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On wet or contaminated runway, use of nose-wheel-steering above taxi speed may result in hydroplaning of nose-wheels, hence in loss of nose-wheels cornering force and, thus, in loss of directional control.
If differential braking is necessary, pedal braking should be applied on the required side and be completely released on the opposite side, to regain tire cornering.
Landing on Wet or Contaminated Runway
Page 2

AIRBUS INDUSTRIE
    Flight Operations Support

Briefing Note 8.7 - Crosswind Landing provides expanded information on directional control under crosswind conditions.
Assessing Landing Distance
Landing distances are provided in the FCOM and QRH for a dry runway and for the following runway conditions and contaminants:
.  
Wet;

.  
6.3 mm (1/4 inch) standing water;

.  
12.7 mm (1/2 inch) standing water;

.  
6.3 mm (1/4 inch) slush;

.  
12.7 mm (1/2 inch) slush;

.  
Compacted snow; and,

.  
Ice.

Actual landing distances are provided for all runway conditions and assume:

.  
An even distribution of the contaminant;

.  
The use of full pedal braking beginning at touchdown; and,

.  
An operative anti-skid system.

Autoland landing distances using autobrake are published for all runway conditions.
In addition, correction factors (in %) are provided to account for the following effects:
.  
Airport elevation: . Typically, + 5 % per 1000 ft;

.  
Wind component: . Typically, + 10 % per 5 kt tailwind component; . Typically, – 2.5 % per 5 kt headwind

component; and,

.  
Thrust reversers effect:

.  Thrust reverser effect depends on runway condition and type of braking, as illustrated by Figure 4.
                                                                                       Getting to Grips with                                            Approach-and-Landing Accidents Reduction

Understanding Stopping Forces during Landing Roll
Figure 1 shows the distribution of the respective stopping forces, as a function of the decreasing airspeed, during a typical landing roll using autobrake in LOW mode and maximum reverse thrust ( see also Briefing Note 8.4 -Optimum Use
of Braking Devices ).
The total stopping force is the combined effect of:
.  Aerodynamic drag, including the impingement drag ( green curve );
Note :
The term aerodynamic drag refers to the drag of the airplane during the rollout (including the impingement drag, on fluid contaminated runway), not to the (inappropriate) technique of keeping the nose high to (supposedly) increase the overall aerodynamic stopping force.

.  
Reverse thrust ( blue curve ); and,

.  
Braking and rolling drag, including the displacement drag ( red curve ).

Typical Decelerating Forces during Landing Roll

Stopping Force

Autobrake LOW Mode

Airspeed ( kt )
Figure 1

Landing on Wet or Contaminated Runway
Page 3

Stopping Energy Distribution on Contaminated Runway
Figure 2 illustrates the contribution to the total stopping energy of the different braking devices, as a function of the desired or achieved stopping distance, on a runway contaminated with . inch of water.
　
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