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New Technology Allows Air Ambulance to Rescue Patient in Storm


A brand new flight technology with the potential to save countless lives was utilized for the first time on an air ambulance in Iowa last week.

On Tuesday, Mercy One, a medical helicopter operating out of Mercy Medical Center in Des Moines, received the call to rescue the 15-year old victim of a rollover automobile crash. The mission was to pick up the critically-injured patient from the Chariton Airport and fly her to the medical center 55 miles away for further care.

Weather conditions were poor; A storm with torrential rains had rolled into the region, bringing winds of reducing the pilot’s visibility to a mere 50 feet — but the crew of Mercy One had an experimental ace up their sleeves that day.

Their helicopter was equipped with a state-of-the-art air navigation technology called a WAAS (Wide Area Augmentation System). Hospital officials told KCCI-TV that the air ambulance pilot “relied” on the WAAS to fly through the rainstorm.

The lead pilot of Mercy One, Chuck King, told Radio Iowa that the weather conditions were bad enough that the aircraft would not have been able to respond to the call under visual flight rules, so they had to depart under instrument flight rules. He noted that the FAA had cleared them to do so, and to utilize the new equipment, only a week earlier.

King explained to Radio Iowa that the Wide Area Augmentation System is based on vertical navigation:“Vertical navigation means that we can make instrument approaches to lower minimums. The old system, with GPS approaches, would allow us to go around 500 feet above ground. WAAS, with vertical guidance, allow us to go as low as – in the case of Mercy – 266 feet off the ground. So, that’s much improved capability.”

The FAA originally began development of WAAS to enhance and augment the Global Positioning System with increased accuracy, integrity, and availability. As far as the accuracy goes, it typically has a margin of error of less than 1 meter laterally and less than 1.5 meters vertically — much better than the FAA even requires.

Without WAAS, disturbances in the ionosphere, orbital satellite errors, and clock drift create too much uncertainty and margin of error in the GPS signal to meet the requirements for a precision approach. Precision approaches provide altitude information, distance from the runway, elevation information, and course guidance at all points along the approach, typically with lower altitudes and weather minimums compared to non-precision approaches.

FAA Diagram

Officials at Mercy Medical Center have stated that the Wide Area Augmentation System will allow the hospital helicopter to safely fly more air medical missions. The FAA is expected to approve Mercy One to make low-level landings in inclement weather in more locations within the next 4 to 6 weeks.

According to Larry Roberts of Bell Helicopter, WAAS technology combined with the Bell 429 (the model of Mercy One) allow medical helicopter operators engaged in instrument flight rule operations to fly missions that were “unthinkable” in the past.

“This total aircraft solution will increase the number of missions that are flown and ultimately save more lives,” he said.

Air ambulance pilots can potentially use WAAS to fly in otherwise “blinding” snowy or rainy weather. In past years, rough weather has caused approximately 250 missed emergency calls within Mercy Medical Center’s response radius. The same rough, ultra-low visibility weather conditions that formerly made these flights impossible or extremely dangerous to perform are now easily navigable using the somewhat still-experimental technology.

The FAA is closely monitoring and collecting data from the Mercy Medical Center flight program to help develop public use criteria of WAAS procedures and prepare for broader future use of the technology under the FAA’s NextGen program, which we reported on late last year.

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  1. Sandra Billings

    5 / 2 / 2011 8:46 am

    This is great! Just from a safety standpoint it would be great to have it installed on all rotor aircrafts.


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