Airport Operations

light. The “slightly below glidepath” indication is a steady red Below Glidepath On Glidepath Above Glidepath light. If the aircraft descends further below the glidepath, the red light starts to pulsate. The “above glidepath” indication Far Bar Far Bar Far Bar is a pulsating white light. The pulsating rate increases as the aircraft gets further above or below the desired glideslope. Near Bar Near Bar Near Bar The useful range of the system is about four miles during the day and up to ten miles at night. [Figure 14-32] Runway Lighting There are various lights that identify parts of the runway complex. These assist a pilot in safely making a takeoff or landing during night operations. Figure 14-29. Two-bar VASI system. Runway End Identifier Lights (REIL) Runway end identifier lights (REIL) are installed at many A tri-color system consists of a single-light unit projecting airfields to provide rapid and positive identification of the a three-color visual approach path. Below the glidepath is approach end of a particular runway. The system consists indicated by red, on the glidepath is indicated by green, and of a pair of synchronized flashing lights located laterally above the glidepath is indicated by amber. When descending on each side of the runway threshold. REILs may be either below the glidepath, there is a small area of dark amber. Pilots omnidirectional or unidirectional facing the approach area. should not mistake this area for an “above the glidepath” indication. [Figure 14-31] Runway Edge Lights Runway edge lights are used to outline the edges of Pulsating VASIs normally consist of a single-light unit runways at night or during low visibility conditions. projecting a two-color visual approach path into the final [Figure 14-33] These lights are classified according to the approach area of the runway upon which the indicator is intensity they are capable of producing: high intensity runway installed. The “on glidepath” indication is a steady white lights (HIRL), medium intensity runway lights (MIRL), and High Slightly High On Glidepath Slightly Low Low more than 3.5° 3.2° 3° 2.8° less than 2.5° Figure 14-30. Precision approach path indicator for a typical 3° glide slope. ber m A n Above glidepath Gree Amber On glidepath d Re Below glidepath Figure 14-31. Tri-color visual approach slope indicator. 14-17