![]() This higher glide path is intended for use only by high-cockpit aircraft to provide a sufficient threshold crossing height. The lower glide path is provided by the near and middle bars and is normally set at 3°, whereas the upper glide path, provided by the middle and far bars, is normally 1/4 degree higher. ![]() Three-bar VASI installations provide two visual glide paths. Two-bar VASI installations provide one visual glide path that is normally set at 3°. Where the installation consists of 12 or 16 light units, the units are located on both sides of the runway. VASI installations consisting of 2, 4, or 6 light units are located on one side of the runway, usually the left. This installation may consist of either 6 or 16 light units. Some VASIs consist of three bars-near, middle, and far-which provide an additional visual glide path to accommodate high-cockpit aircraft. Most VASI installations consist of two bars-near and far-and may consist of 2, 4, or 12 light units. ![]() A VASI installation may consist of 2, 4, 6, 12, or 16 light units arranged in bars referred to as near, middle, and far bars. The visual glide path of the VASI provides a safe obstruction clearance within +/-10° of the extended centerline and up to 4 NM from the runway. These lights are visible from 3 to 5 miles during the day and up to 20 miles at night. Legally speaking.A system of lights arranged to provide visual descent guidance information during the approach to a runway. Therefore, seeing only to the roll bar by DA means missed approach-even though you can see 1,400 feet of approach light system ahead of you. Also, if you can’t see past the roll bar, you can’t see “the red terminating bars or the red side row bars” anyway. Few ILS approaches, and no LPV approaches, allow visibility that low without special equipment or authorization. If you reach a 200-foot DA and can’t see the roll bar that’s 1,000 feet short of the threshold, you have less than 1,800 feet of visibility. With only 2,400 feet of visibility, you probably won’t see a visual glidepath until the roll bar has passed under the nose. The PAPI or VASI is about 1,000 feet beyond the threshold, so fly attitude and resist any pitch changes. However, I’ll reiterate: Even though the ALSF-2 provides some roll and yaw information, it says nothing about glideslope. I wouldn’t quibble over 100 feet on the edge of legal. If you can only see to the 500-foot barrette, visibility is closer to 2,300 feet. ![]() Total length for the SSALR and MALSR, including the RAIL, is 2,400 feet. Otherwise, SSALRs and MALSRs are identical. The SS means a maximum brightness that’s higher than the M. The flashing lights still extend the full 1,400 feet, but because they’re all alone for much of that they get a new name: Runaway Alignment Indicator Lights, or RAIL. The outer section only has the solid white lights for 400 feet. The SSALR and MALSR have the inner section with no side rows and half the lights turned off (so they appear every 200 feet). Good weather, low budgets or inconveniently placed shopping malls off the approach end of the runway can mean parts of the ALSF-2 get turned off or never installed. Now that you have the big picture, use the accompanying chart as we cut it down. So, here’s more trivia: you could see the red termination bars or the red side-row bars, but never both. So where are the red terminating bars mentioned in FAR 91.175? They’re on an ALSF-1, which is the same length as an ALSF-2 but has a different inner section. ![]()
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