PLASI-2000
2Pages

P L A S I 2000 PULSE LIGHT APPROACH SLOPE INDICATOR FOR AIRPORTS The PLASI, Pulse Light Approach Slope Indicator, is a ground-installed, self-contained device, which visually provides vertical glide path information including correct position and direction, as well as degree of deviation and rate of change of deviation from the correct glide path. The pilot receives this information with minimum need for analysis and interpretation. Minimum range of 4 miles (6.5 kilometers) is sufficient for any aircraft to adjust to a steady-state glide position for desired touch down. The device generates and projects four horizontal bands of light, only the pilot at any given instant can see one of which. From the landing pilot’s view, the center band is a steady white light (projected as a .35 degrees high angular wedge, 16 degrees wide with the apex at the upper band of white light pulsing from the PLASI Approach Aid). This center band defines the correct glide path. An upper band of white light pulsing at approximately 2 1/4 (2.25) pulses per second is a wedge approximately 2.5 degrees high by 16 degrees wide. This gives above-glide path indication. A similar lower band of pulsing red light provides the below-glide path information. An “In-between” path signal is a solid red sector of .175 degrees height by 16 degrees width, which is the slightly below glide path signal and advises the pilot that he is at 2.65 degrees (for 3 degrees approach) when at the lower edge of the steady red. The pulses of the white and red above and below lights vary in length from continuous at the edge of the glide path to zero length at the off glide path limit of visual contact. These variations in light pulse length (long near the path -shorter and shorter as deviation from glide path increases) give the pilot quantitative deviation information. Rate of change of pulse length provides rate of deviation from or closure with the glide path. The visual presentation is accomplished through the use of optical components: a moveable shutter, and a red filter. One (1) tungsten Halogen Lamp is positioned behind the condenser lens. For reliability, an automatic lamp changer inserts a new lamp if the one in use fails. Signal (Beam) Angles: W idth: 16 degree s minimum. Height: Above glide path signal pulsing white light- 2.5 degrees On glide path signal: steady white - .35 degrees. Slightly below glide path signal: steady red light - .175 degrees. Below glide path signal: pulsing red light - 2.5 degrees. Glide path: The glide path is defined as the vertical angle established between the center plane of the steady white light and the landing surface. This glide path can be preset at any angle to accommodate the desired approach path considering obstructions, type of aircraft, and applicable regulations. (See Figure 1) Range: The signal is visible from at least four miles (6.5 km) under day or night conditions. Pulsing Frequency: The above-glide path white and below- glide path red lights pulse at approximately 2.25 pulses per second. These pulses vary in length from continuous at the edge of the on-glide path signal to zero at the edge of the 2.5 degrees off-glide path signal. Environment: PLASI meets the environmental conditions as specified in FAA Advisory Circular 150/5345-52 dated June 21, 1988. The operating systems are enclosed in a sealed composite case. Power Requirement: Permanent Installations: The basic power supply required at the PLASI unit shall be a nominal 115VAC to 120VAC, with a frequency of 50 or 60 hertz, single phase alternating current. To improve the service life of the BVA lamps, a voltage limiter unit is used to provide stabilized voltage to the lamp. Maximum power required is 1567 Watts. Temporary Installations: A portable generator of 2.5KVA minimum can be used for a power source when PLASI is set up as a temporary installation.

Display Panel: The alphanumeric display located on the control module inside the PLASI case will assist in trouble shooting operational problems by indicating what, if any, component has failed. Night Dimming: A photo detector (used in conjunction with the control module, and a manually variable voltage control in the voltage limiter control unit) sets the desired night brightness. NOTE: The manual control sets the night voltage by visual trial. Once this has been established for the particular environmental location, the light sensor automatically controls the day-night voltage. Automatic...