Warning: This report contains details which some readers may find disturbing.
The failure of two vital instruments is the focus of officials working to understand why an Air Tindi flight came down near Whatì in January, killing the two crew on board.
Pilots Will Hayworth and Zach McKillop lost the use of their attitude indicators, one after the other, before the crash.
Attitude indicators tell a flight crew how the plane is oriented relative to the horizon. (Altitude, also important in flight, is a different concept.)
Once use of the indicators had been lost, the plane embarked on a precipitous descent and hit the ground at devastating speed. A preliminary assessment deemed the crash “not survivable.”
Receiving an update at a conference in Yellowknife, northern aviation executives were audibly shocked as Jonathon Lee, from the Transportation Safety Board of Canada, gave details of the flight’s final moments as investigators understand them.
The aircraft had already started its descent toward Whatì, where it intended to pick up workers destined for the Ekati diamond mine, when the second attitude indicator failed, said Lee.
The first was known to be out of service before the aircraft took off. The weather was overcast and the pilots – at 12,000 feet when the second indicator broke – would have been in cloud, with no visibility.
“From this position to the accident was only 70 seconds in terms of time,” Lee told more than 100 attendees at the Northern Air Transport Association’s annual conference, inside Yellowknife’s Explorer Hotel.
“There was a peak descent rate of 32,000 feet per minute,” he continued, to sounds of shock from some in the room.
Regular commercial flights descend at around 1,000 to 3,000 feet per minute, depending on the aircraft type; an emergency descent might be 6,000 feet per minute.
This aircraft, a King Air 200, eventually hit trees at an approximate speed of 380 knots, said Lee – roughly equivalent to 700 kph.
About 60 percent of the wreckage, which was spread across a large area outside Whatì amid trees and in deep snow, has been recovered to date.
Displaying a photograph of the aircraft’s fragmented remains, Lee said: “It gives you an example of the energy that was involved and the importance of the data we did get from the aircraft. When you have this to work with, it becomes difficult to understand what went on.”
Thanks to RCMP officers using metal detectors, the flight’s cockpit voice recorder has been recovered for study. The first officer’s non-functioning attitude indicator is also being analyzed.
Some items relevant to the investigation remain at the crash site. “We’re just-about ready to go back and recover the rest of the wreckage,” said Lee.
Partial panel concerns
The focus of the investigation rests on the attitude indicators, which are a primary piece of equipment in any aircraft – particularly when relying on instruments alone as visibility drops.
In this incident, while the captain’s attitude indicator failed in mid-air, the flight crew had noticed the first officer’s indicator was not working while still on the ground in Yellowknife. The crew chose to continue their departure.
Above, a graphic depicts an example attitude indicator.
Lee said the investigation would analyze the crew’s decision to fly, and whether anything else – such as their access to on-board iPads featuring an app known as ForeFlight, which includes a simple, digital attitude indicator – could have helped them avoid a crash.
Hayworth and McKillop would have been trying to deal with what is known as a “partial panel” emergency, where pilots must command a plane without the use of some key elements of the control panel.
Lee hinted at concerns regarding how pilots across Canada are trained for such situations.
“The last time [partial-panel flying] showed up in Transport Canada documentation for instrument flight tests was 1992,” said Lee. Transport Canada, the federal department governing transportation, is a separate entity to the Transportation Safety Board, which investigates accidents and makes safety recommendations.
“Currently, the only time a pilot is tested on partial-panel flying skills is when they do their commercial flight test,” said Lee. “After that, there are no more assessments, officially.”
The cockpit voice recorder of the Air Tindi flight is shown upon its discovery by a team equipped with metal detectors.
Previous investigation reports show the safety board expressing concern about partial-panel training and assessment for at least a decade.
Flying without the availability of attitude indicators, in limited or zero visibility, is considered exceptionally difficult.
A 1954 study, well-known in the industry, showed that pilots with no previous instrument-flight experience (unlike those in the Air Tindi incident) could, on average, keep an aircraft safely airborne for only three minutes in a partial-panel, zero-visibility exercise. None lasted longer than eight minutes.
Lee told Cabin Radio the contents of his presentation had been shared with Air Tindi, and the families of those involved in the incident, prior to this week’s conference.
However, Hayworth’s partner said she had received no contact from the Transportation Safety Board regarding its update until approximately 3pm on Tuesday – after Lee’s presentation had concluded.
An aunt subsequently called Cabin Radio to state Hayworth’s direct family had received no contact at all regarding the new information.
Investigators’ work continues and a final report has yet to be published.
Lee also provided an update on the Transportation Safety Board’s investigation into an accident at Little Doctor Lake, near Fort Simpson, in August 2018, which left three tourists dead.
A draft of that investigation’s final report is almost ready for confidential review before its publication, Lee told conference attendees.
The safety board has already issued an advisory to Transport Canada regarding what Lee termed the “age-old” issue of the Cessna U206’s flaps blocking the rear doors – as happened at Little Doctor Lake – making it more difficult to exit the aircraft in emergency situations.