It can be difficult to persuade seagulls to follow the rules, but pilots generally want to comply - they just don't always know how. Every pilot should know that there are five general types of signs: mandatory, location, direction, destination, and information signs. Mandatory signs have a red background with white numbers or letters. Location signs, direction signs, and destination signs may have yellow writing on a black background or black writing on a yellow background. Information signs always have white writing on a black background. Each type of sign is pictured and described in the Aeronautical Information Manual (AIM).
For the sake of safety and standardization, signs at all U.S. airports conform to this format. But that wasn't always the case. At one time, airport operators could provide runway and taxiway information using signs of their choosing. While the basic information was always there, the shape, size, and colors of the signs varied between airports. The potential for confusion was tremendous and seriously compromised safety, leading to uncounted runway and taxiway incursions. Even with today's uniform signs, runway and taxiway incursions happen at an alarming rate, and we, as safety-conscious pilots, must be ever vigilant to avoid them as we move about all airports - especially complex, busy ones. Understanding, interpreting, and obeying airport signs is one of the keys to safely operating your aircraft.
Mandatory Signs
Let's begin with a review of mandatory signs. These red signs are designed to stand out above all others. They denote runway entrances, critical areas, or areas where entrance by aircraft is prohibited. The sign identifying a runway typically has a number only, as in 33 for Runway 33, and is found at the end of the taxiway leading directly to the beginning of the takeoff end of the runway.
Runway holding position signs also are mandatory. These signs indicate that you have reached the intersection of two runways; the first number identifies the runway to your left, and the second number identifies the runway to your right. Arrows adjacent to the runway numbers indicate the approximate alignment of each runway relative to your position and the direction to that runway's threshold. If you see the abbreviation APCH after the runway number, you are nearing the approach or departure area of a runway that must be operationally protected so that taxiing aircraft do not interfere with landing or departing aircraft.
At some airports you will see a mandatory sign that reads ILS. This means that when the instrument landing system is being used in certain meteorological conditions (usually when the ceiling is less than 800 feet above ground level and visibility is less than two statute miles), you must hold short of the sign and the hold-short lines painted on the taxiway so as to avoid interfering with approaching traffic which receives electronic guidance from antennas near your position.
Be certain that you have clearance from air traffic control, typically the ground controller, to cross any runway marked by a mandatory sign. Upon receiving initial taxi clearance, or while taxiing, you may be instructed to hold short of an area that is "guarded" by a mandatory sign. If you are operating at a nontowered field or an airport whose tower is not in operation at the time, you as pilot in command must make the decision when it is safe to enter an area that is protected by a mandatory sign. Be sure to communicate your intentions on the designated unicom or common traffic advisory frequency (CTAF) and listen for other aircraft in your operating area.
One other mandatory sign you may encounter is the no-entry sign. This indicates that aircraft are prohibited in the area, usually because of a one-way taxi restriction or because it is close to a vehicle service road that may be mistaken for a taxiway.
If you are unsure how to carry out your taxi clearance, stop, swallow your pride, and ask air traffic control for progressive taxi instructions. When you make this request, controllers will guide you precisely to where you are supposed to go, even telling you when to turn. Even airline pilots sometimes need this extra help. Remember that it is always better to ask than to guess.
Location Signs
The next group of signs is called location signs. These simply identify either the taxiway or runway on which the aircraft is located. Sometimes these signs are used in conjunction with red runway holding position signs, or they may be positioned to help pilots determine which runway they are on, especially where runways converge. Use your magnetic compass heading indication to verify your position in relation to the runway location sign. If your magnetic heading is 150 degrees and the sign in front of you reads 15, then you know exactly where you are. This is a good example of how properly using checklists can improve safety. If you follow your checklist and set your heading indicator before taxiing, it can help to guide you on the ground.
The runway boundary sign, another type of location sign, looks like an upright picture of a runway holding position marking (the solid and broken yellow lines painted on the pavement just as you enter the runway safety zone). You may also see an ILS critical area boundary sign, another upright pictorial usually located near a red mandatory sign. These enhance the visual cues painted on taxiways and can be used as a guide in determining if you are clear of a runway or an ILS critical area.
Direction And Destination Signs
Our next stop on the airport signage tour is direction signs. These are easy to identify because they always include one or more arrows. These are especially helpful at large airports with many taxiways and are usually seen in conjunction with taxiway location signs. The signs with yellow lettering on a black background tell you which taxiway you are on. The signs with black lettering and arrows tell you that you are approaching the intersection between the taxiway you are currently on and another taxiway. The arrows indicate the direction in which you must turn in order to access the identified taxiway when you reach the upcoming intersection.
Destination signs also include directional arrows that may point to runways, airport terminal buildings, fixed-base operators (FBOs), or military areas. If the arrow points to a taxiway serving two runways, a dot will separate the two numbers, indicating that the runways are common to the taxi route.
Information Signs
Information signs provide just that - information that you may need. One type of information sign, the runway distance remaining sign, may cause relief or anxiety depending on how your last landing went. These signs are found on one or both sides of the runway. If you have just landed your aircraft long on a 5,000-foot runway, you might notice a sign with a white numeral 1 on a black background. That sign tells you that there are 1,000 feet of runway remaining and you may want to review why it took you 4,000 feet of runway to come to a stop. Runway distance remaining signs provide added situational awareness during landings and takeoffs and can prove extremely helpful when you are deciding whether you have enough runway remaining to perform a touch and go or go-around.
As airports grow busier and more complex, you must do your part to ensure your safety and that of other pilots and passengers around you. If you don't often operate at large airports, your sign language skills can get rusty. Periodically review the AIM. Be sure that you know what the signs are telling you, then follow their instructions. Safety couldn't be simpler.
