background image

Pilot/Controller Glossary






SAFETY ALERT− 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− 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− 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− A software enhance-

ment to ASDE−3, ASDE−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−3. The Safety Logic

System for ASDE−X and ASSC is an integral part of

the software program.


a. ALERT− An actual situation involving two real

safety logic tracks (aircraft/aircraft, aircraft/vehicle,

or aircraft/other tangible object) that safety logic has

predicted will result in an imminent collision, based

upon the current set of Safety Logic parameters.


1. Alerts generated by one or more false

surface−radar targets that the system has interpreted

as real tracks and placed into safety logic.

2. Alerts in which the safety logic software did

not perform correctly, based upon the design

specifications and the current set of Safety Logic


3. The alert is generated by surface radar targets

caused by moderate or greater precipitation.

c. NUISANCE ALERT− 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 secon-

dary radar 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 (for example,

helicopter, pipeline patrol, non−Mode C overflight,


d. VALID NON−ALERT− A situation in which

the safety logic software correctly determines that an

alert is not required, based upon the design

specifications and the current set of Safety Logic


e. INVALID NON−ALERT− A situation in which

the safety logic software did not issue an alert when

an alert was required, based upon the design

SAIL BACK− A maneuver during high wind

conditions (usually with power off) where float plane

movement is controlled by water rudders/opening

and closing cabin doors.

operating in the same direction when:

a. They are following the same track in the same

direction; or

b. Their tracks are parallel and the aircraft are

flying in the same direction; or

c. Their tracks intersect at an angle of less than 45