Estimated reading time 18 minutes, 25 seconds.
On a September morning In 2015, a Utah Department Of Public Safety (UDPS) Airbus H125 was supporting search-and-rescue (SAR) efforts for an overdue female hiker. The setting was at 11,000 feet in the Lone Peak Wilderness, a rugged recreation area 20 miles southeast of Salt Lake City.
Sadly, when the female was located, she was deceased. She was found on a small rocky ledge below a foot trail leading to a mountain summit. Investigators determined she had fallen several hundred feet while negotiating the trail.
Recovering the victim presented logistical issues. There was no practical way to carry the body down, no place for a helicopter to make a flat pitch landing and, at the time, no readily available helicopter short-haul or hoist assets. Instead, in similar situations, UDPS helicopter crews and their SAR partners often used one-skid and toe-in ‘hover techniques’ to deploy and recover personnel.
Through the years, UDPS had been successful employing these techniques, but there were a handful of close-call instances where aircraft operated too close to trees or other hazards. In one case, a rotor blade nicked a tree limb, requiring the aircraft be downed and undergo inspection.
These events generated discussions, first among the crews and eventually with department leadership, seeking safer, more efficient alternatives to hover techniques. Crews wanted to explore the merits of rescue hoists; department leadership, however, were unfamiliar with hoist operations and wary.
Until 2015/2016, UDPS operated two AStar helicopters: an Airbus H125 and a Eurocopter AS350 B2. They had two full-time pilots, one part-time pilot and a small cadre of DPS Highway Patrol Troopers cross-trained as part-time tactical flight officers (TFO).
It was during the mission in the Lone Peak Wilderness, while conducting what was otherwise a routine one-skid maneuver to recover the female victim, that a tragedy was narrowly averted.
“One member of the recovery team had secured himself to a rope that was anchored above the tip path plane of the helicopter,” explained Kent Harrison, who was piloting that day. “As they approached the helicopter to begin loading, a main rotor blade came into contact with the rope, approximately 10 inches from the blade tip. It sounded like a shotgun blast going off and the aircraft was immediately shaking like crazy.”
The rotor blade did not sever the rope. Instead, it pulled the rope through 1/4 of the rotor disk’s rotation and introduced it into the tail rotor. A tail rotor blade snagged a portion of a Prusik Sling that was attached to the rope and cast the rope clear of the aircraft. “In that 1/4 rotation, it snapped the Prusik, broke the StarFlex in the rotor head, hit the tail rotor and pulled the rope off, all in one fell swoop,” said Harrison.
From a stable hover, balancing the right skid on the ledge, the aircraft violently rotated left 180 degrees. “I remember the aircraft feeling like it was out of control,” he recalled. “As I was trying to arrest the spin, I became aware that the tail hit the side of the mountain.”
When the rope strike occurred, the TFO had been standing out on the left skid, ready to receive the victim to secure her in the rear cabin. When the aircraft rotated, he was thrown off the skid. His rescue belt and lanyard attached to the aircraft saved him from a fall that would have likely been fatal. The TFO regained his composure, climbed onto the skid and back into the aircraft.
Upon regaining control of the aircraft, Harrison and his partner made a controlled descent to a safe landing 1,000 feet below in an unoccupied community park. “I wasn’t in auto rotation. I can only describe it as, [the helicopter] was kind of in its happy place with the StarFlex being broken. It was just in a state of rotation that it was not creating a lot of vibration, I still had control, the tail rotor was intact, and the aircraft was actually flying when I told it to. So, we kept flying.”
A better way
The incident prompted renewed talks with department leadership about the inherent dangers associated with the hover techniques. Auditors from the outside were brought in to assess the aviation program and make recommendations for improving safety and efficiency. Everyone understood something needed to change and it seemed implementing a hoisting program needed to be seriously considered.
The H125 involved in the Lone Peak incident was declared a total loss. When the department moved to replace the aircraft, they chose another Airbus H125. This one, though, would be equipped with a hoist. They also received approval for installing a hoist on the legacy AS350 B2.
These new acquisitions, however, came with stipulations from department leadership. The unit could seek bids from outside hoist training providers – and even go through training – but they were not authorized to conduct missions.
After careful consideration of bids from several training providers, Oregon-based Air Rescue Systems (ARS) was selected. “One thing we liked about ARS, they had a start-to-finish plan,” said UDPS chief pilot Luke Bowman.
“They had all the gear they’ve developed and manufactured … and [it was] proven in the field. And then they had a thorough training plan. We had no idea where to start. They came in and helped us get the aircraft set up so we had a starting point.”
The first training occurred in the fall of 2016. It was a basic course, assuming UDPS had zero hoisting experience. ARS provided all the gear: harnesses, rescue software and hardware; UDPS only needed to provide the helicopter and a hoist.
“They were very open, kind of a clean slate,” said ARS president Bob Cockell. “There hadn’t been any hoisting by anyone on the team before. They just said, ‘yep, bring it.’ That’s a cool stance to teach to when people are so willing to accept the process.”
The course begins with two full days in the classroom: lectures, PowerPoint and video presentations introducing the concepts, principles, and fundamentals of the techniques they’d be learning – fluid-dynamic hoisting.
“There are inarguable physical laws that pertain to hoisting and more importantly to load control,” said Cockell. “I believe that most understand the ‘what,’ but few can articulate the ‘how’ and most importantly the ‘why’. We understand the physics of flight … why not the physics of hoisting? You can argue technique … but you cannot change the physical rules that apply.”
These techniques are based on math, physics, and the fundamentals of helicopter aerodynamics. Newton’s three laws of motion — the acceleration of gravity, centripetal force, reaction-force pairs and pendulum theory – are just a few components of the didactic course.
These concepts are then applied through the flight portion of the class and students are always pleasantly surprised to discover the outcomes are exactly as predicted. These techniques have been made popular by ARS’s teachings and have earned endorsements from civil, para-public, and military helicopter operators.
“There is static hoisting, there’s dynamic hoisting, then there is what we teach: fluid-dynamic hoisting – a focus on harnessing the movement, energy, and inertia created,” Cockell explained. “It takes the approach: at all costs, keep the aircraft moving. If the aircraft is not climbing, then it’s descending. If the hoist load isn’t going in, it’s coming out. We stop long enough to drop or pick the load and that’s it. Period.
“You want to use these physical laws that apply to the load and the helicopter to keep the load as stable as possible and untouched by the outflow from the [helicopter] for as long as possible. Disturbed flow, spiral slipstream, tip vortices, V2 velocities, shadow collapse, stagnation line outflow acceleration, and radial wall-jet “push” must be understood to a high degree to be able predict the impact to our operations before it happens.”
Being reactive rather than proactive is a losing battle. Exposing the load to this chaos leads to one thing: unwanted movement – spins, swings, and conical rotations (often incorrectly termed oscillation).
“So, you keep the aircraft moving,” said Cockell. “We’re doing a lot of alternate profiles other than just 12 o’clock/nose into the target, to keep the hoist load from being impacted by the out-flow energy.
“With a little finesse, we fly the helicopter like we’re not hoisting. If you’re going from point A to B, you simply fly over there. If you need to climb the aircraft while you’re hoisting or if you need to descend, then lateral movements – crabbing, backing, hook turns – while you’re hoisting. There just aren’t any hard profiles. That’s the base concept for fluid-dynamic hoisting. It’s having a broad and detailed understanding of the physical laws, math and theory that makes these outcomes guaranteed.”
Day three involves a half day in the hangar familiarizing students with equipment, aircraft rigging, and procedures. Then it is on to the practical exercises: four full days and one half-day of flying and hoisting in the field. These are high tempo, approaching 30 hours of flight time with 120 to 140 live load hoist evolutions each day.
Throughout the entire initial UDPS training, ARS trainers were somewhat surprised to see the genuine interest of many senior officials from the agency leadership.
“Several members of our immediate [department] leadership came out and observed a lot of the training,” recalled Bowman. “They came to a couple days of ground school and were there for every day of the field training.
“[Our Colonel] knew that something needed to change, but he didn’t know what. The hoist concerned him; he didn’t understand it. So, he came to the training … and really liked Bob’s class and presentation. He became a lot more comfortable at the end of that training.”
“It was pretty amazing to have the guy making the decisions out there with us every day,” said Cockell. “Ultimately, he said, ‘if we’re going do this, then I want to experience it.’ So, he rode the hoist as a rescuer and then volunteered to be the victim during some of the scenario-based rescues at the end of the class. That’s a big statement by their leadership. He’s putting his guys’ lives in our hands. I think he personally wanted to be part of the vetting process.”
After that initial training class in the fall of 2016, the Aero Bureau committed a great deal of time to further training amongst themselves to fine-tune their hoist competency. By December, that commitment and the evolution of the hoist program earned the confidence of department leadership. The bureau was given the green light to begin conducting hoist missions.
ARS continues to be the UDPS hoist training provider, conducting one class annually, using different challenging settings throughout the state, such as high-altitude vertical walls and desert red rock slot canyons.
“The second [UDPS] course was an advanced course, focusing more on harder victim extractions,” said Cockell. “We did a very specific vertical wall course: over-flying techniques for approaching the victim without blowing them off, accessing the victim, device utilization, and then being able to take them from the wall, dynamic descending patterns to take them down and away – at altitude, at night. We had them master that because, in real life, they’re challenged with that stuff every day.”
Today, the UDPS Aero Bureau operates three hoist-equipped H125s. They have brought aboard additional full- and part-time personnel among the pilot ranks as well as TFO/rescue specialists and maintenance positions. Presently, they’re operating the only public safety aircraft in Utah.
Over the last several years, they have tallied impressive statistics for their SAR and law enforcement missions. Since 2019, they have averaged locating/rescuing 138 lost/missing individuals, performed 69 hoist rescue operations, and assisted in 83 arrests each year.
Their main base is in Salt Lake City, but this past summer they opened a second at the southern end of the state in St George. With its proximity to several national parks and other popular recreation areas, the base will likely experience a high volume of SAR calls. They have also identified the town of Moab, in the eastern portion of the State, as another strategic location into which they could expand in the future. The base would give UDPS aircraft a 45-minute or less response time to anywhere in Utah.
“The ARS training has increased safety across all of our operations, not just hoisting,” said Bowman. “They have a very good method of doing overall risk assessments … [and] we’ve implemented the same risk evaluation process for everything we do, which has increased our safety across the board.
“We’re in a smaller, single engine aircraft, an H125, and in some of these environments, because of the mountains and the altitudes, we can’t always just sit there and hover. If we were in a twin engine aircraft with single engine fly away performance, it wouldn’t matter that much. You could be there all day long while doing a static hoist. But in a single engine aircraft, it’s better for us to use these dynamic, moving techniques,” he added.
“The theories and techniques ARS have been teaching us have come a long way to match our aircraft’s abilities and performance to our hoist mission needs. And their curriculum is constantly evolving, which has expanded and improved our team’s capabilities and confidence. This allows us to get the most out of the hoist and accomplish the mission safely and in the most
efficient way possible.”