Sunday, July 1, 2007
Common Mistakes: Keep Your Eye on the Ball, and the Horizon, and the Trees, and...
A precise, active scan of what’s going on inside and outside the cockpit is key to safe, smooth flight.
VERTICAL FLIGHT IS AN EXCLUSIVE ENGINEERING FEAT that only rotorcraft deliver. But this privilege has its drawbacks. Being both statically and dynamically unstable, helicopters only stay airborne by using opposing forces. Therefore, if something goes wrong, things unravel quickly. Not surprisingly, careful scanning of critical instruments and flight cues is mandatory.
This fact was highlighted at the 2005 International Helicopter Safety Symposium held in Montreal, Canada. It brought together 265 representatives, including designers, manufacturers, international regulatory communities, and the insurance industry. Civilian and military entities were in attendance. The symposium concluded that helicopter accident rates were "excessive and unsustainable."
This decision was based on reports by the likes of Mike Kriebel, senior vice president of the U.S.-based Aviation Underwriters Assn., who revealed the country’s civil helicopter accident rate, in comparison to its general aviation statistics, showed helicopters were 30 percent more likely to crash.
"Helicopters are designed to work out of holes in the trees, mountain tops, boats, platforms. These are dangerous environments."
To find out more, Rotor & Wing canvassed three senior flight instructors based in one of Australia’s aviation-training hubs, Southeast Queensland. We drew on the experience of individuals who cumulatively have over 36,000 hr pilot- in-command time.
"It’s not necessarily that things are going wrong," said Tub Matherson, chief pilot and chief flight instructor for Chopperline in Caloundra. "There are many considerations, one being we operate closer to obstacles."
Matherson said because helicopters don’t work off airfields and engage in low-level flying, this was a key factor for the accident rate topping that of fixed-wing aircraft.
"Helicopters are designed to work out of holes in the trees, mountain tops, boats, platforms, and these are dangerous environments," expanded Matherson. "A Boeing 747 works off 10,000 ft of smooth runway with many navigation aids, but helicopters rarely have that luxury."
"You have to look at the nature of what we are doing," concurred Mike Becker, chief pilot and chief instructor at Becker Helicopters in Maroochydore. "Typically helicopters work in hostile environments to do jobs airplanes can’t."
Therefore careful scans both inside and outside of the helicopter are crucial during any flight, but these scans change from mission to mission.
"Pilots performing different tasks will utilize different scans and look at different factors," said Matherson. "For example, a long-liner won’t be giving a lot of attention to the horizon and his panel as it’s not applicable...he’ll be spending his time focused on the load."
"Indeed, all different job applications, and the people performing them will naturally have different priorities," agreed Peter Doyle, another senior instructor and pilot with over 10,000 hr logged. "When you are performing differing types of work the priority of the scan changes." Doyle emphasized each job demanded different protocols to stay safe, and that a proficient scan doesn’t just encompass instruments in the cockpit. It requires a regimented monitoring of factors around the helicopter, cross-referenced with mandatory checks on the machine’s current aeronautical ability.
For example, if you are low-level, be it agricultural spraying, firefighting, scooping up victims in search and rescue (SAR) missions, or performing sling operations, monitoring turbine output temperature (TOT) in a jet-powered craft or engine rpm in a piston helicopter is imperative.
Even under such high pilot workload, our instructors agreed that 90 percent of the pilot’s time would be necessarily allotted to tracking factors other than eyeballing instruments, such as wind direction and obstacles.
The Scan Outside is Key
"There is no point in paying too much attention to instruments and flying into a tree," said Becker. "Our priorities are to aviate, navigate, and communicate. So scanning instruments is conducted as required for the task in hand."
There is no set method to instrument scans that can be transposed for the wide range of jobs rotary-wing craft achieve. The knowledge of what instruments to monitor and when comes from the pilot’s situational awareness, tapping on sensitivities both inside and outside the cockpit, as the pilot adapts to mission priorities.
"Each job requires individual monitoring, so therefore different instrument scans become applicable," said Doyle. "There is no set protocol. [Your scan] must be modified for what you are doing, although a majority of any pilot’s attention should be focused outside the cockpit, gauging wind, sun and other critical factors."
That said, when flying piston-engine machines, these senior flight instructors concluded, a typical scan must incorporate constant attention to engine rpm. And when flying turbines, careful monitoring of turbine output temperature (TOT) is numero uno.
"After a while, an experienced pilot will attune his ear to the correct engine revolution sound, but without this talent a careful watch of the narrow band of the helicopter’s rpm is essential," said Doyle.
"However, in more sophisticated turbine machines which always have ‘governors’ (the device which automatically matches power with pitch) you have other priorities.
"When in these helicopters it’s imperative to check TOT and make sure you are not breaching temperature or torque limits."
"It’s true that turbine engines will generally let you pull more power than the handbook limits suggest," said Becker, referring to transients. "You must keep a close watch on power levels, particularly when performing lifting operations or any solution which demands a high power setting."
It’s not just checking everything is within operational limits. It’s realizing which direction the needles are heading. When scanning instruments, a cursory glance just doesn’t cut it.
"Observing that it’s in the green is one thing," said Doyle. "Realizing where the gauge was 5 min ago, and taking that into account is something else."
"Knowing if something is going up or down compared to the last check is a big step to realizing that you may have a situation," Doyle said. You must get to know your machine and know where normal operational limits are."
A thorough knowledge of the flight manual, helicopter characteristics, and relevant scans are essential to stay safely airborne. The protocols may change from machine to machine and application to application, but basic ingredients are always maintained.
Any breach of the guidelines may lead to a bad day. Helicopters perform a wide range of duties, but applicable scanning and concentration, coupled with a rigid application of flight theory and checklists is the only way to fly safe and minimize accidents.