Read More: Bad Assumptions
November 17, 2020

Unclear responsibilities between pilots can lead to a deadly outcome.

A flight review conducted by a CFI without significant make-and-model experience has come to be recognized as insidiously hazardous—especially when the client is also the aircraft owner.

It’s natural for the instructor to believe the client knows the aircraft, while the client simultaneously trusts the instructor to keep them both out of trouble. The result can be a dangerous vacuum of authority, with each party expecting the other to take the initiative in responding to the unexpected. In a truly urgent situation, this ambiguity can be disastrous.

A similar, if more obvious, dynamic applies when an experienced airman not trained as an instructor serves as a novice’s “safety pilot”—not in the 14 CFR 91.109 sense of training in simulated instrument conditions, but to guard against errors in procedure or judgment while flying VFR. Whether prompted by insurance requirements or general caution, the practice rests on the assumption that the high-timer will pay close attention and be quick to intervene when needed … neither of which is necessarily second nature to someone whose extensive pilot-in-command time doesn’t include teaching.

Add in the potential fatigue from a long cross-country flight—say, to deliver a newly purchased aircraft—and perhaps creeping complacency after uneventful hours in the air, and the veteran’s presence may provide less of a safeguard than either party believes.

The Flight

On Sep. 25, 2018, an Airbus Helicopters AS350 B3e departed from the company’s factory in Grand Prairie, Texas. On board were four people: the 42-year-old private pilot and owner of the aircraft who’d just taken delivery of the helicopter; his two sons, ages 11 and 14; and the 53-year-old safety pilot, who was director of operations and chief pilot of two commercial operators that flew the B2 model of the AS350. The National Transportation Safety Board (NTSB) attributed his presence to “insurance coverage purposes,” though he’d also become friends with the owner over the summer.

Three days, 20 flight hours, and more than 30 assorted “sightseeing, fuel, and rest” stops later, they landed at Juneau International Airport (PAJN) in Alaska. After refueling, they took off again shortly before 10 am on Sep. 28, bound for their next fuel stop in Yakutat on the Gulf of Alaska.

The owner was the pilot flying, as he apparently had been throughout the trip. His plan was to leave the safety pilot in Wasilla before flying the last 60 miles home to Anchorage.

After clearing the mountains west of Juneau, the helicopter descended to 500 to 700 feet, heading northwest along the coastline. As it crossed Glacier Bay National Park about 60 miles northwest of Gustavus, the pilot asked the others whether they’d like to land on a beach to stretch their legs. A minute later, the safety pilot pointed out a long stretch of beach to their right, and the pilot began a right turn. The safety pilot’s hands were off the controls, and his feet were on the floor.

The pilot then twisted the throttle from the Flight to the Idle position and lowered collective slightly. Rotor rpm decayed into the gauge’s yellow cautionary range within 5 seconds.

Seven seconds after reducing power, the pilot reached for the center console to mute the low-rpm warning horn. Rotor rpm continued decreasing to its recorded low of 254 rpm, and 18 seconds after the initial power reduction the helicopter crashed into Lituya Bay.

All four occupants were thrown from the wreckage. The elder son regained consciousness in the water and managed to make it to shore. He was eventually rescued by the US Coast Guard and hospitalized in Anchorage. The safety pilot’s body washed ashore about three-quarters of a mile from the accident site. The bodies of the pilot and his younger son weren’t recovered.

The Pilots

The aircraft owner–pilot had more than 1,000 hours of fixed-wing experience. He’d logged 59 hours in the Robinson R44 while earning his helicopter rating. On Jun. 4, 2018, he completed the factory AS350 B3e transition course with 3 hours of dual instruction in the aircraft and 1 hour of simulator time. He got another 1.5 hours of dual at the factory on Aug. 5, giving him a total of 4.5 flight hours in the accident make and model. Over the summer, he flew 18.3 hours in an AS350 B2 operated by the safety pilot’s company.

The safety pilot’s widow told investigators that the owner–pilot’s skills impressed her husband and their company’s check airman: both considered him “a really good stick.” By the day of the accident, the owner–pilot had accumulated an estimated 103.8 hours of helicopter time.

The safety pilot held a commercial certificate with single-engine land, multiengine land, single-engine sea, and helicopter ratings, but he wasn’t a flight instructor. Of his estimated 15,350 flight hours, 4,350 had been flown in the AS350 series. His company flew no B3 models, however, and during an interview with investigators, the surviving son said his father seemed much more familiar with the details of this model than did the safety pilot.

The Aircraft

The 2018 model helicopter had flown just 13.7 hours when delivered and about 40 hours by the time it crashed. It was equipped with a Genesys Aerosystems HeliSAS autopilot and stability augmentation system and an Appareo Vision 1000 cockpit image recorder that captured four frames per second. The FADEC (full authority digital engine control) system and the associated event data recorder (EDR) of the 952–shaft horsepower Safran Arriel 2D turboshaft engine recorded engine parameters and failure flags at 1-second intervals.

Normal procedure in the AS350 B3e is to twist the throttle from Idle to Flight during run-up and leave it there until completing the postflight engine and rotor shutdown checklists. Moving to Idle in flight would be done in a practice autorotation, but the NTSB noted that the beach wasn’t an ideal landing zone for a full-down auto, and the survivor told investigators they hadn’t done any autorotations on the way up from Texas.

The Analysis

By the time the investigators arrived, the wreckage of the fuselage had washed onto the beach and been partially covered by sand. More than 25 gallons of fuel were recovered on-site. Examination of the wreckage ruled out fuel contamination and showed no evidence of pre-impact failure of the engine, transmission, main rotor, or collective and cyclic controls. The tail boom and tail rotor were never recovered.

In the last 16 seconds captured by the FADEC and EDR recordings, the twist grip went from Flight to Idle to Flight to Idle and back to Flight. All recorded parameters responded appropriately to those inputs.

The Appareo recording captured not only images but also GPS coordinates and pitch, roll, yaw, and acceleration data. The last data stream showed that the helicopter was level at 618 feet and 116 knots, pitched 6 degrees nose down, before the pilot rolled the throttle to Idle. The instruments showed 395 rpm at 8.5 first-limit indicator (FLI).

Within 5 seconds, the FLI needle dropped to 1.75 and rotor speed decayed to 328 rpm; the only control input was slight left pedal by the pilot. The helicopter gained 12 feet of altitude while losing 4 knots of ground speed. The panel’s Horn light illuminated 1.75 seconds later when the pilot muted the low-rpm warning. Rotor rpm was down to 290 at 1.25 FLI. The helicopter hadn’t yet begun to descend but continued to slow, pitched 3 degrees nose up.

Four seconds later, “loose objects in the cabin showed an indication of a negative g-force.” The twist grip was still at Idle, and rotor speed was 259 rpm. Slight forward-left cyclic inputs were recorded, but it was unclear who made them; both pilots had their hands on their grips. Impact occurred 6 seconds later. The helicopter fell 600 feet in the last 10 seconds.

The Takeaway

The details of the accident sequence defy ready explanation. Why did the pilot twist the throttle to Idle at 600 feet—after making 30-plus normal landings in the preceding three days? Why did his safety pilot fail to correct that move immediately, or at least after the panel’s twist-grip annunciator lit up? And why did the pilot mute the low-rpm warning horn rather than lower collective?

With the bulk of the pilot’s helicopter experience in the R44, whose low-inertia rotor system’s susceptibility to blade stall made it the subject of a Special Federal Aviation Regulation mandating specialized training, the horn might have been expected to trigger him to instantly lower collective.

The survivor told investigators that both his father and the safety pilot froze on the controls—and that he knew something was wrong right away because the phone on his knee “flew up and stuck to the ceiling.” 

Shortly after the accident, he told a state trooper that his father looked “like a two-year-old … sort of in shock.” He recalled both pilots “snap[ping] out of their trance” just a second and a half before the helicopter hit the water, with his father yelling, “No!”

Not at all unclear is that a high-timer’s scrutiny of a new pilot doesn’t necessarily provide the safety margin both expect—particularly if that high-timer hasn’t cultivated a flight instructor’s reflexive paranoia. 

Read More: Practice Makes Perfect
August 15, 2020

Three ditching survivors acknowledge owing their lives to underwater egress training.

When there are only seconds in which to respond, thorough drilling in the appropriate procedures can be crucial to successfully confronting a life-threatening emergency. With no time to puzzle out a response or even read a checklist, survival depends not just on remembering the correct sequence of steps but on having practiced it recently and often enough to execute it precisely and without hesitation—in a situation certain to be more ­chaotic and frightening than the typical training environment.

In its final report on the Jan. 28, 2019, ditching of a Sikorsky S-64E during firefighting operations in Victoria, the Australian Transport Safety Bureau (ATSB) noted that

each crewmember recalled the rehearsed drills from their helicopter underwater escape training (HUET). They identified their seat belt and nearest exit to orientate themselves in the aircraft. They all waited until the last moment to draw a breath, and did not unbuckle and exit the helicopter until [its] motion had ceased. The crew reported that it was not possible to see anything underwater, and that jet fuel contamination was present…. HUET enabled the crew to act rationally and decisively when submerged in the cockpit and to use the regularly-practiced drills to escape the aircraft.

The report also credits the provision of a helmet cord-release mechanism with facilitating their escape, as 

neither pilot unplugged their helmet. However, the extension cords from the aircraft to the helmet plug allowed the plug to release, preventing the helmets from snaring the pilots.

Both pilots and the crew chief in the rear-facing aft-stick seat were able to inflate their life jackets, reach shore under their own power, and hike through “dense bush” to a road, where they were rescued.

The Aircraft and Crew

Built by Sikorsky as an S-64 in 1969, the accident aircraft had been upgraded to an S-64E Aircrane. Subsequently operated by Erickson Inc. and registered as N173AC, it boasted two 4,500–shaft horsepower Pratt & Whitney engines and had been fitted with a 2,650-gallon water tank and flexible pond snorkel for water-bombing missions. The snorkel’s dedicated high-pressure pump could fill the tank in about 30 seconds, requiring only about a 45-second hover. Erickson’s website advertises that the S-64E can drop up to 25,000 gallons per hour from a dip site suitably close to the drop site.

Describing the crew as experienced would be a substantial understatement. The more senior of the two pilots had flown helicopters for 44 years, including 20 years operating the S-64 and 20 years fighting fires in Australia. On the accident flight, he was serving as ­second-in-command (SIC), the pilots having switched positions at the end of every two-hour duty cycle. The pilot-in-command (PIC) had 18 years of helicopter experience, 4 of them in the S-64, and the crew chief’s 34 years as a helicopter engineer included 26 “maintaining and developing the S-64.”

Read More: Untangling the East River Crash
June 08, 2020

A failure to “mitigate foreseeable risks” proves lethal.

Aviation’s approach to risk management has evolved into a two-pronged strategy:

  • Try to identify every potential failure point and update your equipment, systems, and procedures to reduce or eliminate those hazards
  • Devise strategies, preferably multilayered, for coping with whatever emergencies arise from the hazards that remain.

The results are safety features that have become so common that they’re taken for granted, from the redundancy of essential equipment to guards protecting flight-­critical switches to company procedures limiting pilot discretion in marginal weather.

And the risk mitigation process is necessarily iterative: when previously overlooked hazards or rare combinations of circumstances result in accidents or emergencies, the industry responds with a fresh round of analysis, ideally leading to further improvements.

Human nature and the high cost of equipment retrofits have made progress on some fronts very slow, but the long-term trend of aviation safety should arc toward the reduction of all risks not intrinsic to the act of flight itself.

The March 11, 2018, ditching of a Liberty Helicopters AS350 B2 in New York’s East River drew widespread attention for several reasons, from the sequence of events that brought down the ship to the peculiarly awful manner in which all five passengers lost their lives. The accident triggered renewed scrutiny of the controversial practice of claiming exemption under 14 CFR 119.1(e)(4)(iii) to operate air tours under Part 91 without a letter of authorization through advertising them as photo flights, a practice that the National Transportation Safety Board (NTSB) for many years has urged the FAA to ban.The incomplete inflation of the AS350 B2’s emergency floats prompted a fresh look at the rigging and maintenance of those systems. Most fundamental, though—and most damning—was the failure the NTSB called out as the first contributing factor in its finding of probable cause: the two operators’ “deficient safety management, which did not adequately mitigate foreseeable risks.”

Read More: Risky Business
January 17, 2020

Why do experienced pilots ignore obvious hazards?

It’s dark—very dark. The trip is a short hop with passengers through mountainous country sliced by narrow valleys. You’re not familiar with the destination, but you’re very familiar with the 50-year-old helicopter and have the benefit of military flight training leading to a decades-long career of low-altitude law enforcement and search-and-rescue (SAR) missions.

Three new electronic flight displays were installed in the aircraft’s instrument panel barely three months ago. The weather conditions don’t pose undue problems. Given all these circumstances, you should be prepared to determine whether it’s safer to fly high or stay low, right?

The Flight

Ten minutes before 6:00 pm local time on Jan. 17, 2018, a Vietnam-era Bell UH-1H Huey lifted off from New Mexico’s Raton Municipal Airport (KRTN), carrying five passengers to a private gathering on a ranch about 35 miles east, near the town of Folsom. Civil evening twilight had ended 15 minutes earlier and the night was dark, with a setting crescent moon providing “0%” illumination, according to the US Naval Observatory. However, skies were clear. Visibility was officially reported as 10 miles but essentially unlimited.

Roughly 10 minutes after takeoff, the helicopter’s skids ran onto the top of a mesa barely 100 feet higher than the surrounding desert. The Huey slid across the mesa for 110 yards before one main rotor blade hit the ground, leaving a 25-foot scar. The entire main rotor assembly separated and came to rest 20 yards farther along, close to the tail rotor and its gearbox. The cabin tumbled another 66 feet before rolling to a stop upside down and catching fire.

The one passenger who survived was hospitalized with a broken shoulder and broken arm. She told investigators that “the stars were very bright” and that there was no turbulence during the flight. 

The investigators reported that the surviving passenger recalled “no unusual noises, no observed warning lights” and that “everything appeared normal.… [They] were in level flight when she heard a big bang as the helicopter hit the ground.” 

When the aircraft came to a stop, the passenger was left hanging upside down from her seat belt with jet fuel pouring over her but was able to release her belt and escape the wreckage as the helicopter caught fire. Several explosions followed, and the passenger managed to call 911 to report the crash.

Temperatures were near freezing (1ºC at departure from Raton). The other four passengers, including a 3,140-hour commercial helicopter pilot with 120 hours of UH-1H experience, died before the first responders reached the scene two hours later. The pilot survived long enough to be rescued but succumbed during transport. He told one first responder that “it was all his fault and he flew into terrain.”

Read More: Hang Up and Fly!
December 10, 2019

Distracted flying turns a mundane mission into tragedy.

It’s hard to think of many aspects of modern life that haven’t been penetrated by our smartphone culture. For younger users in particular, phones have largely replaced road maps, cameras, radios, and reference libraries. They’re used around the clock to play games, look for love, and diagnose illness, not to mention shop for everything from paper goods to real estate. Increasing numbers of pilots rely on them to file flight plans, check NOTAMs, and get weather updates en route—all without ever exchanging pleasantries with a Flight Service briefer.

The potential for distraction posed by this explosion of entertainment and commercial options—and yes, legitimate aviation activities—likewise spans a great many domains, but the risk of ensuing mayhem might be greatest in the transportation sector. The loss of situational awareness for a driver, pilot, or pedestrian can lead to tragic outcomes. This is why eliminating distractions in all modes of transportation has made repeated appearances on the National Transportation Safety Board’s (NTSB) Most Wanted List of Transportation Safety Improvements. As the recitation in the preceding paragraph suggests, most of the mischief attributable to ill-timed acquiescence to the cell-phone compulsion doesn’t involve actual telephone conversations … but there are exceptions.

The Flight

On Sep. 15, 2017, a commercial pilot and reporter for Albuquerque, New Mexico, television station KRQE flew the station’s helicopter to Roswell to cover a Friday night football game. He spent the night there, lifting off shortly before 4:00 pm the following afternoon to return to Albuquerque International Sunport (KABQ). Winds were light and visibility excellent under high broken ceilings. At 4:07, he placed a call to a rental car agency at Sunport, but the call disconnected after just three seconds.

At 4:12, he called again. He was a frequent customer, and the agency employee who took the call recognized his voice. She said later that while she wasn’t aware he was in a helicopter, he did sound “busy or distracted—like talking to my husband when he was working on his car.” After confirming that he’d receive a discounted rate for that day’s rental, they began discussing a future reservation. After one minute and 47 seconds, the call disconnected “in midsentence” and the pilot didn’t call back.

Near the high desert village of Ancho, a resident saw a plume of smoke rising from a neighborhood ranch and went to investigate. He found the burning wreckage of the helicopter at the end of a 300-foot debris path and notified local authorities. Fire eventually consumed most of the aircraft.

The Pilot

The 64-year-old pilot, a native New Mexican, held a­ ­commercial certificate for single-engine airplane, multi-engine airplane, and helicopter. He was also a helicopter CFI and held a remote (drone) pilot certification. He’d renewed his second-class medical certificate on April 2, less than six months before the accident, with no limitations beyond the required use of corrective lenses. His medical application listed 8,800 hours of total flight time that included 150 hours in the preceding six months.

He was also a veteran journalist with more than 40 years’ experience, including nearly 30 with the station. Colleagues described him as one of its best “reporters, writers, editors, photographers,” a mentor who taught new staff “how to be a good person on top of being a good reporter.”

The Aircraft

The 1989 Bell 206L-3 had completed its last inspection on June 6, at which time it had been flown for 8,798.7 hours. Its engine had been operated for 7,956.1 hours and 7,623 cycles. It had been modified for newsgathering with the addition of a camera pod under its chin.

Read More: Too Much Fun
May 20, 2019

Did a pilot’s search for adventure lead to tragedy instead?

Aviation is exhilarating. The career paths that make up the industry’s pilot pipeline couldn’t be sustained if it weren’t. The steep expense of initial training, the long hours and low pay of flight instruction, the tedium and hazards of pipeline patrol, air tours, and offshore shuttles are all made tolerable by the innate joy of flight. If pilots occasionally indulge in the taste for the thrills that originally attracted them to flight training, well, that’s only human nature.

Of course, most of what’s considered safety culture consists of thwarting human nature, or at least restricting its scope for circumventing the rational mind’s efforts at risk assessment and mitigation. That’s the reasoning behind standard operating procedures that remove as many decisions as possible from the individuals who actually operate the aircraft.

The Flight

N74137 was an Airbus AS350 B3 air ambulance operating from Air Methods’ local base in Globe, Arizona. Early in the afternoon of December 15, 2015, it was dispatched to transport a cardiac patient from Globe to Mesa. The flight was crewed by a pilot, flight nurse, and flight paramedic. Conditions were characteristic of the Phoenix area in December: clear skies, light northwest winds, and essentially unlimited visibility.

The flight was short, about 25 minutes, and the patient remained stable throughout. After unloading him, the helicopter refueled at Phoenix-Mesa Gateway Airport (KIWA) before departing for home.

Data recovered from the aircraft’s onboard Appareo GAU2000 data logger, which obtained position and altitude data from its own internal GPS and airspeed and altitude readings from the helicopter’s pitot-static system, showed the helicopter initially traversing the area around Gold Canyon at about 500 feet above ground level (agl). As it approached the Superstition Mountains heading east-northeasterly, it climbed enough to begin skimming over the hills at altitudes ranging from more than 1,000 feet above the valley floors to as little as 240 feet above the peaks.

During the last three minutes of the flight it flew even lower, remaining below 800 feet agl and crossing ridgelines with less than 50 feet to spare. After traversing the rim of Rogers Canyon just 30 feet above a saddle, the ship descended and accelerated, following the canyon floor. Ground speed reached 148 knots at an altitude of no more than 300 feet agl as the helicopter tracked toward the next ridge.

The flight paramedic later recalled hearing the pilot say, “Oh, shit” and seeing him making “jerky fast hand movements” on the controls. After a hard right bank the paramedic likened to “try[ing] to do a U-turn at 60 miles an hour,” the aircraft hit the next ridgeline just below another saddle point at an altitude of 5,035 feet. It was 5:23 p.m.

The Pilot

The 51-year-old commercial pilot had logged 5,670 hours in a 25-year flying career. He was the Globe base’s safety officer, a role that the paramedic said he “took very seriously.” The pilot was well liked by his teammates, in part because of his willingness to help clean the aircraft and equipment after transports. The paramedic also described him as liking to fly lower than their other pilots, but “not like dangerously low or anything.”

The paramedic also mentioned the pilot’s service in the US Army, as did other flight crew at the Globe base. It would appear, however, that he didn’t fly for the army. His résumé cited no military flight experience, and the file assembled during the National Transportation Safety Board (NTSB) investigation includes his honorable discharge with the explanation “Failure to qualify for flight training – no disability.” His civilian medical certificate required the use of corrective lenses.

The Flight Controls

The NTSB’s report makes particular note of the phenomenon of servo transparency, a condition in which the aerodynamic loads generated by the main rotor system exceed the forces produced by the aircraft’s hydraulic system. The difference “is transmitted back through the pilot’s collective and cyclic controls” and increases rapidly, potentially creating the impression that the controls have jammed. On helicopters like the AS350 with clockwise-turning main rotors, “it results in a right and aft cyclic motion accompanied by down collective movement.”

The amount of feedback is proportional to the severity of the maneuver that instigates it, but it “normally lasts less than 2 seconds when the pilot is aware of the conditions and relaxes the pressure on the controls”—not the most natural reaction to a mountain ridge rushing toward you at 250 feet per second. The paramedic’s impression of the flight’s final seconds was “Hard right. Lost altitude fast. See it coming. Then we just hit …”

Search and Rescue

The helicopter’s emergency locator transmitter was undamaged but did not activate … until the wreckage was moved onto a flatbed trailer during recovery.

The flight was tracked by satellite, but the staff at the national communications center failed to notice its disappearance for more than two hours. Some time after 7:30, they alerted Air Methods’ Operations Control Center, which launched a search. Company aircraft located the accident site at about 8:30 p.m., but because of the steep terrain and limited access had to summon another helicopter with hoist equipment to lower medics to the scene. The first rescuers reached the victims at 9:54, four and a half hours after the crash.

The pilot had stopped breathing shortly after impact. The paramedic found himself hanging in his straps outside the high side of the wreckage. His glasses and helmet “were gone.” He cut himself free with his trauma shears and dropped to the snow, falling into a stream of fuel leaking from the ruptured tanks. The flight nurse was conscious but badly hurt, pinned under the wreckage with the right skid across his throat and jaw. The paramedic’s own injuries left him unable to walk. They tried to use their mobile phones but couldn’t get a signal.

Temperatures dropped rapidly after the sun set, and both men began suffering from hypothermia. The flight nurse diagnosed himself with a collapsed lung, but his aspiration needles were in a pocket of his flight suit that was out of reach beneath the wreckage. His breathing became increasingly labored until he succumbed.

His autopsy showed multiple rib fractures with a left-sided flail chest (a serious condition where a segment of the rib cage becomes detached from the chest wall) and significant internal bleeding from intraabdominal injuries. His Injury Severity Score was graded as 22 (severe), and the NTSB concluded that “it is unlikely that he would have survived until help arrived even if the initial notification of the crash had occurred more rapidly.”

The paramedic was eventually able to signal the search aircraft with the light on his mobile phone. He survived and provided investigators with his account of the flight.

The Takeaway

It should go without saying: the purpose of satellite tracking is to guarantee immediate response when an aircraft can’t be accounted for. A prompt initiation of search-and-rescue efforts might have located the wreckage before sunset, making it easier for rescuers to reach the scene and minimizing hypothermia. Interviews with staff at the communications center suggested that unusually heavy volume in her sector might have overloaded the relatively inexperienced specialist tracking the flight, the kind of single-point failure institutional systems are presumably designed to prevent.

But of course there’d have been no need for search or rescue had the pilot chosen to cross the mountains at a conservative 1,000 feet above the peaks. Skies were clear, and the altitude records set by the AS350 B3 include landing on the summit of Mt. Everest, so neither the meteorological nor service ceiling was a factor.

From outside, one can see no practical reason to risk the ship and its crew by zipping 30 feet over ridgelines and racing down canyons at 150 knots. But as the paramedic recalled, “Each pilot has their own little route … I say they’re like surfers. They have their own little way they do things.” The accident pilot’s preferred route to Globe from the west passed “some rock formations … he just liked to fly by.”

Three days after the accident, Air Methods’ chief pilot issued a critical bulletin announcing a zero-tolerance policy for violations of the minimum VFR altitude standards set by the company’s General Operations Manual. Increasing consumer sales of unmanned aerial vehicles (drones) were cited as a reason.

Read More: Identifying Risks in Real Time
February 26, 2019

Don't mistake bad vibrations for business as usual.

There are emergencies … and then there are emergencies. The distinction lies in whether the time frame for responding affords the luxury of, say, consulting a checklist.

In helicopters, many incidents fall into the second class: the pilot’s reaction must be both immediate and exactly correct to avoid balling up the machine. Losses of main rotor rpm (especially in low-inertia systems) or tail rotor control can escalate beyond hope of recovery if those relatively brief sequences of memory items aren’t executed in order and without delay.

Ground resonance is another example. If a fully articulated rotor system becomes unbalanced, the resulting vibration can excite a sympathetic vibration in the airframe. If its frequency is close to the airframe’s natural harmonic frequency, the two vibrations amplify one another until the helicopter shakes itself to pieces. In one famous case in Utah’s Grand Staircase–Escalante National Monument, the aircraft was essentially destroyed within four seconds of the vibration’s onset. The most common cause is a rough touchdown that knocks one blade out of phase with the others, but significant vibration from any cause can have the same effect.

The required response depends on the helicopter’s energy state. If the rotor is still at flying rpm, an immediate lift-off—adding power as necessary—allows the fuselage’s vibrations to dissipate while any out-of-phase blades realign themselves automatically. At low rpm, lowering collective and reducing power to idle may succeed in saving the aircraft. Between those extremes, catastrophic damage is likely, whatever the pilot does—one reason they’re trained to maintain full rotor speed until the helicopter is fully down, settled, and secure.

The Flight

Shortly before 10:00 a.m. on February 15, 2018, an Airbus AS350 B2 landed on the timber pad of a telecommunications tower at Bear Rock, three miles west-northwest of Tulita in Canada’s Northwest Territories. On board were the pilot and one passenger. Photographs taken shortly after the accident show that the pad was mostly clear, with patches of ice covering perhaps 20 percent of its surface. 

The weather was seasonably cold at -27°C (-17°F). With no preheat available on site, the pilot initiated an engine run about 30 minutes after landing in accordance with the AS350 flight manual supplement, Instructions for Operations in Cold Weather. The pilot later acknowledged having noticed some vibration, which he described as “consistent with those felt over the previous three days, both on the ground and during flight.”

At 11:08 a.m. he began a second engine run. Start-up was normal, and the engine accelerated smoothly to 70 percent Ng (gas generator speed). However, when the pilot increased fuel flow to the flight position, the helicopter began to buck fore and aft on its skids.

The pilot reduced fuel flow in response, only to have the bucking intensify, leading him to suspect ground resonance. He increased fuel flow but did not advance it fully or lock it into its flight gate before raising collective, and neither the engine nor main rotor rpm reached their flight-governing ranges before the helicopter lifted from the pad.

The helicopter yawed and drifted to its left as engine rpm spooled up while the main rotor rpm decayed. Two minutes after engine start, the ship descended into the hillside and tumbled down the slope. The pilot—who was wearing his four-point harness but no helmet—managed to extricate himself from the wreckage after the engine shut down. He walked back to the tower’s service building where his passenger administered first aid. 

After the pilot reported the accident, a company helicopter dispatched from Fort Simpson arrived about 3:00 p.m. Both men were initially flown to Yellowknife. The pilot was subsequently airlifted to Edmonton for treatment of injuries including a badly broken arm. Six months later, he was back at work but had not yet returned to flight duty.

The Pilot

The 5,277-hour commercial pilot had 2,017 hours in AS350s, with 6.5 hours in the previous week and 11.7 in the preceding 90 days. He held a Category 1 medical certificate and had completed recurrent training in the AS350 the month before the accident. His age has not been reported.

The Aircraft

The AS350 B2 has a fully articulated, three-bladed main rotor powered by a single 732-horsepower Turbomeca Arriel 1D1 turboshaft engine. Its Starflex rotor head provides full articulation without hinges or lead-lag dampers; instead, flexible thrust bearings at the inboard ends of the mounting sleeves allow the blades to flex, flap, and move in the lead-lag axis, while elastomeric frequency adapters at the sleeves’ outboard ends provide damping. The accident aircraft was manufactured in 1989 and had served for 46,214 cycles comprising 11,005 hours of flight time.

Its landing gear featured two vibration-absorbing systems: flexible steel strips extending downward from the aft ends of the skids, and hydraulic dampers between the front horizontal crosstubes and the fuselage. After the accident, the operator tested the damper assemblies. The right damper (which had seen 1,395 hours of service compared to the left damper’s 3,001) failed the initial functional test, then passed after overhaul. The history of the accident sequence, however, makes it seem unlikely that inadequate damping was a factor.

Four days before the accident, in order to hangar the aircraft overnight, all three main rotor blades had been removed by a technician with the assistance of the same pilot. After they were reinstalled the following morning, the pilot did a ground run and noticed increased vibration.

Although vibration analysis equipment was available at the site, vibration levels were not measured, nor were blade tracking and balance assessed as required by the aircraft’s maintenance manual. Furthermore, the removal and reinstallation of the main rotor blades weren’t recorded in the journey log, contrary to Canadian Aviation Regulations. Investigators learned that the maintenance shop routinely removed and remounted blades without making the required logbook entries.

The vibrations continued throughout the six hours the pilot flew the helicopter during the intervening three days. “During this time,” according to the Transportation Safety Board of Canada’s (TSB) report, “no action was taken to verify or rectify the vibration and no aircraft journey log entries were made.” With no measurements having been recorded, the preaccident tracking and balance status of the rotor could not be determined.

The Response

Following the accident, the operator’s parent company emailed its pilots and maintenance personnel to remind them of the requirement to document all removals and reinstallations of rotor blades in the journey logs. It also instituted an audit procedure to more systematically track those events. Recurrent training for company pilots also stressed the need to record any sudden changes in vibration levels. While the TSB’s report doesn’t state this explicitly, it’s hoped this training also reinforced the importance of investigating and resolving any sudden increases in vibrations before further intensification.

The Takeaway

Professional pilots—particularly those operating in remote locations and extreme environments—can develop a tolerance for apparently benign aircraft anomalies. But discrepancies as seemingly trivial as a burned-out indicator lamp can become the kind of emergency that requires quick recourse to memory items if the wrong thing happens at the wrong time. It’s up to the certificate holder to establish operating procedures, backstopped by applicable national regulations, that remove those decisions and the accompanying temptations from its pilots’ hands. But written procedures count for little if company culture doesn’t identify and call out violations.

Students and low-time pilots might be taken aback by the notion of flying a helicopter that’s had its main rotor blades remounted without first checking blade track and balance. The rotational momentum of all that mass spinning hundreds of times per minute would seem to raise the prospect that any imbalance would quickly build toward catastrophe. But in the field, the need to shelter aircraft from a bitter climate in limited hangar space made this an unremarkable practice—in part, no doubt, due to the lack of adverse consequences up to that time.

In this case, a highly experienced pilot noticed increased levels of vibration without apparently finding them alarming. Over the course of six hours flight in the harsh conditions of a Northwest Territories winter, they presumably did not worsen enough for his survival instincts to command a return to the maintenance hangar. But while pilot-in-command authority should always admit grounding an aircraft in the interest of safety, it’s the operator’s responsibility to identify risks that can’t be left to pilot discretion.

Read More: Lost in Transition
November 14, 2018

Shortcuts in transition training can turn even routine operations into adventures—or tragedies.

“If it’s got wings, I can fly it.”

The phrasing suggests that this attitude is chiefly a fixed-wing problem, but it has parallels in the rotorcraft world. True, airplanes—with their combination of dynamic stability in flight and vastly reduced range of potential landing sites—probably do more to encourage this kind of thinking.

Helicopter pilots may be more apt to recognize the different skills required to go from hovering an R22 to making pinnacle landings in a Chinook (or vice versa), but they can still underestimate the extent of training needed to move between craft of more similar size and power. Thorough transition training imparts the mastery needed to deal promptly and effectively with the unexpected.

While it may be an extreme example, the fatal crash of an Airbus AS350 B3E during an attempted dolly landing in calm weather in Carlsbad, California, shows just how inadequate transition training can severely limit a pilot’s ability to use the aircraft … and to respond to whatever emergencies might arise.

The Flight

N711BE, a 2014-model AStar with just 33 hours on the airframe, took off from Carlsbad shortly after 2:00 p.m. on November 18, 2015. At the controls was the ship’s new owner, a 65-year-old bank president who’d bought the helicopter the previous month. His 60-year-old passenger was also a helicopter pilot, but he had no AS350 experience and only about 180 hours of rotorcraft time overall.

The AStar returned to the airport a little over two hours later and was cleared to land on Runway 24. The pilot descended to the runway at midfield, turned left at Taxiway A3, and then hover-taxied along Taxiway A. The wheeled dolly from which it had departed was at the west end of the Premier Jet FBO (now Atlantic Aviation) ramp, so the pilot approached it from the east, heading directly toward the sun.

His first landing attempt came up short, with the skids roughly centered on the cart’s back edge. The helicopter teetered back until its tail skid hit the ground, then began to rock back and forth, gaining enough force to kick away the chock securing the dolly’s left front wheel. The platform spun a half turn to the right, with the helicopter following it for the first 90 degrees before spiraling upward into a hover.

The pilot then set it down—prudently, one would think—on the ground, straddling the line between the ramp and the taxiway. When questioned by the tower controller, he replied, “Yeah, they didn’t chock my cart, and I was like a skateboard out here.” The controller turned him over to ground control while the line crew resecured the dolly, this time adding chocks to a third wheel.

After taking off and climbing to about 20 feet, the pilot made three more approaches to the dolly. He broke off the first two about 5 feet up.

A witness on the ramp captured footage of the third try, which ended with the helicopter hovering for about a minute before again touching down short, with the rear half of the skids hanging off. The helicopter rocked back, forward, and then back again, striking the tail skid for a second time before pitching forward, rolling right, and briefly climbing out of sight behind a hangar. FBO security cameras recorded the aircraft spinning 180 degrees left and pitching up 45 degrees.

According to the National Transportation Safety Board (NTSB) report, “the tail rotor and vertical stabilizer assembly then struck the ground and separated, and the helicopter hit the ground left side low, bounced, and rotated another 360° before landing hard on its belly. Once on the ground, the main rotor blades continued to spin, while the helicopter started spinning on its belly, as the engine continued to operate.”

Over the next five minutes, the aircraft slid some 530 feet down the ramp, spinning at a rate of about once per second until the tail boom and vertical stabilizer broke off. At that point the helicopter rolled onto its side, shearing off the main rotor blades. The engine kept running until it was smothered by fire crews.

In-cockpit images recorded by the helicopter’s Appareo Vision 1000 flight-data monitor suggest that the pilot lost consciousness at the initial impact. His passenger remained conscious for about two more minutes but could not shut off the engine or even move the collective’s throttle control from its “FLIGHT” detent. Both deaths were attributed to multiple traumatic injuries.

The Pilot

Investigators never located the pilot’s logbooks. His last four medical applications, filed during the preceding five years, all cite identical numbers: 25,000 hours of total flight experience with 200 in the previous six months. His January 2011 medical application claimed 25,400 hours of flight time.

He held a private pilot certificate with ratings for airplane single-engine and multi-engine land, single-engine sea, instrument airplane, and rotorcraft helicopter, with a type rating in the Cessna CE-525S Citation. He had earned his helicopter certification in 2001, taking his checkride in a Bell 206B-3. His application for that rating cited 14,000 hours in airplanes. Before buying the AS350, he had owned a Bell 407 and “several” Citation jets.

Three instructors who’d flown with him were interviewed during the investigation. None had ever seen his logbooks, much less made any entries in them.

The fixed-wing CFI who had given him recurrent Citation training over the past six years described him as “a high time pilot with lots of turbine jet experience” who had “owned several Citation jets and helicopters in his life and operated them for many years single pilot.”

However, the accident pilot was concerned that his reaction times had begun slowing with age. Though he had spoken of regaining currency and buying another Citation, his training had been intermittent; he had never completed the full refresher course.

The CFI believed that since his wife’s death a decade before, his client had begun “taking a more cavalier attitude toward flying; he would often let the airplane get ahead of him, [and] would not be concerned.” He characterized the pilot as “a proud and successful person, with strong ego.”

During their conversations, the accident pilot had also described his discomfort with landing the AStar, particularly “on carts,” and said that he was considering selling it. He had “agreed whole-heartedly” with the suggestion that he “just put it on the ramp” if not comfortable with the dolly landings.

The two helicopter CFIs who’d flown the AS350 with him gave similar accounts. (Both were colleagues at the company from which he had bought the ship.) The company’s chief pilot described him as “relatively competent” and “good flying from ‘A to B,’ once airborne,” but he had also insisted that the accident pilot complete the Airbus factory transition course before beginning formal training in the helicopter. He described their nine hours of dual as “familiarization/demo flights.”

His colleague flew with the accident pilot just once, for two hours on November 13. Much of that time was spent simulating dolly landings by using cracks in the pavement and taxi lines to simulate the right front corner of a cart. The accident pilot had heard that engaging the stability augmentation system would enable him to “land it like a pro,” but throughout two attempts the instructor saw him fighting the system’s inputs “with unsatisfactory results.” After that, they had turned the system off.

Both instructors noticed that previous shoulder surgery had left the pilot with limited mobility in his left arm. He was unable to climb up to inspect the rotor head during the preflight inspection and had to use his right arm to lift his left hand to the engine start switches. Both urged him not to fly without an instructor until he had completed systematic transition training and taken enough additional dual to become comfortable with the aircraft.

The chief pilot was “incredibly surprised” to learn of the accident, as he understood that the accident pilot would not fly the helicopter without supervision until he had taken the factory course. It turned out that he had registered for a B3 pilot transition course scheduled to begin November 2 but called to defer on October 31.

The Helicopter

During the flight with the second helicopter CFI, the pilot had mentioned his “5,000 hours” in the Bell 407 and complained that the AS350 “felt backwards.” There was, of course, a reason for this: while nearly identical in engine output, their main rotors turn in opposite directions.

Numerous images—from the Appareo flight recorder, security cameras at Carlsbad, and witnesses on the ramp—show the AStar yawing significantly (up to 150 degrees) just after liftoff, indicating that less than 11 hours in that aircraft hadn’t yet recalibrated the pilot’s deeply ingrained habits of pedal inputs. Further complicating his efforts to land on the dolly was the fact that the tips of the AStar’s skids are too far aft to be seen from the pilot’s seat, necessitating cultivation of other visual references. The 407’s skid tips are in clear view through the chin bubble.

The Takeaway

Reading this—or the NTSB report—it’s hard to understand why that first tailstrike didn’t convince the pilot that it was time to leave the helicopter on the ramp and resume training another day. Having at least come close to damaging a multimillion-dollar machine, why take any more risks?

For that matter, his decision to not only fly a machine he had admitted made him uncomfortable but to attempt the one maneuver he found most difficult is hard to fathom. As often seems to happen with financially gifted professionals flying high-end aircraft, the same traits that bolstered his business success—many of which also distinguish good professional pilots—may have made it hard to acknowledge even temporary limitations.

This pilot had both the background and innate ability to develop the needed proficiency … if he had taken transition training as seriously as his earlier aviation education. “If it’s got rotors, I can fly it” is an even more precarious attitude than the ­version involving wings.