User's Manual

UL-801 Installation Manual
Page 4
23-20-06 15 December 2011
FANS-1 is the original version of FANS developed by Boeing and FANS-A is the
corresponding version developed by Airbus. Both of these versions are interoperable with
worldwide ATC facilities and use the Aircraft Communications Addressing and Reporting
System (ACARS) network. UniLink’s FANS-1/A+ implementation is designated as such
because it is functionally equivalent to, and combines many of the best features of both
Boeing’s FANS-1 and Airbus’ FANS-A implementations.
Future Air Navigation System (FANS) is principally comprised of three applications:
• Air Traffic Services ATS Facilities Notification (AFN)
AFN allows the aircraft and an ATS provider on the ground to exchange addresses, as
well as information about which FANS applications they support.
• Automatic Dependent Surveillance-Contract (ADS-C)
ADS-C allows multiple ATS providers to command position reports and other situational
data at regular intervals or in response to events specified by the ATS provider, such as a
change in altitude or lateral deviation. ADS-C requires no crew interaction.
• Controller-Pilot Datalink Communications (CPDLC)
CPDLC provides capabilities to substitute for traditional voice communications for
routine communications between a pilot and an air traffic controller. CPDLC messages
can be used to request and grant clearances, to inform the ground of the aircraft’s position
and situation, and to provide instructions to the crew, such as “Climb To Reach FL390
By 2200” or “Proceed Direct To TUNTO”.
C. Field-Loadable Software and Databases
The UniLink application software, Customer, ATC, and Geographic databases are loadable
in the field or at an authorized Universal Avionics dealer. During the software loading
process, automatic and manual version number verification procedures are performed to
ensure the compatibility of the software and database. A separate manual, 23-20-08, provides
the Field Loading procedures.
Detection of Corrupted or Partially Loaded Software
All loadable software and databases contain a 32-bit Cyclic Redundancy Check (CRC). The
data-loading software function calculates a CRC upon receipt of a file and compares it to the
CRC included with the loaded data file thus rejecting any files whose contents have changed
during the loading process.
Determination of the Effects of Loading the Inappropriate Software
The system has been designed to guard against inappropriate software or database loading
based on version numbering. Loadable application software only functions with versions of
the hardware and boot software that supports the version type of software loaded. If an
incompatibility is detected during power-up checks, the system is placed into a state in which
no normal functions can occur. Only appropriate loadable databases and applications will
function with compatible versions of the main application software.