2. APPROACH AND LANDING
Approach definition
Approach and landing speeds
• Maximum speeds
• Minimum speeds
• Final approach speed
Landing weight limitations
Climb requirements
Landing distances
Factors affecting landing distance
Charts
3. APPROACH
The approach is defined as a flight phase where the aeroplane
configuration is changed from clean configuration to landing
configuration, and the aircraft is positioned in such a way that it can
safely touch down at the correct part of the runway on landing.
Landing limitations are usually less constraining than takeoff ones.
This may lead to a minimisation of the importance of landing checks
during dispatch.
4. SPEEDS
MAXIMUM SPEEDS
Maximum speeds are established for the operation of some movable
devices of the aircraft, in order not to damage them. These speeds are
usually included in the speeds placard, which is placed somewhere in
the cockpit. Some of these speeds are:
Maximum speed brakes speed: In most aircraft this speed is equal to
the Vmo / Mmo speed.
Maximum flaps extension speed (Vfe): It is the maximum speed at
which slats/flaps can be operated.
Maximum landing lights extension speed: Some aircraft (MD-80) have
to deploy the landing lights since they are not allocated in the airframe.
Thus, a speed limitation exists in order to extend the lights.
Maximum Wiper operation speed: Sometimes a maximum speed for
wipers operation is established.
5. SPEEDS
Maximum landing gear operating speed: This is the maximum speed at
which the landing gear can be extended or retracted. Sometimes the
speed limit for extension is different from the one for retraction.
Maximum landing gear extended speed: The maximum speed with the
landing gear down. Be careful, sometimes it is greater than the landing
gear retraction speed.
6. SPEEDS
MINIMUM SPEEDS
For a given weight and configuration, two minimum speeds are
established:
1. Minimum manoeuvring speed (VMAN): It is the minimum speed which
permits banks of up to 30º with a given configuration. For clean
configuration, this speed is known as VCLEAN. If we want to fly below
this speed, bank angle must be limited to 15º; or, to keep full
manoeuvrability, slats/flaps must be extended.
VMAN = 1.5 Vs1
7. SPEEDS
2. Reference speed (VREF): It is the steady landing approach speed at
the 50 feet point for a defined landing configuration. It is used as a
reference (hence its name) for calculating the final approach speed
and the landing distance.
VREF = 1.3 · VS0 = 1.23 VS1g
8. SPEEDS
FINAL APPROACH SPEED (VAPP)
VAPP is the actual aircraft speed during landing, 50 feet above the
runway surface.
The flaps/slats are in landing configuration, and the landing gears are
extended.
It is based upon the reference speed.
To calculate VAPP, we will increase VREF in 5 kts, plus a value depending
on the wind. This value is calculated in a different way for each
aircraft. An additional correction may be made with some systems
inoperative:
VAPP = VREF + 5 kts + ΔVwind and/or gusts + ΔVsystems inoperative
9. LANDING WEIGHT LIMITATIONS
Every flight must be planned in such a way that the actual landing
weight is less than the operational landing weight:
ALW ≤ OLW ≤ MLW
The OLW is affected by these factors:
Climb requirements in approach configuration.
Climb requirements in landing configuration.
Runway length
Braking capability and tyre limitations.
Pavement limitations.
10. CLIMB REQUIREMENTS
In case of performing a missed approach procedure, the aircraft must
be able to climb with a minimum gradient. Two different minimum
gradients have been established, one for approach configuration and
another for landing configuration:
APPROACH CONFIGURATION
• Gear up
• Flaps approach
• 1 ENG OUT
• TOGA thrust
• Speed = 1.5 · VS1
APPROACH 2 ENGINES 3 ENGINES 4 ENGINES
MIN
GRADIENT 2.1 % 2.4 % 2.7 %
11. CLIMB REQUIREMENTS
LANDING CONFIGURATION
• Gear down
• Full flaps
• All engines operative
• TOGA thrust
• Speed = 1.3 · VS0
LANDING 2 ENGINES 3 ENGINES 4 ENGINES
MIN
GRADIENT 3.2 %
13. LANDING DISTANCES
LANDING DISTANCE
It is the distance measured between a point 50 feet above the runway
threshold, and the point where the aircraft comes to a complete stop.
50 ft
Landing distance
VREF
14. LANDING DISTANCES
The landing distance is measured under certain conditions:
Standard temperature.
Landing configuration.
Stabilised approach at VREF over the threshold.
Determination on a level, smooth, dry, hard-surfaced runway.
Acceptable pressures on the wheel braking systems.
Usage of spoilers.
No use of reverse thrust.
Additional landing distances are also certified with degraded braking
means (spoiler inoperative, one brake inoperative…).
15. LANDING DISTANCES
LANDING DISTANCE AVAILABLE
It is the length of runway which is declared available and suitable for
the ground run of an aeroplane landing.
It is also a declared distance, and it will be equal to the TORA if there
is no displaced threshold. Stopways are not included in the LDA.
16. LANDING DISTANCES
The landing distance available (LDA) may be shortened due to the
presence of obstacles under the landing path, noise abatement, etc.
When there is no obstacle within the approach funnel, as defined
below, it is possible to use the runway length to land.
17. LANDING DISTANCES
However, if there is an obstacle within the approach funnel, a
displaced threshold is defined considering a 2% plane tangential to the
most penalizing obstacle plus a 60 m margin.
In this case LDA = TORA – Displaced threshold
18. LANDING DISTANCES
LANDING DISTANCE REQUIRED (JET)
A turbo-jet aircraft must be able to land within 60% of the LDA*.
50 ft
Landing distance required (60 % LDA)
Landing distance available (LDA)
* Another way of expressing it is LDA = 167 % LDR.
19. LANDING DISTANCES
LANDING DISTANCE REQUIRED (TURBOPROP)
A turboprop aircraft must be able to land within 70% of the LDA.
50 ft
Landing distance required (70 % LDA)
Landing distance available (LDA)
* Another way of expressing it is LDA = 143% LDR.
20. LANDING DISTANCES
LANDING DISTANCE REQUIRED (WET RUNWAY)
If the runway is wet, then the landing distance required is 115% of the
corresponding LDR for a dry runway.
50 ft
Landing distance required (dry runway)
Landing distance available (LDA)
Landing distance required (wet runway) = 115% LDR (dry)
21. FACTORS AFFECTING LANDING
WEIGHT
If weight is increased, VREF will be higher, giving as a result a longer
landing distance.
DENSITY ALTITUDE
Since VREF is expressed in terms of IAS, an increase of DA will increase
TAS, so the landing distance will be increased as well. A rule of thumb
is: an increase of 1000 ft in DA produce a 2% increase of the landing
distance.
RUNWAY SLOPE
Since maximum slope is 2%, its effect on the landing distance is
considered negligible.
22. FACTORS AFFECTING LANDING
WIND
Since wind changes ground speed, it is obvious that headwind will
reduce the landing distance and tailwind will increase it. Take into
account that performance charts compute 50% of headwind and 150%
of tailwind, as a margin for safety reasons.
FLAPS
Flap setting will change VREF, and therefore landing distance. High flap
settings will give short landing distances, while lower flap settings will
result in longer distances.
23. FACTORS AFFECTING LANDING
FLYING TECHNIQUE
One of the factors that most affect landing distance in a real flight is
the flying technique. If landing speed is not properly maintained, glide
path is too steep or the height above threshold is higher than usual,
the landing distance may be increased dramatically.
Therefore it is essential to fly a good approach in order to have a good
landing.
INOPERATIVE SYSTEMS
If some of the braking systems is inoperative (spoilers, one of the
brakes, anti-skid…), the landing distance will also be increased. It is
important to check LDA in such cases.
