Bendix-King KLX-100 GPS/COMM Flight Review
Richard Kaplan
the mail this week -- actually, it came UPS 2nd Day Express after
I waited over six months for its arrival :-). The GPS cost $1195
from Aircraft Spruce and Specialty.
I first decided to buy a handheld GPS in August 1995, primarily as
a backup in case of electrical failure while IMC and secondarily as
a navigation backup during VMC conditions. Since IMC flight is my
primary concern, I chose the GPS/COMM unit because I felt that the
ability to communicate, or at least to receive weather reports, is
a high priority for IFR flight, second of course only to
*aviation* and *navigation*.
As many of you may realize, this is currently the only available
combination GPS/COMM, which made the selection easy. On the other
hand, production was delayed by months apparently for technical
reasons causing interference between the GPS and the COMM. In the
interim since I placed my order, I was tempted to order the Garmin
GPS-90 for its pseudo-IFR-approach features, and I was extremely
tempted to purchase the new Lowrance AirMap for its apparently far
superior map... but the more I think about it, even though the
visual appeal of a nicer screen such as on the Lowrance cannot be
argued, I cannot see any more *utility* which I would obtain from
that model. A moving map helps to orient me while maneuvering on
approach (which the KLX-100 does fine) and the main function of the
GPS is to give me a constantly updated distance, bearing, and
groundspeed relative to my destination (which the KLX-100 also does
fine). Being able to identify the names of interstate highways as
I pass over them is a neat feature (especially for passengers), but
if I am ever in the soup with no electrical system and
near-minimums weather, I'd gladly trade fancy graphics for
reception of ATIS weather and/or vectors to an ASR approach. [Yes,
your mileage may vary... I suspect there may be much debate in
rec.aviation.* and the aviation press re: the KLX-100 vs. the new
Lowrance unit as the current "hot" GPS.]
Anyway, onto the unit... It weighs 1.7 pounds with batteries and is
quite compact. A headset adapter and external antenna are
included; the unit works fine outside with the internal antenna,
but the external antenna is required in a car or in an aircraft.
During a 2 1/2 hour flight, I lost GPS navigation only once
for 10 seconds while using the external antenna; this may have been
due to my home field's location in a valley near the Allegheny
mountains. Battery life (8 AA cells) according to the book ranges
from *18* hours in GPS-Only mode to 4 Hours 15 minutes with fairly
intensive use of GPS/COMM combined. In GPS/COMM mode, the system
will not allow transmission when less than approximately 2 hours of
battery time remains; only COMM reception and GPS navigation are
functional. In my experience, the transmitter was cut off 1 1/2
hours into a 2 1/2 hour flight of multiple approaches; perhaps this
was because I used alkaline rather than Lithium batteries, as
suggested for optimum performance.
The GPS functions are comparable to some of the very early
moving-map units, e.g. a relatively small screen with limited
graphics and with the potential for screen clutter unless the range
is set appropriately. Again, however, I do not see any
*functional* limitations to this; I was able to quite easily orient
myself in relation to all nearby airports and quickly obtain a
bearing and distance to each. Moreover, the database includes the
COMM frequencies for all airports and, thus, it is possible not
only to locate the nearest airport but also to quickly tune
the communication frequency at that airport and announce an
emergency landing... a very nice feature. Other COMM and NAV
features also integrated into the database include
location-sensitive Fight Service Station, Center, and NOAA Weather
frequencies... again very nice in an emergency.
An interesting feature which I found to be quite helpful is a
simulated HSI indicator which simultaneously displays actual
aircraft track on a simulated DG, desired aircraft track in the
form of a heading bug, and a CDI needle. When flying a
conventional VOR-driven HSI, aircraft heading is matched against
desired aircraft track; here, aircraft *actual track* is matched
against desired aircraft track. I found therefore that it was
possible to compensate for changing winds aloft more
quickly than with a VOR alone; wind correction becomes intuitive,
even with a partial panel simulation in the rest of the aircraft.
This simulated HSI is useful enough to make this GPS unit quite
helpful in the event of vacuum failure as well as electrical
failure. The response is sufficient to allow a relatively
no-stress approach with no aircraft DG or AI. [With my
safety pilot present], I even tried an approach without *any*
gyros, e.g. with the AI, DG, and turn coordinator covered... I had
to lower the gear in my Mooney to keep things reasonably under
control, and on a couple of occasions I approached 60 degrees of
bank due to the lag time in the system... but, if this *ultimate*
IFR emergency did occur, I do believe very much it would be
possible for me to fly enroute to VFR weather using only the GPS;
an approach would be a possibility, but one only to be left as a
drastic no-other-options out.
The database in the unit includes hard- and soft-surfaced public
use airports in the Americas as well as VORs. NDBs are not
included; however, up to 500 user waypoints can be programmed in
either by latitude/longitude or by radial/distance from any other
waypoint; I was able to program in the NDB for my home field, for
example, using radial/distance information from the approach
plate. Updates are available at an extra cost [specific price not
mentioned in the documentation] and must be downloaded from an "IBM
Compatible" computer via a proprietary RS-232 cable [again specific
price not mentioned in the documentation].
Overall, I would recommend this unit highly for an instrument pilot
seeking utility in an emergency. For a VFR pilot who might want a
true "map" like display, one of the more graphics-intensive
competing units might be more appropriate. I suppose the ultimate
compromise might be the new Lowrance AirMap GPS and a separate
handheld COMM transceiver, but I suspect that might get to be a bit
much to handle in an emergency, not to mention keeping track of
battery replacements.
----------------------
Richard S. Kaplan, M.D. CFI/AME Mooney N9688M
Uniontown Medical Rehabilitation
500 West Berkeley Street
Uniontown, PA 15401
Phone: (412) 430-5340
Email : rka...@pennet.com