Taxiway Surface Markings Tutorial

Welcome to a tutorial on taxiway surface markings! I've put together a list of important surface markings that appear in Infinite Flight and have explained them and provided examples below. If you feel anything should be added or revised, please message me down below!

» Centreline

» Runway Taxi-Holding Position (RTHP)

» Intermediate Taxi-Holding Position (ITHP)

Centreline marking consists of a single continuous line marking the center of a taxiway. Where a taxiway crosses a runway, the Taxiway Centreline Marking indicates the route to be followed but the marking is interrupted as necessary so as not to interfere with the runway markings. Double lines, as seen below, are the taxiway edge lines. Do not go past these.

Another thing to note is that when taxiing from your gate to a runway, use the inside taxiways (furthest from the runway). When taxiing to parking, use the inside taxiways (closest to the runway). This helps keep the flow of traffic continuous and limits the use of “hold position” and other commands that may seem annoying to aircraft trying to depart.

When turning on taxiways, please turn only when the outer centrelines curve to connect the four directions. If there are just two centrelines intersecting, these should be used to go straight, not to turn left or right on to a different taxiway. Note that this is only true if the airport you are taxiing at has both (90-degree lines and curved lines). If it has only the former, you may turn on them.




Return to Top

Runway Taxi-Holding Position (RTHP) markings occur on each taxiway leading to a runway in order to prevent taxiing aircraft from penetrating the designated protection zone either side of a runway, which needs to be kept clear during runway use. This zone will also, where applicable, allow for the protection of the ILS Sensitive Area. There are two forms of RTHP marking:

  • Runway Holding Position - Two solid and two broken lines across the full width of the taxiway normally at right angles to its centerline with the broken lines closest to the runway.
  • ILS Critical Area Holding Position - A “ladder” mark laid across the full width of the taxiway and normally at right angles to its centerline.

If only one type is present, it will always be the former. Where there is more than one RTHP, all the additional ones will be of the second type.

In the image below, the yellow and black thicker lines leading up to the hold short line are meant to show pilots that a runway and RTHP is coming up to prevent runway incursions. These are known as enhanced taxiway centrelines and are OK to taxi on.


C1FAF3F5-3A73-4BE5-BD67-65F12E54FF7F Runway-Holding-Position-MarkingW
Credit to

I’ve seen the most trouble on the expert server with the hold short line (runway holding position). Hold short means hold behind. Here are a few examples of what to do and what not to do if you haven’t been cleared to enter the runway:

Credit to

Notice how the aircraft above is behind the hold short line. The front gear is not on the line or past it. Also, notice how the aircraft is not trying to get as close as possible to the line without passing it. The pilot knows that they will not get a faster takeoff clearance if they are closer to the runway.

The FAA states:

When instructed by ATC, “Hold short of Runway XX”, the pilot MUST STOP so that no part of the aircraft extends beyond the runway holding position marking. When approaching runways at airports with an operating control tower, pilots must not cross the runway holding position marking without ATC clearance. Pilots approaching runways at airports without an operating control tower must ensure adequate separation from other aircraft, vehicles, and pedestrians prior to crossing the holding position markings. An aircraft exiting a runway is not clear of the runway until all parts of the aircraft have crossed the applicable holding position marking.

Credit to

Above, we see what is called a runway incursion. Even having your nose an inch on or over the hold short line is considered a runway incursion (unless you’ve been cleared to enter the runway).

The FAA defines a runway incursion as any occurrence at an aerodrome involving the incorrect presence of an aircraft, vehicle or person on the protected area of a surface designated for the landing and takeoff of aircraft.

Please do not incur on a runway on the expert server. If you do, you may be warned with “You were not cleared to enter the runway, please exit the runway.” and then issued a violation for failing to hold short. Note that IFATC doesn’t have to warn you, they may go straight to a violation. Tip: If you can’t see the hold short line, you’re too far!

More on ILS critical areas:
Air Traffic Control protects the ILS critical areas when arriving aircraft are inside the outer marker/final approach fix (FAF) on an ILS approach, and the reported ceiling is less than 800 feet or visibility is less than 2 miles. Basically, if the weather is bad and arrivals can’t see the runway well, they must use the ILS. Past the ILS critical area, aircraft and vehicles on the ground will interfere with the signal, making it very hard for the arrival to find the runway with the localizer and glideslope.

Return to Top

Intermediate Taxi-Holding Position (ITHP) markings may be found at airports where the taxiway layout is complex or involves many intersecting taxiways. ITHPs may be established in order to protect a priority taxiway route ahead of the marking and are marked by a single broken line laid across the full width of the taxiway normally at right angles to its centerline.

ITHPs are included in Infinite Flight’s airports but are not enforced by IFATC. Of course, they may still be used to designate right of way. Here is a screenshot of an ITHP in Infinite Flight:


Obviously, there are many more markings out there, but these are by far the most important and critical. I hoped you learned something from this or maybe even remembered something. And please, do not pass the hold short line. It does no good for anyone and can cause go-arounds and even violations.

Return to Top

banner made by @Aviator_Ace


I knew all of this, but I absolutely love the post and the dedication you put in! This will hopefully help so many people


Thank you! It really is a problem, and the best way to deal with it in my opinion is to teach!


RE: Runway incursion? Looks like a simple LUAW instruction while an aircraft crosses downfield.


Great tutorial. In addition to runway incursions, our Realism™ brigade is often fond of holding short of the ILS critical area and requesting takeoff on 😎 days with a ceiling of 10,000 FT. Not necessary unless the two criteria below are in play. Keep it “Real” my friends…

Air Traffic Control protects the ILS critical areas when arriving aircraft are inside the outer marker/final approach fix (FAF) on an ILS approach, and the reported ceiling is less than 800 feet or visibility is less than 2 miles


Well, the picture is from an actual runway incursion that happened. It could be a LUAW but I think you get the point of the picture. :D


Thank you! You’re totally right about the ILS critical area.

To me, that looks like a plane is lined up on the runway with a LUAW clearance and then the plane going onto the runway is just crossing it

1 Like

I’ll update it for clarity.

edit: hope it makes more sense now @N1RG

1 Like

Really great topic! I think for some people it‘s very helpful.

1 Like

So the black and yellow are the good lines to go on

1 Like

You mean the black and yellow thick centerline leading up to the hold short line? If that is what you mean, yes, that is fine to be on. It is a warning to pilots that the hold short line is coming up.

Thanks for this tutorial! I actually didn’t know about the ILS critical holding point.


This is a joke right? The FAA aim clearly states — When instructed by ATC, “ Hold short of Runway XX ,” the pilot MUST STOP so that no part of the aircraft extends beyond the runway holding position marking

No part of the aircraft should be beyond the hold short line.

1 Like

Totally. The whole aircraft must be behind the whole of the RTHP.

Wow! great job, I hope many new players see this :)

1 Like

Thank you! It means a lot!

Yeah, it’s not too “critical” in Infinite Flight, but still good to know. I often see aircraft holding short behind the ILS critical holding point.

1 Like

Actually something else you can add: Don’t taxi on the boundary line of the apron. Some people can’t tell which one is the taxiway sometimes.

Do you means the white taxi boundaries in-between the aprons?