(For radio stations: Bill's public radio work can be licensed via PRX).
Like many of you I'm a bit afraid to fly. I'm so alert I listen to every noise a jet makes and, for piece of mind, I've had to learn the source of all these sounds. So, today I'm going to tell you what hear when a jet takes off. Maybe it will give you some comfort like it does me.
As the jet is pushed back you'll hear the pilot turn on the hydraulic pumps to prepare the breaks for take-off. Then the engines are started with a blast of air from the auxiliary power unit - that is air from the terminal. Inside you'll notice the air-conditioning go off - there is only enough air to run either the air-conditioner or start an engine. As the engines spin they're soon able to suck in enough air on their own to burn fuel and the air conditioning comes back on.
As the jet taxis to the runway the pilots adjusts the flaps - you'll hear the hydraulics again, or if you're near the wing you can see the flaps move. They increase the lift so the jet can take off safely. Once the pilots are cleared for take off you'll heard the pitch of the engines change as the turbines rotate faster, generating more power for take off.
The pilots have worked out three speeds: Vee one, Vee R, and Vee two. The jet first reaches Vee one, the maximum speed at which the pilots can stop the plane. If any error lights go on in the cockpit, or for any reasons the pilots think something is wrong they will bring the plane to a halt. Above about 100 miles per hour the automatic brakes become active. This means that if the pilot turns down the power the breaks kick in. It will be pretty dramatic because the autobrakes cannot see the end of the runway; they just get the message "stop!" It is the main reason you should keep your seatbelt on, and why you should have a safety seat for your child.
As the jet travels down the runway you'll feel every few seconds a bump if the pilot drives right on the center line: there's a light every seventy-five feet. And sometimes you'll hear the overhead compartments shake: don't worry they are lightweight plastic and have nothing to do with the structural integrity of the plane. Next the jet reaches Vee R, the speed where the planes nose rises. But the jet doesn't take off until it reaches Vee Two. At this speed it can take off with one of its engines out. As the jet leaves the ground you'll hear the landing gear come up. In a few minutes you'll hear - and perhaps see - the pilot retract the flaps. They're no longer needed; they are just making the flight bumpy now. Sometimes you'll hear the jet power down slightly - maybe even level off. Likely the pilot is just obeying local noise ordinances and speed restrictions. One thing you won't hear in the first few minutes is the pilot.
The Federal Aviation Administration forbids, for the first ten thousand feet, any talking in the cockpit except that needed for flying. In another few minutes you'll reach a cruising altitude where, as the pilots say, you should sit back and relax. Unless, of course, for you're a fearful flyer like me, and now that you've just taken off you're now thinking of the landing.
Copyright 2000 William S. Hammack Enterprises