Have you ever wondered when looking out the window as your plane is maneuvering for a landing, how steep those turns actually are? The slight jolt in your stomach combined with the view out the window (what seems like all ground or all sky depending on which side you’re on) gives the impression that your plane is nearly on its side.
The truth is the airlines try not to freak you out and keep things comfortable in the cabin. Jumbo jet turns are impressive but not as drastic as your senses are telling you.
Two Forces At Work
Let’s keep things very simple. Planes in flight need to move forward (speed) to keep a constant flow of air over the wings. This constant flow of air provides lift. As you gain altitude upon takeoff, the wings are angled up. When you reach a cruising altitude, speed is reduced and the wings are angled in a way to provide and equal balance between two forces: lift and gravity.
At takeoff in particular, as the plane accelerates, you can feel the gravitational force (g-force) increase. You feel heavier in your seat (the forward momentum is pushing you into the seat). At cruising altitude your plane is no longer accelerating and you feel “normal” i.e. at 1 g.
What Happens When A Plane Turns
There are ailerons on airplane wings what help with direction and lift. (Basically flaps of metal.) Going straight, the aileron are generally straight. To turn an airplane right, the left aileron goes down, the right goes up. This causes the left wing to go up, and the right wing to go down. In this configuration, the plane is now at an angle, with increased overall drag (because the ailerons up or down are less aerodynamic than a straight wing).
Increased drag slows the airplane. Also, in a turn, there’s less area of lift under a wing, causing it to lose altitude. However, to compensate, pilots angle the airplane up as well as increase thrust (speed) to maintain a constant altitude during a turn. You’ll probably feel those changes in your stomach.
Keeping You Comfy
Passenger jets typically don’t bank more than 30 degrees on a turn. They’re capable of more but the steeper the turn, the more thrust needed to keep the plane from losing altitude. Turns at angles more than 30 degrees would cause more g-forces which wouldn’t help airsickness or nervous fliers.
So despite it looking like your plane is about to do a barrel roll on every significant turn, next time you fly, know it’s probably only banked about 20-30 degrees at most. Once you’re on the ground you’ll hear the flight attendants say cross-check, here’s why.
[Second photo by: Nicoguaro]