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Cockpits usually seem to have windows that are high up and it doesn't seem from pictures that they would allow a pilot to look down so easily while sitting in their seat. Please correct me if that is wrong because that is the basic assumption of this question.

Then how do pilots know where the centerline is on the taxiway and runway? They always seem to taxi with nose wheel almost always on that line even when turning. Are there some instruments that help them? Or its the same logic as in a car as to how you find out where the lines are?

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They don't. They keep it on the yellow line ;-). Only runways have white marking. On taxiways and apron the marking for aircraft is yellow and white marking is for service vehicles. –  Jan Hudec Jul 23 at 11:26
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Anecdotally, I cant see the ground in front of my car particularly well either yet I manage to stay in lane. Its called spatial awareness and comes with practice (like everything). –  Jamiec Jul 23 at 14:29
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Just for better searching for anyone reading it, it's "spatial awareness", for some odd historical reason. Google probably doesn't care, but other systems might. –  Cornelius Jul 24 at 10:56
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@Cornelius - odd historical reason - from the latin, spatium meaning space. –  Simon Jul 24 at 11:22
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@warren - Then maybe read again. :) –  Cornelius Jul 25 at 18:19

6 Answers 6

up vote 33 down vote accepted

Aligning yourself in the middle of a straight taxiway isn't a problem. On the 747, if you put yourself in the middle of the taxiway as you see it beyond the nose, you'll be in good shape. If you're the captain, you can hold yourself a little left of the perceived center, but not much, because you're looking at from an eye level over 30 feet up as I remember. If the taxiway has those little metal reflectors sticking up on the centerline, you can play games trying to keep one of the nose wheels hitting them. You can just barely feel going across them. Or, since the nose gear is two wheels, you can play with getting the reflectors between the two wheels if you're really bored.

Turns on a taxiway present a bit more of a challenge insofar as keeping the center line because the nose gear is behind you, but one develops a feel for it. A 90 degree turn from a narrow taxiway onto another narrow taxiway is a little challenging, especially if the taxiway you're on T's into the one you're turning onto. All you'll see out the front window as you start the turn is grass. Also, on narrow taxiways, you can't see the taxiway out the side window from your normal sitting position.

If you need to do a 180 on a runway, you need to remember that when you first get yourself on, say, the right side of the runway, the nose gear isn't there yet, and the wing and body gear have even further to go. You have to run yourself along the side of the runway a sufficient distance so that the airplane is aligned with the edge of the runway before you start your turn.

Personally, I found taxiing a 747 one of the more fun things in life.

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I love 747s, thanks for the insight :) –  Iceman Jul 23 at 7:52
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I've always wanted to drive a city bus, just for the challenge. You've found me a new challenge in life! Sadly, for a software developer, it seems even less likely to become true than the bus dream. At least MiGs are not out of the question. –  dotancohen Jul 23 at 19:09
    
@dotancohen - but taxiing a small plane is not out of the question as a software developer :) –  warren Jul 25 at 14:32
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@warren And software development (or a sort) is not out of the question as an airline pilot (retired). See 747.terryliittschwager.com. One of these days I may even get it done (if I live long enough). –  Terry Jul 25 at 18:10
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@Terry: I've seen the site, it's linked from your profile page! I just might one day taxi a small plane, that is in my daughter's hands now. I've promised to her flying lessons since she's four. She's seven now and more eager than ever. Sometimes I think that we have children in order to live our dreams through enabling them. –  dotancohen Jul 27 at 5:18

Airbus documentation claims the pilot can see 20° below horizon directly ahead (provided the seat is adjusted as recommended). Given the window of A320 is about 4m above ground, the closest point is about 11m ahead of them. And the nose wheel is more than 2m behind where the pilots sit. In larger aircraft it's of course proportionally further.

So it's not that bad, but there is some problem. Out on the large taxiways seeing how the yellow lines extend to distance. It's really similar to a car. The closest point pilots see is further away, but the taxiways are proportionately larger.

Near the terminal or assigned apron spot, external guidance is usually provided. The simplest method is by ramp marshal:

air marshal

Large airports usually have visual docking guidance system that serves the same purpose:

enter image description here

Several different systems exist.

Last, some new aircraft have cameras that can provide video to cockpit. A380 has a camera behind the nose wheel for more precise taxiing and camera on tail that provides better perspective for judging clearance to obstacles as while wingtips are visible from cockpit in most aircraft, that angle makes it difficult to judge the clearance.

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Thanks Jan, that almost confirms my guess. And yeah A380 has a number of camera views available, saw on documentaries. –  Iceman Jul 23 at 7:53

The question (& other answers) assume an airliner, but since that wasn't specified, I'll chime in for some tail draggers:

For some tail wheel aircraft, the short answer is they don't. If you watch a Pitts Special, a P-51 Mustang, a Gee-Bee, or other large engine wheel in the back airplane, you'll see them make a series of "S-turns" as they taxi. The pilot sits too low to see forward past the engine when all 3 wheels are on the ground.

The solution is to "zig zag" down the taxiway. That way you can look out one side then the other & have some idea where you are.

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Thanks! That was nice and so true, very relevant to the question. –  Iceman Jul 24 at 3:01
    
I was watching videos about P47s in WWII and they solved that problem by having a soldier lie on the wing while the pilot taxied out. There were dozens of planes that took off together and the soldiers efficiently guided the pilots to the runway. –  JScarry Jul 28 at 23:32
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Even more important than taxiing, because of lack of forward visibility, a 3-point landing in a taildragger is done using mostly peripheral vision, keeping the plane centered between the runway side edge markings. –  rbp Oct 14 at 14:57

Lets turn this question around. How do you stay in your lane when driving (not everyone can do this well)? Unless you are looking directly to your near side, you can't see the line on that side and you certainly cannot see the lines on the far side. So how do you stay centered in the lane? You use context cues and spatial awareness, extending the lines that you see the places they go that you cannot see. You know your vehicle and roughly where the lines you can see need to be visually placed to ensure you are in the lane.

Airplanes work the same way. We see the taxiway markings ahead of us and we can infer where they are under us. We know our airplanes and where these markings should be relative to cues we have in the airplane to put the plane on the centerline. If there is one thing pilots tend to be good at, it is spatial awareness and keeping the airplane on the centerline is on application of that skill.

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That absolutely makes sense, thanks! –  Iceman Jul 27 at 3:01

In my experience taxing 727, 737, 757, 767, DC-9, MD80, L-1011 - if you kept the centerline between your legs you'd be ok. Sounds odd now that I type this and read it, but it worked.

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You seem to be saying that you don't really need to travel down the exact centreline, which is fine, but doesn't actually answer the question of how pilots do seem to do a pretty good job of following the exact centreline. –  David Richerby Jul 23 at 18:54
    
@DavidRicherby he's actually spot on how we follow the exact centerline. The trick is we don't try to be exact but it ends up looking that way; we use rules of thumb like where to put the centerline relative to the panel or your legs. These rules of thumb tend to be good, which is why it appears we have some other special trick to exactly follow the line. –  casey Jul 26 at 17:25
    
@casey In that case, the answer should be edited to clarify this. (Well, actually, your own answer makes it much clearer.) –  David Richerby Jul 26 at 18:01

To me it is just one of those things you get used to doing.

When I first started flying I would concentrate very hard while taxing and sometime miss the forest for the trees (what there was a plane at that intersection!!). But, after a while it becomes second nature.

A bigger issue was using your feet instead of your hands to turn left or right. Also, learning to use differential thrust to bring a side around (turn left, increase right engine power) takes a bit of time. And correct aileron position in gusty winds can also be fun.

Since my experience is all in piston single and twins, and a few light turboprops, I wonder if the big boys have the same issues.

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And correct aileron position in gusty winds can also be fun: Shouldn't ailerons not be used for turning on ground? they don't seem to provide any assistance do they? –  Iceman Jul 24 at 3:33
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@Hanky웃Panky: Ailerons are not used for turning on ground, but during take-off run in cross-wind they need to be suitably positioned to prevent wingtip strike as the wind will tend to roll you over as you rotate. –  Jan Hudec Jul 24 at 6:36
    
Well, airliners (that @Hanky웃Panky apparently meant) have nose wheel steering connected to separate tiller, so you taxi with outboard (i.e. left on captains side, right on F/O's side if installed) hand and don't need to bother with differential thrust nor differential braking there (most of the time; pilots still know it for the case nosewheel steering fails). –  Jan Hudec Jul 24 at 6:39
    
With light planes you need to use ailerons and elevators when taxing in gusty winds. But not to assist in turn. Rather you want to have ailerons and elevator position such that they appropriately counteract the lift generated by a gust. This site, freepilotinfo.blogspot.com/2010/01/…, has the classic diagram for appropriate aileron and elevator position while taxing. The trick is remember to change whenever you make a turn or the wind shifts. –  JerryKur Jul 24 at 15:50
    
Thanks @JerryKur that makes sense. –  Iceman Jul 25 at 7:54

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