gerous drift in dust. Army Apache pilots
use AH-64 hover symbology to make
brownout landings, and similar cockpit
cues have migrated to Air Force cockpits.
The Rockwell Collins Common Avionics
Architecture System (CAAS) in new Chinooks incorporates symbology developed
for the AATD Brownout Situational
Awareness Upgrade (BSAU). BSAU
velocity vector, acceleration cuing, radar
altitude and vertical speed symbology
helped test pilots make brownout landings at Yuma in 2004 and appear on the
CAAS displays in the operational CH-
47F and MH-47G. CAAS is also part of
the UH-60M upgrade of the Army Black
Hawk, and derivative displays will go into
the aging Marine CH-53E and new fly-by-wire CH-53K.
To provide motion cues to pilots in
brownout, the Dutch National Aerospace
Laboratory is investigating helmet displays, and the Dutch contract research
organization TNO has experimented with
vibrating belts. TNO’s “Fly Tact” is a
vest and belt with “tactors,” vibrating elements like those used in mobile phones.
Cuing symbology also works with
integrated flight controls to enhance
stability in brownout. The Air Force
Special Operations Command upgraded
MH-53M Pave Low and HH-60G Pave
Hawk helicopters with an Altitude Hold
Hover Stabilization system and improved
cockpit symbology. Marine MV- 22 and
Air Force CV- 22 tilt rotors have flight
path vector displays that let crews make
brownout landings manually with cues
on the hover indicator or automatically
using the fly-by-wire hover-hold function.
The baseline UH-60M Black Hawk
now in production has a coupled autopilot, and the UH-60M Upgrade in test
introduces fly-by-wire to better stabilize
DVE approaches and landings. Boeing
Chinook engineers, meanwhile, claim the
BAE Digital Automatic Flight Control
System in the CH-47F achieves nearly the
same results at lower cost. With an automatic departure mode, DAFCS is already
credited with saving lives when pilots lost
spatial orientation in brownout.
Hover symbology and enhanced flight
controls nevertheless do nothing to avoid
landing zone obstacles hidden by dust
clouds. In 2006, the AFRL tested the
Photographic Landing Augmentation
System for Helicopters (PhLASH) on a
Hawk, and derivative displays will go into
Photo courtesy DARPA
Pave Low MH-53M. Applied Minds Inc.,
of Glendale, Calif., built a gimbaled, 16
Mpixel camera with an infrared strobe
and laser rangefinder to image the landing zone before entering the cloud. The
pilot saw a clear picture of the LZ as it
was 20 to 30 seconds before landing, geo-registered on the real world with a GPS
receiver and inertial measurement unit.
The see-and-remember PhLASH had
the resolution to spot small obstacles but
could not show hazards entering the LZ
after brownout occurred.
Brownout initiatives now look to
integrate see-through sensors with synthetic vision displays. Though AFRL
tests showed mid- to long-wave Forward
Looking Infrared (FLIR) sensors had
twice the dust-penetrating performance
of electro-optical cameras, the 3-to- 5
micron or 8-to- 12 micron targeting and
navigation FLIRs on combat helicopters
are essentially blind in brownout. Successful brownout tests have used millimeter wave radar and ladar to paint a
landing picture.
Radar Returns
Clear-air Phase II tests of the Sandblaster
brownout system in January 2009 showed
synthetic vision integrated with milli-
meter wave radar and fly-by-wire flight
controls could indeed bring pilots to safe
brownout landings. Limited by safety
rules on the AFDD Black Hawk, the
Sandblaster system took the helicopter
to a 25-foot hands-off hover in simulated
brownout at Moffett Field, Calif., and
showed landing zone obstacles on a head-
down display.
Sandblaster hover display shows low-speed flight symbology on Honeywell
SLEEK synthetic vision terrain display.
