.  
Wind shear;

Preventing Runway Excursions and Overruns
Page 1

.  
Cross-wind component;

.  
Inaccurate information on wind and/or runway conditions; and,

.  
Reverse-thrust effect in crosswind and on contaminated runway.

Crew technique or decision factors:
.  
Incorrect crosswind landing techniques (e.g., drifting during the decrab and align phase, absence of decrab when landing in high crosswind conditions);

.  
Inappropriate differential braking by crew;

.  
Use of nose-wheel-steering tiller at high speed; and,

.  
Vacating the runway at an excessive speed.

Systems factors:
.  
Asymmetric thrust (i.e., forward thrust on one side, reverse thrust on opposite side); or,

.  
Uncommanded differential braking.

Factors Involved in Runway Overruns
The following operational factors and circumstances are observed as recurring patterns, alone or in combination, in runway-overrun events:
Weather factors:
.  
Unanticipated runway condition (i.e., worse than anticipated);

.  
Inaccurate surface wind information; and,

.  
Unanticipated wind shear or tail wind component.

Performance factors:
.  Incorrect assessment of landing distance following an in-flight malfunction or an MEL condition affecting:
.  aircraft configuration (e.g., slats, flaps or roll spoilers);
.  lift dumping (e.g., ground spoilers);or,
.  braking capability (e.g., anti-skid);

.  
Incorrect assessment of landing distance for prevailing wind and runway conditions; and,

.  
Inoperative brake(s) not accounted for per MEL/DDG provision.

Crew technique or decision factors:
.  Unstable approach path (steep and fast):
.  Landing fast (up to V APP + 40 kt at runway threshold); and/or,
.  Excessive height over threshold (up to 220 ft) resulting in a long landing;
.  
Absence of go-around decision, when warranted;

.  
Captain (PNF)’s decision to land following intention or initiation of go-around by first officer (PF);

.  
Long flare ( allowing the aircraft to float to bleed an excess-speed uses three times more runway than decelerating on the ground );

.  
Failure to arm ground spoilers (usually associated with thrust reversers being inoperative);

.  
Power-on touchdown (i.e., preventing automatic extension of ground spoilers);

.  
Failure to detect the non-deployment of ground spoilers (e.g., absence of related standard call);

.  
Forward throttle/thrust levers movement resulting in the premature retraction of ground spoilers and in the loss of autobrake;

Preventing Runway Excursions and Overruns
Page 2

.
Bouncing and incorrect bounce recovery; Standard operating procedures (SOPs):

.  
Late braking (or late takeover from autobrake system, when required); and,

.  
Reduced braking efficiency while assuring directional control in crosswind conditions.

Systems factors:
.  
Loss of pedal braking; or,

.  
Antiskid malfunction resulting in aquaplaning (as evidenced by extensive spots on all affected tires).

Prevention Strategies and Lines-of-Defense
The following prevention strategies and lines-of-defense should be implemented to address the factors involved in runway excursions and overruns:
Policies:
.  
Define policy and procedures to promote the readiness and commitment to go-around if the conditions for a safe landing are not achieved.
　
中國航空網 www.k6050.com
航空翻譯 www.aviation.cn
本文鏈接地址：Getting to Grips with Approach-and-Landing Accidents Reducti(147)