The glideslope is a wedge-shaped projection from the Fresnel lens at a 3.5-degree angle with glideslope
information present from 3/4 degrees above to 3/4 degrees below the projected glideslope. In addition,
the meatball can be seen from up to 20 degrees on either side of the runway centerline. Because the
glideslope is wedge shaped, its lateral and vertical tolerance is wide at the start and narrows to a point at
Use the Fresnel lens to maintain proper glideslope. Remember, the Fresnel lens gives you only glides-
lope, not lineup, information. Use peripheral vision to scan the AOA indexer for maintaining proper AOA.
Figure 22: GLIDESLOPE INDICATIONS (FRESNEL LENS/AOA INDEXER)