REVERSION WHEN FD ORDERS ARE NOT FOLLOWED
These reversions occur when the aircraft is in manual flight and the pilot fails to follow the FD bars.
CONDITIONS  EVENT  CONSEQUENCE 
FD engaged AP Off A/THR active (IDLE thrust) DES, OP DES or EXP DES engaged  IAS = VLS - 2 kts IAS = VLS - 17 kts (if speedbrakes extended)  Automatic engagement of SPD mode on A/THR, and consequently of V/S (FPA) mode on FD to regain the target speed, or VLS, whichever is the greater. 
FD engaged AP Off A/THR active (CL thrust) CLB, OP CLB or EXP CLB engaged  IAS = VMAX + 4 kts where VMAX = VFE or VLE or VMO/MMO  Automatic engagement of SPD mode on A/THR, and consequently of V/S (FPA) mode on FD to regain the target speed, or VMAX, whichever is lower. 

A319/A320/A321 FLIGHT CREW TRAINING MANUAL  NORMAL OPERATION BRIEFINGS FLIGHT DIRECTOR MODE REVERSIONS  1.02.35  Page 3 
REV 21  MAY 98 

REVERSION DUE TO EXCESSIVE V/S
When an excessive V/S has been selected, the aircraft cannot achieve the V/S demanded. The airplane is trying to maintain a V/S and a speed, but the priority is to maintain the V/S. When this is not possible, speed will decrease (climbing) or increase (descending) up to a maximum. After this point, a mode reversion will occur to protect the airplane from entering a potentially hazardous situation. The table below explains the consequences of selecting excessive V/S and the reversions. They apply equally with autopilot engaged or not.
CONDITIONS  REVERSION OCCURS WHEN  CONSEQUENCE 
Excessive V/S -FPA > 0 selected  IAS = VLS + 5 kt  Open mode engages in order to regain the target speed. 
Excessive V/S -FPA < 0 selected and clean configuration  IAS = VMAX - 5 kt where Vmax = VMO/MMO  OP CLB engages when the FCU selected altitude is higher than the current airplane altitude. 
Excessive V/S -FPA < 0 selected and configuration other than clean  IAS = Vmax + 4 kt where Vmax = VFE or VLE  OP DES engages when the FCU selected altitude is lower than the current airplane altitude. 

The reversions with autopilot engaged can be demonstrated using the FMGS Freeplay Trainer.
Reversions are recognised by monitoring the FMA.

06 - COMPLETION STANDARDS
.  Demonstrates a thorough knowledge and understanding of flight guidance and the various reversion modes
07 - COMMON ERRORS
.  
Lack of appreciation of flight guidance reversions

.  
Incorrect procedure following reversions

.  
To understand the philosophy of the FPV and FPD.

.  
To correctly interpret the information given by the FPV.

.  
Uses FPV to achieve desired flight path.

A319/A320/A321 FLIGHT CREW TRAINING MANUAL  NORMAL OPERATION BRIEFINGS FLIGHT DIRECTOR MODE REVERSIONS  1.02.35  Page 4 
REV 21  MAY 98 

A319/A320/A321 FLIGHT CREW TRAINING MANUAL  NORMAL OPERATION BRIEFINGS USE OF TRACK / FPA / FPV / FPD  1.02.36  Page 1 
REV 21  MAY 98 

02 - SCHEDULE
Briefing duration : 20 minutes
03 - EQUIPMENT
.  
FMGS Freeplay Trainer

DOC references :

.  
FCOM 1.22.10 (FCU)

.  
FCOM 1.22.30 (FPD)

.  
FCOM 1.31.40 (PFD)

.  
FCOM 3.04.31 (Use of FPV)

04 - INSTRUCTOR’S ACTIONS
Briefing of the following key points.
MAIN
.  
Use of HDG/VS - TRK-FPA pushbutton and associated FCU indications, FMA modes and PFD/ND changes.

.  
Differences in trajectory between HDG and TRK, VS and FPA.
　
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