The Ultimate Cone of Confusion

I was taught that a pilot could always trust his compass. But that lesson didn’t account for flights over the magnetic north pole.

General Dynamics RB-57F Canberra
Able to loiter above 60,000 feet, the General Dynamics RB-57F Canberra was ideal for high-altitude scientific observation and capable of carrying a 700-pound payload 3,000 miles.

When the Air Force taught me to fly, at Webb Air Force Base in west Texas in 1964, my classmates and I were told that the one instrument that would never fail us is the little alcohol-filled magnetic compass that every airplane has mounted squarely in the pilot’s line of sight. Compasses, we were taught, were immune to the Cone of Confusion, which occurs whenever a pilot is directly above an electronic navigational beacon such as a Tactical Air Navigation (TACAN) system or a Very-High-Frequency Omnidirectional Range (VOR) system, which makes the navigational needle spin because it can’t find a radial from the beacon.

The instructors who imparted this wisdom had never flown into the ultimate Cone of Confusion, the ones over the magnetic north and south poles. There, the magnetic lines of force are vertical, so north is straight down. Twelve miles up, the cone is wide enough to make any pilot’s compass spin like a merry-go-round while it tries to find north.

The winter of 1968-1969 was a period of peak solar activity. The number and size of sunspots were at the high point in the sun’s 11-year cycle. Although there isn’t a direct causal relationship between them, a solar flare could be a clue that we should expect what is now called a coronal mass ejection, an eruption of solar wind that carries radioactive particles away from the sun. CMEs tend to originate from the most active areas of the solar surface,  so groupings of sunspots sometimes indicate that a CME is on its way.

The solar wind and radiation directed toward Earth are blocked by the magnetosphere—magnetic lines of force surrounding the planet. The radiation follows these magnetic pathways around the curvature of Earth and enters the atmosphere at the north and south magnetic poles. The Northern and Southern Lights (Aurora Borealis and Australis Borealis) are visible evidence of this process.

In the summer of 1859 (way before I joined the Air Force), observers recorded seeing an enormous sunspot. The Carrington Event—named for British astronomer Richard Carrington, who determined that activity on the sun can create geomagnetic disturbances here on Earth. It was powerful enough to send sparks shooting out of telegraph machines in North America and Europe. The Northern Lights were seen as far south as Cuba and Hawaii, while the Southern Lights were visible from Santiago, Chile. A solar storm of that magnitude would be potentially catastrophic today, given our reliance on electricity and telecommunications technology. But back in 1968, when observers believed a CME was imminent, the scientific community requested that an airplane equipped with radiation-measuring apparatus be in position over the magnetic north pole. The aircraft would be at its maximum altitude, and would stay there as long as fuel permitted.

At the time of my flight, the Boeing Supersonic Transport and the British-French Concorde were in development. Both airplanes would fly at high altitude between North America and Europe, and some of these flights would pass close to the north magnetic pole. Their passengers could be exposed to solar radiation. At the same time, Apollo spacecraft were beginning to fly, and the astronauts would also be exposed.

No one knew how much or what kind of radiation might result from a big CME pointed at Earth or what effect this radiation would have on astronauts or the people aboard the aircraft. Nor did we have a good understanding of how solar radiation might affect the delicate electronics of an aircraft or satellite.

Moreover, the exact speed of the solar energy was not known. Some scientists theorized it might arrive in eight minutes—the time it takes light from the sun to reach us—but others thought it would move much slower. The time difference between a sunspot and the appearance of the Northern Lights was known, but whether the appearance of the lights correlated with the peak of the radiation from a CME was not understood at that time. (We have since learned it can take up to eight days for solar wind and the radiation carried with it to travel from the sun to Earth.)

The 58th Weather Reconnaissance Squadron, based at Kirtland Air Force Base in Albuquerque, New Mexico, had the only airplane for the job: the Martin–General Dynamics RB-57F Canberra, a descendant of the English Electric Canberra bomber. With a crew of two—a pilot and a navigator, both wearing pressure suits—the airplane was capable of carrying a 700-pound payload (radiation-measuring equipment, in this case), traveling a range of 3,000 miles, and loitering above 60,000 feet. General Dynamics modified the Martin B-57 into the RB-57F by increasing its wingspan from 64 to 122 feet, doubling the wing’s chord and the area of the vertical stabilizer, and upgrading the engines to produce more than twice the thrust.

The 58th flew the F-model for a variety of high-altitude tasks, including sampling debris following nuclear tests, sniffing the air for evidence of nuclear tests by other nations, recording the radiation levels in the atmosphere at various altitudes and latitudes, and photographing the development of thunderstorms, among other missions.

Just after Thanksgiving in 1968, two crews flew from Kirtland to Eielson Air Force Base, near Fairbanks, Alaska. We had flown north from Eielson toward the geographic pole many times on other radiation-measuring missions, but this would be our first mission to the magnetic pole.

After a pair of practice runs to collect baseline data—we were never told exactly what metrics the instruments aboard our aircraft were collecting, though I do recall being told before one flight that a beef roast had been loaded into the bomb bay as part of our study!—we stood by awaiting word of a solar flare. With luck we would record and sample a CME.

On our first flight to the magnetic north pole, on December 6, my navigator Bill Moore and I learned that our supposedly infallible magnetic compass became unusable in the Cone of Confusion. Even the gyro-stabilized compass spun, though not as dizzyingly fast as the little one.

This was a novelty, not a crisis. The compass was not an RB-57F navigator’s only tool. If you are beyond the range of a VOR or TACAN station—in the middle of the ocean, for example-—the RB-57F has a periscope sextant the navigator can use to determine position via the sun, moon, or stars.

Returning to the pole was always north, no matter where you were on the edge of the cone. When it came time to return to Eielson, some object—the sun, moon, stars, or Northern Lights—would be visible in the sky, so depending on the time of day, Bill told me to turn right or left until one of these guideposts was where he wanted it on the canopy. At 60,000 feet, the horizon is 400 miles away, so you can also see lots of things on the surface of Earth to keep yourself oriented.

Flying at those latitudes at night, it seemed we were flying right through the Northern Lights. They’re actually more than 100 miles above Earth, but when they stretch from horizon to horizon and are so bright, it seems like you’re flying inside them. I’ve rarely seen anything so beautiful.

Following our last flight to the pole, on December 12, Bill and I were sent back to Albuquerque because the dosimeters we always wore indicated we had received what our flight surgeon later told us was a higher dose of radiation than an X-ray technician would be permitted in a month.

This had the fortunate side effect of getting me home in time for Christmas. While choosing gifts that year for my wife, four-year-old daughter, and two-year-old son, I wondered if Santa Claus had ever been concerned about radiation exposure. It’s a good thing he knows the North Pole route by heart. A spinning compass, as Bill and I learned that year, would’ve been no help to him.

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This story is a selection from the December/January issue of Air & Space magazine

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