HTAWS to be mandated on all EMS helicopters

FAA says only TSO'd equipment meets required specs.

By Stuart Lau
ATP/FE/CFII. Boeing 747, 747-400, 757/767, CRJ, Saab 340

HTAWS holds the potential to reduce fatal CFIT accidents. Several integrated avionics systems use licensed software technologies from companies such as Honeywell, Sandel and Thales. Honeywell and Sandel offer retrofit solutions.

In Apr 2, 2012, FAA released draft guidance outlining the technical requirements for a widely expected mandate that will require the installation of terrain awareness and warning systems (TAWS) on all helicopter EMS (HEMS) aircraft.

Accordingly, the release of draft AC 27-1B and AC 29-2C is a clear signal that the final ruling could be released as soon as July this year. The final hurdles are reviews by both the US Dept of Transportation and Office of Management & Budget—steps that typically result in delays of up to 12 months.

The draft documents state that a helicopter TAWS (HTAWS) is requir­ed for helicopter air ambulance operations under 14 CFR Part 135 (Subpart L–CFR 135.605). Compliance is assured by employing systems that meet or exceed the minimum standards set forth in the existing FAA TSO C194 and RTCA DO­309 documents.

First published in Dec 2008, TSO C194 is the helicopter equivalent and more general version of fixed-wing TSO C151b. RTCA DO309 outlines minimum operational performance standards (MOPS) for HTAWS.

The timeline for this rule change predates a 2006 NTSB special investigation report (SIR) on EMS accidents in aviation. During this timeframe, the EMS aviation industry was experiencing rapid growth, both in the number of aircraft flown and, unfortunately, in the frequency of fatal accidents. Of the 55 accidents analyzed in the NTSB SIR, 75% involved helicopters.

As a result of this investigation, 4 recommendations—3 operational, with the addition of HTAWS equipage—were made to FAA. Adoption of these recommendations, according to the NTSB study, had the potential to affect the outcome of nearly 50% of the accidents in a positive way.

By the end of 2008—the industry's worst year—there had been an additional 15 accidents and 35 more fatalities. This marked increase in HEMS accidents and fatalities combined with inaction by FAA prompted NTSB to add these original 4 recommendations to its "Most Wanted List of Transportation Safety Improvements."

Another industry study, conducted by Honeywell Aerospace, suggests that in 2008 nearly 50% of HEMS accidents and fatalities could have been prevented using HTAWS equipment. Collisions with terrain, obstacles and wires continue to be a steady killer in this segment of aviation.

Following an unprecedented 4-day NTSB public hearing on HEMS safety in Feb 2009, FAA finally did act. During an Apr 22, 2009 testimony before the House Committee of Transportation and Infrastructure, FAA Dir of Flight Standards John Allen announced that the agency had initiated the formal rulemaking process that would address several key industry best practices—including HTAWS—to raise the bar on helicopter safety.

In the NPRM released in Oct 2010, the agency initially targeted all commercially operated helicopters for HTAWS, but now it says, "The agency believes the greatest benefit would be realized by helicopter air ambulance operators because a much greater percentage of their operations are conducted at night and in off-airway routing and involve un­improved and unfamiliar landing areas."

Once the rule is finalized, nearly 1000 HEMS aircraft will be required to be TAWS-equipped within 3 years. FAA documents indicate that 41% of the current HEMS fleet has TAWS equipment. Retrofitting aircraft with TSO-compliant HTAWS equipment costs anywhere from $19,000 to $55,000 per aircraft—not including installation and down time—depending on the system selected.

Unfortunately, since FAA does not oversee public use aircraft, this rule will not apply to the 40 "orphaned" HEMS operators. Operators of public use fleets will have to continue to install HTAWS voluntarily. Major public use fleets include the National Park Service, Maryland State Police and Los Angeles Fire Dept. (See sidebar on p 99.)

Risky business

Sandel's ST3400H HeliTAWS offers protection from terrain, obstacle and wire strike threats and is the only TSO C194 compliant panel-mount solution. Rockwell Collins has chosen Sandel's HeliTAWS software for use in its rotorcraft-integrated avionics system.

As highlighted above, this focus on HEMS operations is warranted. In a study commissioned by the University of Chicago Aeromedical Network, Ira Blumen and his team of researchers concluded that the death rate of HEMS crews is 9 times greater than other risky occupations such as mining and agriculture.

Death rates among aeromedical crews are 50 times greater than all other industries, according to the National Safety Council.

The past 10 years of accident statistics substantiate these claims. Since 2003, there have been on average 12 fatal HEMS accidents per year—or 1 fatal accident every month.
In addition to NTSB, many industry groups support the installation of terrain and obstacle avoidance equipment on HEMS aircraft.

The Intl Helicopter Safety Team (IHST), Flight Safety Foundation, Air Medical Physician Assn and Air Medical Operators Assn all support the use of HTAWS technologies to mitigate the CFIT threat.

Fixed-wing operators using TAWS/ EGPWS have all but eliminated the threat of CFIT in their operations. Airlines began using early GPWS in the late 1960s and the more advanced "forward looking" EGPWS in 1996.

Since 2000, FAA has mandated TAWS on all turbine-powered fixed-wing aircraft with 6 or more passenger seats. The first HTAWS were introduced to the rotorcraft community in 2001. Four years later, FAA began recommending voluntary TAWS equipage for helicopters operating at night and in certain operations.


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