University of Bielefeld - Faculty of technology
Networks and distributed Systems
Research group of Prof. Peter B. Ladkin, Ph.D.
AIRCRAFT ACCIDENT INVESTIGATION REPORT 96-5
Airbus Industrie A300B4-622R, B1816
April 26, 1994
Aircraft Accident Investigation Commission
Ministry of Transport
Prepared for the WWW by
Safety Promotion Comt.
All Nippon Airways
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
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
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
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
- As of September 5 1994, in compliance with CN
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
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
"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
- 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
- Thorough understanding of operating procedures for
disengagement of Go Around mode specified in the Aircraft
- 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
- 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
- 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
- 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
- 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.
- 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)
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
- Within 60 days after the effective date of this AD,
modify the FCC's in accordance with Airbus Service Bulletin
6. SAFETY RECOMMENDATIONS
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
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
|(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
- 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
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
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
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
- 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
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
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
- 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
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
- 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
reinforcement of the command system in an emergency;
- facilities and equipment required for fire fighting and
- cooperation with related authorities and parties;
- periodic training, and so on.
Peter B. Ladkin, 1999-02-08
Last modification on 1999-06-15
by Michael Blume