The US National Transportation Safety Board has elevated the issue of emergency medical services helicopter safety, adding the topic to its list of high-priority safety improvements and preparing a three-day hearing on the topic in February.
At a 28 October annual meeting in Washington to review the status of its "most wanted" safety improvement list, board members justified the critical ranking by noting that there had been seven fatal EMS crashes, resulting in 28 deaths already in 2008, up from the two fatal crashes both in 2006 and 2007. The most wanted list is a metric the NTSB created in 1990 to track solvable issues with the greatest impact on all modes of travel.
NTSB attempted to boost EMS safety with a series of recommendations to the US Federal Aviation Administration in 2006 after completing a special investigation of 55 fixed-wing and helicopter EMS accidents. Officials determined that 29 of the accidents could have been prevented with the use of enhanced procedures, including flight dispatch oversight and risk analyses before each flight, in addition to technological solutions like helicopter terrain awareness and warning systems (HTAWS). Four recommendations followed the release of report, none of which have yet to be fully closed out by the FAA.
Perhaps the most effective intervention available is HTAWS. the NTSB says the technology may have helped pilots avoid terrain in 17 of the 55 accidents analysed in the 2006 report. The FAA for its part launched an RTCA committee that year to create minimum operational performance standards for HTAWS, work that was completed in March. In next few months, the FAA expects to publish a technical standard order for the equipment, which will likely be followed later by a rulemaking to mandate HTAWS.
Honeywell, a key provider of HTAWS, has shipped 1,100 units to date for installation into a wide range of helicopter models using supplemental type certificates. Sikorsky includes the units as standard equipment in its S-92 and S-76 helicopters. Based on its fixed-wing enhanced ground proximity warning system, the helicopter system is modified to account for the unique rotary wing operating environment.
Changes include eliminating low-altitude warnings - below 750ft (229m) above ground - when airspeed is below 60kt (111km/k) and not in the vicinity of an airport, a combination that indicates the helicopter is probably landing. Above 70kt however, the alarms sound. Along with terrain, Honeywell's database includes all obstacles higher than 30.5m above the ground.
Source: Flight International
