August 23, 2006
Air Traffic Control
Last night, my wife’s crazy friend left to head back to CA (finally!!). Of course, she was scared out of her mind about flying, made doubly so by the bad weather we had in Atlanta. Always one to throw fuel on a fire, I had to correct her (and my wife) when they asserted that commercial planes had RADAR to detect the other planes in the air.
It made me think, how many things of this nature are people completely clueless about? I’m not a pilot, but have spent a fair amount of thought on planes, as my brother is a Marine pilot (helo and fixed-wing), and I was in a small Piper with my close college friend at the controls when we stopped* a plane in mid-air. So I know quite a bit, at least for a layman, about how aircraft fly, some of the differences in private and commercial aviation, and how this whole system fits together.
But how many people think that a pilot of a 747 is the one making sure they don’t run into other aircraft, with onboard RADAR as their guide? I’d say it’s quite a bit, largely due to movies like Top Gun, where pilots do have onboard tracking and targeting RADAR. Yet nothing of the sort is in common use. Our Air Traffic Control system is controlled by people in office-type buildings staring at computer screens and talking to pilots on radios. Thousands of airplanes in the air at a time, traveling at hundreds of miles per hour through crowded airspace; it’s a wonder that we don’t have more collisions. We’ve got a very complex system of RADAR, onboard transponders, banks of outdated computers, and a heck of a lot of human interaction, all making sure that people get where they’re going with an absolutely miniscule chance of trouble.
How does it work? Well, for that, I’ll point you over to HowStuffWorks.com. To put it simply, before a commercial plane takes off, the pilot files a flightplan with the FAA, which helps everyone along the route to be warned that they’ll be expected to be certain places at certain times. The country’s airspace is divided into zones, and as a plane travels through each zone, it is routed by controllers on the ground. This is accomplished by RADAR that identifies that planes are in the air, where they are, their speed and heading, and by a transponder onboard the aircraft, which tells the controller which plane is which**. The controllers take care of routing planes around weather, congested airspace, and turbulence, for every plane within their geographical zone. As the plane traverses from one zone to another, it is passed to the next zone’s controllers.
It’s an insanely complex system. It’s built on a network of hundreds and thousands of people working in concert with technology to keep big multi-ton cylinders riding Bernoulli, filled with hundreds of passengers, from becoming a tragedy. And it works.
In fact, it’s one of those systems that is a credit to governmental action. Of course, I think if the private sector was left in control, it’s not something that wouldn’t be accomplished. And, of course, if the private sector was in control, the system would likely be much more modern and capable of handling more traffic than the FAA system. But the FAA administers the air traffic control system much better than the government administers the US Postal Service or the IRS. Funny how thousands of passengers’ lives create a bit more incentive than customers angry over lost mail. It doesn’t need to be done by government, but at least government does it relatively flawlessly.
Even more, it’s a system that reminds people how complex our world is and how well it works. I can’t remember the last aviation “close call” I heard about on the news. It’s been several years (if not decades) since the last mid-air collision I’ve heard of. Our air traffic control system, fighting old technology and barely designed to keep up with the current load, manages to work, because those thousands of people do their job every day. Thousands of people working to make sure their own small piece is done right (for the controllers, due to desire not to be fired, for the pilots, desire not to die) ensure that passengers make it to their destination and that people afraid to fly are the irrational exception, not the rule.
Reminds me a bit of a market, the open-source community, or a large corporation. Everyone in our nation doing a small thing, often for our own self-interest, and as a result we have a society that accomplishes great things. The Air Traffic Control system doesn’t have one central computer or central planner determining who flies when. It’s a bottom-up system, with pilots eager to be granted permission to fly 3,000 ft higher to avoid turbulence for passengers, controllers trying to fit a puzzle full of fast-moving aircraft into limited space, and yet it’s a tremendous success. Most government (in)action is defined by failure, and yet in this incredibly complex system, failure is so rare as to be a horrible tragedy when it strikes. Pretty wild, if you ask me.
*Yes, I said stopped in mid-air. That’s not a good way to put it, of course. Our airspeed was still positive, it was just our groundspeed that was zero (or slightly negative). Aim a Piper into a strong wind, cut the power significantly and raise the nose to a near-stall angle of attack, and you may just find yourself “hovering” with zero groundspeed.
**If you remember Sept 11th, there was incredible confusion over what flights were missing, and which (how many) were and were not hijacked. While you’d think it would be simple to ask which planes just aren’t where they’re supposed to be, it’s not that simple. It becomes a process of elimination, and searching for planes that aren’t responding to air traffic controller’s instructions. Changes to the system could solve this in the future, but as far as I am aware, the FAA has not advocated the sort of changes that would be required.
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Well, as a pilot and aviation enthusiast let me say you’re close, but not quite there.
Some aircraft do have traffic avoidance radar, though it’s uncommon. Most large commercial aircraft have weather radar, though to an extent that is being replaced with sattelite weather.
MANY aircraft, and ALL commercial aircraft with more than 19 seats in U.S. registry (and most other countries for more than 30 seats) do have active traffic avoidance systems called TCAS/TCAD, which interrogate other aircraft transponders. These give pilots altitude and proximity information for traffic avoidance.
You can see an explanation of the system here:
http://en.wikipedia.org/wiki/TCAS
Of course this sytstem only works if all the aircraft involved have transponders (some very light aircraft, or very old aircraft don’t), and those transponders are turned on an functioning properly.
Additionally, there are now sattelite link traffic and radar services (to complement weather serviceS), which actually give pilots radar and tagging images from ATC.
Oh and the stopping in midair trick is really fun if you have first time PAX. For my best friends 18th birthday, I took him up in a 172, and it was a very windy day. We started practicing MCA (minimum controllable airspeed) maneuvers and we flew backwards, sideways etc… Then we started doing some power-on stalls which scared the crap out of him. Great fun.
Whoa! That’s a little over my head but I can relate a little. I try not to think about what the pilot is doing when I fly. I let him do the driving and I relax in my seat. I hope your wife’s friend made it home OK.
BTW: I am in the middle of taking a ham radio class and I am having a ball. I am going for the teck liscense and hopefully I start working on Morse Code later in the year.
I heard somewhere in the past that Air Traffic Controllers have the most stressful jobs on the planet. A quick internet search both confirmed and denied that (like everything else on the web), but here is one link:
http://wlb.monster.com/articles/tenhealthiest/
Chris,
Thanks for setting me straight. I wasn’t aware of the TCAS.
That same night in the Piper, it was myself, my buddy at the controls, and two girls. Oddly enough, for “proper CG”, he sat left front seat with the girl he liked best at the copilot seat, and I was right-rear next to the girl I was interested in… The funniest thing was him talking on approach about how “low-wing” aircraft like the Piper are smoother on landing, trying to impress these girls with a silky put-down, as he hit a little air pocket and pretty much slammed it down… I don’t think it was very impressive… Fun times
Air traffic controllers and pilots I want fat and happy.
Hehe, power-on stalls.
“I can’t remember the last aviation “close call†I heard about on the news.”
That’s because it isn’t often covered when it is news. There are usually at least one or two at altitude close calls a year, plus several more on the ground or in the pattern close to an airport. We just don’t hear about them.
That said, it is still a VERY low percentage of total flights, so your point still stands.