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Networks and distributed Systems
Research group of Prof. Peter B. Ladkin, Ph.D.
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China Airlines
Airbus Industrie A300B4-622R, B1816
Nagoya Airport
April 26, 1994

Aircraft Accident Investigation Commission
Ministry of Transport

Prepared for the WWW by

Hiroshi Sogame
Safety Promotion Comt.
All Nippon Airways

Peter Ladkin
Universität Bielefeld

Sections 4 to 7

July 19, 1996


While the aircraft was making an ILS approach to Runway 34 of Nagoya Airport, under manual control by the F/O, the F/O inadvertently activated the GO lever, which changed the FD (Flight Director) to GO AROUND mode and caused a thrust increase. This made the aircraft deviate above its normal glide path.

The APs were subsequently engaged, with GO AROUND mode still engaged. Under these conditions the F/O continued pushing the control wheel in accordance with the CAP's instructions. As a result of this, the THS (Horizontal Stabilizer) moved to its full nose-up position and caused an abnormal out-of-trim situation.

The crew continued approach, unaware of the abnormal situation. The AOA increased the Alpha Floor function was activated and the pitch angle increased.
It is considered that, at this time, the CAP (who had now taken the controls), judged that landing would be difficult and opted for go-around. The aircraft began to climb steeply with a high pitch angle attitude. The CAP and the F/O did not carry out an effective recovery operation, and the aircraft stalled and crashed.

The AAIC determined that the following factors, as a chain or a combination thereof, caused the accident:
1. The F/O inadvertently triggered the Go lever
It is considered that the design of the GO lever contributed to it: normal operation of the thrust lever allows the possibility of an inadvertent triggering of the GO lever.
2. The crew engaged the APs while GO AROUND mode was still engaged, and continued approach.
3. The F/O continued pushing the control wheel in accordance with the CAP's instructions, despite its strong resistive force, in order to continue the approach.
4. The movement of the THS conflicted with that of the elevators, causing an abnormal out-of-trim situation.
5. There was no warning and recognition function to alert the crew directly and actively to the onset of the abnormal out-of-trim condition.
6. The CAP and F/O did not sufficiently understand the FD mode change and the AP override function.
It is considered that unclear descriptions of the AFS (Automatic Flight System) in the FCOM (Flight Crew Operating Manual) prepared by the aircraft manufacturer contributed to this.
7. The CAP's judgment of the flight situation while continuing approach was inadequate, control take-over was delayed, and appropriate actions were not taken.


8. The Alpha-Floor function was activated; this was incompatible with the abnormal out-of-trim situation, and generated a large pitch-up moment. This narrowed the range of selection for recovery operations and reduced the time allowance for such operations.
9. The CAP's and F/O's awareness of the flight conditions, after the PlC took over the controls and during their recovery operation, was inadequate respectively.
10. Crew coordination between the CAP and the F/O was inadequate.
11. The modification prescribed in Service Bulletin SB A300-22-602 1 had not been incorporated into the aircraft.
12. The aircraft manufacturer did not categorise the SB A300-22-6021 as "Mandatory", which would have given it the highest priority. The airworthiness authority of the nation of design and manufacture did not issue promptly an airworthiness directive pertaining to implementation of the above SB.



5.1 Measures taken after the Accident

Measures taken by the authorities, operators and manufacture were as follows:

5.1.1 Taiwanese civil aviation authorities

As of May 3 1994, the authorities ordered China Airlines to complete the modification to the FCCs promptly, in accordance with the Airbus Industrie's SB(A300-22-602 1).

As of May 7 1994, the authorities ordered China Airlines to provide supplementary training to A300-600R pilots, re-evaluate their proficiency and submit pilot training and reevaluation plans to the authorities.

As of September 5 1994, in compliance with CN (CN 94-185-165(B)) released by DGAC, the authorities issued an airworthiness directive, AD-83-A300-1 55, ordering flight manual revision and FCC modification within 24 months following the effective date of the directive. This was done in order to prevent an abnormal out-of-trim situation from arising from a prolonged override of the APs (engaged in CML)) by acting on the pitch axis via the control wheel, which could create difficulties in controlling the aircraft.
The authority also issued AD83-A300-155A, the revision to AD83-A300-155, in compliance with AD(94-2 1-07) released by FAA, and on February 15 1996, revised AD83-A300-155A in compliance with DGAC CN (CN94-185-165(B)R1).

5.1.2 China Airlines

China Airlines had completed the modifications specified in Airbus Industrie's SB(A300-22-602 1) by September 7 1994.

China Airlines re-checked the proficiency of all their pilots. In particular, the rechecking of the A300-600R pilots was observed by officers of the Taiwanese civil aviation authorities.

China Airlines carried out special inspections of engines, flight control systems and autopilot systems on all their aircraft.
On the A300-600R aircraft in particular, unscheduled inspections (A checks) were completed by May 311994.

5.1.3 Bureau Enquêtes Accidents (BEA), Direction General de 1' Aviation Civile (DGAC), FRANCE

On June 8 1994, BEA transmitted the following recommendation to DGAC:

"We recommended that a study be performed for the modification of the aircraft, with all necessary accompanying measures, leading to the disconnection of autopilot when a pilot overrides it while in Land and Go Around modes. The modifications resulting from this study should be made mandatory."


On August 17 1994, DGAC issued an airworthiness directive, CN(CN94-1 85-165(B)) (effective as of August 27 1994), to order flight manual revisions and FCC modification within 24 months of the effective date of the directive, in order to prevent an abnormal out-of-trim situation from arising by a prolonged override of the APs (engaged in CML)) by acting on the pitch axis via the control wheel, which could create difficulties in controlling the aircraft. Furthermore, on January 311996 (effective as of February 10 1996), DGAC issued CN94-185-165(B)R1 (revised from the previous CN) to order flight manual revision and other measures.

5.1.4 Airbus Industrie

Airbus Industrie notified all operators of A300/A3 10 and A300-600 aircraft by FAX (Al/ST-F 472.2200/94) dated May 5 1994 of the hazards of overriding the APs by means of the elevators while the APs are engaged in LAND or GO AROUND mode.

On December 13 1994, Airbus Industrie re-categorized modifications to FCC (stated in the already issued SB(A300-22-602 1)) from "Recommended" to "Mandatory" in accordance with CN(CN94- 185-165(B)) released by DGAC.

5.1.5 Civil Aviation Bureau, Ministry of Transport of Japan

The Civil Aviation Bureau handed Japan Air System a Notice of Director of Engineering Department entitled "Observance of Operating Procedures for Automatic Flight Control System Prescribed in Aircraft Operating Manual" on May 10 1994, and gave instruction on the following matters, while requesting them to submit reports of the measures that they would take to conform to the instructions;

Positive verification of selected AP modes during approach.

Thorough understanding of operating procedures for disengagement of Go Around mode specified in the Aircraft Operating Manual.

Thorough attention to the following cautions regarding the use of Autopilot specified in Paragraph 1 "General (5-5-1)" of Section 5 "AFS" of Chapter 5 "Procedures and Techniques" and (4) "AP in CML)" in Paragraph 5 "Auto-pilot/Flight Director" of Section 3 "Automatic Flight" of Chapter 8 "Systems" in the Aircraft Operating Manual for Airbus A300-600 series aircraft;

Working on the pitch axis against the AP in CML) may lead to a hazardous situation in LAND and GO AROUND mode. So if any abnormal flight control behavior is encountered during these flight phases:
  • check AP status (FMA, FCU)
  • if AP engaged, disconnect it and take over.

On the longitudinal axis, autopilot override does not cancel the AP autotrim orders. So with AP in CMI), if the pilot counteracts the AP (elevators orders), the AP will move the THS (autotrim orders) so as to maintain the aircraft on the scheduled flight path. A risk of out-of-trim is real and may lead to a hazardous situation in land and go-around mode only.


Monitoring of operating conditions of the trim control wheel during approach, in particular when the AP is engaged.

Early implementation of the company's plan to accomplish the FCCs modification (Airbus SB A300-22- 6021) to add an autopilot disengagement function which is activated by applying a force on the control wheel in Go Around mode above 400 feet radio altitude.

On May 10 1994, the Bureau requested, through an appropriate channel, the Taiwanese civil aviation authorities to re-instruct China Airlines in order to be absolutely assured of flight safety, and at the same time inform them of the fact that the actions shown in the above paragraph (1) had been taken.

On May 12 1994, the Bureau issued an instruction to Japan Air System saying that the company should also take similar measures for the Airbus A300B2K-3C and A300B4-2C series aircraft, operated by the company, which contain the same AFS characteristics as those of the A300-600 aircraft.

On August 25 1994, the Bureau issued an airworthiness directive, TCD(TCD-4078-94, effective as of August 27 1994), ordering that, with regard to A300B4-220FF, A300B4-203FF and A300B2-203FF aircraft as well as A3 10 and A300-600 series aircraft, the flight operating manuals should be revised and the FCCs modification mentioned in the above paragraph (1)-(r) accomplished within 24 months in order to prevent an out-of-trim situation from arising from control wheel operation while the AP(s) engaged in CML) mode, which could create difficulties in controlling the aircraft.
This TCD complied with the airworthiness directive, CN(CN 94-185-165(B)) of DGAC.
Also, on February 2 1995, the Bureau issued TCD-4078-1-95 (a revision from the above-mentioned TCD), effective as of the same day, which required implementation of the changes included in the revision within seven days of the effective date of the TCD. This revision complied with the airworthiness directive AD(94-2 1-07) issued by Federal Aviation Administration (FAA) of the U.S.A.

The Bureau is planning to deploy a large chemical fire vehicle(loading capacity of 12,000 litters), a water supply wagon (loading capacity of 8,000 litters) and a electric power supply wagon in fiscal year 1995 through 1996, as well as a large chemical fire vehicle (loading capacity of 12,000 litters) and a chemical fire vehicle (loading capacity of 4,500 litters) in fiscal year 1996 through 1997 at Nagoya Airport Office.

5.1.6 National Transportation Safety Board (NTSB) and Federal Aviation Administration (FAA), U.S.A.

(1)The NTSB made the following recommendations to the FAA:

Require operators of the Airbus A300 and A3 10 series airplanes to provide immediate and recurrent training to fight crews on the hazards of attempting to counter autopilot commands by manual control forces when the airplane is being flown with the autopilot engaged in the LAND or GO AROUND mode (A-94-164).


Review the logic of the Airbus A300 and A3 10 series automatic flight control systems and require modification as necessary so that the autopilot will disconnect if the pilot applies a specified input to the flight controls or trim system, regardless of the altitude or operating mode of the autopilot. (A-94-165)

Require modification of Airbus A300 and A310 series autopilot systems to ensure that the systems provide a sufficient perceptual alert when the THS is in motion, irrespective of the source of the trim command. (A-94-166)

(2) The FAA issued the following airworthiness directives (AD 94-21-07), effective as of November 2 1994:
Applicability: all Model A3 10 and A300-600 series airplanes.

Within 10 days after the effective date of this AD, revise the Limitations Section of the FAA-approved Airplane Flight Manual(AFM).

Within 60 days after the effective date of this AD, modify the FCC's in accordance with Airbus Service Bulletin A300-22-602 1.



As a result of the accident investigation, the Aircraft Accident Commission makes the following recommendations:

1. To the Taiwanese civil aviation authorities:

Require China Airlines to implement the following:
(1) Reinforcement of education and training programs for flight crews

Understanding of the design concept of advanced technology aircraft and establishment of the operational concept for such aircraft

Since it is considered to be important in the operation of advanced technology aircraft for an airline to establish its own operational concept based on a full understanding of the design concept of the manufacturers, China Airlines should reinforce the education and training system for flight crews so that each crew member will fully understand the concept and its application can be rooted more firmly in daily operations.

Reinforcement of education and training on the Automatic Flight System.

China Airlines should review the following to deepen crews' understanding of the AFS functions of advanced technology aircraft.

The reinforcement of education and training programs for controls and operations which crews rarely experience in daily flight, such as mode changes and manual overrides during auto flight.

The establishment of measures which allow crews to easily recall the controls and operations described in a. above in flight in order to effectively implement them.

Methods for enhancing crews' understanding of important technical information on flight operations issued by aircraft manufacturers.

Measures to ensure that through education and training, crews do not activate the GO-lever of the A300-600R inadvertently, and that they take appropriate actions if this occurs.
(2) Establishment of appropriate task sharing

China Airlines should review the following to ensure that Cockpit Resource Management is performed most effectively when the CAP has the F/O to perform the PF task.

Task sharing between the CAP and the F/O.

Situations which require the CAP taking over the PF task from the F/O.


Implementation of preflight briefing on mutual confirmation of the items of a. and b. above.

(3) Improvement of crew coordination

Standardization of terms

China Airlines should standardize the terms used for instruction, response, confirmation and execution of operations in order to ensure that crews can have appropriate situational awareness of the flight.

Procedures of AFS mode change

China Airlines should improve the procedures for mutual confirmation by crews of operation and monitoring of the AFS mode changes of advanced technology aircraft.

Reinforcement of standard call out

China Airlines should ensure the implementation of standard call outs in order to enhance the effectiveness of 0 and 02 above.

(4) Establishment of standardization of flight.
China Airlines should standardize flights by prescribing items that must be checked according to the flight attitude. This will 1) allow crew members to have an adequate situational awareness of the flight conditions and make the correct decisions based on their awareness, and 2) eliminate any effects of crew members' individuality.

2. To Airworthiness Authority of France:

Require Airbus Industrie to implement the followings;
(1)Improvement of the AFS functions of A300-600R

Improvement of the AP disconnect and override functions
Airbus Industrie should review the AP disconnect and manual override functions, by which crews can safely control the aircraft irrespective of flight altitude or phase by applying a force exceeding a certain level on the control column.

Incorporation of out-of-trim prevention functions
Airbus Industrie should consider incorporating functions to prevent an abnormal out-of-trim condition from arising from a prolonged override operation of the autopilot by acting on the pitch axis via the control column, which moves the THS in the opposite direction to the elevator movement.
In this connection, Airbus Industrie should review the relationship between the Alpha floor function and out-of-trim condition.

Improvement of warning and recognition functions for THS movement
Airbus Industrie should study warning and pilot-recognition enhancement functions which alert the pilots directly and actively to those situations which arise when the THS enters, or is close to, an out-of-trim situation, or when it continues to move for more than


a certain period of time, regardless of AP engagement or disengagement.
(2) Improvement of descriptions in the FCOM of the A300-600R type

The descriptions of the following in the FCOM of A300-600R should be improved from the operational viewpoint.

AP manual override
  • the purpose of the function
  • the descriptions of the system
  • the difference between the supervisory override function and the manual override function
  • the examples of possible situations which may arise, the corresponding procedures for confirmation and subsequent operations to be performed.

Disengagement of GO AROUND mode
  • the procedure for disengagement
  • the procedure for selecting other modes
  • the connection between the display changes on the FMA and the actual changes occurring in the aircraft.

Recovery procedures from out-of-trim situation
  • examples of possible scenarios and their corresponding detection procedures
  • the recovery procedure from out-of-trim situation when the AP is engaged and disengaged, respectively.
(3) Positive dissemination of technical information to operators

In the event of an accident or serious incident, Airbus Industrie should promptly disseminate the systematical explanation of its technical background to each operator, and furthermore should positively and promptly develop modifications, prepare the Service Bulletin(SB) and revise the FCOM to preclude the recurrence of such incidents.

3. To Airworthiness Authority of France:

Review the following along with Airbus Industrie.

A review of the AFS, taking into account crews' ability and behavior in an emergency or abnormal situation.

The AFS is designed with various factors under consideration; its functions are complicated. Therefore there are some occasions where it would be difficult for pilots to recognize the operating condition of the AFS or properly predict the effect of a mode change on the flight. There is a possibility that crew might be unable to take proper action when using functions which are rarely used in daily flights.
Because human thinking ability is restricted in times of high stress, such as in an emergency or abnormal situation, it would be even more difficult for crews to take action within a limited period.


It is considered that there is a limit to how thoroughly a crew can be taught to deal with such situations by routine education and training.

Accordingly the design of the AFS (function, mode display method, warning and crew recognition function) should be reviewed, taking into account pil9t's behavior and human cognitive process under an emergency or abnormal situation.



In view of the China Airlines accident, the Aircraft Accident Investigation Commission proposes the following to Minister of Transport of Japan.

1. Standardization of AFS specification for advanced technology aircraft

With regard to the AFS functions of advanced technology aircraft presently operated by Japanese airlines, there exist functions, the details of which, with the present level of education and training, cannot easily be understood or used by crew members, such as: man-machine interface-related functions, e.g., the function, display and operational procedure for flight mode, and AP override and disconnect functions; flight-protection functions.

There also exist differences in the above AFS functions among different aircraft manufacturers.

The above functions are directly linked to flight safety, and are deeply connected with the theory of how to carry out aircraft-type transition training for airline pilots. Considering these points a study should be conducted, from the standpoint of the state of operator, as to the following, in relation to the AFS functions described above:

Items to be covered by crew training;
Items to be considered in AFS design.

As to the items of which the specifications are desired to be standardized, an appropriate measures should be taken, via relevant international organizations or other appropriate bodies, to encourage such standardization to be incorporated, by the state of design and manufacture, into AFS specifications.

2. Reinforcement of the fire fighting and rescue system

As to the civil aviation fire fighting and rescue systems at airports in Japan, an urgent review should be made and the necessary measures taken in relation to the following, taking into account possible accident scenarios:

reinforcement of the command system in an emergency;

facilities and equipment required for fire fighting and rescue operations;
cooperation with related authorities and parties;
periodic training, and so on.


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Peter B. Ladkin, 1999-02-08
Last modification on 1999-06-15
by Michael Blume