Curacao, Changi, Spaceport America, Zaragoza, Lelystad… What is common among these airports? Seemingly nothing but do not be misled by appearances. All these airports are getting ready to launch and receive sub-orbital flights in the not too distant future. While our industry is still trying to figure out how to integrate Unmanned Aerial Systems (UAS) into the civil air traffic management environment, private industry is throwing another challenge at us: sub-orbital vehicles.
Although sub-orbital flight may seem like the plaything of a few crazy bilioners, it is anything but. There is huge potential in this and it is not for nothing that so many entrepreneurs led by Richard Branson, as well as visionary airports, are getting on the band wagon. Even mighty KLM is involved, albeit only in a marketing capacity… for now anyway.
So what kind of aircraft or spacecraft if you like are we talking about and what do they mean in terms of air traffic management requirements?
A typical first generation sub-orbital vehicle is a kind of rocket powered machine that takes off from a runway and boosts itself to an altitude of around 330.000 feet at which space is commonly considered to begin. Skimming the top of the atmosphere the vehicle and all within it, experience a short period of weightlessness before it tips over and glides back to a runway to land. In a way this is reminiscent to what the Space Shuttle used to do but then on a much reduced scale.
Clearly the success of the mission depends on ensuring that both the ascending (powered) trajectory and the return (gliding) trajectory are flown with no distortions induced by outside factors. No en-route restrictions for a sub-orbital flight and no holding before arrival… In return however the sub-orbital flight gives ATM a pair of ultra precise trajectories which they will fly, come hell or high water.
This latter should make sub-orbitals good neighbors in principle. In practice the problem will be that those ultra-precise trajectories are rather inflexible. If they want to hit the runway on their return, they must follow the single trajectory that leads them there and there is no question of considering alternative trajectories that may fit better with the prevailing ATM situation. This is how a good neighbor will become a pain in the six o’clock…
Luckily not all sub-orbital vehicles behave like the space shuttle on landing. Some are being planned with normal jet engines which are turned on once the glide has brought them low enough. Although these types can fly a normal approach pattern, you can bet that fuel quantity will be an issue, at least in the first few years of development.
Of course some airports (and the airspace around them) are better suited to this kind of operation than the others. Spaceport America in New Mexico will probably have it easier than Lalystad which is just 30 miles from Amsterdam… The initial mission profile of these vehicles is simple. Take the Lynx being built by Xcor Aerospace in California. It accommodates just a pilot and one passenger or 120 kg of cargo. The profile? Up, skim, down.
Is there a market for this? Ticket sales on the available machines have just started and 30 tickets sold is considered a success. At around 95.000 $ a pop you cannot expect more. But in time the price will come down and interest go up. Furthermore, 120 kg is a lot of mass for science experiments and selling those few minutes of weightlessness will be big business. Even parabolic-flights, the current cheapest method of creating a few seconds of weightlessness, cost more on a pound per pound basis. So, yes these things need to be taken seriously and the steps to integrate them smoothly into the existing environment need to commence sooner rather than later.
Of course a very big burden will be on ICAO and the CAAs of countries where such operations are planned in terms of certifying the machines on the one hand and developing the procedures for their air traffic management handling on the other. They will be walking in uncharted territory while the pressure from industry will be enormous.
Even more than UASs, suborbital flight is perceived as the pre-cursor to the next big forward jump in aviation and who would want to be left behind?
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