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<h1>Flight Inspection Technology</h1>
<h2>General</h2>
<p>From August 1998 FPL standardized on the use of AD-FIS flight inspection systems
for all its work. The AD-FIS is a highly integrated and fully digital flight
inspection system, which derives its technical superiority from advanced
methods in real-time data processing and precision satellite navigation.</p>
<p>Due to a high level of software support in the system, operation of
the system is simple, easy to learn and allows the flight inspector to
focus on the assessment of the measured data. Several multi-tasking
features allow to save flying time with the equipment and to maximize
productivity of the available flight inspection aircraft. High emphasis
was placed on crew co-ordination in the flight inspection aircraft, which
is improved through flight inspection displays in the cockpit and
autopilot coupling.</p>
<h2>Operational Concept</h2>
<p>The flight inspection procedures of the AD-FIS for the calibration of radio
air navigation stations are based on the ICAO recommendations (DOC 8071),
CAP 670, the FAA flight inspection manual and correspond to the requirements of
NATO STANAG A Et P-1(B).</p>
<p>The system is entirely operated from an operator console with two colour
liquid crystal displays (LCD), keyboard with function keys, trackball and
audio control. The navaid inspector selects the procedures, output selection and
, most important, data analysis. The FIS computer will perform most other system
management tasks, such as receiver switching, frequency tuning and position
reference selection. It is configured for this purpose by an extensive database
including a detailed facility library. System operation has been designed to
reduce operator workload to a minimum and to present the required information
in a clear and easy to interpret manner. Particular attention was paid to
consistent operator action throughout all calibration tasks.</p>
<h2>System Description</h2>
<p>A block diagram of the ADFIS system follows this section. The ADFIS system consists
of the following subsystems:</p>
<ul>Flight inspection receivers</ul>
<ul>Position reference system</ul>
<ul>Data processing equipment</ul>
<ul>Operator console</ul>
<ul>Aircraft interfaces</ul>
<p>The FIS computer reads digital and analogue data from the flight inspection
receivers and the position reference system, normally via ARINC 429 data bus.
The genuine sensor data is directly recorded on a mass storage unit, which allows
its complete reprocessing without any loss of information. Simultaneously to the
recording process, the data is used to calculate station parameters such as errors
and mean values. Output to a printer is generated via standardized Centronics
printer interface.</p>
<p>A hard disk drive in the mass storage unit contains the flight inspection software
and the database. The database, which includes data acquisition channel assignment,
map data and a facility library, which, is maintained by Flight Precision Limited.</p>
<p>The map data for the display screens is generated on the basis of digital map data
from Jeppesen.</p>
<p>The FIS configuration includes the following flight inspection receiver set:</p>
<ul>Dual Nav-receiver for ILS and VOR calibration</ul>
<ul>Marker receiver</ul>
<ul>TACAN interrogator for TACAN calibration</ul>
<ul>DME interrogator for DME calibration</ul>
<ul>ADF</ul>
<ul>Transponder</ul>
<ul>VHF and UHF, radio Oscilloscope</ul>
<ul>Spectrum Analyser</ul>
<p>The AD-FIS is supplied from an interface panel in the cabin, such that no complex
modifications have to be performed on the aircraft.</p>
<p>The data from the position reference sensors is also transmitted in digital form
to the computer and processed there to calculate the reference positions. An UHF
telemetry link serves as a data up-link from the deployable ground equipment.</p>
<p>Independent VHF and UHF radios as well as intercom allow the flight inspector to
listen in on the cockpit conversations and to communicate with the ground personnel.
Audio signals from the receivers can be switched to the intercom to verify proper
identification codes of the navigation stations.</p>
<p>The FIS computer is equipped with a digital IEC bus controller, such that the
system can automatically be calibrated and can control supplementary equipment
such as a spectrum analyser.</p>
<h2>Position Reference System</h2>
<p>The AD-FIS includes an option of position reference equipment, which can meet
any operational requirement of approach aid calibration:</p>
<ul>Laser tracking coupled with INS and barometric altimeter</ul>
<ul>Differential GPS</ul>
<p>Each variant has its individual strengths and advantages in a
specific operational environment.</p>
<p>For en-route calibration, the AD-FIS relies on a coupled system of
GPS and baro altimeter. This system is fully ground independent and allows
in combination with the AD-FIS software features the substantial reduction of
en-route flying hours.</p>
<p>For ILS the laser tracking system is currently the most accurate and proven
system. It achieves a repeatable positioning accuracy at the threshold of
better than 15 cm.</p>
<p>The laser tracker is set up next to the runway in the vicinity of the glide
path antenna and hence does not interfere with regular air traffic during the
calibration.</p>
<p>The laser tracker operates in the near infrared band and only requires a
passive set of prism reflectors on the aircraft, which are installed in form
of a removable reflector.</p>
<h2>Antennas</h2>
<p>The following set of antennas is installed on the calibration aircraft:</p>
<ul>Combined LLZ/GS U-dipole antenna</ul>
<ul>ILS Loop antenna</ul>
<ul>L-Band antennas</ul>
<ul>ADF-antenna</ul>
<ul>VHF/UHF communication antenna</ul>
<ul>GPS antenna</ul>
<ul>Telemetry antennas</ul>
<h2>On-Board Data Processing Equipment</h2>
<p>Beyond the flight inspection receivers, the on-board data processing
equipment includes the components of the telemetry package and the
data processing system. The on-board data processing unit comprises an
airworthy computer AERODATA AD-VC6 in the size "1 1/2 ATR short" according
to the ARINC specification 404A. The computer is based on the Motorola
processor 68060 and is designed almost completely in CMOS technology. It
consists of the following components:
<ul>CPU 68060 with 2 Mbytes EPROM, 32 Mbytes RAM and 2 serial interfaces
RS-422 and RS-232, respectively</ul>
<ul>Multi purpose time management and digital/analogue I/O interface ARINC-429
interfaces</ul>
<ul>Analogue interface with 16 channel 12 bit A/D converter</ul>
<ul>Transputer Module with INMOS T800</ul>
<ul>SCSI-Bus interface</ul>
<ul>Digital multi purpose bus interface</ul>
<ul>High-speed oscilloscope card</ul>
<ul>2 Colour Display Controllers</ul>
<p>The oscilloscope card represents a high-speed digital signal buffer, which
can record video signals following a trigger impulse. Data in the buffer can
be displayed on the LCD-screens. The card fulfils the function of a two-channel
digital memory oscilloscope.</p>
<p>The mass storage subsystem AD-MS 2 is equipped with a 2 GB fixed disk drive
for the operating system and MODAMS-FI, a magneto optical drive which is used
for the storage of flight inspection results and a 1.44 MB floppy disk drive
for software transfers.</p>
<h2>Ground-Based Equipment</h2>
<p>The ground-based equipment includes</p>
<ul>DGPS ground reference station</ul>
<ul>Laser tracking system with ground station</ul>
<p>The DGPS ground reference station is integrated into a transportable box
for easy deployment at the various airports.</p>
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