Airport Operations

• Direction signs—yellow background with black inscription. The inscription identifies the designation of the intersecting taxiway(s) leading out of an intersection. White Green White Yellow • Destination signs—yellow background with black inscription and arrows. These signs provide information on locating areas, such as runways, terminals, cargo areas, and civil aviation areas. • Information signs—yellow background with black inscription. These signs are used to provide the pilot with information on areas that cannot be seen from the control tower, applicable radio frequencies, and noise Figure 14-28. Airport rotating beacons. abatement procedures. The airport operator determines the need, size, and location of these signs. runway is a precision or nonprecision instrument runway. • Runway distance remaining signs—black background Some systems include sequenced flashing lights that appear with white numbers. The numbers indicate the to the pilot as a ball of light traveling toward the runway at distance of the remaining runway in thousands of feet. high speed. Approach lights can also aid pilots operating under VFR at night. Airport Lighting Visual Glideslope Indicators The majority of airports have some type of lighting for night Visual glideslope indicators provide the pilot with glidepath operations. The variety and type of lighting systems depends information that can be used for day or night approaches. By on the volume and complexity of operations at a given airport. maintaining the proper glidepath as provided by the system, Airport lighting is standardized so that airports use the same a pilot should have adequate obstacle clearance and should light colors for runways and taxiways. touch down within a specified portion of the runway. Airport Beacon Airport beacons help a pilot identify an airport at night. Visual Approach Slope Indicator (VASI) The beacons are normally operated from dusk until dawn. VASI installations are the most common visual glidepath Sometimes they are turned on if the ceiling is less than 1,000 systems in use. The VASI provides obstruction clearance feet and/or the ground visibility is less than 3 statute miles (VFR within 10° of the extended runway centerline and up to four minimums). However, there is no requirement for this, so a nautical miles (NM) from the runway threshold. pilot has the responsibility of determining if the weather meets VFR requirements. The beacon has a vertical light distribution The VASI consists of light units arranged in bars. There are to make it most effective from 1–10° above the horizon, 2-bar and 3-bar VASIs. The 2-bar VASI has near and far light although it can be seen well above or below this spread. The bars and the 3-bar VASI has near, middle, and far light bars. beacon may be an omnidirectional capacitor-discharge device, Two-bar VASI installations provide one visual glidepath or it may rotate at a constant speed, that produces the visual that is normally set at 3°. The 3-bar system provides two effect of flashes at regular intervals. The combination of light glidepaths, the lower glidepath normally set at 3° and the colors from an airport beacon indicates the type of airport. upper glidepath ¼ degree above the lower glidepath. [Figure 14-28] Some of the most common beacons are: The basic principle of the VASI is that of color differentiation • Flashing white and green for civilian land airports between red and white. Each light unit projects a beam of • Flashing white and yellow for a water airport light, a white segment in the upper part of the beam and a • Flashing white, yellow, and green for a heliport red segment in the lower part of the beam. The lights are arranged so the pilot sees the combination of lights shown in • Two quick white flashes alternating with a green flash Figure 14-29 to indicate below, on, or above the glidepath. identifying a military airport Other Glidepath Systems Approach Light Systems Approach light systems are primarily intended to provide a A precision approach path indicator (PAPI) uses lights similar means to transition from instrument flight to visual flight for to the VASI system, except they are installed in a single row, landing. The system configuration depends on whether the normally on the left side of the runway. [Figure 14-30] 14-16