HELI-PLASI
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PERFORMANCE SPECIFICATIONS H E L I - P L A S I 2000 PULSE LIGHT APPROACH SLOPE INDICATOR FOR HELIPORTS 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. From the landing pilot’s view, the device generates and projects four horizontal bands of light, only one of which can be seen by the pilot at a given instant. The center band is a steady white light projected as a .60 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 aboveglidepath indication. A similar lower band of pulsing red light provides the below-glidepath information. An “In-between” path signal is a solid red sector of .30 degrees height by 16 degrees width, which is the slightly below glide path signal and advises the pilot that he is at 5.4 degrees (for 6 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. This variation in light pulse length (long near the path - shorter and shorter as deviation from glide path increases), gives 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: Width: 16 degrees minimum. Height: Above glide path signal pulsing white light- 2.5 degrees On glide path signal: steady white - .60 degrees. Slightly below glidepath signal: steady red light .30 degrees. Below glidepath signal: pulsing red light - 5.0 degrees. Glidepath: The glidepath is defined as the vertical angle established between the center plane of the steady white light and the landing surface. This glidepath 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-glidepath white and below- glidepath red lights pulse at approximately 2.25 pulses per second. These pulses vary in length from continuous at the edge of the on-glidepath signal to zero at the edge of the 2.5 degrees off-glidepath 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 installati

Display Panel: The alphanumeric display located on the control module inside the PLASI case will assist in 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 Lamp Changer: A rotating lamp changer containing four 900W tungsten halogen...