Also this may be a whole other post I need to make but bonus question for anyone interested in answering: Why can I perceive the tilt(like the cabin is angled more towards the sky or is leaning to the left or right) of the airplane cabin even though I am in the same upright position in relation to the actual cabin itself?
In: Physics
Planes have to land on the runway they’re told to and from the direction they’re told to. That is rarely in the direction they are flying , so some turn is needed. Also they have to follow certain patterns in the sky to minimize the effect of their noise. That can require turns on approach which may resemble a spiral.
Bonus answer: I believe most of your awareness of tilt comes from visual clues. You can also sense an increase in downward force, but most of that is perpendicular to the cabin floor. One advantage to banking is minimizing the effect of the turn on the passengers. If they turned using only the tail rudder, everything on your tray table would slide off. They use both the rudder, elevators and ailerons in a coordinated turn.
Planes follow very specific air space instructions when approaching and departing airport airspace. This is done to keep everything orderly and following the same path as to not have two planes crossing paths, a highway ramp in the skies if you will.
Just the second question: because you still feel the gravitational pull and that goes straight down of course.
As far as perceiving the tilt goes your body still senses the rotation and tilt while sitting even though you yourself cannot see it. The physics of the rotation and tilt still act upon your body and your body reacts to it alerting your brain to the fact you are no longer on a even plane.
The only time I’ve ever been on a plane that spiraled down during descent was because traffic was backed up and in a holding pattern due to bad weather. Every other flight though just adjusts to whichever runway and lands without spiraling down.
Part 1: it’s so that they can climb to a higher altitude while impacting the littlest possible area around the airport. Airplanes flying overhead are noisy. The area immediately around an airport has to deal with it because they are already near an airport. But if the airplanes are required to spiral up/down, then the areas a little farther away from the airport don’t have to deal with it at all because the plane is already so high by the time it’s flying over those parts.
Part 2: It’s because of something called proprioception. Your ears have fluid and structures inside of them whose job it is to tell your brain how your body is situated in space (using the term space very genetically here – not pike outer space, just “in existence”). They signal of you are leaning forwards/backwards, left/right, diagonal, or any other way. They help you keep your balance. People who have problems with these “vestibular” structures often suffer debilitating vertigo.
They don’t usually spiral, but may need to do a partial circle to orient from their general flight direction to orient toward the runway approach being used.
Something no one else has touched on (unless I missed it) is that for some of the busiest airports, there are just too many planes trying to use the same handful of runways.
Take a look at this [screenshot](http://prntscr.com/o2lj9v). This happens to be Hartsfield-Atlanta, the busiest airport in the world… see all the light blue planes? They’re all landing at ATL.
Between flight scheduling and air traffic controllers (ATC), everything’s generally pretty smooth, but sometimes there are just too many incoming flights to get them spaced out all nice and pretty like that. There are FAA mandated minimum distances between planes, so the planes that are coming in on straight shots have to be X distance apart (if at the same altitude) or Y distance apart if more than Z feet different in altitude.
All of those planes still have to get on the ground, so there are times when, instead of a straight shot to the runway, the line of planes will have to circle the airport so that ATC can keep everyone at the mandated spacing.
Another way to think about it…. if you go to an amusement park, and you’re among the first in line for a ride, you don’t generally have to go through the whole serpentine queue, right? They’ve got a couple of chains disconnected and you can skip entire waiting areas. As the day goes on and more people enter the park, workers come by and fasten the chains, and make everyone on the outside of the chain “load up” those waiting areas, right?
Same deal. If ATC can have planes speed up or slow down to keep the spacing right, generally they’ll try to get all the planes (from one direction) to just make a longer straight line, and everyone shoots a straight approach. One guy’s coming in from Miami (or somewhere else), ATC will have everyone behind a specific flight slow down a little and get that Miami flight in the middle. Too many planes, they open the queuing areas with TV’s showing cartoons, and everyone circles around the airport, from the top down.
Here are a couple of images that might help clarify, in case I’ve muddied the water too much…
[Separate stacks](https://www.heathrow.com/file_source/HeathrowNoise/Images/Heathrowoperations/stacking590.gif)
[Conventional vs. linear holding patterns](https://www.heathrow.com/file_source/HeathrowNoise/Images/Heathrowoperations/stacking590.gif)
2 things:
it minimizes the distance required to start the maneuver, if they didnt do this, planes would need to start descent way before evne seeing the airport, which could lead yto #2
2: air space organization, wen you have multiple planes coming in and out you wanna make sure each of them as their own deidcated space for maneuvers, therefore you want them donig stuff the way it takes up the least air space possible
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