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PFDs provide increased situational awareness to the pilot by
replacing the traditional six instruments used for instrument
flight with an easy-to-scan display that provides the horizon,
airspeed, altitude, vertical speed, trend, trim, rate of turn
among other key relevant indications. Examples of PFDs
are illustrated in Figure 3-45.
Synthetic Vision
Synthetic vision provides a realistic depiction of the aircraft
in relation to terrain and flight path. Systems such as those
produced by Chelton Flight Systems, Universal Flight
Systems, and others provide for depictions of terrain and
course. Figure 3-46 is an example of the Chelton Flight
System providing both 3-dimensional situational awareness
and a synthetic highway in the sky, representing the desired
flight path. Synthetic vision is used as a PFD, but provides
guidance in a more normal, outside reference format.
3-28
Figure 3-45. Two Primary Flight Displays (Avidyne on the Left and Garmin on the Right).
Figure 3-46. The benefits of realistic visualization imagery, as
illustrated by Synthetic Vision manufactured by Chelton Flight
Systems. The system provides the pilot a realistic, real-time, threedimensional
depiction of the aircraft and its relation to terrain
around it.
Multi-Function Display (MFD)
In addition to a PFD directly in front of the pilot, an MFD
that provides the display of information in addition to primary
flight information is used within the flight deck. [Figure 3-47]
Information such as a moving map, approach charts, Terrain
Awareness Warning System, and weather depiction can all
be illustrated on the MFD. For additional redundancy both
the PFD and MFD can display all critical information that
the other normally presents thereby providing redundancy
(using a reversionary mode) not normally found in general
aviation flight decks.
Advanced Technology Systems
Automatic Dependent Surveillance—Broadcast
(ADS-B)
Although standards for Automatic Dependent Surveillance
(Broadcast) (ADS-B) are still under continuing development,
the concept is simple: aircraft broadcast a message on
a regular basis, which includes their position (such as
latitude, longitude and altitude), velocity, and possibly
other information. Other aircraft or systems can receive this
information for use in a wide variety of applications. The
key to ADS-B is GPS, which provides three-dimensional
position of the aircraft.
As an simplified example, consider air-traffic radar. The radar
measures the range and bearing of an aircraft. The bearing is
measured by the position of the rotating radar antenna when it
receives a reply to its interrogation from the aircraft, and the
range by the time it takes for the radar to receive the reply.
An ADS-B based system, on the other hand, would listen
for position reports broadcast by the aircraft. [Figure 3-48]
These position reports are based on satellite navigation
systems. These transmissions include the transmitting
aircraft’s position, which the receiving aircraft processes into
usable pilot information. The accuracy of the system is now
determined by the accuracy of the navigation system, not
measurement errors. Furthermore the accuracy is unaffected
by the range to the aircraft as in the case of radar. With radar,
detecting aircraft speed changes require tracking the data and
changes can only be detected over a period of several position
updates. With ADS-B, speed changes are broadcast almost
instantaneously and received by properly equipped aircraft.
3-29
Figure 3-47. Example of a Multi-Function Display (MFD).
Figure 3-48. Aircraft equipped with Automatic Dependent Surveillance—Broadcast (ADS-B) continuously broadcast their identification,
altitude, direction, and vertical trend. The transmitted signal carries significant information for other aircraft and ground stations alike.
Other ADS-equipped aircraft receive this information and process it in a variety of ways. It is possible that in a saturated environment
(assuming all aircraft are ADS equipped), the systems can project tracks for their respective aircraft and retransmit to other aircraft
their projected tracks, thereby enhancing collision avoidance. At one time, there was an Automatic Dependent Surveillance—Addressed
(ADS-A) and that is explained in the Pilot’s Handbook of Aeronautical Knowledge.
3-30
Figure 3-49. An aircraft equipped with ADS will receive identification, altitude in hundreds of feet (above or below using + or -), direction
of the traffic, and aircraft descent or climb using an up or down arrow. The yellow target is an illustration of how a non-ADS equipped
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Instrument Flying Handbook仪表飞行手册上(59)
