NTSB: No Rush to Judge

Tuesday, September 21, 2010
By George Hatcher

George’s Point of View

As urgent as the idea of an NTSB recommendation sounds, there is apparently no rush. The latest NTSB safety recommendation to EASA is rooted in a 2001 crash: American Airlines Airbus Flight 587. (see narrative below)

Probable cause of this accident was the in-flight separation of the vertical stabilizer as a result of the loads beyond ultimate design that were created by the first officer’s unnecessary and excessive rudder pedal inputs. (i.e. The pilot used the rudder and it fell off.)

(To put this into simplistic car terms, your car just skidded on some ice. You did some fancy and extreme steering which may or may not have been necessary. And the steering wheel just came off in your hands. Pretty much all you can do now is spectate and die.)

The pilot’s unnecessary and excessive rudder pedal input was based on a violent wake turbulence encounter. The pilot’s “unnecessary and excessive” rudder pedal input broke the rudder.

Isn’t this a dubious conclusion? Isn’t this like blaming a car crash on a driver hitting brakes too hard? The airbus had just taken off and encountered turbulence. Since when do flight controls not handle “aggressive input”?

Initial suggestions included pilot retraining. (I.E. don’t fix the problem, train the pilots to work around it.) This month, the NTSB encouraged modification of European certification standards. In other words, the NTSB wants to physically limit the rudder movement to what the design can safely manage. Maybe that makes more sense than expecting a pilot engaged in a desperate struggle to save a failing plane to have to make accommodations for flighty flight controls.

Some take the angle that the problem lies in the rudder design and/or composition. In 2001, the FAA was one of those so inclined.

On November 16, 2001, the FAA issued emergency AD 2001-23-51 warning of failure of the vertical stabilizer-to-fuselage attachment fittings, transverse (side) load fittings, or rudder-to-vertical stabilizer attachment fittings, if not corrected, could result in loss of the vertical stabilizer and/or rudder and consequent loss of control of the airplane. The FAA considers that, before structural failure, it may be possible to detect indications of possible failure modes that could result in separation of the vertical stabilizer from the airplane. These indications include edge delaminations, cracked paint, surface distortions, other surface damage, and failure of the transverse (side) load fittings. Similarly, indications of failure of the rudder assembly, which could lead to failure of the vertical stabilizer, may also be detectable with such an inspection.

This failure has happened more than once.

In the Air Transat flight 961 incident (also a 300 series Airbus) out of Varadero, Cuba, the rudder disintegrated. The pilot in that flight questions the integrity of the rudder design and composition.

Here another point that has been commonly made. Aircraft have had rudders made of aluminum for 70 years without them disintegrating. With high tech composites, planes are falling out of the sky.

In March 2006, US safety investigators recommended rudder inspections on Airbus A300-600 jets because a FedEx A300-600 rudder damaged during maintenance.

Tested on the ground by Fed Ex engineers, in the Fed-Ex A300 cargo plane, the hydraulic system which actuates the rudder tore a hole around the hinges exactly where the rudders of both flight 961 and flight 587 did. Coincidence? I think not.

Does the certification process need an overhaul? I think so.

Have a couple of dead pilots again become convenient scapegoats for/by using the very computer controlled flight control system that they believed protected them? I bet I know what the pilots think.

Flight 587, Official NTSB narrative of the crash
On November 12, 2001, about 0916:15 eastern standard time, American Airlines flight 587, an Airbus Industrie A300-605R, N14053, crashed into a residential area of Belle Harbor, New York, shortly after takeoff from John F. Kennedy International Airport (JFK), Jamaica, New York. Flight 587 was a regularly scheduled passenger flight to Las Americas International Airport, Santo Domingo, Dominican Republic, with 2 flight crewmembers, 7 flight attendants, and 251 passengers aboard the airplane. The airplane’s vertical stabilizer and rudder separated in flight and were found in Jamaica Bay, about 1 mile north of the main wreckage site. The airplane’s engines subsequently separated in flight and were found several blocks north and east of the main wreckage site. All 260 people aboard the airplane and 5 people on the ground were killed, and the airplane was destroyed by impact forces and a postcrash fire. Flight 587 was operating under the provisions of 14 Code of Federal Regulations (CFR) Part 121 on an instrument flight rules flight plan. Visual meteorological conditions prevailed at the time of the accident.

The accident airplane arrived at JFK about 2231 on the night before the accident. The airplane had been flown from San Jose, Costa Rica, to JFK with an intermediate stop in Miami International Airport, Miami, Florida. During postaccident interviews, the pilots of the flight leg from MIA to JFK indicated that the flight was smooth and uneventful.

Flight 587 was the first leg of a 1-day roundtrip sequence for the flight crew. American Airlines records indicated that the captain checked in for the flight about 0614 and that the first officer checked in about 0630. The gate agent working the flight arrived at the departure gate about 0645. She stated that the flight attendants were already aboard the airplane at that time and that the captain and the first officer arrived at the gate about 0700.

About 0710, the airplane fueling process began. The airplane fueler indicated that, during the fueling process, he saw one of the pilots perform an exterior inspection of the airplane. He finished the fueling process about 0745 and stated that he saw nothing unusual regarding the airplane.

Statements provided to the Port Authority of New York and New Jersey Police Department by American Airlines maintenance and avionics personnel indicated that, sometime between 0730 and 0800, the captain reported that the number 2 pitch trim and yaw damper system would not engage. Two avionics technicians were sent to the airplane to investigate the problem. They performed an auto flight system (AFS) check, which indicated a fault with the number 2 flight augmentation computer. The circuit breaker was then reset, another AFS check was performed, and no fault was detected. In addition, an autoland system check was performed, and that test also did not detect a fault. The avionics technicians estimated that they were in the cockpit for 5 to 7 minutes.

The cockpit voice recorder (CVR) recording began about 0845:35. The CVR indicated that, about 0859:58, the airplane was cleared to push back from the gate. About 0901:33, the ground controller provided the flight crew with taxi instructions to runway 31L, and the first officer acknowledged these instructions. About 0902:05, the captain told the first officer, “your leg, you check the rudders.” (The first officer was the flying pilot, and the captain was the nonflying pilot.) Data from the flight data recorder (FDR) showed that, about 0902:07, the rudder pedal check began. The FDR data also showed that a maximum right rudder pedal deflection of about 3.7 inches was recorded about 0902:11 and that a maximum left rudder pedal deflection of 3.6 inches was recorded about 0902:19. About 0902:23, the first officer responded, “rudders check.” The FDR data showed that the rudder pedals returned to their neutral position about 0902:25.

About 0906:53, the ground controller provided the pilots of Japan Air Lines flight 47, a Boeing 747-400, with taxi instructions to runway 31L. About 0908:01, the ground controller instructed the Japan Air Lines pilots to contact the local (tower) controller. About 0908:58, the ground controller instructed the flight 587 pilots to follow the Japan Air Lines airplane and to contact the local controller. The first officer acknowledged this instruction.

About 0911:08, the local controller cleared the Japan Air Lines airplane for takeoff. About 0911:36, the local controller cautioned the flight 587 pilots about wake turbulence and instructed the pilots to taxi into position and hold for runway 31L. The first officer acknowledged the instruction. About 0913:05, the local controller instructed the Japan Air Lines pilots to fly the bridge climb and to contact the departure controller at the New York Terminal Radar Approach Control (TRACON). About 0913:21, the flight 587 captain said to the first officer, “you have the airplane.”

About 0913:28, the local controller cleared flight 587 for takeoff, and the captain acknowledged the clearance. About 0913:35, the first officer asked the captain, “you happy with that [separation] distance?” About 3 seconds later, the captain replied, “we’ll be all right once we get rollin’. He’s supposed to be five miles by the time we’re airborne, that’s the idea.” About 0913:46, the first officer said, “so you’re happy.”

The National Transportation Safety Board’s airplane performance study for this accident0 determined that flight 587 started its takeoff roll about 0913:51 and lifted off about 0914:29, which was about 1 minute 40 seconds after the Japan Air Lines airplane. About 0914:43, the local controller instructed the flight 587 pilots to turn left, fly the bridge climb, and contact the New York TRACON departure controller. About 5 seconds later, the captain acknowledged this instruction. Radar data indicated that the airplane climbed to 500 feet above mean sea level (msl) and then entered a climbing left turn to a heading of 220º. About 0915:00, the captain made initial contact with the departure controller, informing him that the airplane was at 1,300 feet msl and climbing to 5,000 feet msl. About 0915:05, the departure controller instructed flight 587 to climb to and maintain 13,000 feet msl, and the captain acknowledged this instruction about 5 seconds later. About 0915:29, the CVR recorded the captain’s statement “clean machine,” indicating that the gear, flaps, and slats had all been retracted.

About 0915:35, flight 587 was climbing through 1,700 feet msl with its wings approximately level. About 1 second later, the departure controller instructed flight 587 to turn left and proceed direct to the WAVEY navigation intersection (located about 30 miles southeast of JFK). About 0915:41, the captain acknowledged the instruction. The controller did not receive any further transmissions from flight 587.

FDR data indicated that, about 0915:36, the airplane experienced a 0.04 G drop in longitudinal load factor, a 0.07 G shift to the left in lateral load factor, and about a 0.3 G drop in normal (vertical) load factor. The airplane performance study found that these excursions were consistent with a wake turbulence encounter. Between 0915:36 and 0915:41, the FDR recorded movement of the control column, control wheel, and rudder pedals. Specifically, the control column moved from approximately 0º (neutral) to 2º nose up, 2º nose down, and back to 0º; the control wheel moved a total of seven times, with peaks at 18º right, 30º left, 37º right, 34º left, 5º left, 21º left, and 23º right, before moving to between 5º and 6º left; and the rudder pedals moved from about 0.1 inch left (the starting point for the pedals) to about 0.1 inch right and 0.2 inch left before moving to 0.1 inch left. The airplane performance study indicated that, during this time, the rudder moved from 0º (neutral) to about 2º left, about 0.6º right, and back to 0º.

During the wake turbulence encounter, the airplane’s pitch angle increased from 9º to 11.5º, decreased to about 10º, and increased again to 11º. The airplane’s bank angle moved from 0º (wings level) to 17º left wing down, which was consistent with the turn to
the WAVEY navigation intersection.

At 0915:44.7, the captain stated, “little wake turbulence, huh?” to which the first officer replied, at 0915:45.6, “yeah.” At 0915:48.2, the first officer indicated that he wanted the airspeed set to 250 knots, which was the maximum speed for flight below 10,000 feet msl. At that point, the airplane was at an altitude of about 2,300 feet msl.

FDR data indicated that, about 0915:51, the load factors began excursions that were similar to those that occurred about 0915:36: the longitudinal load factor dropped from 0.20 to 0.14 G, the lateral load factor shifted 0.05 G to the left, and the normal load factor dropped from 1.0 to 0.6 G. The airplane performance study found that these excursions were also consistent with a wake turbulence encounter. According to the FDR, the airplane’s bank angle moved from 23º to 25º left wing down at 0915:51.5, the control wheel moved to 64º right at 0915:51.5, and the rudder pedals moved to 1.7 inches right at 0915:51.9.

At 0915:51.8, 0915:52.3, and 0915:52.9, the CVR recorded the sound of a thump, a click, and two thumps, respectively. At 0915:54.2, the first officer stated, in a strained voice, “max power.” At that point, the airplane was traveling at 240 knots. About 0915:55, the captain asked, “you all right?” to which the first officer replied, “yeah, I’m fine.” One second later, the captain stated, “hang onto it. Hang onto it.” The CVR recorded the sound of a snap at 0915:56.6, the first officer’s statement “let’s go for power please” at 0915:57.5, and the sound of a loud thump at 0915:57.7. According to the airplane performance study, the vertical stabilizer’s right rear main attachment fitting fractured at 0915:58.4, and the vertical stabilizer separated from the airplane immediately afterward. At 0915:58.5, the CVR recorded the sound of a loud bang. At that time, the airplane was traveling at an airspeed of about 251 knots.

According to the FDR, the rudder pedals moved from 1.7 inches right to 1.7 inches left, 1.7 inches right, 2.0 inches right, 2.4 inches left, and 1.3 inches right between 0915:52 and 0915:58.5. Also, the FDR showed that the control wheel moved 64º to the right at 0915:51.5, 78º (full) to the left at 0915:53.5, 64º to the right at 0915:55.5, and 78º to the left at 0915:56.5.

The airplane performance study estimated that, at 0915:53.2, the rudder was deflected 11º to the left, and the sideslip angle at the airplane’s center of gravity (cg) was about 4º to the left (after peaking temporarily at 5º to the left).21 At 0915:56.8, the rudder was deflected 10.2º to the left, and the sideslip angle was about 7º to the left. At 0915:58.4 (the time that the right rear main attachment fitting fractured), the rudder was deflected between 10º and 11º to the right, the sideslip angle was between 11º and 12º to the right, and the airplane experienced a 0.2 G shift to the right in lateral load factor.

The CVR recorded, at 0916:00.0, a sound similar to a grunt and, 1 second later, the first officer’s statement, “holy [expletive].” At 0916:04.4, the CVR recorded a sound similar to a stall warning repetitive chime, which lasted for 1.9 seconds. At 0916:07.5, the first officer stated, “what the hell are we into…we’re stuck in it.” At 0916:12.8, the captain stated, “get out of it, get out of it.” The CVR recording ended 2 seconds later. The airplane was located at 40º 34′ 37.59″ north latitude and 73º 51′ 01.31″ west longitude. The accident occurred during the hours of daylight.

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