Well, they’ve done it. A team from the National Aerospace Laboratory in the Netherlands has managed to solve all the aviation world’s problems with a single stroke! Air pollution, noise complaints, weather constraints, airspace issues — you name it, they’ve fixed it.
The answer? Circular runways. Or, as the team behind it prefers to call it, “The Endless Runway”.
Over the past month or so, I’ve been deluged with emails, texted links, and social media taggings (which, for the most part, are about as useful as the ones with spray paint) seeking my thoughts on this “revolutionary” concept. To be fair, that descriptor was a magazine click-bait addition; the authors of the proposal refer to it as “radical and novel”.
And indeed, they’re right — as long as your view of history doesn’t go back any more than 70 years. This is particularly ironic, because the proposal spends a considerable amount of time discussing early ideas for race-track style runways. What is left unsaid is that none of them came to fruition. Perhaps there’s a reason for that.
The world’s first runways, while admittedly not “endless”, were circular. The control authority and horsepower of early aircraft was quite limited, so they needed to takeoff and land directly into the wind. Land was plentiful and cheap, so the first airports were nothing more than open fields of flat land, usually with a windsock directly in the center. Pilots would overfly the field, look at the sock in order to determine the wind direction, and then land directly into it. This is also why airports, even to this day, are sometimes referred to as ‘fields’.
The open field/circular runway went away for many reasons, not the least of which was the increasing landing distances needed by the larger, faster airplanes. The open field concept persisted through World War II. By that time, most fixed-wing aircraft were capable of handling significant crosswinds, but other air vehicles such as blimps, were still sensitive to wind conditions and could not countenance a crosswind.
(To be fair, sometimes these early airports were square rather than round. Near my home is a large square park which was at one time just such a facility. It measured one mile on each side, and is today called “Mile Square Park”.)
Proponents of the circular runway claim it will revolutionize air travel. I’ve read all the documents in their proposal, and although they don’t seem to include biographical information on the contributors, it seems that whoever came up with this scheme clearly does not fly and certainly doesn’t understand how aircraft, air traffic, and airports really work. If they did, they’d know the drawbacks of such a layout far exceed the benefits. Speaking of which, let’s look at those.
- shorter travel distances on the airport
- operating the runway under all wind conditions
- reduced take-off and landing separation
- reduced land use for the airport infrastructure, leading to a smaller environmental footprint
- Winds in most places are not random. There is a prevailing wind direction, and airports are only built after extensive meteorological studies to determine the predominant patterns. For example, here in Southern California, most runways are oriented toward the beach since we are blessed with an almost perpetual on-shore breeze. Airports in other parts of the country (the Midwest comes to mind) do have a wider variety of wind conditions, but those are accounted for by the airport layout — typically a triangular shaped series of three intersecting runways. This solves the crosswind issue sufficiently. The proof is in the last half century of flying. The YouTube videos you’ll see of airliners landing in gale force crosswinds are click bait. Nothing more.
- Crosswind landings would be more difficult on an Endless Runway, owing to the constantly changing heading. Most crosswinds are from a steady direction. A round runway surface only ensures that the direction and velocity would be in constant flux throughout every single takeoff and landing. And the banked runway surface only ensures that a wind-whipping obstacle is always right next to the airplane. Does that sound safer to you?
- A circular runway means you can’t expand the airport. The circle literally traps the infrastructure inside. If you want to see an example of that, look at LAX. Better yet, try to drop someone off at the airport at any time of the day or night and you’ll see what a nightmare it can become.
- If the takeoff and landing direction was constantly changing, traffic conflicts would not be reduced. They’d be magnified. Especially when the wind might change at one airport but not at another. Traffic patterns at closely-spaced metropolitan airports are carefully designed to avoid conflicts. The Endless Runway would complicate them beyond my ability to even describe it.
- Instrument approach procedures, which are already complex enough, would be infinitely more so, and localizer-based systems like ILS and LDA would be made almost useless since they are straight-line, single beam projections.
- Arrival and departure procedure issues would be myriad. Let’s just consider IMC conditions and the need to ensure arrival and departure paths are clear of obstacles. If airplanes are arriving and departing from 360 different headings, then you’d have to eliminate all obstacles in every direction. Keep in mind these obstruction-free zones assume the loss of an engine just after V1, meaning the airplane is not going to climb very well. You’d be unable to put an airport near any population center. Or you’d have to remove all towers, buildings, and structures of any height for miles around in every direction.
- There’s an old saying: the devil you know beats the devil you don’t. If you deal with aircraft noise — and let’s face it, many of us do — it’s going to be a lot easier to live with when it’s predictable. Now consider launching and recovering three airplanes all at the same time from varying directions. The noise would be scattered all over the place. Instead of a narrow corridor of sound which exists mainly under the departure path of a straight runway oriented in a single direction, you’d expand that footprint dramatically.
- Right now, most large airports are equipped with multiple runways. If one runway needs to be closed for maintenance, due to fouling, a disabled aircraft, or other reason, you have the remaining runways available. If you embrace the Endless Runway, any of these events would shut down the entire landing surface and close the airport completely.
From every perceivable angle, the Endless Runway is a half-baked idea conceived by a team which lacks the practical understanding of aviation infrastructure you’d find in any student pilot. I’m sure it looks good on paper, but in the real world their solutions don’t hold water, no matter how many equations they write. They’d have been better served by studying existing airports and runways to determine why they’re built the way they are. Believe it or not, there’s a reason behind it, and from where I sit the system works remarkably well.
There is one truly critical issue they’re trying to solve: a dearth of capacity. It’s undeniable that our ground-based aviation infrastructure (aka airports) is overcrowded. But changing the shape of the landing surface won’t fix that. The only answer is to build more airports and runways.