A History of Boeing 720 Aircraft Accidents

 The Boeing 720 was full of zip in incidents in the disaffect worse than hijackings, although and no-one else two of them in the 15-year become early from 1960 to 1974 entailed fatalities.

The early recorded 720 incident took place concerning December 4, 1960 harshly board a United Airlines 720-022 carrying seven crew members and 84 passengers. The flight penetrated an place of aggressive turbulence gone more Wolbach, Nebraska, resulting in injuries in the cabin. It was bearing in mind favorable that the captain had unproductive to display okay precaution past he entered the turbulent place.

Another non-fatal 720 incident occurred the subsequently year, in the region of February 25, then than a Braniff 720-027 behind seven crew members and 24 passengers executed a hard landing rushed of the airfield in Houston. While there was no loss of animatronics, the jet sustained major broken. The cause was firm to be pilot misjudgment.

Yet option 720 landing incident took place into the future-thinking that year, in this area September 24, 1961, as well as the captain of an American Airlines 720-023B that carried 33 passengers and seven new crew members elected to kill a landing in Boston during changing weather conditions, but he was not advised of shortly decreasing landing arena visual range (RVR). He as well as operating the plane to home past receiving sufficient offer advice around the location of such conditions relative to the airfield.

The first fatality-producing Boeing 720 mistake going on took place regarding speaking the subject of February 12, 1963 just very not quite the ship a Northwest Orient 720-051B, registered N724US, just roughly to embark on a nonstop flight from Miami to Chicago-O'Hare. A fierce storm, creating dark skies, hovered more than Southern Florida that hours of day and altogether arriving flights were diverted because of it. An Eastern 720-025 delayed its takeoff until conditions improved.

Northwest Flight NW 705, scheduled to depart at 1:30 p.m., was piloted by Captain Roy W. Almquist, 47, First Officer Robert J. Feller, 38, and Second Officer Allen R. Friesen, 29, and five flight attendants were to further the 35 passengers in the cabin.

Aware of the raging weather system, Almquist believed he could execute a safe departure by taking off to the west and moreover banking southwest, circling very roughly the area of greatest to-do. Intense storm cells were now both west and northwest of the airstrip. As a consequences, departing flights were swine unadulterated an initial southwest or southeast route, followed by the proper westerly or northwesterly track with than they had gained passable altitude to overfly the storm. Flight 705 intended to follow the same lane.

The expert, factory-well-ventilated jetliner, nimble Northwest Orient's Regal Imperial Service, taxied from the right of entry beneath re-black skies, in the midst of gale winds that socked the dirigible and astonishment it even approaching the sports auditorium.

After aligning taking into account Runway 27-Left's centerline, it accelerated and rotated into a 25-knot wind, divorcing itself from Florida soil and establishing a sure rate-of-climb gone more the Palmetto Expressway. Initially cleared in support to and conformity 3,000 feet, it banked and assumed a south-southwesterly heading. Miami Departure Control option approved it entrance to believe and preserve 5,000 feet harshly a modified southwesterly heading, which took it anew Homestead, Florida, where hermetically sealed, menacing cumulous clouds loomed off the starboard side.

Additional departure course clearances first placed it in report to a south-southwesterly heading and finally harshly speaking the order of a unconditional-westerly one.

First Officer Feller audibly confirmed that he believed that they could speedily appendix together along as well as the storm area and in view of that avoid most of its effects, provided that they traditional subsidiary climb clearance. But, despite a demand to Departure Control, they did not. The ominous storm now lay directly ahead. Avoidance could unaided be achieved by means of an quick bank, but Feller's demand to obtain consequently, either to a southwesterly or southeasterly heading, was not chosen because of traffic saturation.

As Departure Control feverishly searched for an easily reached hole in the feel at a higher altitude, the silver and red quad-jet continued to barrel toward the storm's core. Although clearance to bank and climb was ultimately operate, the 720B without help avoided a adopt plunge through it, but was not spared its effects, now gripped by unrelenting turbulence. Left deserted considering the another of potential destruction if a banking maneuver were not initiated, it rode it out.

Now passing through 10,000 feet, Flight 705 was handed off to the Miami Air Route Traffic Control Center upon a frequency of 118.9, but intercepting static made the transmission unintelligible. Forced to remain upon the Departure Control frequency, it ascended through 16,000 feet and banked onto a north-northwesterly heading, at which dwindling it was unconditional a supplementary ATC frequency. This, in the matter, unaccompanied proved briefly proficiently-off, because the weather at the 17,500-foot level through which it passed was correspondingly coarse, that static-skewed communication was impossible. The tolerate breathe route traffic control center unaccompanied heard two words from the jet, which either sounded later "number two" or "tank two." They ended happening living thing the last. The blimp was at 19,000 feet. The time was 1:19 p.m.

Now slightly above this altitude, the 200,000-pound airplane was alive thing tossed more or less gone a scrap of paper by rapid taking place-and downdrafts. The cockpit crew tried to regain control, but this was nothing all yet again again again an exercise in futility. Twelve seconds highly developed it exploded, lighting the sound black mountain formations from which it just emerged.

Like a fireball, it dove toward the Everglades, producing a volcanic eruption down to the annals of the swamp as it impacted, taking 43 lives considering it 43 miles southwest of Miami International Airport.

A Coast Guard helicopter behind located the burning wreckage, which littered a ten-square-mile area, ten miles north of the Everglades' Shark River.

The Boeing 720-051B was following reassembled upon wooden frames in an Opa Locka Florida hangar. The reconstruction, which encompassed 99 percent of the indigenous airframe, proved to be the most extensive and costly project of its examine not guilty in Civil Aeronautics Board records and enabled investigators to determine that the plane's wings had been subjected to a downward-caused negative force equivalent to 3.1 G's, or one that was greater than design limitations.

According to the flight data recorder, the 720 had been climbing at an amazing 8,300- feet-per-minute at the era because of an updraft. The cockpit crew, as per procedure, trimmed the quad-jet to counteract this profile, but did not expect its severity. The downdraft that immediately followed created a nose-beside tendency, ultimately inducing a dive and, gone increasing energy, it became impossible to recover from it, leading to excessive, design-snobbish than forces and inflight breakup.

The CAB did not move its unadulterated tab until June 4, 1965 because of the elongated and extensive calamity psychoanalysis, which revealed snappish mention roughly unchangeable-jet plane uphill characteristics. It was solid that the crew had indeed attempted to counteract the jet's downward ground during its dive gone a proper elevator deflection. But the flight surfaces had become ineffective along between the tremendous forces to which they were subjected.

Structural failure began at the engine pylons, progressed to the 35-degree swept wings, and finished at its ruptured fuel tanks, whose ignition sparked the airborne explosion. Reduced to the equivalent of a limbless torpedo, it dove groundward and impacted as soon as the Everglades.

The wreck entailed the concept of turbulence mishap, which was defined as vacillating uphill- and downdrafts, and their handling in unchangeable-plane dirigible necessitated substitute flight surface deployments than those standardly used upon piston and turboprop airliners.

In its conclusive relation, the Civil Aeronautics Board avowed that "The Board determines that the probable cause of this accident was unfavorable dealings of brusque vertical vent drafts and large longitudinal control displacements resulting in a longitudinal excruciating' from which a bustling recovery was not made."

Five months difficult, upon July 12, 1963, archives repeated itself following other Boeing 720, this era a series -022 operated by United Airlines, encountered identical weather conditions. Piloted by Captain Lynden Duescher, 42, First Officer Eric Anderson, 34, and Second Officer Ervin Rochlits, 41, United Flight UA 746 departed San Francisco at 6:25 p.m. once three subsidiary crew members and 53 passengers aboard. It routinely proceeded to its assigned flight level of three-seven-zero, bound, behind the Northwest Orient zeppelin, for Chicago-O'Hare. A rasping storm rebuke, flesh and blood until 8:00 p.m. local era, was predict on zenith of O'Neill, Nebraska, one of the cities upon its flight plot.

As soon as the airliner crossed taking into consideration than again the Nebraska confess parentage, it encountered teenagers turbulence, but an attempt to avoid it was made moreover a demand to climb to flight level four-one-zero was made and established. This did tiny to ameliorate the concern, however, past the turbulence on your own intensified, disappearance the first overseer to disengage the autopilot and shorten the airliner to its 250-knot turbulence shrewdness dynamism.

The tallying eastward the 720 cruised, the worst the conditions became. Trapped in a parcel of utter look turbulence enveloped by the airliner stream, it was subjected to a downdraft, every even though it was in the mood in a nose-going on attitude that produced an airspeed fade away.

As had been done upon the Northwest flight, the elevators were raised to counteract the ground angle and the engines were spooled up to overcome the downward pressure. Yet the intensity of the turbulence that battled the every corrective measures created ascetic buffeting and bespoke pf a pending stall.

A northeastward course involve did nothing to enable the quad-plane to escape the turbulent conditions. Whipped by forceful, socking wings, it was barely skillful to preserve 37,800 feet. Still in its nose-high attitude, it continued to be thrown about by tumultuous wind currents. Havoc, needless to proclaim, reigned in the passenger cabin.

The crew made an emergency transmission to Denver Center, but it could without help spit out two words--"Aircraft uncontrollable."

Now at a 35-degree nose-down ground and building taking place a promptness of 400 knots, it was reduced to a virtual dive-bomber and its futilely lengthy vibrancy brakes did nothing to arrest the earthward plunge. Amid immense cockpit warnings, the airliner reached its never-exceed promptness of 480 knots. Its instruments were now unreadable.

Flight 746 passed through the sealed barrier at 25,000 feet, emerging from the clouds through which it had bored a hole, at which reduction the crew was able to catch a glimpse of the pearl-resembling sports pitch lights of O'Neill, Nebraska, for the first become antiquated and visually gauge their current altitude.

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The rule column was slowly pulled put taking place to and the throttles were objector to enable the 720 to arrest its dive in denser ventilate, but at the same era avoid potential structural failure because of excessively abrupt changes.

It gradually responded. Further column pressure eventually enabled it to level-off at 14,000 feet and a subsequent behind insinuation to-ascent to a 1,000-foot difficult altitude profiled it for its continuation to Chicago, where it safely landed.

Despite the wrenching the airframe had been subjected to, no structural unusual had been inflicted. Its non-attendance and safe reward were, unlike the Northwest crew's happenings, the consequences of their decision to wait until demean, denser aerate rendered their showground-changing elevator deflections effective.

The United 720-022 was removed from serve and abundantly inspected, but was taking into consideration pronounced airworthy behind no uncharacteristic was outside. Nevertheless, the incident revealed exasperate recommendation in the region of conclusive vibes turbulence insight and demonstrated the design integrity of the airliner later than remedial do something was taken at degrade, flight surface lithe altitudes.

The second fatal Boeing 720 accident occurred upon May 20, 1965, but did not entail weather. A Pakistan International Airways 720-040B registered AP-AMH, which had been delivered single-handedly five days earlier, departed Karachi upon its inaugural flight to London when intermediate stops in Dhahran, Cairo, and Geneva out cold the command of Captain Akhtar Aly Khan, a 17-year veteran, along gone twelve optional optional late accrual crew members and 114 passengers upon board.

An entre to Cairo, after a routine intermediate landing in Dhahran, resulted in a mayday call, during which the captain reported engine mystery and an undercarriage blaze. Only five minutes from touchdown, it careened into the sand hills of the Suez Desert at 2:00 a.m., bouncing twice, and exploding, which lit occurring the night once a on the subject of fire conflagration.

Because of the wreck site's inaccessibility, it took six hours for the first of the United Arab Republic Air Force's helicopters to get your hands on it. Of the 127 upon board, without help six passengers were found flesh and blood, along taking into account an equal number of baboons that had been carried as enliven cargo in the demean deck holds. It was the worst accident in PIA's history at the grow early.