PRIMUS
r
1000 Integrated Avionics System
A28--1146--112--00
8-29
Modes of Operation
The SPD mode is basically an airspeed mode, however, it differs from
a standard IAS or Mach mode in the following ways:
D
Although SPD mode (in the long term), tracks the reference airspeed,
short--term emphasis is on vertical speed. This minimizes vertical
speed excursions due to disturbances or large airspeed changes.
D
Vertical operations are monitored to prevent the aircraft from flying too
slowly. Below 120 knots, the vertical mode is overridden and is
replaced by SPD hold mode. This is underspeed (MIN SPD)
protection.
D
All vertical operations must be monitored to prevent the aircraft from
exceeding V
mo
/M
mo
. If, however, V
mo
/M
mo
is exceeded, the flight
guidance system switches to the SPD hold mode. This is overspeed
(MAX SPD) protection.
NOTE:
The only annunciation of MIN SPD or MAX SPD
submodes is displayed on the left side of the attitude
director indicator (ADI).
The SPD mode is annunciated on the PFD by a green IAS or MACH at
the vertical capture location, as shown in figure 8--23.
