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.
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.
Credit to midwestflyer.com
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 dallasnews.com
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 studentpilotnews.com
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.
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.