This discussion contains extracts from a report by the Air Transport Safety Board of Canada. It’s to promote safety and not to establish liability.

Piper PA-28-180, C-GGOR

2 NM W of Brisco, British Columbia, Canada.

24 November 2023

History of the flight

The aircraft took off on a recreational VFR flight from Vanderhoof Aerodrome (CAU4) to Invermere Aerodrome (CAA8) with only the pilot on board.

Shortly after departing CAU4, the aircraft appeared on radar at 1243 climbing through 3000’. At 1255 it levelled off at 9,500’. It flew east and disappeared from radar at 1331. At 1421, the pilot communicated with a family member via text message that he was passing the village of Valemount, and at 1508, that he was flying at 11,500’.

The occurrence flight was conducted above 10,000’ for an unknown duration.

At approximately 1554, the aircraft was seen in a vertical dive, approaching the ground at high speed. It was reported to have executed an abrupt pull-up from the dive to a level attitude at approximately 300’ to 500’. It then reportedly had a wing and nose drop before impacting the ground in an inverted attitude.

A ground and air search was initiated after the crash was reported to emergency services on 911. No ELT signal was received. The crash site was found more than 17 hours after the occurrence.

The pilot was fatally injured. The aircraft was destroyed. There was no post-impact fire.

Pilot information

The pilot held a PPL, issued in July 2022, and a valid Category 1 medical certificate. He had accumulated approximately 243 hours, of which approximately 170 hours were in the occurrence aircraft.

The pilot had flown this aircraft between CAU4 and CAA8 on a regular basis over the previous 10 months and had flown the route 13 times. These flights had an average flight time of 4.1 hours.

Weather information

There was no cloud ceiling and the visibility was greater than 20 statute miles. Weather was not considered to be a factor.

Aircraft information

The aircraft was built in 1963. It had a 180 hp Lycoming O-360-A3A engine and a fixed-pitch propeller.

Fuel

The pilot had a history of using 91-octane gasoline, known as MOGAS. The POH requires that the aircraft use aviation-grade fuel. In order to operate the aircraft with other than aviation-grade fuel, such as MOGAS, a supplemental type certificate (STC) is required, however this was not issued. It could not be determined if this was a contributing factor to the outcome.

Maintenance

The aircraft’s last annual inspection had been completed on 28 March 2023.

An airworthiness directive exists requiring inspection of the exhaust-type cabin heater to reduce the risk of carbon monoxide poisoning. The aircraft’s technical records indicate this AD was not completed and was overdue by more than eight months; however, carbon monoxide poisoning was determined not to be a factor in the occurrence.

Engine examination

The investigation found no indication that a component or system malfunction played a role in this occurrence.

Stall warning system

The aircraft was equipped with a stall warning system, which consisted of a red-filtered, incandescent lightbulb that illuminated when the system detected the aircraft was at, or near, a stalled condition.

A lightbulb filament analysis showed that the typically tightly wound coils of the filament were severely stretched. This occurs when an illuminated light filament becomes more ductile as a result of the high temperature from its illumination and is then exposed to sufficient shock. This filament stretching indicates the stall warning light was illuminated at the time the aircraft struck the ground.

Supplementary oxygen

Flying unpressurized aircraft at altitudes above 10 000’ ASL without supplemental oxygen can lead to hypoxia.

The Canadian Aviation Regulations state:

Where an aircraft is operated at cabin-pressure-altitudes above 10,000 feet ASL but not exceeding 13,000 feet ASL, each crew member shall wear an oxygen mask and use supplemental oxygen for any part of the flight at those altitudes that is more than 30 minutes.

Where an aircraft is operated at cabin-pressure-altitudes above 13,000 feet ASL, each person on board shall wear an oxygen mask and use supplemental oxygen for the duration of the flight at those altitudes.

The aircraft was not equipped with oxygen masks, or supplemental oxygen. The investigation could not determine how long the aircraft was operated above 10 000 feet ASL.

Wreckage and impact information

The aircraft came to rest in a wooded area in an inverted attitude. The wreckage indicated a high-angle impact with little forward velocity. One propeller blade exhibited rearward bending whereas the other blade had a slight forward bend, which is consistent with low or no propeller rpm at the time of impact. The aft section of the fuselage and tail were bent to the right, and both wings were found on the left side of the fuselage, indicating rotational forces existed when the aircraft struck the ground.

Survival aspects

The aircraft was equipped with an automatic fixed ELT on 121.5 MHz and 243 MHz. The ELT did not activate. It was found in the OFF position.

Safety messages

While the investigation could not determine the specific cause of the occurrence, it found some maintenance required for the safe operation of the aircraft had not been performed. Owners and operators of aircraft are reminded that compliance with legally required aircraft maintenance activities, including airworthiness directives and supplementary type certificate requirements, is essential for the safe operation of all aircraft.

Jim’s Comments

The thing about hypoxia is that you don’t see it creeping up on you with murder in its eye. If a hungry lion suddenly appeared in the cockpit you would immediately recognise the danger and you would do something about it. You might offer it your bacon sanga, or shoot it in the head.

My point is the lion would make itself known to you. You would smell the brute, hear its roar and feel its hot breath on your neck.

Hypoxia, on the other hand, will kill you just as dead, but it’s a sneaky bastard. It will induces euphoria and gently lull you into a peaceful sleep. You may awake shortly before your components mingle with those of a hot Lycoming.

Hypoxia is the gentle sting ray that killed Steve Irwin, the Aussie Crocodile man. I has no warning teeth like a lion or croc.

It seems that this pilot lived a few seconds longer. He appeared to have been woken – probably by the terrifying sound of rushing air and then the sight of scenery filling his windscreen.

He hauled on the pole – missed the planet but then kept hauling until he spun into the tundra.

Some years ago I was returning to George from an airforce camp on the Limpopo. The aircraft ZS-DPI, was a magnificent red and white 250 Comanche with tip tanks. This meant we could easily fly the length of South Africa in one hop.

In round figures it’s 900 statute miles and we cruised at a bit over 180 mph which made it a 5 hour flight. To avoid summer turbulence we flew at flight level 105.

I had three pax, but the guy in the front with me was our intelligence officer, a really bright guy called Casey Adderson. We chatted about hypoxia and Casy found it hard to believe that he was in any way mentally impaired, so we conducted a test. I’d give him headings and time how long it took him to work our the reciprocal. We averaged his times over ten tests and it came out to be around 25 seconds.

After landing we did the same exercise over a cup of coffee in the airport restaurant and he was doing it in less than five seconds.

This means that for most of the trip we were totally unaware that the lion was sniffing the air and smelling our blood.

On another trip I was flying two visiting Portuguese Airforce generals up the Caprivi Strip in the same aircraft. This was during our disagreement with Castro and the naughty communists.

We were at flight level 115 in order to be pretty much out of range of SAM 7s. It was just after lunch and a hot day and I managed to go to sleep at the helm. Fortunately the autopilot prevented my pax from noticing their captain had gone AWOL.

We have all dozed off for a second or two while driving a car, while knowing full well that this can end in death – but we still do it. I have actually done it on a motorbike on a dirt road in Tanzania.

Take home stuff

The four big dangers of hypoxia are:

  • Being a bit slow out of the starting gate.
  • Thinking that you are pretty smart – like after you have got outside a couple of snorts.
  • Knowing that you will definitely manage to stay awake.
  • Being totally unaware of the lion lying on the back seat.