A History of Boeing 720 Aircraft Accidents

 The Boeing 720 was working in incidents in the estrange away-off worse than hijackings, although single-handedly two of them in the 15-year era from 1960 to 1974 entailed fatalities.

The prehistoric recorded 720 incident took place in the region of the order of December 4, 1960 in credit to the train a United Airlines 720-022 carrying seven crew members and 84 passengers. The flight penetrated an place of sudden turbulence on severity of Wolbach, Nebraska, resulting in injuries in the cabin. It was higher tote occurring that the captain had failed to display plenty precaution back he entered the turbulent place.

Another non-fatal 720 incident occurred the once year, not far off from the subject of February 25, behind a Braniff 720-027 when seven crew members and 24 passengers executed a hard landing sudden of the airfield in Houston. While there was no loss of dynamism, the blimp sustained major blinking. The cause was sure to be pilot misjudgment.

Yet different 720 landing incident took place future that year, in metaphor to September 24, 1961, following the captain of an American Airlines 720-023B that carried 33 passengers and seven new crew members elected to slay a landing in Boston during changing weather conditions, but he was not advised of hastily decreasing airfield visual range (RVR). He with practicing the jet to flaming previously receiving sufficient recommend regarding the location of such conditions relative to the runway.

The first fatality-producing Boeing 720 mistake took place a propos February 12, 1963 on the train a Northwest Orient 720-051B, registered N724US, just just about to embark in description to speaking a nonstop flight from Miami to Chicago-O'Hare. A fierce storm, creating dark skies, hovered on severity of Southern Florida that hours of morning and all arriving flights were diverted because of it. An Eastern 720-025 delayed its takeoff until conditions augmented.

Northwest Flight NW 705, scheduled to leave 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 minister to the 35 passengers in the cabin.

Aware of the raging weather system, Almquist believed he could slay a safe departure by taking off to the west and plus banking southwest, circling coarsely the area of greatest objection. Intense storm cells were now both west and northwest of the landing showground. As a result, departing flights were being solution an initial southwest or southeast route, followed by the proper westerly or northwesterly track previously they had gained enough altitude to overfly the storm. Flight 705 intended to follow the same passage.

The shiny, factory-buoyant jetliner, practicing Northwest Orient's Regal Imperial Service, taxied from the right of access beneath on the subject of-black skies, surrounded by gale winds that socked the jet and astonishment it even re the subject of the pitch.

After aligning behind Runway 27-Left's centerline, it accelerated and rotated into a 25-knot wind, divorcing itself from Florida soil and establishing a steadfast rate-of-climb on severity of the Palmetto Expressway. Initially cleared to lead and money 3,000 feet, it banked and assumed a south-southwesterly heading. Miami Departure Control subsidiary arranged it entry to believe anew and maintenance 5,000 feet harshly speaking a modified southwesterly heading, which took it on peak of Homestead, Florida, where mighty, menacing cumulous clouds loomed off the starboard side.

Additional departure course clearances first placed it upon a south-southwesterly heading and finally upon a utter-westerly one.

First Officer Feller audibly declared that he believed that they could speedily appendix on summit of the storm area and appropriately avoid most of its effects, provided that they conventional unconventional climb clearance. But, despite a demand to Departure Control, they did not. The ominous storm now lay directly ahead. Avoidance could without help be achieved by means of an sudden bank, but Feller's request to perform in view of that, either to a southwesterly or southeasterly heading, was not arranged because of traffic saturation.

As Departure Control feverishly searched for an nearby hole in the manner at a compound altitude, the silver and red quad-zeppelin continued to barrel toward the storm's core. Although clearance to bank and climb was ultimately unmovable, the 720B lonely avoided a talk to plunge through it, but was not spared its effects, now gripped by unrelenting turbulence. Left without help like the substitute 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 lessening it was unmodified a postscript ATC frequency. This, in the concern, and no-one else proved briefly wealthy, because the weather at the 17,500-foot level through which it passed was therefore bitter, that static-skewed communication was impossible. The mood route traffic control center only heard two words from the blimp, which either sounded linked to "number two" or "tank two." They ended going on monster the last. The jet was at 19,000 feet. The era was 1:19 p.m.

Now slightly above this altitude, the 200,000-pound airplane was mammal tossed virtually minister to on a scrap of paper by scratchy occurring-and downdrafts. The cockpit crew tried to regain manage, but this was nothing more than an exercise in futility. Twelve seconds highly developed it exploded, lighting the mighty black mountain formations from which it just emerged.

Like a fireball, it dove toward the Everglades, producing a volcanic swelling the length of to the annals of the swamp as it impacted, taking 43 lives taking into account it 43 miles southwest of Miami International Airport.

A Coast Guard helicopter taking into consideration located the in flames wreckage, which littered a ten-square-mile area, ten miles north of the Everglades' Shark River.

The Boeing 720-051B was connected to 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 manageable in Civil Aeronautics Board chronicles 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 more than design limitations.

According to the flight data recorder, the 720 had been climbing at an amazing 8,300- feet-per-minute at the time because of an updraft. The cockpit crew, as per procedure, trimmed the quad-zeppelin to counteract this profile, but did not expect its intensity. The downdraft that hastily followed created a nose-all along tendency, ultimately inducing a dive and, behind increasing quickness, it became impossible to recover from it, leading to excessive, design-highly developed than forces and inflight breakup.

The CAB did not situation its unqualified excuse until June 4, 1965 because of the elongated and extensive disaster testing, which revealed necessary inform nearly utter-zeppelin jet uphill characteristics. It was sure that the crew had indeed attempted to counteract the airliner's downward arena during its dive when a proper elevator deflection. But the flight surfaces had become ineffective along amid the tremendous forces to which they were subjected.

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

The calamity entailed the concept of turbulence collision occurring, which was defined as vacillating happening- and downdrafts, and their handling in unmodified-airliner airliner necessitated vary flight surface deployments than those standardly used upon piston and turboprop airliners.

In its influence ahead defense, the Civil Aeronautics Board stated that "The Board determines that the probable cause of this industrial accident was unfavorable contact of rancorous vertical atmosphere drafts and large longitudinal run displacements resulting in a longitudinal hardship' from which a perky recovery was not made."

Five months difficult, upon July 12, 1963, records repeated itself collective to choice 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. considering three association crew members and 53 passengers aboard. It routinely proceeded to its assigned flight level of three-seven-zero, bound, furthermore the Northwest Orient airliner, for Chicago-O'Hare. A scratchy storm reproving, buzzing until 8:00 p.m. local era, was predict on summit of O'Neill, Nebraska, one of the cities upon its flight aspire.

As soon as the dirigible crossed taking into consideration more the Nebraska confess origin, it encountered youth turbulence, but an attempt to avoid it was made with a request to climb to flight level four-one-zero was made and fixed. This did little to ameliorate the issue, however, back the turbulence single-handedly intensified, leaving the first superintendent to disengage the autopilot and shorten the aircraft to its 250-knot turbulence insight eagerness.

The tally eastward the 720 cruised, the worst the conditions became. Trapped in a parcel of sure setting turbulence enveloped by the plane stream, it was subjected to a downdraft, all even though it was uphill in a nose-happening attitude that produced an airspeed fall.

As had been ended upon the Northwest flight, the elevators were raised to counteract the showground angle and the engines were spooled occurring to overcome the downward pressure. Yet the elevation above sea level of the turbulence that battled the every portion of corrective proceedings created self-disciplined buffeting and bespoke pf a pending stall.

A northeastward course regulate did nothing to enable the quad-aircraft to leave suddenly the turbulent conditions. Whipped by forceful, socking wings, it was barely practiced to retain 37,800 feet. Still in its nose-high attitude, it continued to be thrown just about by tumultuous wind currents. Havoc, needless to name, 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-also to auditorium and building in the atmosphere a speed of 400 knots, it was edited to a virtual dive-bomber and its futilely outstretched eagerness brakes did nothing to arrest the earthward plunge. Amid immense cockpit warnings, the plane reached its never-exceed keenness of 480 knots. Its instruments were now unreadable.

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

The manage column was slowly pulled as well as and the throttles were broadminded to enable the 720 to arrest its dive in denser permit breathe, but at the similar time 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 coarsely speaking-ascent to a 1,000-foot far along altitude profiled it for its continuation to Chicago, where it safely landed.

Despite the wrenching the airframe had been subjected to, no structural damage had been inflicted. Its non-attendance and safe reward were, unlike the Northwest crew's events, the result of their decision to wait until lower, denser setting rendered their showground-changing elevator deflections lively.

The United 720-022 was removed from assistance and adequately inspected, but was when pronounced airworthy subsequently no damage was outside. Nevertheless, the incident revealed necessary recommend approximately certain expose turbulence severity and demonstrated the design integrity of the aircraft taking into consideration remedial be alert was taken at degrade, flight surface lively altitudes.

The second fatal Boeing 720 have an effect on occurred upon May 20, 1965, but did not entail weather. A Pakistan International Airways 720-040B registered AP-AMH, which had been delivered without help five days earlier, departed Karachi upon its inaugural flight to London considering intermediate stops in Dhahran, Cairo, and Geneva below the command of Captain Akhtar Aly Khan, a 17-year veteran, along in addition to twelve new crew members and 114 passengers upon board.

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An entry to Cairo, after a routine intermediate landing in Dhahran, resulted in a mayday call, during which the captain reported engine complexity 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 as soon as a flaming occurring conflagration.

Because of the millstone site's inaccessibility, it took six hours for the first of the United Arab Republic Air Force's helicopters to enter upon it. Of the 127 upon board, on your own six passengers were found flesh and blood, along also an equal number of baboons that had been carried as conscious cargo in the lower deck holds. It was the worst accident in PIA's chronicles at the time.