Narrative:

While descending on the new DSNEE1 arrival going to lgb; we crossed dsnee intersection at 8000 feet and 220 knots. We began our descent to cross mckye at or above 7800 as depicted. ATC called traffic; aircraft X at our 2 o'clock position; level at 7;000 and converging right to left. We visually acquired the boeing just as we crossed dsnee.we were descending on autopilot using FMS/VNAV and when we crossed dsnee the autopilot began a right turn from our 216 degree heading to the 236 heading required by the STAR and initiated a descent to 7800 feet. As we descended and turned; we got a 'monitor vertical rate' annunciation from our TCAS at about the same time as the aircraft leveled at 7800 feet.this is a new arrival and we believe the fact that we were descending and converging with aircraft X triggered the RA. We heard the aircraft X crew advise ATC that they got an RA as well. ATC called us and asked our altitude who was at that time 7800 feet. The rajee departure off ont calls for 7000 feet at rajee and that intersection is just south of dsnee so the step down after dsnee should probably not begin at dsnee; perhaps not till mckye or ATC might have told us to level at 8000 feet until clear of aircraft X.at no time was there any question of a conflict as both crews had each other in sight and communicated that fact to ATC.

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Original NASA ASRS Text

Title: Citation pilot reported that a descent on their arrival was a factor for other traffic departing a close by airport.

Narrative: While descending on the new DSNEE1 arrival going to LGB; we crossed DSNEE intersection at 8000 feet and 220 knots. We began our descent to cross Mckye at or above 7800 as depicted. ATC called traffic; Aircraft X at our 2 o'clock position; level at 7;000 and converging right to left. We visually acquired the Boeing just as we crossed DSNEE.We were descending on autopilot using FMS/VNAV and when we crossed DSNEE the autopilot began a right turn from our 216 degree heading to the 236 heading required by the STAR and initiated a descent to 7800 feet. As we descended and turned; we got a 'monitor vertical rate' annunciation from our TCAS at about the same time as the aircraft leveled at 7800 feet.This is a new arrival and we believe the fact that we were descending and converging with Aircraft X triggered the RA. We heard the Aircraft X crew advise ATC that they got an RA as well. ATC called us and asked our altitude who was at that time 7800 feet. The RAJEE departure off ONT calls for 7000 feet at RAJEE and that intersection is just south of DSNEE so the step down after DSNEE should probably not begin at DSNEE; perhaps not till Mckye or ATC might have told us to level at 8000 feet until clear of Aircraft X.At no time was there any question of a conflict as both crews had each other in sight and communicated that fact to ATC.

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.