Narrative:

Departed ZZZ prior to tower opening. Calm wind with fog forming east of the field and no other traffic talking to flight service or VFR common; so I elected to depart runway xx. While taxiing to the runway a cessna caravan called departing runway X. The caravan turned downwind to the west and reported us in sight and that he would pass behind us when we departed. We departed runway xx on the zzzzzx rnp (required navigation performance) (and announced such on common) departure with the caravan in sight the entire time. Commencing the turn departing xx it was clear that we would pass behind the caravan not vice versa. I maintained visual contact and adequate clearance. Climbing through about 1;000' I got a traffic alert followed by a descend RA. There is terrain to the left and below at that point in the departure. Since we never lost visual contact with the traffic and we were at his 6 o'clock position; and therefore there was no maneuver he could make that would cause a collision; I felt that the safest course of action was to increase my rate of turn away on the departure (increasing lateral separation) and continue to climb. We rapidly climbed away and above the traffic and the RA resolved. At no time did the situation meet the criteria for a near midair collision report.in hindsight I realized that the caravan pilot was probably not familiar with the rnp procedure (nor would he have reason to be) and didn't know I would be turning to the left (south) after takeoff. He probably assumed I would be departing straight out on the runway X localizer (non rnp procedure) which is why he stayed south of the extended runway xx centerline instead of crossing over as I expected. Had I thought of this in advance; instead of after the fact; I would have either given him more time to depart or informed him of my rnp procedural turn.

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Original NASA ASRS Text

Title: Air Carrier Captain reported choosing not to follow TCAS RA alert due to terrain.

Narrative: Departed ZZZ prior to tower opening. Calm wind with fog forming east of the field and no other traffic talking to flight service or VFR common; so I elected to depart Runway XX. While taxiing to the runway a Cessna Caravan called departing Runway X. The Caravan turned downwind to the west and reported us in sight and that he would pass behind us when we departed. We departed Runway XX on the ZZZZZX RNP (Required Navigation Performance) (and announced such on common) departure with the Caravan in sight the entire time. Commencing the turn departing XX it was clear that we would pass behind the Caravan not vice versa. I maintained visual contact and adequate clearance. Climbing through about 1;000' I got a traffic alert followed by a descend RA. There is terrain to the left and below at that point in the departure. Since we never lost visual contact with the traffic and we were at his 6 o'clock position; and therefore there was no maneuver he could make that would cause a collision; I felt that the safest course of action was to increase my rate of turn away on the departure (increasing lateral separation) and continue to climb. We rapidly climbed away and above the traffic and the RA resolved. At no time did the situation meet the criteria for a near midair collision report.In hindsight I realized that the Caravan pilot was probably not familiar with the RNP procedure (nor would he have reason to be) and didn't know I would be turning to the left (south) after takeoff. He probably assumed I would be departing straight out on the Runway X localizer (non RNP procedure) which is why he stayed south of the extended Runway XX centerline instead of crossing over as I expected. Had I thought of this in advance; instead of after the fact; I would have either given him more time to depart or informed him of my RNP procedural turn.

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.