Friday, April 28, 2006

More Random Flying Thoughts

After an hour hurling through the inky blackness, with endless acres of farmland and a succession of little villages passing five miles below, we begin descending and Louisville appears on the horizon, just a faint glow at first, but gathering dimension and detail as we near. Finally we are told to slow and the controllers maneuver us over the city, over people sleeping in their thousands beneath us, the cockpit now glowing from the lights of the city below. The radio crackles over the captain's overhead speaker (he doesn't like the earpiece we typically use), the controller talking almost continuously, pausing only for readbacks.

I remember when I was first learning to fly, another student and I would go and sit along a service road at the Minneapolis airport and watch the Northwest jets and listen to the air traffic control chatter on a scanner plugged into the cigarette lighter of my car. Maybe it's that I'm an aural person, maybe it's a verbal thing; but I was fascinated by this job-specific language, this highly-evolved shorthand that made the aviation world go round. When we began getting our instrument ratings, we had to learn this communication, clumsily trying our hand at the radio calls under the tutelage of a flight instructor, like a child who is lovingly corrected again and again and again until he finally gets it right. We had learned the basics of radio communication during our private pilot rating, since communication with ground and tower controllers is part of flying in and out of any midsized or large airport. But that's a small part of an airline pilot's radio work.

Once you are in the IFR system (for Instrument Flight Rules, as opposed to VFR--Visual Flight Rules), the radio becomes a huge part of your world. Airline pilots live entirely within this IFR system, and in a large airplane, the pilot not flying will keep quite busy with radio communications, often busier than the pilot flying. At first the rapid-fire techno jargon seemed completely incomprehensible, but as we learned the system it became clear that the shorthand is very specific, and at any given moment there is a pretty limited range of things a controller might say to us (and a limited number of specific responses we might be expected to make). Nearly everything we do in an airplane under IFR is monitored by a radar or visual controller, and permission must be sought for almost anything--changes in routing or altitude, significant changes in airspeed, on down to clearances to take off or land, or even to taxi. Most of the time it's them instructing us about what they want or need from us to keep us on happy terms with the other flights populating the sky. Whatever the reason, it's an aspect of the job I've always loved (not as much as flying the airplane, but it's a close second).

As we approach Louisville, there is an expected flow to things: follow a prescribed routing in toward the airport, and expect to be broken off this arrival at a certain point by the controller and given "radar vectors" (literally, compass headings to fly), airspeeds and altitudes, which will maneuver us onto an instrument approach procedure, which will in turn lead us in three dimensions right down to the runway surface. It's my radio from Philly to Louisville, and I talk to probably 15 different people, from company people on specially assigned company frequencies to instrument clearance people to ground and tower controllers at both ends, as well as terminal radar controllers who monitor us and keep us separated from other airplanes in the airport vicinity, and finally "center" controllers who deal with the high-altitude enroute phase of the flight.

Clear skies, calm weather, a happy airplane, it's a beautiful night for flying.

A series of support vehicles meet the airplane as we taxi in, a van to shuttle us to the Air Services Center, a mechanic's truck, someone on a tug with a ground power cart in tow, an off-loading team, sometimes a fuel truck. In the van I call crew scheduling: no further assignment for me tonite.

It's about a fifteen minute walk out of the complex to my car to go back to the crash pad. There is a succession of shuttles which will ferry me out, but on a nice night like this it's good to walk through the buzz of people and vehicles and watch the airplanes landing and taxiing in. This is the closest I get to feeling a part of all that goes on in a huge company where my contribution is small and specific and one of hundreds of different job descriptions.

Interesting how different the landing looks from outside versus inside the airplane. Outside, it's a bit surreal to see something so large (and body-shakingly loud) floating in the air and settling its weight on the ground with a huge puff of blue tire smoke. Inside, we are occupied with our procedures and callouts and with watching the instruments, and lastly with executing the landing flare and touchdown. Every now and then I'll have a little out-of-body JAY-zuss moment on short final where I realize that we are 200,000 or more pounds rushing headlong toward the tarmac, at something like 170 miles per hour, and the yoke and throttles and pedals in front of me will determine the outcome of the meeting. So I know what is going through the mind of each flight crew as I watch airplane after airplane come in and touch down, their landing lights spaced at three or four mile intervals along the glide path for 20 or 30 miles out.

I'm tempted to sit, like old times, and watch the airplanes.


Jeffy said...

Watching the airplanes is certainly a wonderful experience. At the MSP airport it is great how the main entrance road to the airport goes right past the end of the runways and the planes coming in to land pass right overhead (and seemingly very low). They just appear to float in effortlessly and they look so graceful. They remind me of geese gliding in, constantly making slight adjustments and corrections, and making very little noise.

I try to leave some extra time on my airport runs so that I can spend a little watching the planes. At MSP there is a small area on a service road that is almost a designated viewing area. There are always a few cars parked here to watch the planes. Unfortunately, the officials are touchy about folks sitting right in the flight path, so spectators are stuck with this area off to the side and out of the way, but it is still quite an experience.

wunelle said...

In an odd phenomenon which you might have a good physics explanation for, the airplanes taxiing around the airport surface are much, much noisier from in front of them. I used to confirm this when I would preflight the DC-8 and other airplanes would taxi out. An airplane taxiing directly away from you--that is, with you looking straight up the engines' tailpipes--makes no sound whatsoever. But an airplane coming directly at you is almost unbearably noisy.

At takeoff power it's another matter, with so much energy coming out the tailpipe that the noise is everywhere. But at idle power, it must have something to do with how the exhaust is swirling and unorganized and the sound waves are destroyed and dissipated by this swirling exhaust.

Or something!

Jeffy said...

I have seen that phenomenon myself, I think when I have gone with you on service roads close to the runway at MSP.

I have never found a good explanation of how this happens, but it is a very startling thing. With as much noise as these engines can make, it is quite a surprise to have the business end directed at you at close range and fins that there is all of a sudden almost no sound.

My best guess as to how this works is based on the nature of sound. Sound is best described as variations in air pressure. Looking into the output end of a roaring turbine engine probably just puts you in a fairly smooth and constant stream of quite high pressure, and it isn't a noisy place since the air pressure is not fluctuating much. Off to the side this is no longer the case as turbulance introduces variations in the pressure.

Until I hear a better explanation I'll stick with this one.

Esbee said...

There's a park just on the Virginia sie of the Potomac, where if one parks at the water's edge, the planes taking off from National go right over one's head.

Probably was closed immdiately after 9-11 though.

wunelle said...

Actually, these favorite airplane-watching sites are being closed everywhere, as they are too handy for those wanting to do bad things to airplanes. It's a sad loss, tho, since up close I still feel it's magic to watch these happenings.