Narrative:

The event was an entire session on sector 34 at ZDV. The session started [in the evening] and I was working the r-side. There was a great deal of weather in and around the airspace. The northwest arrival gate had just recovered from being shut off and was in the process of using one route with 10 miles in trail for all aircraft trying to enter that gate. The weather forced the way aircraft entered the gate to change every few minutes. We started by using the tshnr arrival and were able to get aircraft in on the east side of a cell of weather. As the weather blew to the east we had to start vectoring aircraft west of the weather and use headings to wrap them around the cell to go direct tomsn direct den. During this time the northeast arrival gate was shut off so aircraft were being offloaded to our northwest gate which was barely working. This was not an issue initially since we didn't have arrivals coming from the west. As we switched to a new routing with headings; we were informed that we were going to be getting arrivals from the west with 20 miles in trail. This seemed like enough to give us a fighting chance to blend two heavy streams despite the weather which forced the arrivals from the northeast side to fly through a gap in the weather about 30 miles across before bending them south on headings. However; because the ground stop was lifted too early; 3 departures from bff and one from cpr were released and under the northeast arrival gate swap stream. We were unaware of this development until it was too late.I was forced to abort my plan but that cost me dearly since I fell behind and was never able to recover from that point forward. Many den arrivals were suddenly stacked with too many people talking to different aircraft to create a coherent plan. I was forced to try and offload two aircraft from the west to the southwest gate. I did this by issuing headings to send them to sector 14 and they helped give them routing and sequence them. This was not enough however. As more arrivals and overflights piled into the sector; I soon lost control of the frequencies despite many attempts to regain control. Every aircraft needed deviations due to the weather. Most aircraft couldn't take headings for the sequence for the weather. When I would issue a clearance I would more often than not unkey and have 2 to 3 other aircraft talking. The volume was so great that I didn't even have time to find the aircraft calling me; especially since my radar assist had to take many hand offs without my knowledge.we were treading water just to stay afloat; let alone try to make a complex sequence happen. We finally received a third person which helped turn the tide in our favor. The northeast arrivals were soon offloaded to the north departure gate to give our sector some breathing room; and the sector 14 controller had to talk to aircraft for much longer than average time and sometimes completely skipped my airspace. The sector was completely overloaded to have made such a scenario happen. I know that all the surrounding sectors and areas were deeply impacted to get us out of that situation. It was extremely dangerous and we are lucky that nothing bad happened. I was informed later that we had traffic counts in the high 30s which is too much for that sector to run safely. This was known before it turned into the dangerous situation. Watching the falcon (radar display replay) is probably the only way to see exactly what happened to do it justice. I was informed that a traffic management review and system service review is going to take place as a result of this. The traffic management unit at ZDV was aware that this situation was developing before it started and chose to allow too many aircraft through that space. They also knew that the sector was at or above capacity since they did the 20 miles in trail from the west on den arrivals to help with that. This was not nearly enough. Overflights should have been pulled out well in advance if they honestly expected us to be able to sequence two streams blending head on. The den arrivals were not given correct routing from ZLC because it was never coordinated.the north departure gate had minimal weather and could have easily and more safely run in the northeast arrivals (which was proven when it was used as an emergency out for us near the end of the session). There was absolutely no reason to have run so many aircraft through sector 34 with that much weather and complexity. It was a total breakdown of the ATC system; especially from a big picture point of view. The practice of running two to three heavy streams into a gate on one route has become common place and it is extremely difficult to do and sometimes dangerous even on a day when embedded weather isn't a factor in the sector doing the sequence. In summation; the sector 34 team was set up to fail despite our best efforts and realistically; I don't believe anybody could have made that situation work. I would recommend having broader tmu restrictions from surrounding airspace as things like this develop. I would also recommend greater ground stop times for aircraft while we are in the midst of these operations. I would also recommend using departure gates for tower in route more readily instead of a last ditch effort. Lastly; having very qualified and experienced controllers in the traffic management unit (tmu) is absolutely vital. The tmu staff should be the best of the best if they are overseeing the big picture of our entire facility and beyond. Training and the choice of staffing should reflect that. Things like this have been going on for years and due to high turnover or complacency (from controllers who sometimes don't actually work traffic anymore) we go through the same things every year as if it was the first time it ever happened.

Related reports:

Google
 

Original NASA ASRS Text

Title: ZDV ARTCC Controller became overloaded with traffic due to the workload created by weather deviations from other sectors routed into his airspace. The Controller feels the Traffic Management Unit did not properly control the workload of this sector.

Narrative: The event was an entire session on sector 34 at ZDV. The session started [in the evening] and I was working the R-side. There was a great deal of weather in and around the airspace. The Northwest arrival gate had just recovered from being shut off and was in the process of using one route with 10 miles in trail for all aircraft trying to enter that gate. The weather forced the way aircraft entered the gate to change every few minutes. We started by using the TSHNR arrival and were able to get aircraft in on the east side of a cell of weather. As the weather blew to the east we had to start vectoring aircraft west of the weather and use headings to wrap them around the cell to go direct TOMSN direct DEN. During this time the Northeast arrival gate was shut off so aircraft were being offloaded to our NW gate which was barely working. This was not an issue initially since we didn't have arrivals coming from the West. As we switched to a new routing with headings; we were informed that we were going to be getting arrivals from the West with 20 miles in trail. This seemed like enough to give us a fighting chance to blend two heavy streams despite the weather which forced the arrivals from the NE side to fly through a gap in the weather about 30 miles across before bending them south on headings. However; because the ground stop was lifted too early; 3 departures from BFF and one from CPR were released and under the NE arrival gate swap stream. We were unaware of this development until it was too late.I was forced to abort my plan but that cost me dearly since I fell behind and was never able to recover from that point forward. Many DEN arrivals were suddenly stacked with too many people talking to different aircraft to create a coherent plan. I was forced to try and offload two aircraft from the west to the SW gate. I did this by issuing headings to send them to sector 14 and they helped give them routing and sequence them. This was not enough however. As more arrivals and overflights piled into the sector; I soon lost control of the frequencies despite many attempts to regain control. Every aircraft needed deviations due to the weather. Most aircraft couldn't take headings for the sequence for the weather. When I would issue a clearance I would more often than not unkey and have 2 to 3 other aircraft talking. The volume was so great that I didn't even have time to find the aircraft calling me; especially since my radar Assist had to take many hand offs without my knowledge.We were treading water just to stay afloat; let alone try to make a complex sequence happen. We finally received a third person which helped turn the tide in our favor. The NE arrivals were soon offloaded to the North departure gate to give our sector some breathing room; and the sector 14 controller had to talk to aircraft for much longer than average time and sometimes completely skipped my airspace. The sector was completely overloaded to have made such a scenario happen. I know that all the surrounding sectors and areas were deeply impacted to get us out of that situation. It was extremely dangerous and we are lucky that nothing bad happened. I was informed later that we had traffic counts in the high 30s which is too much for that sector to run safely. This was known before it turned into the dangerous situation. Watching the Falcon (Radar display replay) is probably the only way to see exactly what happened to do it justice. I was informed that a Traffic Management Review and System Service Review is going to take place as a result of this. The Traffic Management Unit at ZDV was aware that this situation was developing before it started and chose to allow too many aircraft through that space. They also knew that the sector was at or above capacity since they did the 20 miles in trail from the west on DEN arrivals to help with that. This was not nearly enough. Overflights should have been pulled out well in advance if they honestly expected us to be able to sequence two streams blending head on. The DEN arrivals were not given correct routing from ZLC because it was never coordinated.The North Departure gate had minimal weather and could have easily and more safely run in the Northeast arrivals (which was proven when it was used as an emergency out for us near the end of the session). There was absolutely no reason to have run so many aircraft through sector 34 with that much weather and complexity. It was a total breakdown of the ATC system; especially from a big picture point of view. The practice of running two to three heavy streams into a gate on one route has become common place and it is extremely difficult to do and sometimes dangerous even on a day when embedded weather isn't a factor in the sector doing the sequence. In summation; the sector 34 team was set up to fail despite our best efforts and realistically; I don't believe anybody could have made that situation work. I would recommend having broader TMU restrictions from surrounding airspace as things like this develop. I would also recommend greater ground stop times for aircraft while we are in the midst of these operations. I would also recommend using Departure gates for tower in route more readily instead of a last ditch effort. Lastly; having very qualified and experienced controllers in the Traffic Management Unit (TMU) is absolutely vital. The TMU staff should be the best of the best if they are overseeing the big picture of our entire facility and beyond. Training and the choice of staffing should reflect that. Things like this have been going on for years and due to high turnover or complacency (from controllers who sometimes don't actually work traffic anymore) we go through the same things every year as if it was the first time it ever happened.

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.