Sandel Avionics, Vista, Calif., has gained TSO and Part 27 supplemental type certificate (STC) approvals for its ­class-A HeliTAWS helicopter terrain avoidance and warning ­system, which includes a proprietary nuisance-alert elimination feature and high-resolution 3-D terrain display.

The first HeliTAWS fleet installation is for Agusta 109s flown for North Memorial Medical Center, Robbinsdale, Minn. MSP Aero of Minneapolis–an FAA-approved repair station specializing in helicopter and business jet avionics including 800-MHz (P25 compliant) radios, Waas-capable GPS upgrades and STC development–is doing the installations under Sandel’s recently issued STC.

The HeliTAWS is designed to increase the safety of demanding helicopter missions such as helicopter emergency medical services, offshore operations, tactical military support, search-and-rescue and airborne law enforcement. According to Sandel, HeliTAWS exceeds requirements governing en route helicopter TAWS. The ruggedized, self-contained system’s display directly replaces existing radar altimeter indicators.

The company, which is demonstrating the HeliTAWS system at its booth here (No. 4127), claims its TrueAlert technology increases pilot confidence in terrain avoidance by eliminating nuisance alerts, a significant problem with other terrain-warning products that limits their usefulness in helicopter operations. With TrueAlert, Sandel says, pilots can safely take off, cruise, hover and land at off-airport locations without triggering nuisance alerts while still receiving class-A terrain warnings during the entire flight. The system requires no in-flight pilot management.

“We wanted to develop a breakthrough that would significantly raise the bar on HTAWS performance and expectations,” said Gerry Block, Sandel’s president. “The universal complaint with all existing systems has been that during normal helicopter missions the pilot gets unnecessary and distracting alerts. In contrast, HeliTAWS completely eliminates nuisance alerts.

“The difference with HeliTAWS,” he continued, “is that our system works exactly as the pilot expects in all phases of flight. This includes the capability for off-airport landings in terrain-challenged environments, which was quite a technical design achievement.”

The self-contained 3-ATI panel-mounted HeliTAWS incorporates an HTAWS computer, terrain and obstacle databases, plus configurable interfaces for digital and analog avionics. It can serve as a primary radar altitude indicator compatible with virtually all radar altimeter systems. It can also display TCAS, TAS or TCAD traffic.