D01 approach controller reported a track deviation occurred on the ldora STAR arrival into den. Repo...

Attributes
ACN	1582965
Time
Date	201810
Local Time Of Day	0601-1200
Place
Locale Reference	D01.TRACON
State Reference	CO
Aircraft 1
Make Model Name	EMB ERJ 170/175 ER/LR
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Other Instrument Approach STAR LDORA
Flight Plan	IFR
Aircraft 2
Make Model Name	B737 Next Generation Undifferentiated
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Other Instrument Approach STAR BOSSS
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 5
Events
Anomaly	ATC Issue All Types Conflict Airborne Conflict Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy Deviation - Track / Heading All Types

Narrative:

Aircraft X descending via the ldora STAR for 34R and aircraft Y descending via the bosss STAR. Aircraft X did not execute the STAR correctly and went through the localizer and was pointed right at aircraft Y. I turned both aircraft and aircraft X advised he was in TCAS RA and was climbing. Both aircraft were given the ILS 34R. If replayed [another B737] who was two planes ahead of aircraft X did the exact same thing. At the time I was watching aircraft X the whole way in since the sequence was going to be tight. There was no possible way I could have reacted any quicker. We have an RNAV 'descend via' structure that connects to ILS transitions. We also use rnp ar approaches from the downwind. We need RNAV transitions from the RNAV stars to RNAV approaches for the short side stars. If the structure was rnp ar descent rate would be more efficient and more accurate than an ILS transition that is probably being hand flown. Aircraft routinely come off the ILS transitions and we watch the crew try to figure out how; or tell them how to resume it. This causes us extra workload and makes it more difficult to run the sequence. We very rarely see blunders off an rnp ar if the crew was expecting the procedure. Making an RNAV structure that works like the rnp approaches from the downwinds would mitigate or solve this issue.

Original NASA ASRS Text

Title: D01 Approach Controller reported a track deviation occurred on the LDORA STAR arrival into DEN. Reporter stated this is not unusual and stressed the need for RNAV transitions from RNAV STARs to RNAV approaches to minimize these occurrences.

Narrative: Aircraft X descending via the LDORA STAR for 34R and Aircraft Y descending via the BOSSS STAR. Aircraft X did not execute the STAR correctly and went through the localizer and was pointed right at Aircraft Y. I turned both aircraft and Aircraft X advised he was in TCAS RA and was climbing. Both aircraft were given the ILS 34R. If replayed [another B737] who was two planes ahead of Aircraft X did the exact same thing. At the time I was watching Aircraft X the whole way in since the sequence was going to be tight. There was no possible way I could have reacted any quicker. We have an RNAV 'descend via' structure that connects to ILS transitions. We also use RNP AR approaches from the downwind. We need RNAV transitions from the RNAV STARs to RNAV approaches for the short side stars. If the structure was RNP AR descent rate would be more efficient and more accurate than an ILS transition that is probably being hand flown. Aircraft routinely come off the ILS transitions and we watch the crew try to figure out how; or tell them how to resume it. This causes us extra workload and makes it more difficult to run the sequence. We very rarely see blunders off an RNP AR if the crew was expecting the procedure. Making an RNAV structure that works like the RNP approaches from the downwinds would mitigate or solve this issue.

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.

D01 approach controller reported a track deviation occurred on the ldora STAR arrival into den. Reporter stated this is not unusual and stressed the need for RNAV transitions from RNAV stars to RNAV approaches to minimize these occurrences.