1.23 VS1g ≤ V ≤ 1.41 VS1g and check that V ≥ VMCL 

3.3.1.2. Requirements 

The minimum gradients to be demonstrated: 

An approach configuration can be selected, as long as the stall speed VS1g of this configuration does not exceed 110% of VS1g of the related “all-engines-operating“ landing configuration. 

3.3.2. Landing Climb 

The objective of this constraint is to ensure aircraft climb capability in case of a missed approach with all engines operating. The “Landing climb” wording comes from the fact that go-around performance is based on landing configuration. For Airbus FBW, the available landing configurations are CONF 3 and FULL. 

3.3.2.1. Configuration 

N engines 

Thrust available 8 seconds after initiation of thrust control movement from minimum flight idle to TOGA thrust 

Gear extended 

Slats and flaps in landing configuration (CONF 3 or FULL) 

1.13 VS1g ≤ V ≤ 1.23 VS1g and check that V ≥ VMCL. 

3.3.2.2. Requirements 

The minimum gradient to be demonstrated is 3.2% for all aircraft types. 

For all Airbus aircraft, this constraint is covered by the approach climb requirement. In its operational documentation (FCOM), Airbus publishes the maximum weight limited by the approach climb gradient only. Landing climb performance is found in the AFM. 

3.4. External Parameters Influence 

3.4.1. Pressure Altitude 

Approach speed is equal to 1.23 VS1g. But, the corresponding TAS increases with the pressure altitude. 

Consequently, the landing distance will also increase. 

TOGA thrust, used for go-around, decreases when pressure altitude increases. 

Therefore, in the event of a go-around, a decrease in engine thrust implies a decrease in the air climb gradients, which means that: 

3.4.2. Temperature 

Engine thrust decreases when the temperature passes the reference temperature. Therefore, in case of a go-around, the air climb gradients will decrease.

 Temp . . go-around air climb gradients  . 

3.4.3. Runway Slope 

From a performance standpoint, an upward slope improves the aircraft’s stopping capability, and, consequently, decreases landing distance. 

3.4.4. Runway Conditions 

The definition of runway conditions is the same as for takeoff. When the runway is contaminated, landing performance is affected by the runway’s friction coefficient, and the precipitation drag due to contaminants. 

Friction coefficient . . Landing distance . 

Precipitation drag . . Landing distance . 

Depending on the type of contaminant and its thickness, landing distance can either increase or decrease. So, it is not unusual to have a shorter ALD on 12.7 mm of slush than on 6.3mm. 

3.4.5. Aircraft Configuration 

3.4.5.1. Engine air bleed 

Engine air bleed for de-icing or air conditioning, implies a decrease in engine thrust.

 As a result, go-around air climb gradients will decrease. 

Engine air bleed ON . air climb gradients  . 

3.4.5.2. Flap setting 

An increase in flap deflection implies an increase in the lift coefficient (CL), and in the wing surface. It is therefore possible to reduce speed such that the aircraft will need a shorter distance to land (VS1G CONF FULL < VS1G CONF 3). 

When wing flap deflection increases, landing distance decreases. 

However, when flap deflection increases, drag increases thus penalizing the aircraft’s climb performance. 

When landing at a high altitude airport with a long runway, it might be better to decrease the flap setting to increase the go-around air climb gradient. 

4. DISPATCH REQUIREMENTS 

4.1. Required Landing Distance (RLD) 

It is assumed “that the aeroplane will land on the most favorable runway, in still air”. Furthermore, “the aeroplane will land on the runway most likely to be assigned considering the probable wind speed and direction and the ground handling characteristics of the aeroplane, and considering other conditions such as landing aids and terrain”. 

Before departure, operators must check that the Landing Distance Available (LDA) at destination is at least equal to the Required Landing Distance (RLD) for the forecasted landing weight and conditions. 

The RLD, based on certified landing performance (ALD), has been introduced to assist operators in defining the minimum distance required at destination, and allow flight dispatch. 

In all cases, the requirement is : RLD ≤ LDA