Lecture 8:
Approach &
Landing
Performance
AIRCRAFT WEIGHT &
PERFORMANCE
Introduction
Cruise / En-route
Climb
Ta k e - o f f
Descend
Approach
& Landing
• When an aircraft is in vicinity of the destination airport, it
is considered to be in the final approach phase of its flight.
2
Final Approach
• During the final approach, from approximately 10nm
range, the flaps are progressively lowered.
• In addition, the landing gear is also lowered at about 5nm
from touchdown. Both flaps and landing gear produce drag
and will require the addition of power.
• The spoilers are "armed", i.e. they are put in a state
whereby they will be automatically deployed fully on
touchdown.
Landing
• Following the final approach the aircraft will start the
landing phase.
• Landing begins from certain height (35ft/50ft) above the
runway until a complete stop by the aircraft.
• It comprises of an airborne segment, touchdown and a
ground roll (the point from touchdown to reaching a full
stop).
• Once on the ground the thrust reverser and spoilers will
be fully deployed and wheel breaking will be applied in
order to stop the aircraft more efficiently and use less
landing distance.
Landing Performance
• In many cases, the landing distance of an airplane will
define the aircraft landing performance.
• Before commencing an approach, the crew shall check and
confirm that the landing distance required is less than the
landing distance available.
LDR & LDA
•
The landing distance required (LDR) shall be the
horizontal distance required to land and come to a
complete stop from a point on the approach flight path at a
selected height above the landing surface. (ICAO Annex 8
Part IV Paragraph 2.2.3.3.2)
•
The landing distance available (LDA) is the length of the
runway which is declared available by the appropriate
Authority and suitable for the ground run of an aeroplane
landing. (JAR-OPS 1.480(a)(2)(i) (5)).
LANDING DISTANCE
Two types Landing Accidents
Land an aircraft on a runway where the landing distance
available is shorter than the landing distance required will
lead to accidents (overrun on landing).
1. Overrun on Landing:
• A landing aircraft is unable to stop before the end of
the runway is reached.
2. Undershoot on Landing:
• An aircraft attempting a landing touches down in the
undershoot area of the designated landing runway.
Overrun on Landing:
• On 2nd August 2005, and Air France A340, comes in too
high for landing at Toronto Airport during thunderstorm.
The runway is short and the pilots deploy the thrust
reversers too late. The A340 overruns the runway.
Although the aircraft is burnt out, all 309 people onboard
survive by evacuating the aircraft in less than 90 seconds.
• B738, Kingston Jamaica, 2009: On 22 December 2009 a
Boeing 737-823, operated by American Airlines, ran off the
eastern end of runway 12 on landing at Norman Manley
International Airport, Kingston, Jamaica, having landed on
the wet runway with a tailwind.
Overrun on Landing:
• E170, Cleveland OH USA, 2007: On 18 February 2007,
while landing at Cleveland Hopkins International Airport,
USA, an Embraer ERJ170 overran the snow-contaminated
runway.
• DC10, Tahiti Hawaii, 2000 : On 24th December 2000, a
Hawaiian Airlines DC-10 overran the runway at Tahiti after
landing long on a wet runway having encountered
crosswinds and turbulence on approach in
Thunderstorms.
• MD82, Little Rock USA, 1999 : On 1 June 1999, an MD-82
belonging to American Airlines, overran the end of the
runway during landing in thunderstorm. The captain and
10 passengers were killed.
Undershoot on Landing:
• F70, vicinity Munich Germany, 2004 : On 5 January 2004, a
Fokker 70, operated by Austrian Airlines, carried out a
forced landing in a field 2.5 nm short of Munich Runway
26L following loss of thrust from both engines due to icing.
• JS31, Fort St. John BC Canada, 2007 :
• On 9 January 2007, Jetstream 31 from Grand Prairie, Alberta made
an to Runway 29 at Fort St. John, British Columbia and touched
down 320 feet short of the runway striking approach and runway
threshold lights. The right main and nose landing gear collapsed
and the aircraft came to rest on the right side of the runway, 380
feet from the threshold. There were no injuries to the 2 pilots and
10 passengers. At the time of the occurrence, runway visual range
was fluctuating between 1800 and 2800 feet in snow and blowing
snow, with winds gusting to 40 kts.
Factors affecting Landing
Performance
• Put simply, the LDR must be less than the LDA.
• Aircraft performance (LDR and landing speed) is
calculated by consider several factors
• Aircraft performance during landing depends on a number
of factors, principally:
Landing
Speed
Runway
Condition
Wind
Aircraft
Mass
Air
Density
Aircraft
Configuration
Factors affecting Landing
Performance
• Landing speed: The distance required for landing is
proportional to the square of the aircraft’s ground speed
on landing. Thus increased landing speed will give a
significantly increased landing distance requirement.
Factors affecting Landing
Performance
• Aircraft landing mass: Beside the landing speed, aircraft
mass affects the deceleration and the required brake drag
as well.
• Increased mass reduces the deceleration for a given
deceleration force and therefore increases the landing
distance (inertia).
• In the same time, increased mass increases the brake
drag available (greater pressure on the ground) and
this decreases the landing distance.
• However, the major effect is that the landing distance
required will increase with increasing mass.
Factors affecting Landing
Performance
• Wind: The effect of wind on landing distance is large and
deserves proper consideration when predicting landing
distance.
• The wind affects the deceleration force during the landing
roll.
• A headwind component adds to the deceleration force and
therefore increases the braking efficiency & reduce the
landing distance.
• While a tailwind component for the same reason reduces
the braking efficiency & increase the landing distance.
• **Strong cross-winds, turbulence and wind shear make
handling difficult and are likely to result in an increased
landing distance.
Factors affecting Landing
Performance
• Air density: Low density (high temperature, low pressure
or high aerodrome elevation) will give an increase in the
required landing distance due to the decrease of the engine
reverse thrust and higher landing speed.
• Higher air density, shorter landing distance
Factors affecting Landing
Performance
• Runway conditions: Landing performance depends on the
runway braking conditions. A hard dry surface gives the
good braking condition & reduce landing distance.
• If the runway is wet or contaminated the landing distance
achieved will be increased.
• The presence of standing water, snow or ice on the runway has a
particularly serious effect on landing performance and if it cannot
be cleared, it must be reported as accurately as possible. Special
techniques must be used by pilots when landing on contaminated
runways. Ice or snow on the runway or runways on which
hydroplaning occurs will give a very small coefficient of friction.
• If the runway is sloping, the weight component along the
runway will add to or subtract from the deceleration force. A
downhill slope will increase the landing distance required and
an uphill slope will reduce the landing distance.
Factors affecting Landing
Performance
• Aircraft Configuration:
• Failure of the devices which affect the aircraft braking
(flaps, brakes, landing gear, reverse thrust) can have a
serious effect on landing performance.
• These devices must functioning well to stop the aircraft
more efficiently and use less landing distance.
• ↑ Flaps = ↓ Distance
• ↑ Friction = ↓ Ground Roll
Summary
• The most critical conditions of landing performance are
the result of some combination of high gross weight, high
density altitude, and unfavorable wind.
• These conditions produce the greatest landing distance
and provide critical levels of energy dissipation required of
the brakes.
• In all cases, it is necessary to make an accurate prediction
of minimum landing distance to compare with the
available runway.
• A polished, professional landing technique is necessary
because the landing phase of flight accounts for more pilot
caused airplane accidents than any other single phase of
flight.
Hydroplaning
• Hydroplaning or aquaplaning by the tires of vehicle (aircraft) occurs
when a layer of water builds between the rubber tires of the vehicle
and the road surface, leading to the loss control.
• Hydroplaning of aircraft tires is often a contributing factor in take-off
and landing overrun accidents.
Hydroplaning
• The ability to brake can be completely lost when the tires
are hydroplaning because a layer of water separates the
tires from the runway surface.
• Not only reduce braking effectiveness, hydroplaning also
cause aircraft lost directional control.
• There are three types hydroplaning which are:
1. Dynamic Hydroplaning
2. Viscous Hydroplaning
3. Reverted Rubber Hydroplaning
Types of Hydroplaning
1. Dynamic Hydroplaning:
Occurs when there is water on the runway. Water is not
displaced fast enough to allow the tire to contact the
surface, and the tire rides on a wedge of water.
2. Viscous Hydroplaning:
On smooth or contaminated surfaces (oil, rubber, dust,
de-ice fluid, fuel) a thin film of water resists penetration
by the tire and reduces braking action. Can occur at lower
speeds.
3. Reverted Rubber Hydroplaning:
As a tire skids and rubber melts it acts as a seal which
traps water under the tire footprint where it is heated to
steam which supports the tire off the runway surface.
Rotating Tire =9×√PSI
Non-Rotating Tire =7.7×√PSI