Pilot/Controller Glossary  8/15/19  S  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.  b.  FALSE ALERT- 1.  Alerts generated by one or more false  surface-radar targets that the system has interpreted  as real tracks and placed into safety logic.  SAA- (See SPECIAL ACTIVITY AIRSPACE.)  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.  2.  Alerts in which the safety logic software did  not perform correctly, based upon the design  specifications and the current set of Safety Logic  parameters.  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:  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.”  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,  etc.).  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.”  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  parameters.  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.  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  specifications.  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.  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.  SAME DIRECTION AIRCRAFT- Aircraft are  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  degrees.  a.  ALERT- An actual situation involving two real  safety logic tracks (aircraft/aircraft, aircraft/vehicle,  SAFETY LOGIC SYSTEM ALERTS- PCG S-1 