The Weird and Wonderful Logic

A318/A319/A320/A321
Professional
The Weird and Wonderful Logic
Vol
8
8-03-7
10 July 2018
MODES
Next to phases you got to understand Modes. They are not as complex as Phases as there are only three (I
copied this from airbusdrivers.net, a great resource for any Airbus enthusiast) but as they change the way
controls work they are important.
• Ground Mode
o Active when aircraft is on the ground.
o Direct proportional relationship between sidestick deflection and flight control
movement
o Direct proportional relationship between the Thrust Lever levers control setting and
thrust.
o Is active until shortly after liftoff.
o At touchdown, ground mode is reactivated and resets the stabilizer trim to zero.
• Flight Mode
o Active shortly after takeoff and remains active until shortly before touchdown.
o Sidestick deflection and load factor imposed on the aircraft are directly proportional,
regardless of airspeed.
o With sidestick neutral and wings level, system maintains a 1 g load in pitch.
o No requirement to change pitch trim for changes in airspeed, configuration, or bank up
to 33 degrees.
o At full aft/fwd sidestick deflection system maintains maximum load factor for flap
position.
o Sidestick roll input commands a roll rate request.
o Roll rate is independent of airspeed.
o A given sidestick deflection always results in the same roll rate response.
o Turn coordination and yaw damping are computed by the ELACs and transmitted to the
FACs.
o No rudder pedal feedback for the yaw damping and turn coordination functions.
• Flare Mode
o Transition to flare mode occurs at 50' RA during landing.
o System memorizes pitch attitude at 50' and begins to progressively reduce pitch, forcing
pilot to flare the aircraft
o In the event of a go-around, transition to flight mode occurs again at 50' RA.
MINIMUM GROUND SPEED
Minimum Ground Speed (or MINI GS) is rather clever system that protects the aircraft from the dangers of
microburst related windshear. A microburst is a downwards moving pocket of air that can be highly
dangerous to aircraft on approach. Not only because it will ‘push’ the aircraft down but even more because
the aircraft can get in a sudden tail wind situation that will reduce lift or cause a sudden and unexpected
stall.
MINI GS functions by increasing the Final Operating Airspeed thus enhancing the protection against stall.
The increase is based on the wind speed (taken from ATIS) inserted by the crew in the MAG WIND item of
the PERF/APPR page and will only function in MANAGED speed mode.
On the Professional Pilots Rumour Network it was explained by Chris Scott like this: “GS-MINI is, as the
name implies, based on a minimum ground speed. Before the approach, once the crew can predict with