From the archives: This story originally appeared in the August 1930 issue of Popular Mechanics. We’re republishing it now as part of our ongoing look back at Pop Mech’s best feature stories from the last 125 years. It appears here as originally published; some details, terminology, or understandings may have changed over time.

To lovers of outdoors, the mountains between Bellefonte and Aaronsburg, Pa., are numbered among the masterpieces of nature, but pilots of the air mail have christened them the “Hell Stretch,” for they are a barrier that marks the most treacherous flying conditions to be found anywhere in the United States.

Still, day and night, over that stretch, heavily loaded planes, bearing mail and express, plow along. A corps of the most expert pilots in the country—and the most daring—is on the job to see to it that the mail goes through.

The percentage of fatal forced landings and crashes, to be sure, is small compared with the total number of such landings and accidents, and in the repair base at Chicago, they can show you hundreds of bent and twisted steel propellers from ships that have made bad landings or difficult take-offs without fatal results. All of which points to one fact, aviation men say: The odds are heavily in favor of the pilot going through, and of his living in a crack-up even if it occurs along the Hell Stretch.

The question may arise, why are Pennsylvania’s mountains so treacherous? Why are they regarded as the worst country in the United States to fly over?

It is because these mountains are unlike any others in the land. They are not extraordinarily high, few ranges going over 3,000 feet, but there are miles of heavily wooded hills. The air route is dotted with emergency landing fields, but to the left and right of the course, the hills and forests offer small opportunity for landing a plane safely—especially if that landing must be made in the inky blackness of the night or the impenetrable fogs that cuddle close to the ground.

In the west, the mountains are not so heavily wooded. Instead of peaks, the Alleghenies are a series of ridges that rise one a few feet higher than the other, with narrow valleys between—not open valleys as is the case in the Rockies and Sierras. On all but fair days and nights, the clouds usually hang low over the mountain tops and the valleys are dark with fog. And low-hanging clouds and fog are the airman’s worst foes over rugged country.

The mountains have no flat, clear tablelands at their summits to afford any sort of landing place for a disabled plane. Their tops and sides are either densely wooded or bare stone. As a rule, western pilots fly over wilder territory than do the pilots on the eastern routes, yet it once took Harry A. Smith, chief test pilot of the Bellanca company, two days to find his way out of the Pennsylvania mountains after a forced landing.

“I saw no less than two hundred wild deer in the woods,” he said. “Some came so close I could have knocked them over with rocks. They were just curious.”

In the spring and summer, violent rain and electrical storms afflict this region, rising sometimes without notice. In the fall and winter, fog and haze lie low over the mountain tops, shrouding the wooded ranges from the eye of the pilot. And sometimes unexpected wedge-shaped snow and sleet storms beat down from the lake country and strike the route. The mountains are continually snowbound in the winter.

Flight over such a territory as the “graveyard stretch” by day is a job that’s hard enough. But supplant whatever visibility the day flyer may have by total darkness, and add a blinding snow or sleet storm to the cold, and you’ve got a real task for the pilot.

Just below thirty-two degrees Fahrenheit, the mist in the air, or the snow, or the sleet, begins to gather on the wires, struts, wings and tail group, and hurtling through the air at better than a hundred miles an hour packs that formation into ice on the plane. Ice is heavy. The pilot may seek a higher altitude in an attempt to find a colder or warmer stratum to prevent the formation. If he is barging along “hopping the hedges,” skimming the tree tops in an effort to catch the gleam of the marker beacons or danger lights on the higher elevations, he can’t go lower and get rid of that ice. And when the ice reaches a certain weight, he can’t climb, especially if it has formed in such a way as to change the wing curve of his plane and automatically reduce the lift.

Given a set of circumstances like those, you have danger. It’s not very often the big motors quit anymore. It’s not very often the big Boeing, Curtiss or Douglas ships come to grief through failure of even the smallest part. But when ice forms on the wings of a ship mushing along over the tree tops and the pilot can’t get rid of it or climb, he’s got to come down. That’s when the rugged topography of the Hell Stretch or the rest of the mountainous country takes sides against the skill of the stout-hearted man at the controls. The heavy ship comes down, but where and how?

In a storm or fog, the pilot flies “blind,” that is, he pays attention to nothing except the instruments on the board in the cockpit. Perhaps the compass before him goes “haywire,” and he has lost his course. Cruising in the sky surrounded by fog that obscures even the stars from his sight, the pilot loses faith in his other instruments, as some pilots have done, and decides to trust to his fanciful instinct. He flies on to some point where he believes there is a pass in the mountains—but crashes into the mountainside, as many have done.

Paul Collins, veteran pilot of the New York–Cleveland run, had better luck on Hell Stretch than some of his fellow airmen. One cold, gray morning, he leaped into his mail plane at Cleveland, gave his engine the “gun” and went roaring into the murky east. The half-light of day was over the flying field. Bad weather was sensed in the murky offing.

Over northwestern Pennsylvania, Collins struck it. A line squall rose out of the storm, ripped into his plane, smashed off a wing and forced him, after terrible moments of bucking and fighting, to abandon it for a parachute.

Four thousand feet up, at the mercy of the storm, Collins flipped open his safety belt, caught a strut of the remaining wing and swung out into space. He rocked perilously in the sky for a few moments and then, free from his falling craft a second, he let go. Tossed like a leaf in the swirling eddies and fierce currents of the upper air, the flyer gave himself up for lost as his silken savior swung to and fro. Then, true to the faith built into it, the great half arc opened right side up to the steadying weight of his body below, and he floated safely to earth on the wooded countryside of Pennsylvania, near Millstone.

Thomas P. Nelson, flying east with the night mail, got the breaks on November 6, last. Soon after he passed the intermediate landing field at Ringtown, Pa., he noticed that his ship was on fire. He immediately turned back toward the field and began to fight the fire—shutting off his gas, turning on the fire extinguisher.

But the fire extinguisher had frozen.

There was only one thing to do—take to the parachute. But before doing so, Nelson safely guided his blazing craft away from the field and the town toward the open wilderness, where no one could be injured by the crash of the ship. Then he floated safely to land.

He got the breaks that time, but the jinx of the graveyard stretch got him in the end. A month later, a fierce winter storm proved too much for him and he was found dead beside his plane, near Cleveland.

The list of those who have died on Hell Stretch is growing more slowly these days of better instruments, better ships, finer motors and radio than it did in the past. Many expensive tests are being made in an effort to bring the flyers nearer to the goal of positive safety. More expensive equipment is bought and installed. A huge corps of experts is employed continually by the N.A.T. to seek safety and warn pilots of danger.

Radio directional beams that tell the flyer whether he is on his course have provided the latest and, aviators believe, the best weapon so far developed to gain safety. All planes now flying the graveyard route are equipped with radio receiving devices. Headphones on the pilots’ ears tell them whether they are on the course. Weather conditions ahead are given by radio.

Such a system is costly. But the cost matters little when money is weighed against human lives, costly planes and motors, and valuable cargoes.