Английская Википедия:Airborne Express Flight 827

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Шаблон:Short description Шаблон:Use mdy dates Шаблон:Use American English Шаблон:Infobox aircraft occurrenceAirborne Express Flight 827 was a functional evaluation flight (FEF) of an Airborne Express Douglas DC-8-63F (registration N827AX) that had undergone a major modification. On December 22, 1996, during the test flight, the aircraft stalled and crashed, killing all six people on board. Accident investigators determined the cause of the accident was improper crew control inputs.

Background

Aircraft

The aircraft involved was a Douglas DC-8-63 freighter registered as N827AX. The aircraft had been built in 1967 and was previously owned by KLM as a passenger aircraft (with registration PH-DEB) and then Capitol Air and National Airlines (registration N929R). In January 1986 the aircraft was converted into a freighter and delivered to Emery Worldwide (with the same registration). ABX Air (a subsidiary of Airborne Express) purchased the aircraft on June 17, 1996, more than six months before the accident. The aircraft was re-registered as N827AX. It underwent a major overhaul and was delivered to ABX Air on December 15 the same year, just a week before the accident. The aircraft was powered by four Pratt & Whitney JT3D-7 turbofan engines. At the time of the accident, the aircraft had flown 62,800 hours and nine minutes with 24,234 take off and landing cycles.Шаблон:Rp

Overhaul

The aircraft's overhaul was performed by the Triad International Maintenance Corporation (TIMCO) at Piedmont Triad International Airport in Greensboro, North Carolina.Шаблон:Rp During the major overhaul, the aircraft received major avionic upgrades, including the installation of an electronic flight instrument system (EFIS). All four engines were removed. Two of them were overhauled and reinstalled on the aircraft, while the other two were completely replaced by different JT3D-7 engines from ABX Air. Hush kits were installed on all of the engines for noise reduction. The aircraft's stall warning system was tested and declared functional.Шаблон:Rp

Crew

Rather than a captain, a first officer and a flight engineer, Flight 827 was crewed by two captains (one flying, one not flying), and a flight engineer. There were also three aircraft technicians on board.Шаблон:Rp

The captain who was the pilot not flying (though acting as pilot in command (PIC)) was 48-year-old Garth Avery, who had worked for Airborne Express since 1988 and had 8,087 flight hours, including 869 hours on the DC-8. He was seated in the right seat. Avery was also the airline's Boeing 767 flight manager as well as a flight instructor.Шаблон:Rp

The captain who was the pilot flying (though acting as a co-pilot) was 37-year-old William "Keith" Lemming, who had worked for Airborne Express since 1991 and had logged 8,426 flight hours, with 1,509 of them on the DC-8. He was seated in the left seat. Lemming was the manager of Airborne Express' DC-8 flight standards (the position previously having been held by captain Avery) and had previously been a pilot for Trans World Airlines.Шаблон:Rp

The flight engineer was 52-year-old Terry Waelti who, like captain Avery, had been with Airborne Express since 1988. Waelti had 7,928 flight hours, including 2,576 hours on the DC-8. He was also a DC-8 examiner designated by the Federal Aviation Administration (FAA). Waelti had previously served in the United States Air Force (USAF) and was one of the USAF's first flight engineers to be qualified on the Boeing E-4B.Шаблон:Rp

The three technicians were 48-year-old Edward Bruce Goettsch, 39-year-old Kenneth Athey, and 36-year-old Brian C. Scully. Goettsch and Athey both worked for Airborne Express, while Scully worked for TIMCO.

Accident

Initially, Flight 827 had been scheduled to depart from Piedmont Triad International Airport on December 16, but was delayed due to maintenance. An attempt on December 21, (operated by the same crew) was cut short due to a hydraulic problem. Flight 827 finally departed at 17:40 Eastern Standard Time (EST) at nighttime on December 22, 1996, after being delayed due to additional maintenance. The flight climbed to Шаблон:Convert and then to Шаблон:Convert.Шаблон:Rp

Flight 827 was operating under instrument flight rules (IFR). After departing Greensboro, the aircraft was to fly Northwest over New River Valley Airport's VOR, in Pulaski County, Virginia, then to Beckley, West Virginia, followed by other way points in Kentucky and Virginia, and then return to Greensboro. The flight was expected to last two hours.Шаблон:Rp

Shortly after reaching Шаблон:Convert, the aircraft experienced atmospheric icing, which was indicated when the cockpit voice recorder (CVR) recorded captain Lemming saying, "we're gettin' a little bit of ice here," and "probably get out of this," at 17:48:34 and 17:48:37 respectively.Шаблон:Rp

Several landing gear, hydraulic, and engine tests were performed without incident. At 18:05, flight engineer Waelti said, "next thing is our stall series." The next item was a clean stall maneuver test. The crew would slow the aircraft down until the stick shaker activated, record the stall speed and that of the stick shaker activation, and then recover control of the aircraft. In other words, the flight crew would deliberately stall the aircraft. Captain Avery stated that the crew would stop trimming the aircraft at Шаблон:Convert and that the stall speed (V_S) was Шаблон:Convert. Flight engineer Waelti stated that the stick shaker would activate at Шаблон:Convert, which was Шаблон:Convert higher than the calculated stall speed. The flight crew began gradually slowing the aircraft down by Шаблон:Convert per second.Шаблон:Rp

At 18:07, engine power was increased. One minute later at 18:08, a buffeting sensation was experienced at Шаблон:Convert.Шаблон:Rp The following was recorded on the CVR:

18:07:55	Commentary	Sound similar to engine increasing in RPM.
18:08:06	Captain Lemming	Some buffet.Шаблон:Efn
18:08:07	Captain Avery	Yeah. That's pretty early. *.Шаблон:Efn
18:08:09	Commentary	Sound of rattling.
18:08:11	Flight Engineer Waelti	That's a stall right there… * ain't no [stick] shaker.

At this time, according to the flight data recorder (FDR), the aircraft was at Шаблон:Convert.Шаблон:Rp However, the stick shaker had failed to activate.Шаблон:Rp The speed then decreased to Шаблон:Convert and the aircraft entered a real stall.Шаблон:Rp At 18:08:13, captain Lemming decided to terminate the test, called "set max power," and applied full engine power in an attempt to recover from the stall.Шаблон:Rp Although all four engines started to accelerate, engine no. 2 accelerated more slowly.Шаблон:Rp This engine subsequentially experienced a compressor stall.Шаблон:Rp Ground witnesses also noted that the aircraft was making "skipping or missing" sounds.Шаблон:Rp At 18:09, Air Traffic Control (ATC) asked the flight if they had initiated an emergency descent, with captain Avery replying, "yes sir." This was the last communication (and only distress call) from Flight 827.Шаблон:Rp

At 18:09:35, the ground proximity warning system (GPWS) activated and sounded "terrain terrain, whoop whoop pull up." Three seconds later at 18:09:38, the aircraft crashed into a mountain travelling over Шаблон:Convert in a nose-down wings-down position of 26 and 52 degrees, respectively. The crash site elevation was Шаблон:Convert mean sea level (MSL).Шаблон:Rp The aircraft exploded on impact. All six people on board were killed and the aircraft was destroyed.Шаблон:Rp

Investigation

The National Transportation Safety Board (NTSB) launched an investigation into the accident and arrived at the crash site the same day.Шаблон:Rp Both flight recorders were recovered the next morning.Шаблон:Rp Rescue teams also recovered all six bodies. Efforts to reach the accident site were initially hampered due to its remote location. Both flight recorders were recovered the same day.

The aircraft's flight controls were destroyed in the crash, but the NTSB recovered two trim jackscrews horizontal stabilizer.

The NTSB recreated the stall in a simulator. In the simulation, the stick shaker activated at Шаблон:Convert. Despite deepening the stall, no unexpected nose-down pitches or lateral rolls occurred in the simulator. The decreasing airspeed caused the nose to pitch up.Шаблон:Rp

In 1991, another Airborne Express DC-8 entered a real stall during an FEF, but the flight crew was able to recover and test continued with no further incidents. In the 1991 incident, the stick-shaker activated the same time the buffeting sensation occurred. The Federal Aviation Administration (FAA) issued a revised stall recovery procedure to Airborne Express, which they agreed to incorporate. However, the airline had only partially incorporated the procedure at the time of the Flight 827 accident.Шаблон:Rp

Airborne Express' flight operation manual contained only a short section labeled "Test Flights" and the requirements for FEF's read:

At the time of the accident, there were scattered showers of light rain and the cloud ceiling was between Шаблон:Convert and Шаблон:Convert. The reported surface weather at Mercer County Airport in Bluefield stated that visibility was two miles.Шаблон:Rp

Because of the aircraft experiencing icing, it experienced a buffet Шаблон:Convert before the stall speed. The FDR indicated that the aircraft had entered a real stall at Шаблон:Convert, four knots before the stall speed. The NTSB concluding that the icing, regardless of amount, (along with flight control rigging) did not contribute to the accident.Шаблон:Rp

Despite Captain Lemming's timely decision to terminate the stall test, he subsequentially pulled back on the control column from five to ten degrees, allowing the aircraft to enter a real stall.Шаблон:Rp The NTSB notes that he likely did this in an attempt to establish an appropriate pitch attitude and power setting.Шаблон:Rp

Captain Avery did not notice the incorrect flight control inputs made by captain Lemming, though he did attempt to instruct Lemming on to recover the airplane from the roll, but not how to recover from the stall. In addition he did not enhance his instructions or take over control of the aircraft himself. The NTSB noted that since both pilots were captains, had manager positions at the airline, and had similar backgrounds, they would have difficulty challenging each other because of a lack of command authority.Шаблон:Rp Captain Avery, as PIC, should have monitored and challenged captain Lemming's actions, but his both his PIC and instructional roles were informal on the accident flight.Шаблон:Rp

According to both flight recorders and the recovered horizontal stabilizer trim jackscrew, captain Lemming had trimmed the aircraft's horizontal stabilizer at Шаблон:Convert instead of the intended Шаблон:Convert. Airborne Express' procedures required the aircraft to be trimmed Шаблон:Convert before the stall speed. Despite the incorrect trim setting, the aircraft would still have been recoverable from the stall. The NTSB concluded that the captain Lemming's incorrect trimming of the horizontal stabilizer was not a factor in the accident.Шаблон:Rp

The NTSB examined N827AX's maintenance records and reviewed Airborne Express' procedures for testing the stall warning system, but could not determine why the stick shaker was inoperative during the accident flight.Шаблон:Rp In addition, the flight crew's situational awareness that the aircraft was in a stall was short, as they were distracted by the compressor stall on the no. 2 engine and communications with ATC. The NTSB also stated that an angle of attack display on the flight deck could have helped the crew situational awareness. The fact that the crew lacked a visual horizon at nighttime was another factor due to the aircraft being in instrument meteorological conditions (IMC) from the time the stall maneuver was performed until impact.Шаблон:Rp

Neither captain Avery nor captain Lemming had ever flown a DC-8 post modification on an FEF until December 21 (the initial FEF that was aborted), though the director of flight technical programs authorized Avery to serve as a pilot in command on post modification FEF's.Шаблон:Rp

Final report

The NTSB released the final report on July 15, 1997. The "probable cause" section stated the following:

The accident had been caused by pilot error due to captain Lemming's improper flight control inputs and captain Avery's failure to notice them. Another cause was Airborne Express failing to set up a proper program for FEFs, resulting in inadequate training. Contributing factors included the stick shaker failing to activate, Airborne Express' simulators' inaccuracy in stalls, the compressor stall on the no. 2 engine which distracted the flight crew, the flight crew's lack of a visual horizon at nighttime, and Airborne Express not requiring flight tests to be completed before nightfall.Шаблон:Rp Airborne Express agreed with the NTSB that the pilots used incorrect procedures, but disputed two other findings, citing that Avery did have prior experience controlling a DC-8 during a stall, and stated that the revised stall procedures were fully implemented at the time of the accident.

Aftermath

The NTSB issued seven safety recommendations to the FAA. The NTSB also reiterated a previous recommendation regarding the angle of attack following the crash of American Airlines Flight 965 on December 20, 1995: Шаблон:Blockquote

Lynn Scully, the wife of Brian Scully, filed a lawsuit against Airborne Express for $20 million.

Brian Scully's sister, Maureen DeMarco, was killed in the crash of Comair Flight 3272 on January 9, 1997. Maureen was headed to Brian's funeral.

See also

• Air France Flight 447
• Air Transport International Flight 782, another non-scheduled DC-8 flight that crashed one year previously
• Colgan Air Flight 3407
• West Caribbean Airways Flight 708
• XL Airways Germany flight 888T, another flight test where the aircraft stalled and crashed
• LAC Colombia Flight 028

External links

• Cockpit voice recorder transcript and accident summary