Flight Management & Protections

What constitutes the FMGS (Flight Management Guidance system)? Which parts form the interface for pilots?

• FMGC

• MCDU (Interface)

• FCU(Interface)

• FAC

How is it split and what does each part of the FMGS do?

FM and FG

FG - AP / A-THR / FDs

FM - Navigation, Flight Planning, Optimisation, Predictions etc

What are the 4 FMGS Modes?

Dual: Normal operation - FMGCs share data

Independent: Abonormal condition i.e. diff database - “INDEPENDENT OP”

Single: 1 FMGC failed

BACK UP NAV: 2 FMGC failed (If Installed)

How are characteristic speeds calculated?

FACs calculate these speeds to be displayed on PFD.

• FAC uses data calculated aerodynamically (Weights) on older aircraft.

• Uses FMS data i.e. ZFW/FOB on newer aircraft for mcdu/pfd consistency.

Control Laws and Protections:
In normal law, describe pitch control on the ground, in flight and in the flare.

Ground: Pitch is a direct stick relationship with elevator. (Max deflection may be limited based on CG)

In flight:

• Load Factor demand with Protections.

• Auto Trim (Unless certain condtions i.e. High speed prot, Manual trim use…)

Flare: (Passing 50ft)

• Direct

• THS Frozen

• @30ft Nose down pitch to -2 pitch over 8 seconds

State the Load Factor protection limits

-1 < g < 2.5 (Clean)

0 < g < 2

State the Pitch Attitude protections

Conf 0-3: 30deg [25 @ low speed]

Conf Full: 25deg [20 @ low speed]

-15deg

Green == on PFD

FDs dissappear at +25 and -13

State the High AoA protections and when it activates?
What AoA can you increase to and max AoB?

AoA < aProt

When protections are active sidestick becomes an AoA demand.

Has priority over all protections

Without input FCTL Comp maintains aProt.

Crew can increase to aMAX and still make gentle turns (Max AoB 45deg)

Releasing stick will erturn to aProt.

What is ALPHA FLOOR and when is it active?

AoA > aFloor (Between aProt and aMAX)

Applies TOGA to allow acceleration and increase in AoA.

State the High Speed protections and when its active

Active at or above Vmo and ac auto recovers.

• Pitch trim frozen

• Positive Static Spiral Stability reduced to zero.

• Max AoB now 40deg

• Sidestick nosedown progressively reduced and nose up order applied

If sidestick nosedown held, ac will overshoot vmo

At Vmo +16 / Mmo + 0.004 pitch authority reduces to zero

AP disconnect at Vmo +15 / Mmo + 0.004

Which protection has highest priority?

High AoA protection

When is the sideslip target blue? (Beta)

• Slats/Flaps Conf 1-Full

• One THR LVR FLX or MCT

• At least 1 engine > 80% N1

• Thrust asymmetry > 30% N1

Bank Angle:
Positve Static Spiral Stability / Max AOB

33 degrees. (Above this pilot must apply aft pressure)

Max AoB is 67degrees.

What is the Max AoB when High AoA / High Speed Protections are active?

High AoA - 45 deg

High Speed - 40 deg (Positve Static Spiral Stability reduced to 0)

What happens above 45 deg AoB?

FDs dissappear (reappear at 40deg)

How do you know you’re in ALTN LAW?

ECAM and Amber xx (replace green equals protections symbols)

In ALTN LAW what protections do you have?

Protections:

Load Factor

Stabilities:

Pitch Attitude / High Speed / Low Speed

Describe the Pitch Attitude limitation

Available in clean config
Max 20 deg at Sea Level or 8 deg at Max Alt

Reduces sidestick authority and produces nose down order.

Describe Low Speed Stability

Active from Vsw +5-10
Gentle nose down input

Crew can override

Describe High Speed Stability

Above Vmo - Nose up demand

Crew can override

OVERSPEED warning still active

What do you lose in Direct law?

Auto trim and all protections

Do you still have Stall / Overspeed warning in Direct law?

Yes

What do you need to consider in Roll when in Direct law?

Incredibly sensitive and no Turn Coordination