Avionics News March 2018 - 39

Surely, this couldn't be the flight management system
capability introduced in the 1980s with the Boeing 757/767.
Giving the FMS control of engine thrust turned lateral
navigation on its side. VNAV optimizes an aircraft's vertical
performance along a flight-planned route in three dimensions,
or four if it includes a time requirement. This not only reduced
pilot workload, it improved safety in all phases of flight and
increased en route fuel efficiency.
But indeed, that is the case, said Bill Stone, senior manager
of business development for Garmin. "Appropriately
equipped" means, at minimum, the union of a GFC 500
digital autopilot, a GTN 650/750 WAAS/GPS navigator, and a
G5 electronic flight instrument.
Auto-throttle is not incorporated with this system, he
said, "But we have that logic in our wheelhouse. We're
doing it in the Cessna X, Sovereign, and Latitude, as well as
the Cirrus SF50 Vision jet," and this capability will expand
as opportunities arise.
This migration of capabilities is nothing more than the
natural evolution of avionics technology, according to
Stone. The new VNAV capability comes from Garmin's
integrated flight decks. "Serving such a wide range of
products, when we develop capabilities for systems like the
G5000, this allows us to share that technology with other
systems, like the GTNs, so folks in the aftermarket can
enjoy and benefit from those capabilities, as well."
This will allow pilots to assign altitudes, altitude
constraints, crossing restrictions and other altitude-related
parameters in a flight plan. The GTN calculates the
vertical path between these points, and the GFC 500/600
executes them while the G5 displays the flight director's
command bars with the appropriate attitude for pilots who
want to fly by hand.
Avidyne updated its vertical navigation capabilities in its
IFD navigators with a 2017 software update. The terminology
is different (vertical navigation/vertical speed profile in GNS
navigators and vertical constraint/preferred descent rate in the
IFDs), but the capabilities are the same.
For virtually every waypoint in the flight plan, the pilot
can associate a crossing restriction with it. That altitude
restriction can be at the waypoint or so many miles before
or after it. And the altitude can be above, below, or at
a charted altitude requirement. The only waypoints not
open for vertical constraints are the flight's origin, the
destination, if the pilot has selected an approach, and the
missed approach point.
For en route descents, the Avidyne creates a top-of-descent

marker when the pilot has defined an altitude constraint for an
upcoming waypoint that is below the current cruising altitude.
The default rate of descent is 500 feet per minute, but pilots
can change this as needed.
The top-of-descent point appears in green on the moving
map, and the system gives a 10-second countdown and
sounds "a top-of-descent chime when an altitude restriction
is on an upcoming waypoint (either user entered or as part
of an approach)," said Simpson Bennett, Avidyne product
manager. This capability is not available on any waypoint in
an instrument approach past the final approach fix, in holding
patterns, or procedure turns.

On its map page, the Avidyne IFD540 shows the top-of-descent point in green.

"The IFDs do not integrate with auto-throttles," he
continued, nor do they "issue any (airspeed)" messages
regarding power management. The IFD550 does provide
pitch guidance, but it is not certified as primary or standby.
The IFD550 guidance is supplemental in nature."
When the IFD is part of a system that includes a primary
flight display such as the Avidyne Entegra or Aspen EFD1000
Pro, Avidyne's DFC90 digital autopilot provides an enhanced
flight director capability that improves the pilot's ability to
hand-fly approaches.
When the autopilot is engaged, the DFC90's Envelope
Protection feature prevents autopilot-induced stalls and underspeeds and provides aural and visual warnings. When not
engaged, the DFC90's Envelope Alerting system constantly
Continued on following page
avionics news

march

2018

Table of Contents for the Digital Edition of Avionics News March 2018