A320 flight crew reported receiving a TERRAIN warning on approach GEG airport.

Report 1 | Narrative: Day VMC; terrain in sight; visual approach to GEG Runway 26 backed up by RNAV GPS Y 26. Flying direct to NAXAF from an ATC radar vector. Approximately 7;000 feet and over higher terrain. Started a descent to NAXAF to 5;200 feet when we were past (backside) of high terrain. Received a momentary (one aural annunciation) GPWS warning for terrain. Even though we were day VMC and in sight of terrain; I initiated the GPWS escape maneuver and we notified ATC of the event. We climbed to approximately 7;000 feet. Assured we were clear of terrain; we resumed descent to visual/normal/stabilized landing.We were descending away from high terrain.

I knew the altitude from HILIE to CUGEV was 6;700 feet and planned my descent to not go below that altitude until clear of terrain. We were flying direct to NAXAF so CUGEV was removed as a reference point for descent. At some point we were low enough to briefly trigger the GPWS. We both were in terrain mode and did not receive any terrain caution before the terrain warning. Also; the terrain presentation on the 320 basic aircraft is very difficult to see in bright sunlight. We would have had better backup to our visual clues if the terrain presentation on the navigation display wasn't so weak.Better awareness of the possibility of a GPWS warning when visual approach to Runway 26.

Don't descend until past CUGEV.

Report 2 | Narrative: On vectors to final approach course Runway 26; and in VMC with good visibility we were given altitude of 6;500 feet to clear terrain. Over the high terrain to the east of GEG; between OZOLA and CUGEV south of the final course; we were asked if we had the runway in sight and given clearance for the visual 26. The Captain set the next lower altitude on the approach of 5;200 feet and began the descent. We quickly got a 'Terrain' caution and even though we had the terrain in sight and knew we were clear the Captain initiated an escape maneuver. He leveled off at 7;000 feet as I reported our terrain avoidance and climb to ATC.

They reconfirmed our clearance for the visual and we continued to a normal landing with no further issues.Delay starting descent until a bit further beyond the high terrain.

Report 1 | Synopsis: A320 flight crew reported receiving a TERRAIN warning on approach GEG airport.