REPORT on  the incident on 24 September 1994 during approach to Orly (94) to the Airbus A 310 registered YR-LCA operated by TAROM
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FOREWORD

This report presents the technical conclusions reached by the BEA on the circumstances and causes of this incident. In accordance with Annex 13 of the Convention on International Civil Aviation, with EC directive 94/56 and with Law N°99-243 of 29 March 1999, the analysis of the accident is intended neither to apportion blame, nor to assess individual or collective responsibility. The sole objective is to draw lessons from this occurrence which may help to prevent future accidents or incidents. Consequently, the use of this report for any purpose other than for the prevention of future accidents could lead to erroneous interpretations.

SPECIAL FOREWORD TO ENGLISH EDITION

This report has been translated and published by the BEA to make its reading easier for English-speaking people. As accurate as the translation may be, please refer to the original text in French.

GLOSSARY

ADC Air Data Computer
AFS Automatic Flight System
ALT Altitude
AP Autopilot
ATHR Autothrottle
ATIS Automatic Information Service
ATS Autothrottle system
CAPT Capture
CLB Climb
CMD Command
CR Cruise
CRM Cockpit Resource Management
CVR Cockpit Voice Recorder
CWS Control Wheel Steering
DESC Descent
DME Distance Measuring Equipment
ECAM Electronic Centralized Aircraft Monitoring
FAC Flight Augmentation Computer
FAF Final Approach Fix
FCC Flight Control Computer
FCU Flight Control Unit
FD Flight Director
FDR Flight Data Recorder
FIDS Fault Isolation and Detection System
FL Flight Level
FLEX TO Flexible Take Off
FMA Flight Mode Annunciator
FMS Flight Management System
GPWS Ground Proximity Warning System
GS Glide Slope
HDG Heading
IAF Initial Approach Fix
IRS Inertial Reference System
LOC Localizer
LVL CHG Level Change
MCT Maximum Continuous Thrust
NAV Navigation
ND Nose Down
NU Nose Up
PFD Primary Flight Display
PTS Pitch Trim System
TCC Thrust Control Computer
THS Trimmable Horizontal Stabilizer
TLA Throttle Lever Angle
TOGA Take Off  - Go Around
TRP Thrust Rating Panel
VLS Velocity Lower Selectable
VS Vertical Speed
VSS Velocity Stick Shaker

SYNOPSIS

Date and time Aircraft
24 September 1994 Airbus A 310
at 10 h 45 ([1]) registered YR-LCA
   
Site of incident Operator
6 NM east of Paris Orly Tarom, Romania
   
Type of flight Persons on board
Public transport (passengers) 11 crew
  175 passengers
   

Summary

During the approach to Paris Orly, in good weather conditions, the aircraft suddenly started to climb adopting a steep pitch attitude and stalled. The crew managed to recover control of the aircraft and came round to land.

Consequences

  Persons Equipment Third parties
  Killed Injured Unhurt    
Crew    

11

N/A

N/A

Passengers    

175

   

1 – FACTUAL INFORMATION

1.1 History of the Flight

The Romanian Tarom Airbus A 310 YR .LCA, coming from Bucharest as scheduled flight ROT 381, estimated its arrival time at Paris Orly at 10 h 40. The Orly ATIS indicated that runway 26 was in service and visibility announced was ten kilometers with scattered cloud at 2,400 feet.

The aircraft left cruise level 350 at 10 h 30 at the request of regional control. At about 40 NM from the runway, at 10 h 36, it descended through flight level 150. The ATC asked the pilot to accelerate descent so as to reach level 60 in two minutes maximum.

At 10 h 37 m 13 s, the crew contacted approach control. The controller asked them to set a heading of 330° with a base leg for runway 26. The aircraft flew over the Melun VOR at 10 h 38 m 39 s, descended through to 6,600 feet with a ground speed of 400 kt. It was then authorized at 10 h 38 m 44 s to descend to an altitude of 3,000 feet.

At 10 h 41 m 01 s, the approach controller asked the flight crew to change to heading 310 for interception of ILS 26. Conversations in the cockpit show that the runway was in sight, as were certain Parisian monuments.

The Captain was at the controls. He decided to perform an automatic approach and landing. Approach control was not informed of this.

The flight crew started to put the aircraft into the approach configuration, with slats and flaps at 15/0 at 10 h 42 m 05 s, then at 15/15 at 10 h 42 m 53 s. The landing gear was extended at 10 h 42 m 57 s.

Approaching the OYE beacon at indicated speed 250 kt and heading 325, before lining up with the runway, the Captain noted that the aircraft was not capturing the ILS glide slope automatically. He disconnected the AP and continued the approach on manual control, keeping the Autothrottle in operation.

As the aircraft descended through 1,700 feet, at 10 h 43 m 22 s, with a speed of about 195 knots, the Captain asked for flap extension to 20°. The VFE, the speed limit authorized for this new configuration, is 195 knots. When the flap control was set to 20°, the thrust levers advanced and engine thrust increased.

The flight crew countered the nose-up effect resulting from the increase in thrust by using the pitch controls, with the auto-throttle (ATHR) remaining in automatic mode.

The throttle levers were then quickly brought back to the idle position. At the same time, the trimmable horizontal stabilizer started to move in a nose-up direction.

The nose up effect that resulted was countered by the flight crew through gradual nose-down action on the elevators. When the trimmable horizontal stabilizer reached its maximum nose-up value and the elevators also reached their maximum nose down value, the throttle levers, according to the FDR readout, moved rapidly to their stops.

In a few seconds, the flight path started to rise and the pitch attitude went to 60°. Witnesses saw the aircraft climb. It banked sharply to the left and the right and stalled before adopting a strongly negative pitch attitude ( .33 degrees) towards the ground. The maximum altitude reached was 4,100 feet, while a minimum indicated speed of 35 knots was recorded. The stall and ground proximity warnings sounded during the descent. The flight crew managed to regain control of the aircraft, with the lowest point being around a height of 800 feet, that is 240 meters from the ground.

The flight crew then performed a visual circuit, followed from the tower by the controller. The second approach was made with a configuration with slats and flaps at 20/20. Landing took place at 10 h 52 m 25 s. The aircraft went directly to its parking area. After inspections and with authorization from the appointed Investigator-in-Charge, it left Orly for Bucharest, on a ferry flight, on 29 September 1994.

1.2 Injuries to Persons

There were no injured among the one hundred and seventy-five passengers and eleven crewmembers. However, this incident made a strong impression on the passengers.

1.3 Damage to Aircraft

The aircraft remained undamaged.

1.4 Other Damage

None.

1.5 Flight Crew

Captain:

Before being qualified on A 310, the Captain had flown most of his flying hours on BAC 111's.

A 310 type qualification obtained after training courses No. 6393 on 29 December 1992 and No.1266 on 1 March 1993 with Aéroformation.

Appraisals of the Captain were generally excellent, though they did, however, call for improvement in working with ECAM and with FMA, as well as with crew co-ordination.

The investigators were not informed of any previous aeronautical incidents.

First officer:

A 310 type qualification issued by Tarom (training course No. 3437 of 14 June 1994).

The investigators were not informed of any previous aeronautical incidents.

Other person in the cockpit:

A third person, a Tarom pilot being familiarized with A 310, was also in the cockpit.

The investigators were not informed of any previous aeronautical incidents.

1.6 Aircraft Information

1.6.1 Airframe

  • Manufacturer Airbus Industrie.
  • type A 310/325.
  • Serial number 636.
  • registration YR .LCA.
  • registration certificate No. 1261 of 17 May 1994.
  • Airworthiness Certificate issued on 23 August 1994 by the Romanian Civil Aviation Authority, valid until 26 March 1995.

    -          last periodic maintenance inspection: inspection C performed 30 March 1994 according to Swissair maintenance program. At that date, the aircraft totaled 4,538 flying hours and 1,326 cycles.

    1.6.2 Engines

  • Manufacturer Pratt and Whitney
  • type PW 4156 A.
  • serial numbers

             position 1 (left): 724553

             position 2 (right): 724554

  • operation

             position 1: 6,800 hours, 1 898 cycles

             position 2: 4,538 hours, 1 326 cycles

    1.6.3 Weight and Center of Gravity

    When the incident occurred, the aircraft weighed 106 tons and with center of gravity of 25 MAC, these values being within the authorized limits.

    1.7 Meteorological Information

    The overall situation included no potentially dangerous phenomenon for the flight. The meteorological conditions on arrival at Orly were excellent when the incident occurred. "Juliet " information for 10.30 a.m. given by ATIS was as follows :

    1.8 Aids to Navigation

    The last inspection of the runway 26 localizer was performed on 9 June 1994. The inspection of the descent localizer was performed on 22 June 1994.

    The last weekly inspection of the ILS, performed on 19 September 1994, showed normal operation.

    On 24 September 1994, the ILS was working on number two group. No operating anomaly was mentioned in the notebook of the shift technical supervisor responsible for supervision of flight navigation equipment.

    Other aircraft which landed at Paris Orly mentioned no anomalies.

    1.9 Communication

    The transcript of communications between the flight crew and the ATC is provided in appendices 2 and 3. These exchanges can be summarized as follows:

  • 1.10 Airdrome Information

    Orly Airport is a civil airdrome open to public air traffic and is run by Aéroports de Paris. Its reference altitude is 292 feet.

    The Orly ILS 26 approach map is shown in appendix 1. Three standard approaches are defined, one on VOR EPR to the west of the airport and two to the east on VOR MEL and BSN. Tarom flights from Bucharest start their initial approach on VOR MEL. The standard approach provides for this beacon being flown over at FL 80 and for the descent to be continued towards FL 60 on a flight path oriented at 353°. Level 60 should be reached seven nautical miles later and the descent be continued towards 3,000 feet. The start of a turn to the left on passing radial 091° of VOR DME OL allows for alignment on the runway axis oriented at 258°. The ILS glide slope is intercepted at 3,000 feet QNH and at a distance of 8.7 NM from OL.

    In the event of a go around, the climb is made towards 2,000 feet on heading 243 after radial OL 206 then on OL radial 233 up to a distance of 12 NM from OL. At this point, the climb is continued towards 4,000 feet seeking to close on MEL radial 278 .

    1.11 Flight Recorders

    1.11.1 Flight Data Recorder Readout

    The references for the flight recorder (FDR) are as follows:

    In compliance with the protocol between the BEA and the Flight Test Center, the processing of data from this recorder was carried out by the latter body. The work was conducted in the presence of the BEA, police officers and a representative of Tarom.

    As a direct readout of the recorder gave no result, the tape was extracted and was read out. The observations were as follows:

    It emerges from these observations that the FDR had not been functioning for nearly six months. Since the pre-flight test performed by the flight crew only checks for the electrical presence of the recorder, they could not detect the fault found nor bring the airline's attention to the equipment failure.

    1.11.2 Direct Access Recorder Readout

    The cassette from the Direct Access recorder (DAR) was taken from the aircraft. It was read out and analyzed under the control of an investigator from BEA in Bucharest, in the premises of the Technical Division of Tarom, between 26 and 28 September 1994. Representatives from the airline, Airbus Industrie, Romanian Civil Aviation and Swissair were present at this reading.

    Tarom possesses the FLIDRAS acquisition and analysis bay, developed by SAS. It had been recently installed. First validation of the readout parameters was conducted using reference documents provided by Airbus Industrie and Tarom.

    The recorder was read out. Obtaining data and assigning physical values to it was performed without encountering any particular difficulties.

    The validation and correlation work on information from the recorder and the CVR showed the consistency of the two recordings, particularly temporal synchronization and consistency of audio warnings with the associated parameters. However, a desynchronization of eleven seconds interrupted restitution of data from 10 hours 42 m 41 s to 42 m 52 s. The reason for this desynchronization has not been elucidated.

    Analysis of the data shows that:

    See graphs in appendix 5 and reconstitution of aircraft's movements in appendix 6.

    1.11.3 Cockpit Voice Recorder Readout

    The references of the Cockpit Voice Recorder (CVR) are as follows:

    The CVR, placed under seal, was read out on Sunday 25 September 1994 in the BEA laboratories, in the presence of police officers from the Air Transport Gendarmerie. Also present when data was examined were the aircraft Captain and the Paris representative of Tarom. Two copies, intended for Romanian investigators, were made on the same day.

    Conversations in the cockpit were largely in Romanian. The transcript was made at the BEA, with help from representatives of Romanian Civil Aviation; similar work was conducted in parallel in Bucharest. The translation of the transcript is presented in appendix 4.

    Analysis of the noises and audio warnings was conducted with co-operation from the airline, the manufacturer and the French General Civil Aviation Directorate (DGAC.).

    Study of the CVR recording provides the following facts:

    a/ on the auto-throttle

    co-pilot: "It started to increase thrust, I don't know why, but it increased thrust for no reason ... just like in a Go-Around"

    Captain: "The engines increased power and it started to climb ... it started to climb, I couldn't control it!".

    b/ on the automatic pilot

    Captain: "Something's happened here!"

    co-pilot: "The automatic pilot has got something wrong ... We must avoid using the automatic pilot, bring it back to manual!"

    Captain: "Sure"

    3rd person: "But what's happening? You stayed on AP until flying down low, didn't you?"

    Captain: "No, no, I disconnected it, I disconnected the AP, sure I did "

    3rd person: "It didn't obey you"

    Captain: "It stayed practically..." (incomplete)

    3rd person: "On auto, and it started off..."

    Captain: "We won't  fly it until it is under control. We won't fly it".

    c) on the aircraft flight path

    Captain: "I don't know how far up we went"

    co-pilot: "We were close to sixty knots ! "

    3rd person: "Two thousand eight hundred, twenty-eight... it was... It was almost vertical! "

    d) on the maneuver to recover from stall

    Captain: "... from here, up here, I'm just afraid of going over on our back... from here, I've got to stop it from stalling, when it starts to go down, I have speed..." (Reference to the two rolls at seventy degrees left and right and comment on recovery from stall).

    1.12 Examination of the Aircraft after the Incident

    An inspection of the aircraft was made under the control of the Authoritatea Aeronautica Civila Romana, the Romanian civil aviation authority, by Tarom technicians assisted by Swissair (which ensures level C maintenance on behalf of Tarom), Airbus Industrie and Pratt and Whitney.

    During the aircraft stall, the compressors surged. The engines were therefore also checked.

    The BEA investigators were present at this work, which also contributed to the search for the technical causes of the incident. Subsequent to the inspection, the Romanian CAA delivered an authorization for return to service.

    In parallel with these inspections, tests of the flight control system in automatic and manual modes were performed in the presence of the BEA, according to the procedures for on-line verification. The individual test of the calculators and wiring and the test of the LAND mode revealed minor anomalies that are not likely to lead to operational defects.

    The FCU, FAC and trim .switch subassemblies making up the trimmable horizontal stabilizer control circuit were removed for the purposes of the investigation. Their inspection in a specialized workshop showed that the functional characteristics of these subassemblies were within the standards for acceptance on entry into service.

    1.13 Medical and Pathological Information

    No medical examination or analyses were made on crewmembers.

    1.14 Fire

    Not applicable.

    1.15 Survival Aspects

    Preparation of the cabin with a view to landing had been implemented before the event and the occupants of the aircraft were all seated, with seat belts fastened. No one was injured.

    1.16 Tests and Research

    1.16.1 Description of Systems

    The A310 is equipped with an Automatic Flight System (AFS) that controls the aircraft in the pitch, roll and yaw axes. The AFS also controls the aircraft speed and engine thrust.

    The AFS mainly comprises four independent subsystems:

  • Thrust Control Computer (TCC),
  • Automatic Pilot (AP) and Flight Director (FD),
  • Flight Advisory Computer (FAC),
  • Flight Information Display System (FIDS).

    1.16.1.1 Auto-throttle

    The role of the auto-throttle in the Automatic Flight Control assembly is to adjust the thrust of the engines so the aircraft attains the desired performance. Its logic aims at translating an AFS request for a given thrust into an engine instruction.

    1.16.1.1.1 Auto-throttle Architecture

    The auto-throttle includes:

  • a selector panel for maximum thrust mode and automatic or preset mode,
  • a Thrust Control Computer (TCC),

    -          a thrust control servomotor connected mechanically to the throttle levers.

    1.16.1.1.2 Operating Modes and Sub-modes

    Working with the automatic pilot and Flight Director modes, the auto-throttle in one of the TOGA/FLEX TO, CL, CR, MCT modes gives:

  • Switching modes and sub-modes in relation with the Flight Director and the Automatic Pilot modes is managed automatically by the FMC when the PROFILE mode is active. In all the other modes, switching is managed by the TCC: when the AP/FD is in flight path mode (VS, ALT, GS, etc.), the TCC controls speed and activates the SPD-Mach mode; when the AP/FD controls speed (LVL CHG, SRS or GO AROUND modes), the TCC controls thrust and activates the THRUST mode in climb or RETARD in descent.

    Auto-throttle operation automatically leads to arming of the Alpha-floor function. When this function is activated by the AFS, the thrust increases automatically up to the limit value for go around.

    The AFS LVL CHG mode can be used to attain the selected altitude, with the automatic pilot or the Flight Director maintaining speed. If the altitude selected is greater than the altitude of the aircraft, CLB mode is activated, the auto-throttle switches to THR mode and applies maximum thrust displayed on the TRP (Thrust Rating Panel). By design, when the slats are extended, thrust increases up to go around thrust. If the selected altitude is less than the altitude of the aircraft, DES mode is activated, the auto-throttle switches to RETARD mode and applies minimum thrust.

    1.16.1.1.3 Activation - Inhibition

    Arming the auto-throttle is obtained by maneuvering the ATS1 or ATS2 lever on the ATS panel. The auto-throttle function is activated by pressing the ATHR button of the FCU or, on take-off, by pressing the "GO LEVERS" buttons located on the throttle levers.

    Auto-throttle disconnection is obtained:

  • by acting on one of the instinctive disconnection buttons located on the throttle levers,
  • by a second action on the ATHR pushbutton,
  • by positioning the ATS arm levers on OFF,
  • automatically if one of the setting conditions is lost.

    1.16.1.1.4 Displays

    The activated modes are displayed on the FMA. In addition, the keys corresponding to the different maximum thrusts (TOGA, MCT, CL, CR, Auto and FLEX TO) are illuminated on the TRP.

    1.16.1.2 Automatic Pilots and Flight Directors

    1.16.1.2.1 Functions

    The AP's role is:

  • to stabilize the aircraft about its center of gravity while maintaining the vertical speed and set heading ,
  • to keep the aircraft on its acquired flight path (mode hold),
  • to acquire a new flight path (mode acquisition),
  • to perform an automatic landing,
  • to select automatically from among the command modes for thrust the appropriate mode according to the longitudinal mode chosen.

    The role of the FD in manual piloting is to provide flying indications using trend bars shown on the Primary Flight Display

  • in pitch if a longitudinal mode is active,
  • in roll if a lateral mode is active,
  • in yaw for certain automatic take-off and landing phases.

    1.16.1.2.2 Operating Modes

    The operating modes common to the Flight Directors and Automatic Pilots are:

  • in lateral modes : RWY, NAV, VOR, LOC, HDG and HDG SEL
  • in longitudinal modes : SRS, LVL CHG, ALT, VS, PROFILE
  • in combined modes: LAND and GO AROUND.

    Modes are selected on the FCU. The button moved sets the associated mode and lights up. Modes are activated by :

  • the GO LEVERS located on the throttle levers, to activate SRS modes on the ground or GO AROUND in flight,
  • on the FCU, by pulling the buttons assigned to control of vertical speed, heading and altitude,
  • or by pushing the ALT HLD, LVL CHG, PROFILE, HFG SEL, NAV, VOR/LOC or LAND buttons.

    Operation of longitudinal modes

    There are six longitudinal modes: Level Change (LVL CHG), Altitude Hold (ALT HLD), Profile and Vertical Speed (VS), SRS and ALT*.

     

    The Vertical Speed mode is the most basic longitudinal mode. As far as altitude is concerned, the Altitude Hold mode leads to holding altitude and the Level Change mode to acquisition of the altitude displayed in the ALT SEL window.

    LVL CHG controls combined Automatic Pilot and auto-throttle actions so as to perform an altitude change automatically, the AP/FD maintaining the selected speed while the auto-throttle maintains maximum thrust on climb or minimum thrust on descent.

    The angular velocity for movement of the engine power levers controlled by the auto-throttle is constant, one degree per second.

    In automatic pilot and with the auto-throttle active, execution of the LVL CHG CLB is in three stages: climb to Vsel, altitude capture then hold. Computers manage thrust and determine the aircraft's attitude. If no AP is active but if the auto-throttle is active, thrust is displayed by the auto-throttle and the attitude to follow is indicated to the flight crew by the Flight Director. When neither the AP's nor the auto-throttle are active, LVL CHG cannot be executed, except by following the FD bars manually and positioning the throttle levers manually.

    To inhibit or cancel LVL CHG, the flight crew can either cancel the mode by pressing the LVL CHG pushbutton on the FCU, or inhibit it by disconnecting the ATHR, thus making the LVL CHG virtual, or by choosing another vertical mode.

    Note: ALT HLD and Profile modes together with LAND, SRS, RWY, GO AROUND modes, not used during the incident, will not be described.

    1.16.1.2.3 Subassemblies

    The AP-FD assembly includes two common FCC computers and an FCU controller. In addition, the following items form part of the system:

  • Flight Mode Annunciators and FD trend bars,
  • The control actuators for control surfaces and dynamic sensors integrated in the control surface control mechanisms,
  • The control buttons:

             GO LEVERS, integrated in the throttle levers,

             AP instinctive disconnect, situated on the inside of the outer control column horn

    1.16.1.2.4 Operation

    The Automatic Pilots and Flight Directors can be operated separately or jointly.

    If no AP is active on command (CMD), the indications of the FMA and the FD on PFD1 will be associated with FD1, and reciprocally for PFD2 and FD2.

    If an AP is on CMD, the two FMA's will be associated with it but the FD bars on PFD1 and 2 will remain associated with the corresponding FD 1 and 2.

    Combined operation of FD and AP:

  • when the AP is on CMD it keeps the aircraft on the path by executing maneuver orders given by the computers. The trend indications from the FD(s) continue to be represented by the bars on the PFD's.
  • When the AP is on CWS (control wheel steering) it keeps pitch attitude and bank attitude to their values, such that the flight crew can then change them. The FD then works independently of the AP.

    1.16.1.2.5 Display

    a) For an active FD

    There is no FD activation or disconnection button. As soon as the computers are powered up, and on condition that the conditions for activation are fulfilled (availability of FCC, FAC, IRS, ADC and FCU), both FD's are automatically activated in the basic VS and HDG modes. Signaling will then be as follows:

  • FD1 and FD2 light up respectively on FMA1 and FMA2.
  • VS and HDG light up green on both FMA's,
  • The trend bars appear on both PFD's.

    b) For disconnection of an FD

    On disconnection the above display disappears and “FD” appears in red letters on the PFD corresponding to the unavailable FD.

    c) For an active AP

    An AP is activated by moving the corresponding lever on the FCU. It will be in CMD mode. Display will then be as follows:

  • lever in high position,
  • CMD lit up in window under levers,
  • CMD1 (or 2), or DUAL indicator if both AP's are active on FMA.

    The aircraft can then be flown according to the crew's requests, in CWS mode.

    d) For disconnection of an AP

  • manual disconnection: flight crew can disconnect the AP

             either by pressing the instinctive disconnection button,

             or by setting the lever to OFF on the FCU.

    The distinctive "cavalry charge" audio warning is sounded. Disconnection is indicated on the FMA and

    -        the lever is in low position (OFF),

    -        the CMD or CWS flag alarm switches off in the FCU window.

  • disconnection in the event of excess force applied to the control : display will be identical to that in the previous case.

    1.16.1.3 Controlling the Longitudinal Axis

    1.16.1.3.1 Controls

    Pitch attitude controls include, in addition to elevator controls :

  • a PTS panel,
  • two electrical trim control switches located on the control column outer horn,
  • a manual trim control wheel.

    1.16.1.3.2 Checks

    Pitch attitude is controlled by elevators using the control column.

    Setting the position of the THS in the range +3° nose down (ND) to -14° nose-up (NU) cancels control column effort.

    THS setting electrical control orders may come either from the flight crew if the AP is disconnected, or from the automatic pilot. The speed of the adjustment depends on the configuration and speed range of the aircraft. Trim with electrical control has a deflection range of 2.5° (ND) to 13.5° (NU). When commanded by the flight crew, its speed, which depends on the aircraft speed, will at most be equal to 0.9° per second; when commanded by the AP, its speed, which depends on the slats/flaps configuration, is at least equal to 0.5° per second.

    1.16.1.3.3 Display

    A special audio signal called a "whooler" is associated with the THS being moved when commanded electrically by the pilot. This signal is emitted as soon as the duration of the THS movement exceeds one second. The "whooler" will not sound when the THS is commanded by the AP.

    The position of the THS is identified on the graduated wheel adjacent to the manual control wheel.

    On the ECAM, the "Flight controls" page indicates the position of the control surfaces and, in particular, those for the THS and the elevators.

    Disconnection of the pitch trims, effected by the return to low position of the two levers, is indicated by a special message in red letters on the ECAM backed up by an audio warning.

    1.16.1.3.4 THS Trim System Safety

    The lever of one of the two THS trim system control circuits can only be activated or held in position if the conditions for activation are all fulfilled. In the event of damage to one circuit, the second will automatically take over and the ECAM will indicate the failure. In the event of failure of both circuits, the ECAM will indicate this and a "single chime" warning is sounded.

    The trim manual control wheel can override all the other THS setting modes. Moving it leads to the two adjustment circuits being disconnected by electrical control.

    1.16.1.4 Protection of Flight Envelope

    Each of the two Flight Advisory Computers (FAC) provides calculations for the following functions as displayed on the PFD:

  • speed trend,
  • limit speeds,
  • minimum speed for retraction of flaps and slats,
  • maneuver speed single engine conditions in clean configuration,
  • protection with respect to maximum angle of attack and wind shear.
  • The following symbols and functions are used in this report: