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Pilot/Controller Glossary 

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SAA

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(See SENSE AND AVOID.) 
(See SPECIAL ACTIVITY AIRSPACE.) 

SAFETY ALERT

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 A safety alert issued by ATC to aircraft under their control if ATC is aware the aircraft is at 

an altitude which, in the controller’s judgment, places the aircraft in unsafe proximity to terrain, obstructions, 

or other aircraft. The controller may discontinue the issuance of further alerts if the pilot advises he/she is taking 

action to correct the situation or has the other aircraft in sight. 

a. 

Terrain/Obstruction Alert

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 A safety alert issued by ATC to aircraft under their control if ATC is aware the 

aircraft is at an altitude which, in the controller’s judgment, places the aircraft in unsafe proximity to 

terrain/obstructions; e.g., “Low Altitude Alert, check your altitude immediately.” 

b. 

Aircraft Conflict Alert

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 A safety alert issued by ATC to aircraft under their control if ATC is aware of an 

aircraft that is not under their control at an altitude which, in the controller’s judgment, places both aircraft in 

unsafe proximity to each other. With the alert, ATC will offer the pilot an alternate course of action when feasible; 

e.g., “Traffic Alert, advise you turn right heading zero niner zero or climb to eight thousand immediately.” 

Note: The issuance of a safety alert is contingent upon the capability of the controller to have an awareness 

of an unsafe condition. The course of action provided will be predicated on other traffic under ATC control. 

Once the alert is issued, it is solely the pilot’s prerogative to determine what course of action, if any, he/she 

will take. 

SAFETY LOGIC SYSTEM

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 A software enhancement to ASDE

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3, ASDE

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X, and ASSC, that predicts the path 

of aircraft landing and/or departing, and/or vehicular movements on runways. Visual and aural alarms are 

activated when the safety logic projects a potential collision. The Airport Movement Area Safety System 

(AMASS) is a safety logic system enhancement to the ASDE

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3. The Safety Logic System for ASDE

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X and 

ASSC is an integral part of the software program. 
SAFETY LOGIC SYSTEM ALERTS

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a. 

ALERT

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1. 

An actual situation involving two real Safety Logic tracks (aircraft/aircraft, aircraft/vehicle, or 

aircraft/other tangible object) that the Safety Logic System has predicted will result in an imminent collision, 

based upon the Safety Logic parameters. 

2. 

An actual situation involving a single Safety Logic track arriving to, or departing from, a closed runway. 

3. 

An actual situation involving a single Safety Logic track arriving to a taxiway. 

b. 

FALSE ALERT

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1. 

Alerts generated by one or more false surface radar or cooperative surveillance targets, that the ASDE 

system has interpreted as real tracks and placed into Safety Logic. 

2. 

Alerts in which the Safety Logic System did not perform correctly, based upon the design specifications 

and Safety Logic parameters. 

3. 

Alerts generated by surface radar targets caused by moderate or greater precipitation. 

c. 

NUISANCE ALERT

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 An alert in which one or more of the following is true: 

1. 

The alert is generated by a known situation that is not considered an unsafe operation, such as LAHSO 

or other approved operations. 

2. 

The alert is generated by inaccurate cooperative surveillance data received by the Safety Logic System. 

3. 

One or more of the aircraft involved in the alert is not intending to use a runway/taxiway (helicopter, 

pipeline patrol, non

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Mode C overflight, etc.). 

d. 

VALID NON

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ALERT

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 A situation in which the Safety Logic System correctly determines that an alert 

is not required, based upon the design specifications and Safety Logic parameters. 

PCG S

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