers is the distance fully-loaded Mriya can safely take off from, and includes an additional margin for safety reasons. This means that, in theory, the airplane could use shorter runways but it would be put at risk in an emergency.
The Mriya could also use a shorter runway when empty. Reliable data is hard to find, but most cargo aircraft require up to twice as less take-off roll when taking off empty, and there is no reason to doubt that the An-225 can do something similar.
In fact, as is evident in the video below, an empty Mriya can take off very fast, courtesy of its six massive engines designed to carry almost as much cargo as the empty aircraft itself weighs.
Another variable is the elevation of the airport. Runways positioned at or near the sea level typically are shorter, while higher altitudes mean lower atmospheric pressure and, consequently, higher operating speeds. Take-off and landing runs have to be longer when operating from runways that are higher up in the mountains.
When flying, pilots usually use aircraft performance charts that – with take-off weight and atmospheric pressure taken into account – show the take-off distance. Unfortunately, the An-225’s performance charts are not publicly available. So we can only surmise that the figure of 2,400 meters (7,874 feet) assumes either the highest altitude the An-225 can safely take off from, or at least the average one.
Finding Mriya-friendly airports
A total of 2.5 kilometers is a long distance, and building such a runway is a difficult endeavor. Does that mean, for our new airport, that we could use an existing one? How many Mriya-compatible runways are there in the world? Counting them is, seemingly, even more difficult than building them.
The International Civil Aviation Organization (ICAO) assigns each airport an Aerodrome Reference Code, which signifies the size of aircraft that can land there. The largest kind of airport, according to this designation, has a code E4 – meaning they can service aircraft with a minimal take-off distance of 1,800 meters (5,905 feet) and a wingspan of between 65 and 80 meters (213 and 262 feet). This does not say much, because not all E4 aerodromes can take on the mighty Mriya, and some of them would have to extend their runways almost twice over for the An-225 to be able to take off.
This makes worldwide runway length statistics not applicable for our scenario. Another source we can use is the data from the US. According to the CIA factbook, of the 5,000-plus airports with paved runways in the US, only 182 have a runway with a length over 3,047 meters (10,000 feet), and not all of those are long enough for the fully-loaded An-225. So, fewer than 4% of all US airports are big enough for Mriya.
There is another way to find a more accurate number, though. The Airbus A380, the world’s largest passenger aircraft, is just slightly smaller than the An-225, and has a MTOW of 575,000 kilograms (1.3 million pounds). According to Airbus, it requires a 2,150 meters (7,000 feet) landing run when loaded up to the maximum landing weight, and approximately 3,200 meters (10,500 feet) take-off run when operating at MTOW. If the runway is located at an altitude of 1,500 meters (5,000 feet), that last number gets closer to 5,000 meters (16,400 feet).
Airbus also states that the A380 is compatible with more than 140 airports, and up to 400 airports can accommodate it in case of a diversion. So, airports have aerodromes of the required size, but may lack passenger processing capabilities.
This number is, probably, the closest estimate we can get to the number of civilian airports that are compatible with Mriya. But there is one caveat: the An-225 is not limited by civilian airports, and can operate from military ones just as well.
There are a large number of air bases with runways longer than the required 3.5 kilometers. Many big air bases, such as the Edwards Air Force base, have runways reaching or exceeding the length of 5,000 m (16,400 ft). The home base of Antonov Airlines, Hostomel Airbort (GML), located not far from Ukrainian capital city of Kyiv, is a former Soviet air base and has a 3.5 kilometer-long runway, a typical length for modern air bases.
So, while the number of An-225-compatible civilian airports is rather small, the total number of runways where the Mriya can land and take-off from is much more significant.
This article was first published on September 3, 2021.