LNAV

Lateral NAVigation in aviation is a function of autopilot which directs lateral movement of aircraft either according to pre-programmed FMS flight plan during climb, cruise and descent or according to ILS localizer during approach.Lateral navigation is the new terminology for a GPS non-precision approach. The approach minimums for LNAV are higher than other types of area navigation (RNAV) due to the lack of vertical guidance. Aircraft relying on LNAV instrumentation must descend incrementally rather than following a fixed glide slope down to the decision height (DH). Consequently, the DH for LNAV approaches will, in most cases, be higher than for most LNAV/VNAV approaches. In some cases, though, such as when there is an obstacle close to the runway, LNAV's DH will be lower than in LNAV/VNAV approaches. Aircraft flying an LNAV approach descend directly after passing over an obstacle whereas on flying an LNAV/VNAV approach must continue on its glide slope.
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