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Monday, February 1, 2010

Safeguarding HEMS

Obstacle and terrain awareness equipment, night-vision goggles are among recommended avionics for Helicopter Emergency Medical Services (HEMS)

By Ernie Stephens

Emergency medical services operations are inherently riskier than other commercial air missions, particularly where helicopters are concerned. Consider the job of helicopter emergency medical services (HEMS) pilots. Unlike most other aviators in a non-military role, HEMS pilots receive calls for immediate launches that involve life and death situations. They must race to a location they have never been to before, land in a place that was not designed to handle aircraft, board at least one injured person, then get the patient to a hospital. Throw in the complications of darkness, rough terrain and unexpected weather conditions, and you have a recipe for disaster. The icing on this very dangerous cake is the stress of knowing that someone might die if the crew turns down a mission.


With the exception of short-lived downturns interspersed over the years since civil HEMS operations took root in the 1970s, the above circumstances conspired to create an overall upward trend of fatal and near-fatal accidents. Helicopters — often with patients aboard — were crashing into terrain, striking communications towers and clipping power lines at a rate higher than other air operations. They were encountering unexpected cloud cover, overshooting landing zones, and in some cases, colliding with other aircraft.

As the HEMS death toll rose, the National Transportation Safety Board (NTSB) made a number of safety recommendations to FAA, the National Weather Service and two associations that addressed training, crew fatigue and operating rules. Conspicuous in the most recent set of recommendations was a call for greater use of the latest, safety-enhancing avionics.

The list of avionics equipment capable of enhancing safety in those areas identified by the NTSB is relatively short, but the items appearing on it have been warmly welcomed by the men and women who fly HEMS missions. Some are brand new technologies. Others are old technologies that have been upgraded. The most sought after gear for answering the NTSB’s concerns, however, are listed below.

Obstacle Avoidance Equipment. The past 15 years have seen a remarkable increase in obstacle avoidance technology. Engineers are now programming exact locations of manmade obstacles into databases that, when coupled with an onboard GPS, can give the pilot real-time information on what lays in his path, regardless of what he can see outside of the window.

Some may question the need for an expensive upgrade to a new GPS unit just for obstacle clearance information when FAA sectional, terminal area and helicopter route charts depict the same information. But the issue is with accuracy. FAA charts depict upward of 50,000 obstacles to flight that have a height of 200 feet or greater above ground level. But during the six months between chart updates, new towers may have gone up, old ones may have come down, and inadequate towers may have changed size.

In addition, charts sometimes depict obstacles in a slightly different place than they are in the real world in order to accommodate other chart features, such as lettering and symbol placement. That half-of-a-mile difference between where a tower is charted and where it truly is could be critical to a HEMS driver.

The ability of the latest GPS equipment to accurately blend the position of aircraft with the location of obstacles makes the equipment very desirable for HEMS operations. And with a variety of software options and updates available to the consumer, a pilot can have the most recent hazard information available for any location within thousands of miles at his or her fingertips, rather than a limited stack of outdated charts stuffed between the seats.

Helicopter Terrain Awareness and Warning Systems. Like obstacle avoidance, terrain avoidance is critical to the safety of HEMS flights.

The nature of the HEMS beast is to fly around unfamiliar territory at any time of the day or night. In fact, some operators find that the majority of their emergency medical calls are received during the hours of darkness, when a mountain ridge hidden under a featureless sky can eat a helicopter and all aboard.

Aeronautical charts depict mountainous terrain, but not with the kind of detail a HEMS pilot needs. And while helicopter terrain awareness warning systems (HTAWS) have been giving valuable information to pilots for many years, the heightened safety of the newest systems is what the HEMS aviator desires.

Today’s HTAWS gear not only finds the distance between the aircraft and the ground (or water), but crunches topographical data software and GPS information to create a rich, colorful image of the surrounding terrain on a cockpit display and gives an aural warning of potential danger; the perfect tool for the low-level flight profiles flown by HEMS aircraft. ➤ Weather Radar. Inadvertent flight into meteorological conditions is a leading factor in many HEMS crashes. Although experts will argue that pilots should not let the need to transport a severely injured person cloud their aeronautical judgment, the undeniable fact is that many pilots will roll the dice with enroute weather conditions to help someone get to a hospital. And while most aviators have the experience to reasonably assess weather conditions, even the best can be dealt a surprise once airborne.

For decades, airborne weather radar has been standard equipment on high-end corporate planes and airliners, but not so much on their low-flying rotary-wing cousins. Historically, owners have been reluctant to put weather radar on helicopters for reasons of cost versus necessity.

Helicopters have traditionally been short haul aircraft. Their missions and limited ranges are such that the weather at the point of departure will probably be the same as the weather at the destination. And if bad weather materialized during such trips, the pilot often took advantage of the generous Helicopter VFR Minimums to maneuver closer to clouds and in poorer visibility than airplanes. And if worse came to worst, the pilot simply found a small field and set down until the foul weather passed.

HEMS operators, however, acknowledge that their mission legs — frequently as long as 100 nm out — can place their aircraft in more than one type of weather environment. Weather radar, while not the end-all-beat-all answer to avoiding all kinds of meteorological hazards, became a practical piece of equipment for medical service helicopters.

Autopilots. Though not specifically recommended by the NTSB for improving HEMS flights, studies show that when a pilot becomes saturated with other cockpit issues, he or she can fail to maintain positive control over the aircraft. In the worst cases, pilots have flown the aircraft into the ground while trying to look up radio frequencies or flip through charts.

Autopilots, while not a substitute for an attentive pilot or a second aviator, have made it to the HEMS pilot’s wish list of safety items. They are expensive, and have been known to make pilots complacent, but most agree that autopilots coupled to flight directors are a handy tool in the single-pilot cockpit.

Night Vision Goggles. For decades, night vision goggles (NVGs) have been commonplace in military helicopter aviation. Put simply, NVGs amplify existing light, allowing soldiers to see features in the nighttime environment that would otherwise have gone undetected. Like magic, pilots could see and avoid towers, buildings, power lines and other aircraft, plus locate ground personnel and clear landing zones.

The NTSB has gone on record with its belief that widespread NVG use in the HEMS community will significantly enhance safety, but some pilots are not so sure. First generation NVGs, which saw wide service in the 1970s and 1980s, provided the wearer with a brilliant green image that had a tendency to cause night blindness in the wearer once the goggles were removed, a condition that could last as long as 20 minutes. Pilots were reluctant, if not solidly against, using NVGs if there was a risk of not being able to see immediately after coming off of them.

Pilots also were afraid of a phenomenon called whiteout, which occurs when any bright light, such as a street lamp or automobile headlight, enters the goggle’s field of view. The result was the equivalent of staring into two flashlights being held inches from the eyes. It was impossible to see anything while the offending light was present, effectively making the NVGs useless in an urban environment.

Fortunately, today’s NVGs do not significantly ruin one’s night vision. And with technology that makes split second adjustments to account for changes in light, they dampen bright lights before they can cause whiteout.

NVGs, however, represent an expensive upgrade for many operators. Between the cost of the goggles, helmet mounts, batteries and instrument panel modifications, the price tag can reach well into the six-figure range for one aircraft and crew. But even so, NVGs are seen by many as the Holy Grail of safe flying for the HEMS pilot after sundown.

Flight Data Management Systems. While not exactly on the wish list of pilots, HEMS operations managers have joined in the concern expressed by NTSB and FAA that pilots may not always follow prescribed practices that encourage safety. To help monitor pilots’ decision-making and performance, aircraft owners are installing flight data management (FDM) equipment.

FDM gear connects to existing avionics to capture how the aircraft was flown, much in the same way cockpit data recorders, better known as “black boxes,” record flight parameters aboard airliners. The setup can also include video and audio recording of the flight deck.

At the end of a flight, whether routine or troublesome, management can quickly download information about the flight in question, and review it in the form of a graph or an animated recreation on a standard computer. It makes an excellent routine training and pilot evaluation tool as well.

Whether or not the use of the various technologies on the market will help control the inherent danger of flying HEMS missions remains to be seen. And, of course, the cost of such upgrades could prove burdensome on operators’ budgets. But if they prove to be significant tools in the promotion of safety, mandatory use by way of FAA regulation may be right around the corner.

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