AIRBUS PERFORMANCE CALCULATIONS FOR WET and CONTAMINATED RUNWAYS ?

Damp runway: IF the runway surface is not dry and the moisture gives it a shiny appearance the runway is considered Damp.

When the runway surface is covered by any visible moisture or standing water of a maximum of 3mm depth a runway is considered WET . With no possibility of hydroplaning .

What is the runway contamination and how to identify it ?

1- FLUID CONTAMINATION : when the runway surface is covered with any shape of fluid contamination mentioned below with a depth of more than 3mm

Standing water : due to heavy rain and with a depth of more than 3mm .

Slush : it’s snow soaked with water, which spatters when stepped on firmly, it forms when the temperature is approximately at 5°c .

Dry snow : when the snow is compacted by hand and it does not stay compressed when it is released and the wind can blow it .

Wet snow : when it is compacted by hand and stays compact when it is released like (making snowballs ) .

Aircraft performance is affected by fluid contamination due to increases of Hydroplaning and precipitation drag .

2-Hard contamination shapes:

Wet ice : when the ice melts on the runway , when it forms, the direction control and braking is very difficult or not possible due to very slippery runway surface.

Dry ice and cold ice : when the ice takes place on the runway in cold and dry conditions.

Compacted snow : when they use the snow groomer to compresse the snow on the runway to obtain a hard surface .

TAKEOFF & LANDING PERFORMANCE

Takeoff performance considerations :

1-FLEX TAKEOFF not allowed.

2-Takeoff from runway covered with wet ice Not allowed.

3- takeoff is not Allowed if the weight surpasses the permitted weight on dry runway condition.

4- Screen hight at the end of runway is 15Ft instead of 35Ft

5- Derated takeoff is allowed on contamination runways .

6- it’s recommended to make 2 speed calculations for the takeoff one with a contamination depth above the reported one and one with a depth below the reported one , when the contamination depth is above the real contamination depth reported, it has better improvement on the stopping distance as a result of excess drag.

Thanks for Airbus EFB WHICH AUTOMATICALLY MAKES THIS DOUBLE CALCULATION.

7- Reverse can be used as a benefit for takeoff calculations

EQUIVALENCES

– Any form of fluid contamination which is Slush, standing water, wet snow or dry snow is equivalent to wet as its depth is 3mm maximum

– Frost is equivalent to wet .

– When the OAT is above -15c the compacted snow is equivalent to dry snow . Compacted snow is formed at -15°c or below.

– When Dry snow is formed over compacted snow it is equivalent to dry snow .

– When Wet snow is formed over compacted snow it is equivalent to wet snow .

Degradation

For any runway covered with Fluid or Hard contamination with a depth at 3mm or below

RWYCC : Takeoff performance computed with:

(4). Pick compacted snow

(3). Pick dry snow 10mm

(2) slush or standing water (Delay takeoff)

(1) Use ice and dry for calculation

BY CAPTAIN/ AHMED SHEBL

FAA FLIGHT INSTRUCTOR , MBA AVIATION MANAGEMENT , A320,330,310&300-600 CAPTAIN