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AIM 

6/17/21 

1.  Relocation of a Threshold. 

Sometimes 

construction, maintenance, or other activities require 
the threshold to be relocated towards the rollout end 
of the runway. (See FIG 2

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3.) When a threshold is 

relocated, it closes not only a set portion of the 
approach end of a runway, but also shortens the length 
of the opposite direction runway. In these cases, a 
NOTAM should be issued by the airport operator 
identifying the portion of the runway that is closed 
(for example, 10/28 W 900 CLSD). Because the 
duration of the relocation can vary from a few hours 
to several months, methods identifying the new 
threshold may vary. One common practice is to use a 
ten feet wide white threshold bar across the width of 
the runway. Although the runway lights in the area 
between the old threshold and new threshold will not 
be illuminated, the runway markings in this area may 
or may not be obliterated, removed, or covered. 

2.  Displaced Threshold. 

A displaced thresh-

old is a threshold located at a point on the runway 
other than the designated beginning of the runway. 
Displacement of a threshold reduces the length of 
runway available for landings. The portion of runway 
behind a displaced threshold is available for takeoffs 
in either direction and landings from the opposite 
direction. A ten feet wide white threshold bar is 

located across the width of the runway at the 
displaced threshold. White arrows are located along 
the centerline in the area between the beginning of the 
runway and displaced threshold. White arrow heads 
are located across the width of the runway just prior 
to the threshold bar, as shown in FIG 2

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4. 

NOTE

 

Airport operator. When reporting the relocation or 
displacement of a threshold, the airport operator should 
avoid language which confuses the two. 

i.  Demarcation Bar. 

A demarcation bar delin-

eates a runway with a displaced threshold from a blast 
pad, stopway, or taxiway that precedes the runway. A 
demarcation bar is 3 feet (1m) wide and yellow, since 
it is not located on the runway, as shown in 
FIG 2

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6. 

1.  Chevrons. 

These markings are used to show 

pavement areas aligned with the runway that are 
unusable for landing, takeoff, and taxiing. Chevrons 
are yellow. (See FIG 2

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7.) 

j.  Runway Threshold Bar. 

A threshold bar 

delineates the beginning of the runway that is 
available for landing when the threshold has been 
relocated or displaced. A threshold bar is 10 feet (3m) 
in width and extends across the width of the runway, 
as shown in FIG 2

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4. 

2

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Airport Marking Aids and Signs