# How do pilots manage to keep aircraft on centerline during taxi?

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 '14 at 11:26
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 '14 at 14:29
– Jan Hudec Jul 23 '14 at 15:39
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 '14 at 10:56
@Cornelius - odd historical reason - from the latin, spatium meaning space. – Simon Jul 24 '14 at 11:22

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'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 '14 at 19:09
@dotancohen - but taxiing a small plane is not out of the question as a software developer :) – warren Jul 25 '14 at 14:32
@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 '14 at 18:10
@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 '14 at 5:18
@Iceman Good point! I tend to use that expression when, as I think about it now, there are better ways to say what I mean. What I'm meaning to say is that here's something you can do if you have the time and attention span to do so, but I'm not so presumptuous as to say you should or need to do it. I was never bored, but when you're on a long taxi, especially when you're in a lineup, the workload is not high. The taxi checklist is done, you won't be calling for the takeoff checklist until you reach the end of the runway, and a little refining of your taxi skills is a worthwhile activity. – Terry Dec 7 '15 at 18:53

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:

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

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. – Hanky Panky Jul 23 '14 at 7:53
777-300ER (and I think maybe also -200LR) has a camera on the belly as well. – reirab Nov 19 '14 at 15:03

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. – Hanky Panky Jul 24 '14 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 '14 at 23:32
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 '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! – Hanky Panky Jul 27 '14 at 3:01
I will say, though, that I found it a lot easier to keep a car in the lane when I was first learning to drive than to keep an airplane on the center line when I was first learning to fly. Keeping it on the taxiway wasn't hard, but developing enough spatial awareness to keep it consistently on the center line took a little more getting used to than it did in a car. Part of that has to do with the need to keep your focus further in front of you than you need to do in a car. When I first started, my tendency was to keep myself (rather than the center of the airplane) on the center line. – reirab Nov 19 '14 at 15:11

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 '14 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 '14 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 '14 at 18:01

The B777-300 has a Ground Maneuvering Camera System (GMCS) which can be displayed in the flight deck.

It is mainly used to aid in turns (due to the length of the fuselage), but also works well for keeping it on the center line in straight ahead taxing.

Ground Camera Video

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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? – Hanky Panky Jul 24 '14 at 3:33
@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 '14 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 '14 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 '14 at 15:50
Thanks @JerryKur that makes sense. – Hanky Panky Jul 25 '14 at 7:54

Not long ago, I watched someone taxiing a taildragger (conventional gear) aircraft swerve from side to side in what seemed to be an uncontrolled manner, after musing how he could possibly be that bad at keeping the plan going straight, I realized, that when the nose of the plane is concealing the center line, the only way to actually see what is on the taxiway in front of you is to serpentine down the road.

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