CRASHED PLANES SAVE LIVES

Science Illustrated - - CONTENTS - SHUTTERSTOCK & NICOLAI AARØE

Trav­el­ling by air re­mains the safest way to go. Why? Be­cause ev­ery dis­as­ter showed us how to stop it hap­pen­ing again.

Just a few decades ago, plane crashes were com­mon, and killed thou­sands of peo­ple. But af­ter each crash, the causes were care­fully an­a­lysed to im­prove safety. The next step is a new sys­tem that pre­vents planes from dis­ap­pear­ing.

1956 HEAVEN IS A LAWLESS PLACE

41-year-old plane cap­tain Jack Gandy is head­ing di­rectly into the last storm of his life. With 64 pas­sen­gers and six crew mem­bers aboard, his Trans World Air­lines plane took off from the air­port in Los An­ge­les at 9.01 AM, and apart from a de­lay of about 30 min­utes be­fore take-off, Satur­day 30 June 1956 seems to be just another day at the of­fice in the Lock­heed Su­per Con­stel­la­tion cock­pit.

On its way to Kansas City, Mis­souri, the plane will fly over the Grand Canyon, and the ex­pe­ri­enced pi­lot has taken the trip more than 170 times be­fore. But this morn­ing, dark thun­der clouds be­gin to de­velop above the sunny Cal­i­for­nian land­scape im­me­di­ately fol­low­ing take-off. So over the ra­dio, Grady rou­tinely re­quests the con­trol tower's per­mis­sion to climb higher than the in­structed cruis­ing al­ti­tude of 5,800 me­tres, al­low­ing him to avoid the in­tense tur­bu­lence caused by the thun­der­storm.

Gandy gets his per­mis­sion, and as he makes his craft climb, he leaves the city of Los An­ge­les be­hind, head­ing into un­mon­i­tored airspace. In 1956, planes are only guided and mon­i­tored by con­trol towers in the busy airspace above air­ports. Other­wise, just about all the sky over the US is no man’s land, where pi­lots are com­pletely left to them­selves. No radar keeps an eye on them, and no con­trol tower mon­i­tors their where­abouts.

Af­ter 1.5 hours of quiet flight, the Trans World Air­lines plane is over the Grand Canyon in Ari­zona, cruis­ing at an al­ti­tude of 6,400 m. A few kilo­me­tres away, United Air­lines Flight 718 with 58 peo­ple aboard is on its way towards Chicago, Illi­nois. The Dou­glas DC-7, which took off from the air­port in Los An­ge­les only three min­utes af­ter Grady’s flight, is flown by Cap­tain Robert Shirley, who is cruis­ing at an al­ti­tude of 6,400 me­tres, as in­structed.

In the cock­pits of both air­craft, the pi­lots are fo­cused on nav­i­gat­ing through the dense clouds. The vis­i­bil­ity is very poor, and Gandy and Shirley stand no chance of spot­ting each other’s planes, which are head­ing towards each other at a speed of more than 500 km/h.

At 10:31, ra­dio op­er­a­tors in Salt Lake City, Utah, pick up a vague mes­sage from the United plane.

“Salt Lake, United 718 … Ohhh, we're crash­ing,” says co-pi­lot Robert Harm. In the back­ground, the ra­dio op­er­a­tors can hear a

“Salt Lake, United 718 ... Ohhh, we're crash­ing,” is the last ra­dio mes­sage from the co-pi­lot of the DC-7 over the Grand Canyon. LOST FLIGHTS ARCHIVE

high-pitched voice. “Pull up! Pull up,” Cap­tain Shirley orders.

But it's too late. At an an­gle of 25 de­grees, his plane has col­lided with the Trans World Air­lines craft, and the two flights fall al­most ver­ti­cally to the ground like wing-shot birds. Smok­ing pieces of wreck­age are spread across a huge area of the Grand Canyon, and when the res­cue team reaches the dis­as­ter site, the sce­nario is a gloomy one. All 128 pas­sen­gers and crew mem­bers of the two planes have been killed, and not one sin­gle body is found in one piece.

INVESTIGATOR IN­VENTS BLACK BOX

The mid-air col­li­sion is not by any means the first one in avi­a­tion his­tory. In 1950-1955, 65 planes col­lided over Amer­i­can soil. But the Grand Canyon col­li­sion is the by far most deadly, and in the weeks and months that fol­low, the Amer­i­can peo­ple is out­raged. Ev­ery day, there are news­pa­per re­ports about the prim­i­tive flight con­trol ser­vice, which has not at all moved with the times, about the rapidly ris­ing num­ber of air­lin­ers, and the state of com­plete an­ar­chy in the skies.

“Did Out­dated Sys­tem Kill 128?”, the Detroit Free Press news­pa­per rhetor­i­cally asks in the wake of the dis­as­ter.

The pub­lic and politi­cians de­mand a thor­ough mod­ern­iza­tion of air traf­fic con­trol, and the re­quest is heard. As a di­rect con­se­quence of the col­li­sion, the US gov­ern­ment headed by Pres­i­dent Eisen­hower in 1958 es­tab­lishes the first modern avi­a­tion author­ity, the Fed­eral Avi­a­tion Agency, now the Fed­eral Avi­a­tion Ad­min­is­tra­tion, FAA.

The or­ga­ni­za­tion, which will in the fu­ture be­come a model for the avi­a­tion of other na­tions, is given the task of reg­u­lat­ing all as­pects of civil and mil­i­tary avi­a­tion in the US. The FAA is as­signed re­spon­si­bil­ity for es­tab­lish­ing an air traf­fic con­trol ser­vice, which guides, lay­ers, and tracks down all planes through­out Amer­i­can air-space. In other words, the ser­vice is to han­dle all flights, right from the mo­ment the planes are ready for take-off un­til they have landed again.

In the case of the ac­ci­dent above the Grand Canyon, there is no doubt about the cause of the dis­as­ter, but that is a rare ex­am­ple. Crashes are com­mon in the era, and once tragedy has struck, crash in­ves­ti­ga­tors often only have a wreck­age heap to search, when they are to find out what went wrong.

But al­ready in the 1950s, Aus­tralian sci­en­tist David War­ren thought of some­thing that would rev­o­lu­tionise avi­a­tion over time, im­prov­ing air safety con­sid­er­ably. War­ren par­tic­i­pated in the in­ves­ti­ga­tions of a num­ber of in­ex­pli­ca­ble crashes in­volv­ing the world’s first jet air­liner, the Bri­tish De Hav­il­land Comet, which was en­tered into reg­u­lar ser­vice in May 1952.

Af­ter a thor­ough in­ves­ti­ga­tion, in­ves­ti­ga­tors es­tab­lished that the dis­as­ters were caused by metal fa­tigue, and the pri­mary cul­prit was the plane’s rec­tan­gu­lar win­dows. When the cabin was pres­surised, the pres­sure on the cor­ners of the win­dows was so in­tense that the metal cracked. The dis­cov­ery meant good­bye to rec­tan­gu­lar plane win­dows and hello to rounded ones.

“Damn, the son of a bitch is head­ing right towards us,” says Cap­tajn Grubbs, as the KLM Jumbo emerges from the fog.

CLIPPERARCTIC

David War­ren was con­vinced that the in­ves­tiga­tive work would have been very much eas­ier, if he and his col­leagues had had ac­cess to sound record­ings of the pi­lots’ con­ver­sa­tion, be­fore things went wrong. If so, it would have been pos­si­ble to ac­cu­rately re­con­struct what hap­pened be­fore the ac­ci­dents, said War­ren, who in 1954 wrote a re­port about his voice recorder. Three years later, he de­vel­oped a pro­to­type of the de­vice, which is now known as the black box and is stan­dard equip­ment in all ma­jor com­mer­cial air­craft.

To­day, there is not just one, but two black boxes on the planes. Whereas the first one, the cock­pit voice recorder, records all con­ver­sa­tion and sounds in the cock­pit, the sec­ond one, the flight data recorder, stores in­for­ma­tion about cruis­ing al­ti­tude, course, speed, etc.

To crash in­ves­ti­ga­tors, the black boxes are in­valu­able tools, which mean that they have been able to solve lots of dif­fer­ent avi­a­tion crash mys­ter­ies. The knowl­edge with which the boxes have pro­vided ex­perts has meant that air­craft mak­ers have con­tin­u­ously been able to cor­rect er­rors for the ben­e­fit of safety. But when it comes to the most fre­quent cause of crashes – the hu­man fac­tor – tech­ni­cal im­prove­ments are no help. About 3 in 4 crashes are caused by er­rors made by pi­lots or air traf­fic con­trollers – and that per­cent­age is likely to climb.

As for the cost in hu­man lives, the worst day in avi­a­tion his­tory tells the story about how bad things can go. 1977 IMPATIENCE BECOMES FA­TAL In the af­ter­noon of Sun­day 27 March, two Boe­ing 747s are wait­ing for per­mis­sion to take off from the Los Rodeos Air­port on the Span­ish is­land of Tener­ife. In the cock­pit of the one Jumbo from Dutch KLM, Cap­tain Ja­cob van Zan­ten is happy, when the con­trol tower fi­nally al­lows him to take off at 4:30 PM. Due to a bomb in the air­port of the neigh­bour­ing is­land of Gran Ca­naria, all planes have been re-di­rected to the air­port of Tener­ife, which is densely crowded. Now, Am­s­ter­dam is fi­nally wait­ing ahead, and in dense fog, van Zan­ten makes his plane taxi to the end of the run­way, where it is to make a 180 de­gree turn and take off in the op­po­site di­rec­tion.

Some­where be­hind him on the same run­way, another Jumbo from Amer­i­can Pan Am is taxi­ing. Cap­tain Vic­tor Grubbs has been told by air traf­fic con­trollers to get off the run­way and wait un­til the KLM flight has taken off. But in the fog, he can­not find his stop, so he does not move his plane out of the way.

At the end of the run­way, Cap­tain van Zan­ten is ready for

take-off. He is im­pa­tient, and con­se­quently, he does not wait for per­mis­sion from the air traf­fic con­trollers to take off, rather he chooses to ac­cel­er­ate his air­craft at full throt­tle. “We are tak­ing off,” he says over the ra­dio. “Okay. Standby for take­off. We will be back,” the con­trol tower an­swers.

“We are still taxi­ing down the run­way,” the cap­tain of the Pam Am flight warns, but Cap­tain van Zan­ten does not get his mes­sage. His huge steel bird is al­ready roar­ing down the run­way at a speed of 260 km/h, and only too late, he spots the Pan Am Jumbo ahead of him.

“Oh shit,” van Zan­ten says, re­al­iz­ing that a col­li­sion is in­evitable. He tries to climb sharply, as the Pan Am pi­lots strug­gle to get off the run­way.

“Damn, the son of a bitch is head­ing right towards us,” Cap­tain Grubbs says, as the KLM flight ap­pears from the dense fog.

“Get off, get off,” his co-pi­lot, Robert Bragg, shouts, des­per­ately hop­ing their own plane will clear the run­way in time.

But the fates of the planes are sealed. As the KLM Jumbo takes off, its un­der­car­riage and en­gines cut through the Pan Am plane’s roof, and the Dutch plane only flies 200 m, be­fore it falls to the ground, ex­plod­ing in a sea of fire. All 248 pas­sen­gers and crew mem­bers are killed.

The Pan Am plane catches fire, and only 61 of the 396 peo­ple aboard it sur­vive. With a to­tal of 583 ca­su­al­ties, the dis­as­ter is the worst in avi­a­tion his­tory.

“OKAY” IS NO LONGER ON THE LIST

Af­ter the tragedy, an army of Span­ish, Amer­i­can, and Dutch ex­perts strug­gled to shed light on the full cause of the dis­as­ter. The con­clu­sion is that it was pri­mar­ily due to the fact that the im­pa­tient Cap­tain van Zan­ten had taken off without per­mis­sion. The poor vi­sion of less than 300 me­tres contributed, but the trig­ger­ing fac­tor was sev­eral fa­tal com­mu­ni­ca­tion mis­un­der­stand­ings be­tween the Dutch cap­tain and the con­trol tower. Van Zan­ten con­sid­ered the air traf­fic con­troller’s “okay” as con­fir­ma­tion that the plane could take off. But re­ally, the air traf­fic con­troller only ac­knowl­edged that he had re­ceived the mes­sage.

The Tener­ife dis­as­ter made it clear that air traf­fic needed a stan­dard lan­guage. As a di­rect con­se­quence of the ac­ci­dent, avi­a­tion au­thor­i­ties through­out the world in­tro­duced a se­ries of stan­dard ex­pres­sions that are now used in all com­mu­ni­ca­tion be­tween air traf­fic con­trollers and pi­lots. The world “okay” is not on the list.

In or­der to re­duce the risk of com­mu­ni­ca­tion er­rors and mis­un­der­stand­ings even more, both par­ties must speak an oddly stilted for­mal lan­guage. When the air traf­fic con­troller says some­thing over the ra­dio, the pi­lot is to re­peat the mes­sage to con­firm that he has un­der­stood the words.

The record­ings from the black boxes al­lowed in­ves­ti­ga­tors to es­tab­lish the course of events lead­ing up to the col­li­sion in Tener­ife in de­tails – right up un­til the cry of hor­ror that was the last to be heard in the cock­pit of the KLM plane.

LOST FLIGHTS ARCHIVE

Air traf­fic ex­ploded in the 1950s. In the photo, pas­sen­gers in Los An­ge­les board a plane of the type that col­lided with another one in 1956.

TONY COMITI/SYGMA/GETTY IMAGES

583 peo­ple die, when two Boe­ing 747s col­lide at the air­port in Tener­ife. The worst ac­ci­dent in avi­a­tion his­tory was due to a hu­man error.

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