industry The union of affordable new autopilots and displays, like Garmin's G5, brings flight-director guided VNAV to legacy aircraft. UPRIGHT MIGRATION En route vertical navigation comes to the Part 23 aftermarket S T O R Y avionics news S C O T T M . S S P A N G L E R ince the dawn of digital avionics, the capabilities of stand-alone systems that provided capabilities to Part 25 transport category aircraft whose operators could afford them have been steadily migrating to GPS navigators, bringing these capabilities to Part 23 aircraft. One of them, vertical navigation, or VNAV, will more fully realize its potential with the midyear software update for Garmin's GTN units. About halfway through its announcement of the Federal Aviation Administration's supplemental type certificate approval for its GFC 500 autopilot, Garmin appended this interesting capability to the bullet point noting the autopilot's "premium functions and advanced capabilities such as altitude pre-select and indicated airspeed hold mode." It said, "VNAV will be a growth function when appropriately equipped." Garmin's GTN 650 38 B Y * march 2018