Narrative:

I was working R49 and R18 combined with a d-side. Metering for atl. The airport was running visual approaches and not under any strain for volume. As I sat down to take over the sector I noticed numbers out of sequence resulting in delay times. I reshuffled the list which did little to fix the problem. I then proceeded to vector aircraft in order to make the assigned times. After doing so and after we lined them all back up; the numbers shifted from ones and twos up to threes and fours. Almost all aircraft were already reduced to 250kts. I asked the supervisor to call tmu and ask why they shuffled the list without notifying us. Tmu says that they did not. Tbfm [time based flow management] is already; in my opinion; causing us as controllers to take unneeded risks in order to space aircraft out when the airport is not being pressed. I almost went into the hold to make the numbers work today. Now there appears to be an anomaly that causes an unintended shift in delay times after spacing requirements have been achieved. This is one of the many; many issues I've come across in regards to the use of tbfm at ZTL. When I ask questions about why things happen the way they do; I get 5 different answers from five different people. How can we possibly make this work if no one understands how it works?first recommendation: suspend tbfm into atl until we fix the issues. Second: ensure that all smes; tmcs; flms and oms understand how it works so as to be able to answer questions posed by cpcs. Do not operate tbfm again until all controllers in the building have been re-briefed in an all hands meeting or some other medium to allow for addressing of concerns. If no one understands how to use it properly; it will never work here and currently there is an overwhelming distrust of the system and those charged with overseeing its operation resulting in an extremely unsafe environment. Third: the inability to see the numbers on aircraft not in your altitude stratum inhibits the controller's ability to plan the sequence and adjust aircraft accordingly. Three times in the last week I've had aircraft come over so far out of order that the first aircraft in the list was actually number 9 or 10 on the scope. Tmu is either unaware of these situations (i.e.; not paying attention) or unwilling to 'ripple the list' to make it work correctly and therefore we end up with ridiculous numbers that cannot be fixed by the controller because the aircraft that is out of order is so far back. Solution: implement a patch that allows us to see arrival's tbfm numbers in adjacent airspace so that we; as controllers; can plan accordingly; or teach tmu how to properly use the equipment. Additionally; we were all briefed that tbfm would be suspended during weather deviations. This has not been the case; causing additional safety problems and bringing another issue to light: I had an aircraft deviate out of the arrival sector and into a departure sector. The departure sector will not show a time even though they have track control because; as I've been told by a sme; only arrival sectors will see the times. Well then; we either need to suspend tbfm when that happens or patch the system so that all sectors working atl arrivals will see numbers.

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Original NASA ASRS Text

Title: ZTL Controller reported a situation while using TBFM [Time Based Flow Management] into Atlanta when he observed a shift in times that made his job more difficult. Controller wants TBFM stopped until everyone at ZTL understands how it supposedly works.

Narrative: I was working R49 and R18 combined with a D-side. Metering for ATL. The airport was running visual approaches and not under any strain for volume. As I sat down to take over the sector I noticed numbers out of sequence resulting in delay times. I reshuffled the list which did little to fix the problem. I then proceeded to vector aircraft in order to make the assigned times. After doing so and after we lined them all back up; the numbers shifted from ones and twos up to threes and fours. Almost all aircraft were already reduced to 250kts. I asked the supervisor to call TMU and ask why they shuffled the list without notifying us. TMU says that they did not. TBFM [Time Based Flow Management] is already; in my opinion; causing us as controllers to take unneeded risks in order to space aircraft out when the airport is not being pressed. I almost went into the hold to make the numbers work today. Now there appears to be an anomaly that causes an unintended shift in delay times after spacing requirements have been achieved. This is one of the many; many issues I've come across in regards to the use of TBFM at ZTL. When I ask questions about why things happen the way they do; I get 5 different answers from five different people. How can we possibly make this work if no one understands how it works?First recommendation: Suspend TBFM into ATL until we fix the issues. Second: ensure that all SMEs; TMCs; FLMs and OMs understand how it works so as to be able to answer questions posed by CPCs. Do not operate TBFM again until all controllers in the building have been re-briefed in an all hands meeting or some other medium to allow for addressing of concerns. If no one understands how to use it properly; it will never work here and currently there is an overwhelming distrust of the system and those charged with overseeing its operation resulting in an extremely unsafe environment. Third: The inability to see the numbers on aircraft not in your altitude stratum inhibits the controller's ability to plan the sequence and adjust aircraft accordingly. Three times in the last week I've had aircraft come over so far out of order that the first aircraft in the list was actually number 9 or 10 on the scope. TMU is either unaware of these situations (i.e.; not paying attention) or unwilling to 'ripple the list' to make it work correctly and therefore we end up with ridiculous numbers that cannot be fixed by the controller because the aircraft that is out of order is so far back. Solution: Implement a patch that allows us to see arrival's TBFM numbers in adjacent airspace so that we; as controllers; can plan accordingly; or teach TMU how to properly use the equipment. Additionally; we were all briefed that TBFM would be suspended during weather deviations. This has not been the case; causing additional safety problems and bringing another issue to light: I had an aircraft deviate out of the arrival sector and into a departure sector. The departure sector will not show a time even though they have track control because; as I've been told by a SME; only arrival sectors will see the times. Well then; we either need to suspend TBFM when that happens or patch the system so that all sectors working ATL arrivals will see numbers.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.