Narrative:

This is the third one that happened within an hour and twenty minutes of each other. I was in the process of closing my sector for the evening (arctic). My airspace is FL390 and above. As I was starting to hand off aircraft to the sectors below me (wild; and hawki) I noticed that denver 9 was handing off aircraft X to me level at FL410. Then I noticed that they took the handoff back. I started my briefing to the hawki sector they own the airspace on the east side of artic FL380 and below.after finishing my briefing with hawki I began my briefing to the wild sector. They own the west side of arctic when it's closed FL350-FL380. As I was completing my briefing and before I called the adjacent sectors to tell them I was closed I noticed that I just had a limited data block on aircraft X still level at FL410. Aircraft X was getting very close to our boundary so I asked the wild sector if they were watching aircraft X. He asked me if aircraft X was descending to FL330 and then he hung up. He immediately called the denver 9 sector and asked them if they were descending aircraft X to FL330. Just then the conflict alert went off with aircraft Y at FL360! The denver controller asked the wild controller if he should stop aircraft X at FL370. The wild controller said affirmative. Our letter of agreement with denver center is that they need to get lincoln landers down to FL330 by our boundary. The denver controller violated sector arctic and wild by descending aircraft X through their airspace without a point out or handoff. And they violated our letter of agreement.denver center's blatant disregard for separation is astonishing to me. The fact that this has been going on for 20 plus years and nothing has been done about it is just as astonishing! If the wild sector hadn't noticed that aircraft X was descending through his airspace there could have been loss of separation or loss of human lives. Management is well aware that denver center hands us conflicts on a daily basis and I don't see anything being done about it!

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Original NASA ASRS Text

Title: ZMP Controllers reported an airspace violation and two aircraft head on at high altitude; caused by ZDV Center.

Narrative: This is the third one that happened within an hour and twenty minutes of each other. I was in the process of closing my sector for the evening (ARCTIC). My airspace is FL390 and above. As I was starting to hand off aircraft to the sectors below me (WILD; and HAWKI) I noticed that Denver 9 was handing off Aircraft X to me level at FL410. Then I noticed that they took the handoff back. I started my briefing to the HAWKI sector they own the airspace on the east side of ARTIC FL380 and below.After finishing my briefing with HAWKI I began my briefing to the WILD sector. They own the west side of ARCTIC when it's closed FL350-FL380. As I was completing my briefing and before I called the adjacent sectors to tell them I was closed I noticed that I just had a limited data block on Aircraft X still level at FL410. Aircraft X was getting very close to our boundary so I asked the WILD sector if they were watching Aircraft X. He asked me if Aircraft X was descending to FL330 and then he hung up. He immediately called the Denver 9 sector and asked them if they were descending Aircraft X to FL330. Just then the conflict alert went off with Aircraft Y at FL360! The Denver Controller asked the WILD Controller if he should stop Aircraft X at FL370. The WILD Controller said affirmative. Our letter of agreement with Denver Center is that they need to get Lincoln landers down to FL330 by our boundary. The Denver Controller violated Sector ARCTIC and WILD by descending Aircraft X through their airspace without a point out or handoff. And they violated our letter of agreement.Denver Center's blatant disregard for separation is astonishing to me. The fact that this has been going on for 20 plus years and nothing has been done about it is just as astonishing! If the WILD sector hadn't noticed that Aircraft X was descending through his airspace there could have been loss of separation or loss of human lives. Management is well aware that Denver Center hands us conflicts on a daily basis and I don't see anything being done about it!

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.