I posted this some time ago but it's a helluva story. From 'Splash of Colors', by John Nance. Required reading before thinking about La Paz.
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There is one more problem with high-altitude airports—the need of the human body for oxygen. At about 13,000 feet, for one not used to living in such rarefied air, a slight degree of hypoxia (reduced awareness and judgment resulting from too little oxygen to the brain) usually occurs after about thirty minutes. Braniff’s pilots were required to breathe 100 percent oxygen from thirty minutes prior to departure from La Paz, regardless of how they felt. The reason centers around the fact that different people will be affected in different ways, but without the use of on-board oxygen a pilot can become sufficiently hypoxic (and be sufficiently unaware of it) to make significant mistakes reading his charts and checking them. One night in 1974, that is precisely what occurred.
The 220,000-pound Braniff DC-8 (at its maximum weight for this altitude), bound for Lima under a canopy of stars in the most crystal-clear night sky imaginable, rolled onto the first section of the runway with the flaps properly set at 12 degrees and advanced power. The captain, copilot, and flight engineer had been on the ground about an hour and didn’t feel they needed to breathe any oxygen before departure. They were feeling fine and sharp and had been here many times before.
A small piece of paper called a data card and containing the numbers for the takeoff rested on the center pedestal in front of the throttles, over one of the radio control heads—the place the crews normally kept it. As the speed built up and the airspeed indicator on the captain’s panel came off the peg, he glanced down and re-checked his V1 and rotation speeds, which the copilot was to call out when reached. As it indicated on the data card, at 122 knots of airspeed (over 145 knots of ground speed) the copilot called “Ro-tate,” and the captain pulled back on the yoke.
The aircraft felt much heavier than usual; the response to the pull on the yoke was minimal, but finally he managed to get it into about an 8-degree nose-high attitude. And there it stayed. They had used up over 9,000 feet of runway, and the red lights marking the end of the 13,000-foot strip of concrete were coming up fast—at over 165 miles per hour. The DC-8 was still rolling along on its main wheels, nose reared up into the air at an 8-degree angle, airspeed indicator now hovering just above 120 knots, and not accelerating. The captain pulled harder, bringing the nose up a bit farther. Still the red lights grew brighter—and the main wheels stayed on the ground. The heartbeats of all three men quickened slightly, but at such a tense moment, the problems at hand are han-dled quickly but routinely. There is no time for panic, even if that were the normal response of a seasoned airline pilot to a rapidly deteriorating situation—which it is not.
There was now less than 1,000 feet of runway left. The nose was as high as 9 degrees, the indicated airspeed still around 120, and the main wheels were still on the ground. Nothing but blackness seemed to exist to the west of the two red marker lights—nothing but the blackness of the altiplano, fortunately flat as a West Texas pasture between the end of the concrete and the shores of Lake Titicaca 10 miles to the west.
Just as the red lights disappeared from view, the captain did the only thing there was left to do—he pulled hard on the yoke and “yanked” the nose of the giant airliner as high as he could without contacting the tail skid.
As the last vestige of concrete passed beneath the wheels, they had gained a couple of feet of altitude, enough to clear the red lights at the end—but no more. The aircraft was now airborne in “ground effect,” a cushion of air compressed by the huge mass of metal screaming across it and tenuously holding it above the surface. At the captain’s command “Gear Up,” the copilot reached up with his left hand and raised the gear handle. The huge gear doors on the main gear opened, increasing the drag momentarily and canceling any acceleration as they hung suspended over— nothing. There was nothing visible in front of them in the blackness.
The gear thudded into place on the uplocks and the doors closed at last. The captain was holding as high a deck angle as he dared, watching the airspeed finally, slowly, begin to increase, watching the vertical velocity indicator (rate of climb) and keeping it slightly positive, and watching the radio altimeter (an extremely precise in-strument that gives the altitude of the aircraft above the surface with accuracy better than plus or minus 2 feet) showing first almost nothing, then 10 feet—moving ever so slowly upward.
The 220,000-pound machine full of people and baggage and fuel was now screaming along barely off the ground over the flat Bolivian terrain, barely clearing unseen fences and small rises in the land-scape, caught in a position in which the deck angle was so high, and the resulting drag so great, that even the thrust of all four engines at maximum power was barely able to keep the airspeed from drop-ping. The aircraft was leaving a wake of dust and dirt behind it as it skimmed over the ground.
Finally it began to accelerate and gain 20—then 30—then 40 feet. The captain relaxed his back pressure ever so slightly and let the nose drop a tiny bit, which lowered the drag coefficient and made the thrust of the straining turbojet engines greater than the overall drag—and at that moment he knew they would make it.
As the climb-out finally became normal and the DC-8 passed through 2,000 feet above the surface with flaps retracted, the effect of the adrenaline began to overpower the slight hypoxia that had influenced them, and with limbs beginning to shake slightly (and an oblivious load of passengers who never suspected a thing was wrong, never suspected they had almost been in the middle of a monstrous aircraft accident), they yanked out the books and re-calculated the speeds.
There it was. For the weight and the temperature, 140 knots was VR. They had horsed it off 18 knots early, and nearly, well……. The prospect of what would have become of their craft settling down in the dirt on the other side of those lights at 165 miles per hour was too frightening to go into. All three of them knew that if the captain had been too abrupt—dropped one ounce of back pressure after they had lifted off or increased it any—they would be on the ground right now. But his skill deserved mixed accolades—he had checked the airspeeds without oxygen back at the ramp, too. All that skill, all that experience had canceled out a simple but potentially fatal mis-take. At Lima the craft would have stagnated a bit on speed, then gone right on with the takeoff. At La Paz, the margins were so thin, there was little room for error—the error they had made.