By Woodrow Bellamy III | April 3, 2018
British Columbia’s HNZ Topflight is the advanced flight-training subsidiary of Canadian Helicopters. Every year, HNZ trains 350 civilian, military and police pilots in the mastery of terrain airflow, mountain illusions, cirques and other mountain features. It was the first and only school to be accredited by Airbus Helicopters and Bell for mountain-flying training. Its record includes an impressive 160,000 accident-free mountain terrain-training hours across its fleet.
Pilots who train with HNZ could be deployed anywhere in the world. Over the past decade, it’s mainly involved those preparing to fly in Afghanistan, which features challenging mountainous terrain as that found in the Hindu Kush Mountains, for example.
The majority of civilian and military helicopter pilots learn to fly at sea level, where the air has more density and is capable of providing near-optimal lift for rotor clads and engines. However, at high altitudes, pilots must learn to calculate power margins (the difference between how much power they need within the up-flows or down-flows of winds at mountain altitudes, and how much power is actually available based on the helicopter’s weight, pressure altitude and outside temperature).
“The performance charts the [original equipment manufacturer] gives us are very important pre-flight planning tools,” said Dave Schwartzenberger, general manager of HNZ Topflight. “But as soon as you get into the vertical component of wind, those charts are not valid anymore.”
Other than U.S. military helicopter pilots flying in Afghanistan, HNZ has also provided training for every helicopter pilot in the Royal Canadian Air Force and the Royal Canadian Mounted Police. Pilots with the U.S. Federal Bureau of Investigation (FBI), and German and Norwegian air forces also use HNZ.
One of the biggest hazards of mountain flying is avoiding mountain illusions.
“A basic mountain illusion would be down-slope illusion. If you’re flying close to terrain and you turn away from a mountain slope, the tendency is for us looking out the window as the terrain goes down is for our eyes and our mind to say the horizon is a lot lower than what it seems,” said Schwartzenberger.
If the pilot perceives that the horizon is lower than it actually is and falsely matches the aircraft attitude to that false horizon, the helicopter will start to accelerate and descend. Similarly, if the pilot is flying up slope, he or she will perceive a false horizon that is higher than what the true horizon is, and the helicopter will start to slow down and climb. During mountain-flying demonstrations, HNZ also teaches pilots how to properly judge the altitude of a landing spot in the distance.
A pilot looking up slope at a feature in the distance sees a landing spot, and his or her eyes are automatically higher, perceiving that the false horizon is level to that spot, so it looks level from distance, according to Schwartzenberger.
“During the beginning of our course, we use a feature that sits at about 3,500 feet, and as you fly three to four miles back from it, the feature appears to be level to your altitude at about 2,500 feet, even though it is 1,000 feet higher than you,” he explained. “If you were to look at the feature from the same location four miles away level at 3,500 feet, it would look like the spot is below you. This can be difficult to believe, but your eyes are lying to you.”
The HNZ training fleet includes Airbus AS350 B2/B3s, three Airbus H120s, two Bell 407s and a single Bell 206 Jet Ranger. The instructors place an emphasis on hands and feet flying, the basic skills that some of today’s pilots lose over time after flying in cockpits with more advanced levels of automation.
“I think we’re at a really unique point in the industry where there’s so much automation and new tech that students have to be able to use those systems and manage it, but they still need to be able to do hands and feet flying,” said Schwartzenberger. “It’s still a fundamental aspect of being a pilot — being able to operate a collective, a cyclic and pedals.”