Avionics News August 2015 - 46

CAPABILITY,
GIS 25 years' experience provides
quality service of instruments, specializing in altimeters, panel mounted
and remote gyros, including:
KCS55A SYSTEM
KCS305 SYSTEM
KI-256
KEA-346
KVG-350
PN101 SYSTEM
332D-11 SERIES
DGS-65
C-14 SERIES

510 SERIES
NSD 360 SYSTEM
1100 SERIES
1200 SERIES
205 SERIES
4300 SERIES
5000 B SERIES
4000 B SERIES
VG-14 SERIES

RELIABILITY,
Experienced and trained technicians embody a dedicated focus to the customer
expectations that is key to GIS reliability
and customer service. An investment
in updated technology and equipment
enables efficient operations. A family atmosphere is fostered at GIS that insures
the shop runs as a team effort. It is reminiscent of what customers embraced in
the aviation industry years ago.

QUALITY.

Competitive prices, high-quality workmanship, quick turnaround time and
service. GIS personnel have the ability
to meet that challenge to exceed customers' expectations every day. That's
why customers depend upon GIS
full services, from testing, overhaul,
and repairs to exchanges and outright sales.
Try us, you'll be glad you did!

GEORGETOWN
INSTRUMENT SERVICES
FAA CRS# GTNR482X
210 Airport Road * Taylor, Texas 76574

512-352-9000

www.georgetowninstruments.com
4 6

AVIONICS NEWS

AUGUST

2015

SEEING CLEARLY

Continued from page 45

No, manufacturers aren' t marketing their EV S as a traffic-alert or collision-avoidance tool; but when it shows the hot cowl of a white airplane against a flat-white
sky, well, you' re glad to see what that heat-sensing camera sees.
Especially when the EV S beats your own eyeballs and helps the pilot visually
acq uire the traffic - another tool in the cockpit.
THE UNBLINKING EYE
M ost of today' s EV S systems employ thermal imagery based upon infrared
sensors, or " micro bolometers." The sensors are sensitive to heat and can detect
temperature variations smaller than one-tenth of 1 degree Celsius. D epending on
the micrometers design, EV S sensors may be sensitive to long-wave infrared, shortwave infrared or mid-wave infrared energy.
The sensors detect infrared light waves in the range between 900 microns to
1 ,700 microns - a range where the IR penetrates fog and mist with little distortion.
EV S systems deliver daylight-like images from the temperature differences
detected. This allows an image in total darkness, low visibility, smoke, haz e, smog,
dust and light fog - anywhere thermal energy from obj ects is able to penetrate the
density of the atmospheric particles when they are smaller than 1 2 microns.
Conversely, EV S suffers from some limitations in heavier atmospheric conditions
or when the environment does not have thermal variation ( or contrast) that is necessary to present a temperature-based image.
On rare occasions, something known as " thermal crossover" happens when
something passes through in the sensor' s field of view with the same thermal gradient. This makes those obj ects fade to very low contrast, possibly even brief invisibility. It can happen during a period of clear-sky V FR operations.
H eavy rain and cloud cover also may neutraliz e EV S, depending upon sensor
mounting location, airspeed and airflow. One installer likened this phenomenon to
driving your car during a downpour rain without operating wipers.
Of course, weather avoidance practices can help preclude that situation from arising while still delivering on multiple benefits.
EVS VERSUS SVS - AND OTHER TECHNOLOGIES
Synthetic vision systems, or SV S, have grown to arguably become one of the
most-popular options available to pilots flying glass cockpits - or using any number
of portable devices with the proper software.
Glass cockpits across the spectrum from non-TSO' d systems for ex perimental
and light-sport aircraft offer varying levels of SV S. The day, V FR -like view of the
world is a significant advance for the pilots who embrace the technology - a software update for many of these systems.
U sing navigation and positional information from a GP S or inertial reference systems, the SV S system delivers a moving image only as accurate as the most-current
software update to the database. The database may be only days old - or weeks,
even months old.
The EV S image, conversely, is real-time, reflecting what the sensor " sees" right
now. The image is never out of date.
W here an SV S image shows the end of a runway - as of the date the data in the

http://www.georgetowninstruments.com

Table of Contents for the Digital Edition of Avionics News August 2015