or,

.  
The necessary type of braking (i.e., pedal braking or selected autobrake mode) for a desired or required stopping distance.

The contribution of the different braking devices to the total stopping energy on a runway contaminated with . inch of standing water can be compared to their respective contributions on a dry runway, as
illustrated in Briefing Note 8.4 – Optimum Use of Braking Devices, Figure 4 ):
.  
The contribution of the aerodynamic drag increases due to the additional impingement drag;

.  
The contribution of the braking and rolling drag (i.e., net effect of braking force and displacement drag) decreases;

.  
The contribution of the thrust reverser stopping force is independent from the runway condition.

Given Aircraft - Maximum Landing Weight  - V APP – Both Reversers
Sea Level  - ISA – . Inch Water

0
4000

Stopping ( Landing ) Distance (m)
Figure 2
Landing on Wet or Contaminated Runway
Page 4

Landing distance (m)
Runway condition

.  
The selected deceleration rate and the time delay for autobrake activation, as applicable; and,

.  
Runway condition (i.e., contribution of contaminant to the deceleration rate).

Figure 3
                                  ( Typical )

Effect of Thrust Reverser Figure 3 is based on a reference 1000-m landing Runway Condition
distance ( typical landing distance for a manual landing on dry runway with full pedal braking and no reverse ).
For each runway condition, the following landing distances can be compared:
.  
Landing distance for manual landing with full pedal braking; or,

.  
Landing distance for autoland with low or medium autobrake.

For manual landing with full pedal braking or for autoland with autobrake, the effect of runway condition can be assessed.
When autobrake is used, the braking contribution depends on the selected deceleration rate and on

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Factors Affecting Landing Distance
Runway condition and type of braking:
Figure 3 illustrates the effect of runway condition on landing distance, for various applicable runway conditions and for three braking modes.
Effect of Braking and Runway Condition
4000

3500
                                                                                       Getting to Grips with                                            Approach-and-Landing Accidents Reduction

On runway contaminated by standing water or slush, the landing distances with medium or low autobrake settings are very similar, because:
.  
The deceleration rate is driven primarily by the aerodynamic drag, rolling drag and reverse thrust; and because,

.  
　
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