1.  GENERAL INFORMATION

a.        Use of radar data in OE/OD investigation processes remains one of the most accurate methods available to re-create events.  Because of the importance placed on radar data in the determination of the facts surrounding incidents, it is imperative that this data be processed and analyzed using clearly defined procedures that eliminate localized interpretations of how best to extract, present, and assess the information.

b.        NTAP, SATORI, CDR plots, Radar Audio Playback Terminal Operations Recording (RAPTOR), Radar View Point, MSDT ATC Plot and other reduction or playback tools are available to assist in investigations.  As technological advances are made, the ATC system must adjust to these changes and ensure that radar reduction tools are used correctly and consistently throughout the system in order to provide the most accurate recreation possible.

c.        NTAP, SATORI, CDR data, and other reduction or playback tools shall not be arbitrarily used as the primary initiating source (triggering event) for reporting an OE/OD or commencing an investigation.   However, these reduction/playback tools may be used in the investigation of suspected incidents to determine the amount of separation that existed or the position of aircraft.  Additionally, these tools may be used for individual employee performance review/improvement and/or system/facility evaluation. When this is accomplished and a loss of separation is discovered, that error shall be reported, but attributed to the facility as a facility error. Skill enhancement training may be assigned to those employees’ determined to be contributory to these events. However, decertification shall not be imposed.

d.        SATORI, RAPTOR or other playback tool may be used in the investigation of a QAR, suspected OE/OD, pilot deviation, NMAC, TCAS event, miscellaneous incident, or accident; to determine the relative flight tracks, speeds, headings, location and separation of the involved aircraft.  These tools may be used to determine employee and/or pilot performance and/or involvement in the incident, as well the closest proximity.

2.  NATIONAL TRACK ANALYSIS PROGRAM (NTAP)

a.     NTAP was originally designed to assist in Search and Rescue missions aimed at locating missing or suspected downed aircraft. This program has inherent limitations when used to measure aircraft separation.  Three of the major limitations in using NTAP plots to measure separation distances are the following:

(1)       High-speed printer limitations, due to design and physical characteristics of the high-speed printer preclude accurate plotting of NTAP aircraft position symbols. 

(2)       Multiple radar data processing creates a compound environment of surveillance sites with unsynchronized radar scans, producing aircraft target updates in non-uniform time frames.

(3)       Manual measurements and smoothing of flight tracks are subject to human error, creative interpretation, and optical parallax.  In addition, target symbol positions being measured may not accurately represent relative aircraft positional information.

b.     Because of the above limitations, use of NTAP for measuring aircraft separation values, requires specific guidelines to ensure system credibility.  The following procedures shall be used when using NTAP for OE/OD determinations:

(1)       NTAP may be used for OE/OD determinations at an en-route facility provided all the following conditions are met:

(a) A plot size of one-inch equals one-mile is used.

(b) For aircraft speeds of less than 250 knots, input times shall be at least 2 minutes before and after the time of the triggering OEDP alert.  For speeds above 250 knots use at least 1 minute before and after the alert time.

(c)   The following plot keywords are used:

1.       PRI (primary targets); or

2.       BCN (beacon targets); or

3.       LDB (limited data blocks); or

4.       SEL (select plots only BCN or LDB associated with particular beacon codes input on the code card); or

NOTE:
SEL is a stand-alone option or can be used as a sub-option of BCN to plot aircraft on particular beacon codes.

5.       A combination of the above options.

6.       LST A (list data), a special plot keyword is used to create separate data listings for each of the four list (LST) options.

(d)   1/5 mile is added to the distance between the printed symbol centers before making a determination. This accommodates the high-speed printer limitations.

(e)   If target position jumps have occurred, a smoothed line shall be drawn indicating the most probable flight path of the involved aircraft.  That line shall be used for measurement purposes.  When determining the most probable flight path, ensure that a maximum number of printed target symbols are used in the smoothing process.

(f)    The NTAP plot is used to declare an OE/OD only if the Air Route Traffic Control Center (ARTCC) providing the computer data was responsible for the separation of the aircraft involved.

c.     Computer operational error detection software (OEDP) measurements are more precise than NTAP measurements. An error detection alert measurement cannot be invalidated by an NTAP plot measurement by the ARTCC receiving the alert unless at least one target position, used by HOST in the generation of the alert message, is clearly identified as a significant target jump.  All original NTAP plots used to invalidate OEDP alerts shall be forwarded to the facility’s QA office for review, and shall be retained for 45 days.

d.     LST 5 measurements data are more precise than NTAP measurements. When ever possible a LST 5 shall be used to determine closest proximity.

3. CONTINUOUS DATA RECORDING (CDR)

a.        When CDR data is used in an OE/OD investigation(s) the Automated Radar Terminal Systems (ARTS) clock shall be verified as accurate.  In addition, any plotted depiction of targets derived from CDR data shall be certified as accurate and valid.  A statement of such certification shall be added to the plot depiction.

b.        For CDR reductions from ARTS systems that calculate aircraft separation distances both from target “A” to “B” and from target “B” to “A”, use the larger of the two aircraft separation calculations within the same time stamp.

c.        DATA CLASSES

(1)     ARTS IIE & IIIE:

(a)     TA – Tracking Associated Data – Data Block, flight plan information that has been linked between a tracked target (transponder secondary code) and the Flight Data System, NAS or HOST.

(b)     TU – Tracking Unassociated Data – all other tracked secondary and primary targets with limited data blocks that cannot be correlated with the Flight Data System, NAS or HOST.

(c)     RB- Radar Reinforced Beacon Target Reports – All primary and secondary radar data available on any individual track.

(d)     BT – Beacon Target Reports – All secondary radar data.

(e)     RT – Radar Target Reports – All primary radar targets.

(f)      CR - provide Aircraft Type, Scratch Pad, Special Designators - VFR, ENROUTE, TCAS, HEAVY, Radio Failure, Hi-Jack, Emergency, Transponder Indent, Conflict Alert Indicator, MSAW Indicator, and Leader Direction for every time the track is updated on the screen.

(2)     ARTS IIIA:

(a)     TD – Tracking Data – Tracking Associated Data – Data Block, flight plan information that has been linked between a tracked target (transponder secondary code) and the Flight Data System, NAS or HOST and Tracking Unassociated Data – all other tracked secondary and primary targets with limited data blocks that cannot be correlated with the Flight Data System, NAS or HOST.

(b)     TG – Target Reports - Radar Reinforced Beacon Target Reports – All primary and secondary radar data available on any individual track. Beacon Target Reports – All secondary radar data. Radar Target Reports – All primary radar targets.

4.  CDR EXTRACTION and/or VOICE RECORDING REQUEST for RAPTOR CDR Playback

a.    When a CDR extraction and/or voice recording is requested, please use the following guidelines below.  It is imperative that extractions are made exactly as listed below.  Please do not deviate from these specifications unless instructed/requested to do so by AAT-200.

b.        CDR EXTRACTIONS do not use any filters except for time, Data Class and subsystem (radar sensor) unless specifically requested.

(1)     Extract the data, using  “CDR-Editor” or similar extraction tool as follows:

(2)     Data classes for ARTS IIE and IIIE systems=TA, TU, TG and CR

(3)     Data classes for ARTS IIIA systems=TD and TG.

(4)     Save as a single file in ASCII format ending in .TXT.

(5)     For multiple sensor systems, identify the sensor number in use or filter all but primary the sensor in use.

(6)     Please identify and/or provide an electronic copy of the radar map most likely in use during the event.

c.        VOICE RECORDINGS

(1)     If a time channel is not included or a digital voice file is created without a time reference, include the exact time (hh:mm:ss UTC) of the first radio transmission that can be correlated with radar display information.

(2)     When voice recordings are also requested, please indicate the time difference, if any, between the recorder clock and the ARTS clock and ensure you provide the start times and ensure both the time channel and voice is audible.