Sandel’s helo Taws nears certification finish line

 - January 27, 2010, 11:42 AM

Sandel Avionics is concluding certification flight testing of its helicopter-specific terrain awareness warning system and plans delivery of the $18,950 H-Taws shortly after TSO issuance and certification, expected by early April. Sandel president Gerry Block told AIN that with radio altitude and air data computer inputs the panel-mounted H-Taws will meet or exceed performance of any current Taws for helicopters. Like previous Sandel instrumentation, it is form and functionally interchangeable with existing 3-ATI indicators, including radar altimeter displays in rotorcraft panels.

On a recent flight in a Eurocopter AS350B2 AStar from Palomar-McClellan Airport, near Sandel’s Vista, Calif., plant, the H-Taws demonstrated versatility and a variety of display modes with the bright color, high image resolution, direct sunlight viewability and wide viewing angle that have become Sandel panel instrument hallmarks. Afterward, Block said “development software” contributed to the system’s impressive performance. He added, “We’re still tweaking and refining it.”
He said Sandel has been testing newly developed software to provide discrete guidance for both terrain awareness and preparation for intentional landing on uneven ground at remote sites.

Sales director Jerry Henry said the Sandel H-Taws has a $3,250 option for night vision illumination system (NVIS) display lighting with completely unrestricted daylight visibility. Another option will make the H-Taws a primary TCAS or traffic advisory system (TAS) display for an additional $980.

Calling it “the only fully self-contained TSO C194 and TSO C151c compliant H-Taws system,” Block said Sandel has achieved its primary objective to virtually eliminate nuisance alerts. “Eliminating invalid alerts is much more complicated in the helicopter,” he observed, defining a valid alert as occurring only when a threat actually requiring pilot action is detected.

Block said, “We spent a great amount of time on the fixed-wing nuisance alert issue and we’ve tried to take all that technology into the helicopter arena, which has a different set of requirements.” The unit combines both H-Taws and ground proximity warning system (GPWS) functions in the 9.8-inch long 3-ATI indicator featuring Sandel’s patented LED high-resolution rear projection backlight technology.

The Sandel H-Taws will interface with any Waas-capable GPS and, with an air data computer, provide full Class A-equivalent reporting. Although radar altitude is not a TSO C194 requirement, where installed it can provide GPWS functionality by refining descent and hover alerting algorithms. Block noted that the H-Taws terrain map has “a very high resolution, three-arc/sec. horizontal [300-ft. grid],” with sharply defined regionalized obstacle databases. He added that obstacles such as broadcast antennas and power lines are shown separately with one-foot vertical resolution.

Regarding the Sept. 27, 2008, crash in IMC of a Maryland State Police Eurocopter Dauphin 3.2 miles north of Andrews AFB that killed three of the four people aboard, Block stated, “Unquestionably the [H-Taws] system would have alerted the pilot and saved that aircraft if it had been aboard.” The system’s GPWS function would have generated most of the alert, he explained, noting that when GPWS is present in the Taws solution the system goes beyond the en route protection required by TSO C194.

The extent to which a helicopter Taws exceeds the TSO-specified en route protection, such as enhancing safety in low-altitude maneuvering and operations, will be the discriminator between products from different manufacturers, Block predicted.