Random Good to Know Information Flashcards
What is Ground Speed Mini?
GS Mini Explained! A320 (CEO and NEO)
Adam6 months agoAirbus A320
When aircraft flies approach with approach phase activated and speed managed, the managed speed target displayed on PFD is variable. This managed speed target is Vapp displayed on PERF page corrected by GS mini function.
The Ground Speed Mini (GS Mini) function is designed to maintain the aircraft’s energy above a minimum level by accounting for gusts and wind changes, ensuring a stable and safe approach speed. By dynamically adjusting the managed speed target to account for wind changes, it helps maintain the necessary energy levels for a safe landing.
Managed speed target provided by GS Mini is generally higher than Vapp to maintain energy of aircraft above calculated minimum level. (This means aircraft actual approach speed is higher than calculated one!)
FMS computes the Vapp and Flight Guidance continuously computes the manage speed target as per wind changes
GS Mini Calculations
Managed Speed Target = Vapp + K (current head wind – tower reported head wind)
K factor for target managed speed computation depends on CEO or NEO type
Vapp = Vls + 1/3 tower reported head wind
GS Mini = Vapp – tower reported head wind
GS Mini Managed Speed Target Example:
Conditions: Landing Runway 27, Winds 270/15, Vls 125, A320 CEO, Spot Head Winds 25kts
Vapp: 125+5 = 130
GS Mini: 130 – 15 = 115 (minimum ground speed that aircraft will maintain)
Managed Speed Target: 130+1(25-15) = 140
GS Mini computed managed speed target has 2 limits:
Minimum Correction Value: 0 knots (no wind or tailwind conditions)
Maximum Correction Value: +15 knots (maximum increase allowed due to headwind component adjustments)
GS Mini activation conditions:
Approach Phase is active
Managed Speed
GS MINI NEO vs. CEO
The A320 NEO has different speed management characteristics compared to the CEO due to the presence of the Lift Improvement Package (LIP) in the NEO, which is particularly beneficial at higher landing flap angles (40 degrees for the NEO). Due to higher degree of flaps and overall augmented lift, lower approach speed is possible in Airbus A320 NEOs. As a result, the K factor for the managed speed computation is different:
NEO: K factor of 1/3, allowing for more thrust variation.
CEO: K factor of 1.
Below is taken from Airbus Safety:
WHAT IS THE GROUND SPEED MINI FUNCTION?
Significant headwind changes can be caused by the boundary layer effect when the aircraft is getting closer to the ground. Ground speed mini function (fig.21) ensures that the aircraft speed remains at least at VAPP if a stronger than expected headwind were to suddenly drop to the tower wind value or below. The GS mini function is only available when the flight crew uses the managed SPEED mode.
The AFS constantly computes and displays a target Indicated Airspeed (IAS) using:
The approach speed (VAPP computed by the AFS or manually entered in the FMS),
The tower headwind component from the tower wind value entered by the flight crew in the PERF APPR page of the FMS, and
The current wind measured by the ADIRS.
As a consequence, the flight crew must ensure that the tower headwind value has been correctly entered in the FMS, even if it does not increase the VAPP (i.e. headwind < 15kts).
(fig.21)
Ground speed mini function
Why is there a different ‘k’ factor for ground speed mini depending on the aircraft model?
The factor of 1 used on A320ceo aircraft could not be used for the other aircraft models due to differences of their deceleration capability. The A320ceo has a stronger deceleration capability when compared to A320neo, A330/A340 family aircraft, A350 and A380 aircraft.
In the case of a strong ground effect, a lower deceleration capability may lead to an excessive speed at flare. For example, a 20kt headwind at 200ft that reduces to 5kt on ground (corresponding to the 5kt tower headwind inserted in FMS PERF APPR page), a factor of 1 requires a deceleration of 15kt to reach VAPP. With a k value of 0.33, the aircraft only needs to decelerate by 5kt to compensate its lower deceleration capability. It reduces the risk of excessive speed at flare. The drawback is that there is a slight increase in thrust variations in gusty conditions, since the speed increment will not be sufficient to counteract the IAS increase due to a gust. The best overall compromise was demonstrated to be a 0.33 factor.
What is Quick Reference Landing Length?
FCTM
Quick Reference Landing Length
Quick Reference Minimum Runway Length 8000 ft
Flaps full approaches and landings may be conducted normally without reference to the ODM Operational landing distance tables or ACARS Landing Performance Request according to the following guidance.
Quick Reference Landing Length
Includes a 15 % Safety Margin.
Refer to the Landing Performance Application as the primary method for landings with abnormal configurations,MCO’s affecting landing distance, or if above the maximum landing weight (MLW). The ODM may be used as a backup to the Landing Performance Application.
Assumptions:
Airport elevation 2000 ft or lower (including KSLC and KDEN FAOR),
Touchdown no later than 1800 ft from threshold,
Up to Max Landing Weight,
Autobrakes MED,
Wet or Dry runway,
Zero wind and runway slope, and
No reverse thrust.
WARNING
Regardless of runway length or conditions, it is prohibited to initiate an approach on a runway where a ROW alert is expected, unless the appropriate authority provides specific authorization”. In this case, the flight crew must deactivate the ROW/ROP via the TERR SYS button on the MFD SURV page when the aircraft position is less than 15 NM from the airfield”.
Additional stopping performance is available by:
Increased manual braking. Max manual braking provides a shorter stopping distance than max autobrakes.
Landing at a lower altitude, and
Landing at a lower weight.
General Approach Preparation
Atis, Status (ECAM), Landing Performance, 2, 1, Brake, Book
Overview
The normal workflow begins with General Approach Preparation, a review of the approach plate, and if desired, a review of the appropriate approach guide
General Approach Preparation content is used for every type of approach
Individual Approach Guides only contain pertinent information required to execute that specific approach
The technique, “ATIS, STATUS, LND PERF, 2, 1, BRAKE”, will develop good flight crew habit patterns, and prevent errors from being introduced during approach preparation
ATIS
Obtain weather and landing information
Review as required:
Approach RVR/VIS Charts
Airport status
ECAM STATUS
Review aircraft technical status:
DEFERRED PROCs
LIMITATIONS
APP & LDG capability degradations
ALERTS IMPACTING LDG PERF
Landing Performance
Determine landing distance requirements:
FCTM Quick Reference Landing Length (FCTM)
ACARS Landing Performance Request (LPR)
EFB LND PERF application (LPA)
Required with the following limitations:
LDG DIST AFFECTED
LDG PERF AFFECTED
ODM Operational Landing Distance Chart
Flight Plan [F-PLN]
Insert
[F-PLN/ARRIVAL] page
Insert RUNWAY, APPR, VIA, STAR, TRANS, if applicable
Sequence
[F-PLN] page
Sequence flight plan to a logical point
This allows for accurate calculation of TIME, DIST, and FUEL to destination
Verify
Verify CSTR PB [EFIS CP] is selected
Verify F-PLN agrees with the planned approach and missed approach
Verify altitude and speed constraints
Performance [PERF]
Insert
[PERF/APP] page
WIND
Wind entry should not include gust values
TEMP
If -10°C or lower, or as specified in Company Pages, refer to AM 5.3 CTAC
QNH
During QFE operations, flight crew must convert QFE into QNH
Minimums
Enter RADIO / BARO value based on published minimums and according to Delta Ops Specs
Verify
Check or modify the landing configuration when:
an in-flight failure requires a computed VAPP speed or landing flap setting, or
pilot elects to enter a VPILOT speed additive to VAPP, as per FCTM
Check or modify transition flight level
Secondary Index [SEC 2]
SEC F-PLN may be prepared for:
Alternative runways,
Circling approach,
Routing to alternate airport, or
Critical terrain boxes
Brake
Set BTV, or
EFIS CP, PLAN Mode, ZOOM
Selected exit beyond ROW line on landing runway
Select appropriate runway condition
Press the A/BRK PB
Set Brakes MED
Green Dot (GD) speed
Green Dot (GD) speed
Definition
GD speed (fig.1) is the engine-out operating speed in clean configuration.
It provides an estimate of the speed for best lift-to-drag ratio.
GD speed is the managed speed target in CONF CLEAN when the FMS approach phase is activated. It is also the recommended speed to extend flaps to CONF 1 and for a holding in clean configuration.
How is GD speed determined?
How is GD speed determined?
The Auto Flight System (AFS) computes GD speed using the aircraft weight, based on the Zero Fuel Weight (ZFW) entered in the FMS during flight preparation, and the pressure altitude. The GD formula has been set up so that the resulting airspeed provides the best lift-to-drag ratio for a given altitude and aircraft weight, in clean configuration with one engine out.
In some phases of flight, GD is computed to minimize drag
S and F speeds
S and F speeds
Definition
S speed:
In approach phase, S speed is the managed speed target, when in CONF 1 or 1+F. It is the recommended speed to select CONF 2.
It is displayed as a green ‘‘S’’ on the PFD airspeed scale (fig. 2) and shown only when the Slats/Flaps control lever is on position 1 (CONF 1 or 1+F).
F speed:
In approach phase, F speed is the managed speed target, when in CONF 2 or 3. It is the recommended speed to select CONF 3 when in CONF 2, and to select CONF FULL when in CONF 3.
It is displayed as a green ‘‘F’’ on the PFD airspeed scale (fig. 3) and shown only when the Slats/Flaps control lever is in CONF 2 or 3 during the approach phase and go-around.
How are S and F speeds determined?
How are S and F speeds determined?
S and F speeds are obtained using the Stall speed of the corresponding configuration (Vs1g) demonstrated during flight tests multiplied by a specific factor depending on the aircraft type. Margins are kept with the Minimum Control speed at Landing (VMCL) determined during flight tests, and with the maximum speed with Flaps Extended of the next configuration (VFE NEXT):
S or F = VS1G x factor
S = k x VS1G CLEAN with 1.21 ≤ k ≤ 1.23
FCONF2 = k x VS1G CONF 2 with 1.38 ≤ k ≤ 1.47
FCONF3 = k x VS1G CONF 3 with 1.32 ≤ k ≤ 1.36
Define VMO/MMO
VMO/MMO: Maximum Operating speed/Mach number
Definition
In CONF CLEAN, VMO/MMO is the higher limit of the aircraft speed envelope.
How is VMO /MMO determined?
VMO/MMO is derived from the design limit Mach/speed VD/MD by applying a margin related to aircraft dive characteristics. For more details on VMO /MMO determination, refer to the Safety first issue 21 dated January 2016.
Define Limit Speeds
Limit Speeds
During descent, approach and landing, the operation of the aircraft is also framed within limit speeds. Their indication on the PFD or on a placard enables the flight crew to easily identify the aircraft speed envelope.
VMAX: Maximum speed
Definition
VMAX is the maximum speed defining the aircraft’s flight envelope. VMAX is equal to:
- VMO/MMO in clean configuration with landing gears up.
- VFE in high lift configurations with landing gears up.
- VLE/MLE in clean configuration with landing gears down.
- The minimum of VFE and VLE/MLE in high lift configurations with landing gears down.
On the PFD airspeed scale, it corresponds to the lower end of the red and black strip
Define VFE NEXT
VFE NEXT
Definition
The aim of the VFE NEXT is to remind the flight crew the maximum speed at which they can extend the next Slats/Flaps configuration during approach.
VFE NEXT is displayed on the airspeed scale of the PFD (fig. 7).
VFE NEXT is displayed in flight, below FL200 (FL220 on A350).
How is VFE determined?
VFE NEXT is the VFE of the next Slats/Flaps configuration.
Define VLS: Lowest Selectable Speed
VLS: Lowest Selectable Speed
Definition
VLS is the lowest selectable speed for the autopilot and the autothrust. Even if the selected target speed is below VLS, the A/THR will maintain VLS as a minimum. VLS is indicated by the top of the amber strip on the PFD airspeed scale (fig. 9).
VLS (of selected landing configuration: CONF 3 or FULL), is also displayed on the FMS APPR page.
Define ECON DES speed/Mach
ECON DES speed/Mach
Definition
ECON DES speed/Mach is the optimum descent speed/Mach to lower the direct operating costs of the descent.
How is ECON DES speed/Mach determined?
ECON DES speed/Mach is computed by the FMS based on the Cost Index (CI), cruise FL and on the aircraft weight.
Define VAPP: Approach speed
VAPP: Approach speed
Definition
VAPP is the final approach speed when the Slats/Flaps are in landing configuration and the landing gears are extended.
VAPP is displayed in the FMS PERF APPROACH page.
How is VAPP determined?
The VAPP can be computed by the AFS or inserted manually by the pilot through the FMS PERF Page.
VAPP is based on the VLS of the landing configuration. For Airbus aircraft, in normal operations, the VAPP is defined by:
VAPP = VLS Landing CONF + APPR COR
AFS Computation of VAPP
When computed by the AFS, the APPRoach CORrection (APPR COR) used by the AFS is:
APPR COR = 1/3 Headwind with 5kt ≤ APPR COR ≤15 kt
Excepted on some older A320 aircraft where the APPR COR used by the AFS is 1/3 Headwind + 5kt, limited at 15kt.
VAPP Computation by the Flight Crew
The flight crew can chose to insert any VAPP by computing its own APPR CORR as follows:
APPR COR = highest of:
5kt if A/THR is ON
5kt if ice accretion (10kt instead of 5kt on A320 family when in CONF 3)
1/3 Headwind excluding gust
Flight crew speed increment ()
with APPR COR ≤15 kt
() In some situations (e.g. gusty conditions or strong crosswind), the flight crew may choose a higher VAPP than the AFS computation as good airmanship.
During autoland or when A/THR is ON or in case of ice accretion or gusty crosswind greater than 20kt, VAPP must not be lower than VLS + 5kt.
VAPP in the case of a system failure
In the case of a system failure during flight, the flight crew computes a new VAPP value:
VAPP System Failure = VREF + ∆VREF + APPR COR
With VREF = VLS CONF FULL
∆VREF is the speed increment related to the failure to counter associated handling qualities issues and/or increased stall speed.
APPR COR depends on the ∆VREF, the ice accretion, the headwind value and the use of autothrust.
For more information on the determination of VAPP with failure by the flight crew, refer to the Flight Crew Techniques Manual (FCTM).
What is the Energy Circle
Energy Circle
When in HDG or TRK lateral mode, the ND displays the energy circle, and when the aircraft is within 180 NM of its destination. It provides a visual cue of the minimum required distance to land, i.e. the distance required to descend in a straight line from the current aircraft position at its current speed down to the altitude of the destination airport at approach speed. The descent profile used to compute the distance takes into account speed limits, the wind, a deceleration level off segment and a 3° final approach segment (fig.15). In other words, if the destination airport is inside the energy circle, the flight crew needs to lose some energy by extending the speed brakes and/or modifying the aircraft’s trajectory, and/or increasing speed during descent.
What is the Level-off Arrow
Level-off Arrow
Another useful tool to use during descent is the level-off arrow provided by the FMS. It provides an indication to the flight crew of where the aircraft will reach the altitude selected on the FCU (fig.16). A blending of actual wind conditions and the values for winds entered in the FMS are used to improve the accuracy of the computation. If in selected descent, the flight crew can adjust the speed of the aircraft to adapt the descent path or V/S to the situation.
