Wop May, the Mercy Flight to Fort Vermilion, and the Open Cockpit at Forty Below That Proved Aviation Could Survive the Canadian Winter

On January 2, 1929, pilot Wop May and mechanic Vic Horner departed Edmonton in an open-cockpit Avro Avian and flew 400 miles north through -40° temperatures to deliver diphtheria antitoxin to Fort Vermilion, Alberta. They arrived the next day. No one died. The flight became a turning point in the argument over whether aviation could function in the Canadian winter.

Who Was Wop May?

Wilfrid Reid May was born in Carberry, Manitoba, in 1896. The nickname “Wop” came from childhood and stuck for life. By 1918 he was flying Sopwith Camels over France with the Royal Flying Corps.

April 21, 1918 placed May at the center of one of the most examined incidents of the First World War. On one of his first combat patrols, his gun jammed. He was low on ammunition. And he was being followed by a bright red airplane.

Manfred von Richthofen - the Red Baron, the highest-scoring ace of the entire war - broke his own standing orders to pursue May down toward the Somme valley floor. May ran, pushing the nose down, skimming treetops, trying to reach Allied lines. Von Richthofen stayed on him.

Roy Brown, May’s wingman, dove from above and fired. Australian ground troops on the ridge fired from below. Von Richthofen took a single .303 round through the chest. His red triplane landed in a beet field. May crossed the Allied lines and landed his Camel in one piece.

Who fired the fatal round has been argued by historians ever since. What is not disputed is that May, by any reasonable measure, should not have survived.

From the Western Front to Northern Canada

May returned to Edmonton, earned his civilian certificate, and went to work. Northern Canada in the 1920s was a place aviation was quietly remaking - communities that took weeks to reach by dogsled could be reached in hours by air. May was part of the generation doing that work, flying charters, surveys, and anything else that paid.

The country was vast beyond comprehension, and the airplane was the only answer that made sense.

The Crisis in Fort Vermilion

Diphtheria broke out in the community of Little Red River, near Fort Vermilion in northern Alberta, in January 1929. Children were sick. The local antitoxin supply was exhausted.

The nearest supply was in Edmonton. Between the two points: 400 miles of frozen muskeg, boreal forest, and river corridor. No roads. No rail line.

A telegram was sent. A phone call was made. May and his partner Vic Horner said yes.

The Aircraft: An Avro Avian in the Subarctic

The airplane available was an Avro Avian - a light biplane with tandem open cockpits and a Cirrus engine producing 75 horsepower. It was designed for English spring mornings and grass strips in the Home Counties. It was not designed for the Canadian subarctic in January.

That distinction mattered. Cold at that magnitude doesn’t create inconvenience - it creates mechanical failure. Oil thickens to something between syrup and grease. Carburetors ice. Metal contracts. Ignition systems fail.

Horner understood cold the way a mechanic must: as a force that infiltrates every system, quietly, until something stops working. Where May was the pilot whose name ended up in the papers, Horner was the man who kept the airplane alive between legs.

Keeping the Antitoxin Alive

Diphtheria antitoxin cannot freeze. Frozen serum is worthless - the protein structure breaks down and what remains is no longer medicine. But it also cannot overheat. The viable temperature range is narrow, roughly around body temperature.

In an open cockpit at -40°, flying at approximately 100 miles per hour, with windchill turning exposed skin dangerous in minutes, there was exactly one available heat source.

May wrapped the antitoxin in blankets, tucked it inside his flying suit, and held it against his body for the entire flight. His own body heat was the insulation between the medicine and the temperature that would destroy it.

Flying the Peace River Corridor

A direct route from Edmonton to Fort Vermilion would have been shorter. May did not take it. A direct route passed over terrain with no emergency landing options. Frozen rivers were the bush pilot’s safety net - flat, long, usually clear of obstacles. Over river ice, a forced landing offered a chance. Over boreal forest, it offered a prayer.

May followed the Peace River north, adding miles to keep options below him.

At that altitude and airspeed, the cold attacked every exposed surface. May’s goggles frosted from the inside and bonded to his skin. The wind at speed in those temperatures doesn’t just strip heat - it burns first, then numbs, then causes damage you don’t feel until it’s already done.

He flew with one eye on the engine instruments and one on the terrain below, continuously cataloguing landing options. Frozen river. Lake surface. A clearing that might be long enough and firm enough. This running inventory is a discipline that experienced cold-weather pilots develop into habit.

The Overnight Stop at McLennan

They stopped overnight at McLennan, roughly halfway to Fort Vermilion. The overnight temperature dropped to approximately -48°.

The Avian sat in the open. Horner slept a few hours, got up before dawn, and built a fire under the engine cowling to warm the oil before draining it. Not metaphorically - an actual fire, in a tin pan, carefully managed beneath a wooden aircraft in the dark. He knew the margins precisely and built his fire accordingly.

May carried the antitoxin inside, kept it warm, ate, and was back on the ramp at first light. The oil was warmed. The engine was started before the heat had time to leave it. They flew north.

Arrival and Treatment

They reached Fort Vermilion on January 3, 1929.

The whole settlement came out to meet them. Dr. Harold Hamman took the antitoxin and went to work immediately. Treatment began within hours of the airplane landing.

No one died. The outbreak was contained.

The Return

The return trip was harder. Temperature dropped further south. A weather system moved in behind them. The engine ran rough through part of the route. May identified a forced landing site on a lake and kept it mentally filed - always knowing where the nearest option was, always keeping part of his attention in reserve for the emergency that hadn’t happened yet.

The engine held. They reached Edmonton on January 5, 1929.

The newspapers made them heroes. The story went national. The Alberta government eventually honored both men. In interviews from the era, May tended to treat the whole thing as essentially obvious: the medicine needed to get there, they had an airplane, the weather was miserable but that was the situation, so that was what they did.

Why This Flight Still Matters for Pilots

Before January 1929, there was a serious argument in government circles about whether aviation could operate reliably in the Canadian winter. The Fort Vermilion flight was a large part of how that argument was settled.

May and Horner went on to found Commercial Airways, one of the early bush air services operating out of Edmonton. May helped pioneer aerial mail service across the Northwest Territories at a time when the government remained skeptical that airplanes could function in winter. He was right. They were wrong.

When the Second World War came, May was too old for combat but not too old to teach. He ran an air observer school in Edmonton and trained hundreds of young Canadians who went on to fly Halifaxes, Lancasters, and Mitchells over occupied Europe. The generation that flew those aircraft over occupied France included men who learned the basics from a bush pilot who had, more than once, held a dying engine together by refusing to quit.

Wop May died in June 1952 on a hiking trip in Utah. He was 55 years old. Edmonton named a lake after him. The downtown airport where so much of his flying life was based was eventually renamed, but the city’s aviation heritage traces directly back to the men who flew those early northern routes.

Vic Horner outlived him and kept flying into old age. He never achieved the same public profile, which likely suited him. He was a mechanic’s mechanic - a man who measured his contributions by whether the engine ran.

The Fort Vermilion flight is not primarily a story about heroism. It’s a story about preparation and judgment. May’s decision to follow the river corridor instead of a direct route. Horner’s nightly oil management ritual. The choice to carry the antitoxin inside a flight suit against the body rather than stowed in baggage. None of these were dramatic choices. They were systematic ones - the product of experience, honest assessment of conditions, and the discipline to do the unglamorous work before the flight rather than improvise during it.

That calculus applies to anyone who flies in demanding conditions. The underlying principles haven’t changed: know your alternates, manage your systems, never stop cataloguing options.

Further reading: The Canadian Aviation Historical Society has published extensively on this era. Contemporary coverage in the Edmonton Journal archives from January 1929 is worth locating if you have access. Grant MacEwan’s biography of May holds up well. The Alberta Aviation Museum in Edmonton and the Reynolds-Alberta Museum in Wetaskiwin both preserve this history and are worth visiting.

Key Takeaways

January 2–5, 1929: Wop May and Vic Horner flew diphtheria antitoxin 400 miles from Edmonton to Fort Vermilion in an open-cockpit Avro Avian, through temperatures reaching -40°, and returned safely
May had survived a direct pursuit by Manfred von Richthofen on April 21, 1918 - during one of his first combat patrols of the war
The antitoxin was kept viable by carrying it inside May’s flight suit against his body - the only heat source available in an open cockpit at that temperature
Horner drained engine oil every night, warmed it near a fire, and restarted the engine before the heat could leave - a procedure improvised from necessity that became standard cold-weather bush flying practice
The flight helped resolve the government debate over winter aviation in Canada, directly influencing the expansion of bush air services and aerial mail across the Northwest Territories