Air travel's communications killer

On that Sunday afternoon, just before 2 p.m., two Boeing 747s touched down at Los Rodeos. One was a KLM (Royal Dutch Airlines) flight from Amsterdam. The other a Pan American flight from New York. Both were charter flights.

And neither, as fate would have it, was supposed to be on Tenerife at all. Both were originally headed to nearby Las Palmas, where their passengers, nearly 700 in all, were meeting cruise ships bound for the Mediterranean. But earlier in the afternoon, a bomb exploded in a flower shop at Las Palmas airport, and all flights were diverted. Both KLM and Pan Am, along with many others, put down on Tenerife until Las Palmas opened up again.

They taxied to the terminal building, parking right next to each other on the tarmac. It was a hectic scene at the normally lazy Los Rodeos. The ramp was crammed with airplanes -- most of which weren't scheduled to be there in the first place. Jet engines whined, horns blared, cars and trucks darted between aircraft and beneath wingtips.

At just about 5 o'clock, with Las Palmas accepting traffic and the airplanes refueled, the Pan Am and KLM crews received taxi clearance and began to move. Meanwhile, the weather had become terrible, with thick fog, light rain and very little visibility.

The Pan Am jet, in a note of historical irony worth mentioning, was identified on its blue-and-white hull as the Clipper Victor. The doomed Victor was already, in fact, no stranger to notoriety. Seven years earlier this very same airplane made history when it completed the first revenue flight of a Boeing 747, from New York to Heathrow on Jan. 21, 1970. Somewhere on its nose was the dent from a shattered champagne bottle.

>From Clipper Victor, the view from the upper-deck cockpit, some 40 feet above the ground, was a commanding one, high enough for Capt. Victor Grubbs and his crew to see over the roof of the terminal, and above the tails of the other airplanes. Except for one: the KLM 747, which carried the name Rhine.

As the oldest operating airline in the world, KLM was and remains a proud airline with an excellent safety record. In the captain's seat of the Rhine sat Jacob van Zanten, one of the company's top instructor pilots. Frequent fliers may have recognized van Zanten's handsome visage as he walked through the concourse, or down the spiral staircase in the first-class cabin of the 747, for van Zanten himself stared out from some of KLM's advertisements -- in his captain's seat, silver-haired and square-jawed, assuring the world of the punctuality and competence of his country's national airline.

Because of the congestion, the normal route to Runway 30 at Los Rodeos was blocked. Departing planes would have to taxi on the runway itself, in a procedure called a "backtaxi." Reaching the end of the strip, they'd make a 180-degree turn and then take off in the opposite direction.

Both KLM and Pan Am were given permission to backtaxi simultaneously. Van Zanten would go first. He would steer to the end, wheel his 747 around in a great U-turn, and then hold in position until granted permission for takeoff. Behind him was Capt. Grubbs in the Pan Am Clipper. His instructions were to eventually turn clear of the runway to allow van Zanten's departure.

Because of the fog, the airplanes could not see one another. And neither was visible from the control tower. The airport was not equipped with ground tracking radar.

Finally in position for departure, the KLM crew called for its ATC route clearance. This is not a takeoff clearance, but a procedure outlining turns, altitudes and frequencies for use en route. It is normally received well before an aircraft reaches the runway, but the KLM crew had been too preoccupied with checklists and taxi instructions to ask for it until now.

At 5:06, the KLM first officer, sitting just to the right of van Zanten, verified the route clearance with the control tower. He then uttered these mysterious words: "We are now, uh, at takeoff."

For whatever reason, the KLM crew believed it had been cleared for takeoff. "We gaan," van Zanten told his crew. "Let's go." Releasing the brakes of his mammoth machine, the Rhine began barreling down the fog-shrouded runway, completely without permission.

"We are now at takeoff" is not standard phraseology among pilots, its intent perhaps vague. But it was explicit enough to get the attention of both the Pan Am crew and the control tower.

Almost immediately, the tower radioed back to KLM, saying, "OK, stand by for takeoff. I will call you."

At the same time, the Pan Am crew, still on the runway and quite concerned with KLM's final remark, made a call as well. "And we're still taxiing down the runway," announced the first officer.

Either of these transmissions would have been, should have been, enough to stop van Zanten cold in his tracks. Realizing his mistake, there was still time to discontinue the roll. That is, if he'd heard either one.

But because both the controller's and Pan Am's calls were made at the same instant, the only audible sound in van Zanten's ears was the crackle and squeal of a five-second heterodyne.

Further confusion arose as the KLM 747 accelerated. The second officer leaned to van Zanten and asked, "Is he not clear, that Pan American?"

"Oh yes," van Zanten replied emphatically.

Capt. Grubbs is heard saying nervously, "Let's get the fuck out of here." And with that, he and the crew saw the lights of the lumbering KLM jet emerging out of the fog. "Get off! Get off! Get off!" yelled the first officer.

Seconds before impact, van Zanten shouts and attempts to leapfrog his aircraft over the Pan Am, dragging its tail along the pavement for 70 feet. Its landing gear just lifting from the pavement, the Rhine slams into the side of the Clipper Victor, which had veered sharply to the left to avoid the collision.

The KLM aircraft settled back to the runway, skidded another thousand feet and was consumed by fire before a single one of its 248 passengers and crew members could escape. Gutted by fire and explosion, 335 people aboard the Pan Am plane also were killed. (There were 54 survivors from the Pan Am, including the entire cockpit crew.) The combined total of 583 victims represents the highest-ever death toll in an airplane crash of any kind.

Next Page: 25 years later, the heterodyne problem still isn't fixed, though it could be, easily

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