320系列机组课程自动飞行保护

航空

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航空

AUTOFLIGHT MENU Protections 1/33
AUTOFLIGHT MENU
Protections 2/33
An other aspect of the FMGS is the assistance provided to
the pilot to keep the flight safe and within the flight envelope.
This assistance covers:
- The engine failure compensation,
- The low speed protections, and,
- The AP/FD mode reversions.
Let’s look at some of these “protections” in detail.
AUTOFLIGHT MENU
Protections 3/33
In case of an engine failure with AP ON, the FMGS ensures an automatic yaw
compensation in all modes.
This is achieved by the FAC, using the yaw damper at take off and go-around and
the automatic rudder trim in all modes.
Furthermore, the AP/FD SRS pitch mode adjusts automatically the reference
target guidance speed in case of an engine failure at take off or go-around.
NAV
ENGINE FAILURE
COMPENSATION
AUTOFLIGHT MENU
Protections 4/33
Low speed protection is achieved by the following features:
- The A/THR SPEED mode,
- The LOW ENERGY warning,
- The ALPHA FLOOR protection, and,
- The WINDSHEAR protection
LOW SPEED
PROTECTIONS
AUTOFLIGHT MENU
Protections 5/33
When the A/THR is ON and in SPEED mode:
- If the speed target is MANAGED (driven by the FMS) and the speed target
is below the actual maneuvering speed, here F, the A/THR will not allow the
speed to decrease below this maneuvering speed.
- If the speed target is SELECTED (by the pilot on the FCU) and the speed
target is below VLS, the A/THR will not allow the speed to decrease below VLS.
MANAGED
SPEED
SELECTED
SPEED
A/THR
SPEED MODE
AUTOFLIGHT MENU
Protections 6/33
LOW ENERGY
WARNING
If, for any reason such as turbulence, shear, A/THR OFF… the A/C speed drops
significantly below VLS, a repetitive “SPEED SPEED SPEED” aural warning is
automatically triggered by the FAC.
It drives pilot’s eyes to the speed scale, so as to readjust thrust, for example. This
warning takes into account the A/C deceleration rate and current flight path angle which
explains the “LOW ENERGY” wording.
It is available when the A/C is on departure and arrival: between 100 ft and 2000ft RA and
in configuration 2, 3 or FULL (with Flaps extended).
AUTOFLIGHT MENU
Protections 7/33
ALPHA FLOOR
PROTECTION
If the A/C speed still drops more (below the low energy warning) and the angle of attack
increases above a given threshold, the “ALPHA FLOOR” function of the A/THR is
triggered. The A/THR commands full thrust, I.e. TOGA thrust.
AUTOFLIGHT MENU
Protections 8/33
ALPHA FLOOR
PROTECTION
The angle of attack threshold which triggers the “ALPHA FLOOR” is processed by the
FAC as a function of A/C parameters such as configuration, deceleration rate …
When ALPHA FLOOR is triggered:
- A/THR is turned ON (if it was previously OFF), indicated by a white A/THR on the FMA,
- A. FLOOR in green is displayed as the A/THR mode.
The ALPHA FLOOR function is available from lift off down to 100ft AGL.
AUTOFLIGHT MENU
Protections 9/33
WINDSHEAR
DETECTION
If the A/C encounters windshear conditions, detected by the FAC, a red
WINDSHEAR message is triggered on both PFD, associated with an aural
“WINDSHEAR WINDSHEAR WINDSHEAR” warning.
This windshear detection function is available from lift off to 1000ft at
take off and from 1000ft down to 50ft during landing.
AUTOFLIGHT MENU
Protections 10/33
The windshear protection is provided by the FMGC:
- At takeoff and go around, with the AP/FD SRS vertical mode, which commands a pitch ensuring a
minimum positive rate of climb, despite a potential speed drop.
- In approach, with managed speed target: the speed target is automatically adjusted with wind
variations, so as to ensure that the A/C ground speed does not drop below a minimum value (GS MINI).
NOTE: If the angle of attack gets too high and reaches the fly by wire angle of attack protection, the AP
disengages. The fly by wire maximum angle of attack protection assists the pilot to best react.
AT TAKEOFF
AND GO AROUND
IN
APPROACH
WINDSHEAR
PROTECTION
AUTOFLIGHT MENU
Protections 11/33
Let’s now review the mode reversions of AP/FD and A/THR.
The mode reversions are automatic mode changes:
- Which ensure a flight envelope limit speed protection, or,
- Which allow a comprehensive autoflight system behavior
when the pilot modifies a target on the FCU.
AUTOFLIGHT MENU
Protections 12/33
Let’s review the flight envelope limit speed protection with AP ON.
Suppose you are in climb, and you select V/S +3000ft/mn while your target speed
is 315kt. The target altitude is above A/C altitude. The performance capability of the
aircraft does not allow such a high rate of climb.
The AP pitches the A/C up to track +3000ft/mn. The A/THR, in SPEED mode, will
command MAX CLB thrust since the A/C speed is decreasing.
AP/FD REVERSION:
V/SOPEN
AUTOFLIGHT MENU
Protections 13/33
When the A/C speed reaches VLS+5kt, the AP vertical mode reverts to OP CLB
and A/THR mode to THR CLB.
The AP will pitch the A/C down to reaccelerate towards the 315kt target speed.
This reversion ensures the flight envelope low limit speed protection.
AP/FD REVERSION:
V/SOPEN
AUTOFLIGHT MENU
Protections 14/33
Suppose now that we have selected V/S +3000ft/mn, but with an altitude target
below the A/C altitude.
The AP pitches the A/C up to +3000ft/mn and speed decreases similarly.
NOTE: On the FMA you can see that no ALT in blue is shown due to the target altitude
being below the present A/C altitude with the A/C climbing.
AP/FD REVERSION:
V/SOPEN
AUTOFLIGHT MENU
Protections 15/33
AP/FD REVERSION:
V/SOPEN
When the A/C speed reaches VLS + 5kt, the AP vertical mode reverts to OPEN
DESCENT (OP DES) and the A/THR mode to THR IDLE.
Remember:
- With a target altitude above A/C altitude, the reversion is to OP CLB/THR CLB,
- With a target altitude below A/C altitude, the reversion is to OP DES/THR IDLE.
AUTOFLIGHT MENU
Protections 16/33
Let’s see an other case: we are in descent at 3000ft/mn, the target speed is 250kt
and the target altitude is below the A/C altitude.
The performance of the A/C is such that such a high rate of descent leads the
A/C to accelerate...
AP/FD REVERSION:
V/SOPEN
AUTOFLIGHT MENU
Protections 17/33
AP/FD REVERSION:
V/SOPEN
When the A/C speed reaches VMO/MMO - 5kt, the AP vertical mode reverts to OP
DES and the A/THR mode to THR IDLE.
The AP pitches the A/C up to recapture the 250kt target speed. This reversion
ensures the flight envelope high limit speed protection.
NOTE: Depending on A/C configuration, this reversion can occur at VLE + 4kt or VFE +
4kt.
AUTOFLIGHT MENU
Protections 18/33
Here is an other case: we are on approach, high above G/S, in landing
configuration. V/S -2500ft/mn is selected to recover G\S from above, with a target
altitude above the A/C current altitude. Notice that this V/S is actually quite high.
The performance of the A/C is such that this high rate of decent leads the A/C to
accelerate...
AP/FD REVERSION:
V/SOPEN
AUTOFLIGHT MENU
Protections 19/33
AP/FD REVERSION:
V/SOPEN
When the A/C speed reaches VFE + 4kt, the AP vertical mode reverts to OP CLB and
the A/THR mode to THR CLB (this is because target ALT is above A/C altitude).
Hence, the A/C starts to climb with CLB thrust to recapture VAPP, which ruins your
effort to fly back to the G/S.
So, remember, if you are high above G/S, do not use an excessive down V/S...
AUTOFLIGHT MENU
Protections 20/33
We have studied the flight envelope limit
speed protections with AP ON. Let us now
review other limit speed protections with FD
ON and AP OFF (manual flight).
AUTOFLIGHT MENU
Protections 21/33
FD REVERSION:
OP DESV/S
THR IDLE SPEED
Suppose the A/C is manually flown with FD ON (AP OFF). The current vertical
mode is OP DES, the A/THR one THR IDLE.
In order to demonstrate the next reversion, the A/C is pitched up, disregarding
the FD orders given by the FD bars.
The speed decreases...
NAV
AUTOFLIGHT MENU
Protections 22/33
FD REVERSION:
OP DESV/S
THR IDLE SPEED
When the A/C reaches VLS-2kt (or VLS-17kt with speed brakes extended), the
A/THR reverts from THR IDLE to SPEED and thrust is readjusted to recapture the
target speed.
Simultaneously, OP DES reverts to V/S using the actual V/S value at the time of
reversion.
NAV
AUTOFLIGHT MENU
Protections 23/33
Let us see an other case. This time we are in climb, using OP CLB,
which lead to the engagement of THR CLB as A/THR mode. Once again,
we will not follow the bars, pitching the A/C down a little more than
needed.
The speed increases...
FD REVERSION:
OP CLBV/S
THR CLB SPEED
NAV
AUTOFLIGHT MENU
Protections 24/33
NAV
When the aircraft reaches VMO/MMO, the A/THR mode reverts from
THR CLB to SPEED and thrust decreases to recapture the target speed.
Simultaneously, OP CLB mode reverts to V/S on current V/S value.
NOTE: Depending on the A/C configuration, this reversion can occur at
VLE or VFE.
FD REVERSION:
OP CLBV/S
THR CLB SPEED
AUTOFLIGHT MENU
Protections 25/33
As a summary, the flight envelope limit speed protection is
ensured by AP or A/THR (with FD ON, AP OFF) mode reversion
so that:
- At minimum speed, the A/C pitches down or thrust is
added automatically to regain target speed,
- At maximum speed, the A/C pitches up or thrust is
reduced automatically to regain target speed.
AUTOFLIGHT MENU
Protections 26/33
Let’s review some essential mode reversions when you modify
the FCU target altitude during climb or descent.
These mode reversions are designed so as not to modify the
A/C pitch behavior due to the new altitude selection. It leaves it up
to you to decide the further orders you wish to give the FG.
AUTOFLIGHT MENU
Protections 27/33
NAV
Suppose we are in climb (using either OP CLB or CLB) to FL250 as
cleared by ATC. While crossing FL225, ATC requires us to level off at
FL220...
REVERSION TO V/S
ON FCU ALT CHANGE
AUTOFLIGHT MENU
Protections 28/33
NAV
We therefore select the FCU target altitude to FL220. The AP/FD
vertical mode reverts to V/S on the current V/S value.
Notice also that ALT (blue) is not armed.
REVERSION TO V/S
ON FCU ALT CHANGE
AUTOFLIGHT MENU
Protections 29/33
It is then up to the pilot to decide how to regain FL220:
- By dialing the desired V/S target (I.e. down to -1000ft), or,
- By pulling the ALT selector to engage OP DES…
NOTE: You can imagine the same scenario in descent.
NAV
REVERSION TO V/S
ON FCU ALT CHANGE
AUTOFLIGHT MENU
Protections 30/33
We are now capturing the target altitude (ALT* green). The ATC
clears us back up to FL250...
NAV
REVERSION TO V/S
ON FCU ALT CHANGE
AUTOFLIGHT MENU
Protections 31/33
We therefore select the FCU ALT target to FL250.
The AP/FD vertical mode reverts, once again, to V/S, with the current
V/S value.
NAV
REVERSION TO V/S
ON FCU ALT CHANGE
AUTOFLIGHT MENU
Protections 32/33
REVERSION TO V/S
ON FCU ALT CHANGE
It is now up to the pilot to decide how to regain ALT target:
- By pulling the ALT selector to engage OP CLB, or,
- By dialing the desired V/S target (I.e. up to +1500ft)…
NAV
AUTOFLIGHT MENU
Protections 33/33
These are the essential mode reversions linked to FCU
target changes which you may have to do in case of ATC
late clearances.
They ensure no discontinuity in A/C behavior, and
leave you full authority to satisfy these clearances.
NOTE: There are other mode reversions, such as CLB to
OP CLB, or DES to V/S when you select HDG out of NAV,
which follow the same principle.
NEXT
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AUTOFLIGHT MENU Protections 34/33
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EXIT
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飞去无痕

辛苦了，谢谢

airportcn

good................

bocome

空客飞行员指南

tissle

好资料，学习中。。。

diguo

好东西。好好学习一下