FTW96LA269

During climb, the TCAS accrued a TA then a RA down advisory 'don't climb greater than 500 fpm.' The crew simultaneously operated their respective side stick controls when the captain responded with an abrupt maneuver without making a verbal announcement that he was taking command. Input from both side sticks changed the aircraft nose-up pitch from 0.7 degrees to 4.22 degrees in 1.1 second and an aft galley g load from -0.36 g's to 2.27 g's. Subsequently, the Captain Side Stick Position gave an aircraft pitch change to 2.11 degrees nose-down and an aft galley CG of -0.76 g's in a span of one second. Both Side Stick positions cumulatively gave 1.8 degrees nose-up and 2.09 g's at the aft galley in 1.2 seconds. The VFR traffic had visual contact on the Airbus and both aircraft were advised by ATC that the traffic was not a factor. The seat belt sign had been turned 'OFF' and the FA's were preparing for passenger service. FA's reported strong consecutive jolts, without warning, that threw them and items against the ceiling. The captain had the TCAS CBT training. He had not received the simulator TCAS training. The Captain had not participated in CRM.

On June 21, 1996, at 1428 central daylight time, the flight crew of an Airbus A340-200, German Registration D-AIBE, en route from Dallas/Fort Worth Airport (DFW), Texas, climbing to 17,000 feet MSL, responded to a Traffic Alert and Collision Avoidance System (TCAS) alert Traffic Advisory (TA) at 13,800 feet MSL, with a descent maneuver. Operated by Lufthansa Airlines as Flight 436, a Title 14 CFR Part 129 scheduled passenger flight, the airplane was en route to Houston Intercontinental Airport (IAH), Houston, Texas. The two pilot crew, three flight attendants, and 65 passengers were not injured. Four flight attendants sustained serious injuries, and one flight attendant and one passenger received minor injuries. Visual meteorological conditions prevailed and the flight, operating on an IFR clearance, departed at 1418.

During interviews and on the enclosed statements, company personnel and the flight crew reported that Flight 436 departed Frankfurt, Germany, on June 21, 1996, with planned stops at DFW Airport, Texas and IAH Airport, Houston, Texas. As Flight 437, the airplane would return to DFW Airport, Texas, with the final destination of Frankfurt. Flight 436, flown by the First Officer, and cleared for the JOE POOL TWO DEPARTURE, departed on runway 18L at DFW and was subsequently cleared for a left turn heading 160 with a climb to 17,000 feet MSL.

After the airplane climbed through 10,000 feet, the flight crew turned the seat belt sign "OFF" and the cabin crew began preparations for serving the passengers. With a climb pitch attitude set at 5 to 6 degrees, the airspeed accelerated from 250 knots toward an en route climb airspeed as the crew reduced the rate of climb from 3,500 fpm to approximately 2,000 fpm. Between 13,000 feet MSL and 14,000 feet MSL, the aircraft TCAS accrued a Traffic Advisory (TA). The Captain recalled the traffic display at the 12:30 o'clock position with vertical separation of 2,000 feet; however, the First Officer recalled the traffic display at the 13:00 o'clock position with vertical separation of 1,200 feet. The captain recalled that the TCAS went from the Traffic Advisory (TA) indication to a Resolution Advisory (RA) indication "with the command descend, descend." The Captain initiated an immediate descent. The Captain did not make a verbal announcement that he was taking command of the left side stick control.

All Lufthansa A320/A340 aircraft are equipped with a side stick priority feature whereby if the "take-over push button" on either side stick is pressed, the "red arrow" illuminates on the opposite side. The green light illuminates on the side having priority, if the pilot who lost priority moves his side stick out of neutral. In this case, there is also an audio "PRIORITY RIGHT" respectively "PRIORITY LEFT" message. The crew neither recalled observing the lights nor hearing the audio message. Input from both side sticks occurred until the First Officer, noting the Captain's input, moved the right side stick to a neutral position.

During telephone conferences, conducted by the investigator-in-charge, the airplane manufacturer representative reported that a pilot takes the side stick priority by pressing and keeping pressed their take over priority button (P/B) which inhibits the other side stick inputs regardless of its position. If both pilots press their take over P/B, the last pilot to press will get the priority and if the P/B is pressed more than 30 seconds, the priority is latched to that side stick. However, at any time, a deactivated stick can be reactivated by momentarily pressing its takeover push button. If both pilots press their takeover push buttons, the last pilot to press will get the priority. During normal operation both side sticks are active and associated signals are algebraically added; however, flight control parameters are not exceeded during dual side stick inputs. The pitch control of the electronic flight control system is a load demand system. In clean configuration, maximum pitch up command is +2.5 G and maximum down command is -1.0 G. The manufacturer representative further stated that a dual side stick input is available whereby both green lights will illuminate in case of a simultaneous input on both side sticks and there is also a "DUAL INPUT" audio message. Lufthansa personnel reported that these dual input features would be scheduled for installation on their entire fleet of A340 aircraft in 1997. However, on January 14, 1997, Lufthansa personnel reported that the modifications had not been accomplished due to Airbus Industries not offering the "DUAL INPUT" side stick warning system modification for the A340 aircraft. An Airbus Industries representative confirmed on January 30, 1997, that the audio portion "DUAL INPUT" side stick warning system is an installation for the A320; however, the aural warning is currently under development/testing for the A340 and would be available for the A340 in February 1998.

A review of the ATC data (enclosed) revealed the following information. The Cessna 421, N421LF, owned and operated by Lyddon Aero Center at Liberal, Kansas, was en route VFR to Liberal. The pilot called approach control at 1427:16, reported the aircraft position as 28 miles south southeast at an altitude of 14,500 MSL and requested traffic advisories through the DFW Class B airspace. The Cessna 421, N421LF, was assigned a transponder squawk of 0211. At 1427:51, Lufthansa asked the controller about the traffic and at 1427:59 the controller advised Lufthansa that the traffic was at "one o'clock and a mile northbound fourteen thousand five hundred." At 1428:07 N421LF was advised that "traffic passi' just off right's an airbus." At 1428:11, the pilot of N421LF reported "yeah we've been watching him." At 1428:27, the Lufthansa flight crew, who did not have visual contact on the traffic, inquired if the controller had the traffic on radar and the controller responded that the traffic was past Flight 436 and was not a factor. Subsequently, the Flight 436 crew advised the controller that in response to the TCAS Traffic Advisory, "We had to stop the climb [and] descended to avoid the traffic." The flight requested and received priority handling for the continued flight to Houston. At 1456:32 the flight was cleared to land on runway 08 at Houston Intercontinental Airport and landed without further incident.

During a telephone interview, conducted by the investigator-in-charge, the pilot of N421LF recalled having the Airbus in sight and stated that there was adequate VFR separation. The pilot did not observe and was not aware of evasion action by the Lufthansa crew.

Flight attendant accounts of the time of occurrence varied from 8 to 15 minutes after takeoff and 2 minutes to 5 minutes after the seat belt sign had been turned off for the cabin. Two beverage carts had been placed in the forward section of the aft galley in preparation for service to the cabin. The flight attendants (enclosed statements) described the event with the following phraseology:

three strong consecutive jolts that threw me to the ceiling, floor,

and also against a galley wall 5 times,

hit by beverage carts, containers, and other service items,

hefty jolts which occurred without warning,

thrown approximately 5 times against the ceiling,

galley looked like a battle field,

aircraft jolted strongly and we were thrown some 50 centimeters into the air,

followed by another, much stronger blow,

thrown against the ceiling with great force several times, each time falling back to the floor,

thrown around the galley several times without warning,

thrown against the ceiling and the floor several times, and twice lifted some 10 centimeters from the floor.

The Captain, an Airline Transport Rated Pilot with the A340 type rating, had accumulated 1,930 flight hours in the aircraft. He had completed the comp