Narrative:

I was observing operations in the tower cab and heard multiple conflict alerts sounding. Checking our radar display; I saw there was a VFR target (aircraft X) in the corridor between bjc class D airspace and the denver class B; northbound at 7500 MSL. The aircraft was not talking to us and did not appear to be in communication with denver approach either. Aircraft Y was south-eastbound for apa; and was descending; then level at 080. This is another example of an aircraft in that corridor that was operating legally; yet in a potentially hazardous position for conflicts with IFR operations near the class B. I heard another series of conflict alerts sound. At this point; it appeared the same VFR target was in the vicinity of eik airport but now higher; near 8500. A different arrival to apa was descending and then level at 9000 MSL; and this was the conflict causing another series of alarms. The VFR aircraft appeared operating quite close to the class B airspace at this point and if its altitude readout was correct; may have penetrated the airspace while it maneuvered near eik airport. The VFR aircraft turned southbound and appeared to overfly the bjc VOR around 8500; above our airspace (legal; but also potentially in conflict with high performance bjc arrivals/departures). As they flew southbound; I visually confirmed the aircraft was a high-wing. These events highlight the importance of awareness and vigilance for pilots operating VFR in busy terminal areas near controlled airspace. Communication with ATC could have allowed the provision of traffic advisories and control instructions to all the aircraft involved that could have ensured a greater margin of safety between aircraft. I feel like the conflict alert did its job in both of these instances to help ensure the VFR target was not overlooked by controllers at our tower or approach. However; during a busy traffic period; having multiple alarms sound could be a potential distraction from other tasks of higher priority. Long term; I feel like these traffic conflicts raise the possibility of looking into changes to the denver airspace that would help prevent VFR aircraft from operating in some of these areas without ATC approval.

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Original NASA ASRS Text

Title: BJC Tower Controller reported of a problem with VFR aircraft in close proximity to arrival/departure traffic in the DEN Class Bravo. The Controller wants changes made to the Class Bravo for better protection.

Narrative: I was observing operations in the tower cab and heard multiple conflict alerts sounding. Checking our radar display; I saw there was a VFR target (Aircraft X) in the corridor between BJC Class D airspace and the Denver Class B; northbound at 7500 MSL. The aircraft was not talking to us and did not appear to be in communication with Denver Approach either. Aircraft Y was south-eastbound for APA; and was descending; then level at 080. This is another example of an aircraft in that corridor that was operating legally; yet in a potentially hazardous position for conflicts with IFR operations near the Class B. I heard another series of conflict alerts sound. At this point; it appeared the same VFR target was in the vicinity of EIK airport but now higher; near 8500. A different arrival to APA was descending and then level at 9000 MSL; and this was the conflict causing another series of alarms. The VFR aircraft appeared operating quite close to the Class B airspace at this point and if its altitude readout was correct; may have penetrated the airspace while it maneuvered near EIK airport. The VFR aircraft turned southbound and appeared to overfly the BJC VOR around 8500; above our airspace (legal; but also potentially in conflict with high performance BJC arrivals/departures). As they flew southbound; I visually confirmed the aircraft was a high-wing. These events highlight the importance of awareness and vigilance for pilots operating VFR in busy Terminal areas near controlled airspace. Communication with ATC could have allowed the provision of traffic advisories and control instructions to all the aircraft involved that could have ensured a greater margin of safety between aircraft. I feel like the conflict alert did its job in both of these instances to help ensure the VFR target was not overlooked by controllers at our tower or approach. However; during a busy traffic period; having multiple alarms sound could be a potential distraction from other tasks of higher priority. Long term; I feel like these traffic conflicts raise the possibility of looking into changes to the Denver airspace that would help prevent VFR aircraft from operating in some of these areas without ATC approval.

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.