INERTIA: FRIEND OR FOE

I had a bit of free time on my hands and I found this video from the internet quite interesting. Why? Because after viewing this short movie you may or may not realize there is a lot of unseen things happening to this airplane which could easily spell disaster! You have to read the post first then watch the video at the bottom. Anyways, "inertia" plays a HUGE part in the way airplanes fly. Before I begin here is the definiton of inertia:

"The tendency of a body to resist acceleration; the tendency of a body at rest to remain at rest or of a body in straight line motion to stay in motion in a straight line unless acted on by an outside force".

When you throw thousands of pounds into the equation, the part that reads "...or of a body in straight line motion to stay in motion in a straight line unless acted on by an outside force" is pretty significant. As weight of the body increases, the force necessary to alter its path increases. An airplane that is very heavy and is flying in a straight line takes a LOT of force to make it turn and, requires a lot of distance to do it (dependent on its speed too). Likewise when an airplane descends, inertia and gravity are acting on it and it will take a SIGNIFICANT amount of force to change it's flight path...WHY? Because a "body" traveling in a straight line (an airplane descending for instance) "wants' to stay along that straight line. Another thing to consider is stopping that body...that body that is tens of thousands of pounds and just wants to keep going!! All these things act on an airplane all the time, unbeknownst to the average passenger yet carefully and meticulously calculated thousands of times a second by either the auto pilot or the guy who is actually doing the flying. In this video, just look at the mountains surrounding this 757 on approach and look how close they are. With inertia wanting to keep this airplane flying in a straight line, the pilot has NO room for error in his turn. It is a manually flown approach, over a steep incline to the approach end of the runway. You can clearly see the landing gear is only a "few" feet from contacting brush and/or the ground itself while he's still a few hundred feet from the runway. If mismanagement of this inertia occurs and he overshoots the landing zone, he would be very hard pressed to bring all this moving mass to a complete stop in the short landing run available to him. AMAZING LANDING!!