The plane was flying in an anti-clockwise direction, following, it seemed, the path of an irregular oval, for the sound of its motors faded slightly as it curved round to north and west. But within thirty seconds it was approaching again, in a swelling thunder of sound, to the south-west—to the leeward of us, that was—and I could tell from Jackstraw's explosive ejaculation of sound, muffled behind his mask, that he had seen it at the same moment as myself.

It was less than half a mile distant, no more than five hundred feet above the ice-cap, and during the five seconds it remained inside my line of vision I felt my mouth go dry and my heart begin to thud heavily in my chest. No SAC bomber this, nor a Thule met. plane, both with crews highly trained in the grim craft of Arctic survival. That long row of brightly illuminated cabin windows could belong to only one thing—a trans-Atlantic or trans-polar airliner.

"You saw it, Dr Mason?" Jackstraw's snow-mask was close to my ear.

"I saw it." It was all I could think to say. But what I was seeing then was not the plane, now again vanished into the flying ice and drift, but the inside of the plane, with the passengers—God, how many passengers, fifty, seventy?—sitting in the cosy security of their pressurised cabin with an air-conditioned temperature of 70° F, then the crash, the tearing, jagged screeching that set the teeth on edge as the thin metal shell ripped along its length and the tidal wave of that dreadful cold, 110 degrees below cabin temperature, swept in and engulfed the survivors, the dazed, the injured, the unconscious and the dying as they sat or lay crumpled in the wreckage of the seats, clad only in thin suits and dresses. . . .

The plane had completed a full circuit and was coming round again. If anything, it was even closer this time, at least a hundred feet lower, and it seemed to have lost some speed. It might have been doing 120, perhaps 130 miles an hour, I was no expert in these things, but for that size of plane, so close to the ground, it seemed a dangerously low speed. I wondered just how effective the pilot's windscreen wipers would be against these flying ice spicules.