We Guide You Home


John T. Lenhart (ZOA) is the Article 114 Representative for Advanced Technologies & Oceanic Procedures (ATOP).   

ATOP Program   

Background:  The ATOP system processes information consistent with system calculations or expectations (e.g. vertical movement) and provides alerts to controllers when a situation arises or information is received that is out of conformance and/or requires attention or action. This “control by exception” concept has enabled oceanic air traffic operations to advance to a level that would not have been possible under the previous manual system. The ATOP system is anticipated to have the capability and maintainability to meet the future demands posed by new airborne technologies and the associated procedures. 

The ATOP system concept incorporates existing and emerging technologies into a single, integrated system.   

These technologies include:  

  • Flight profile monitoring, utilizing flight data processing and surveillance data processing based on data from the following sources: 

o  Automatic Dependent Surveillance – Broadcast (ADS-B) 

o  Primary and secondary radar 

o  Automatic Dependent Surveillance – Contract (ADS-C FANS-1/A compatible) 

o  Controller-Pilot Data Link Communications (CPDLC) position reports 

o  High Frequency (HF) radio position reports 

  • CPDLC, (FANS-1/A compatible) 
  • Air Traffic Services (ATS)  Inter-Facility Data Communications (AIDC) 
  • NAS Interfacility message set 
  • ATS Facilities Notifications (AFN) (FANS-1/A compatible) 
  • Conflict detection, prediction, and alerting (radar separation and non-radar oceanic separation) 
  • Workload monitor 

The ATOP system manages long-term conflicts (up to two hours), operational requirements (e.g. coordination, workload monitoring), and aircraft requests.   

 The ATOP program consists of an ATOP Program Manager, NATCA National Lead, NATCA Site Leads, and operational area Subject Matter Experts (SME’s) as well as Oceanic Airspace Managers from each Site. We also have representation from AJV-I, AJT, Site Techs, ATOP Second Level Engineering, and ATOP Contract Support.   

As mentioned in last month’s ATOP report Anchorage Center (ZAN) is up and operating on the ATOP T28 build and New York Center (ZNY) and Oakland Center (ZOA) will come up on a time yet to be determined due to the COVID impacts and dynamics. T28 is showing to be a successful build at ZAN and now the ATOP program needs to conduct an operational evaluation on ATOP T29 at the technical center. The week of May 17th is the scheduled and presently approved date. T29 not only delivers a reduced lateral separation standard for qualifying aircraft but also delivers enhancements to realized safety issues with the current ATOP trial probe functionality. The ATOP work group and Site leads look forward to robustly testing and evaluating this build. ATOP T29 content is below.   

ATOP T29 Content includes

  • 51500 –23NM Lateral Separation 
  • 56196 –Enhanced Trial Probe for OOC Reports 
  • 56532 -Unable to Apply 30/30 or D50 Until an ADS-C & CPDLC Connection Has Been Established 
  • 58213 -Enhancement ADS-C Simulation functionality –moved in from T30 
  • 42264 -Portions of Very Long Routes are Discarded Without Warning 
  • 45199 -Too many OOC ADS-C reports generated when aircraft is on a WX deviation 
  • 52168 – Implement a Tolerant Coherency Check for flights moving within the expanded boundaries 
  • 56903 -Increase Active flight Design Limit to 800 
  • 47443 -Duplicate messages when ADS-C Position Report is overdue 
  • 47963 -HOST AM accepted by Ocean21, but profile not updated to reflect AM data 
  • 50532 -Read back not processed 
  • 54374 -Modify ATOP to use the new MEARTS Bypass Display GeomapFormat•574 

This Month the ATOP Program has worked collaboratively with the following Programs/Projects: 

*Future of the Ocean 2035 (FOTO 2035) 

*Acceptable Level of Risk (ALR) National Lead, Paul Behan 

Spaced Based ADS-B (SBA) National Lead, Dan Hamilton 

Along with participating in drafting problem statements and creating functional description narratives (FDN’s) that outline the system problem and the systems desired behaviors, the ATOP NATCA Site leads and subject matter experts are involved in all briefs and approval processes for ATOP enhancements. Always feel free to contact your Site leads or me directly if you have any questions, comments, or inputs in relation to the ATOP system or operational dynamic. Have a great April! 

BUR: JT Lenhart ATOP National Lead 



ZNY: John Fox , ZNY Lead, OCA West (WATRS) SME 


         Todd Tourin, North Atlantic SME 


ZAN: Mark Crabtree, ZAN Lead, SME 


ZOA: Donald White, ZOA Lead, Pacific North SME 


         Catherine Siu, ZOA Pacific South SME 


Jump to top of page