ATL Controller described a loss of separation with a RNAV departure from Runway 8R and another aircraft off Runway 9L; the reporter noting the pilot blamed faulty equipment; adding regardless of fault the RNAV departure procedures should be modified with an initial ATC heading to prevent additional events.

Narrative

I was working Local Control-2; departure runway; and cleared Air Carrier X for takeoff Runway 8R; RNAV to HRSHL. The Pilot read back was correct. After the aircraft was airborne and past the departure end of the runway; I saw the aircraft's wing dip to the left; indicating it was turning to HRSHL; so I switched the aircraft to Departure Control. I then realized the aircraft was still flying straight ahead and called down to the Departure North Controller to advise him. He was already in the process of turning the aircraft northbound away from an aircraft flying a parallel course less than 1 mile off Air Carrier X's right wing which had departed Runway 9L at the same time. Separation was lost and a pilot deviation was filed on the Air Carrier X. The Pilot blamed equipment failure. Recommendation; we continue to have problems with RNAV departures out of ATL. Whether it be controller error; pilot error or in this case; 'equipment failure'; the only solution is to terminate RNAV off the ground and issue headings off the ground 24 hours a day; every day. In addition; we need to have the same headings off each runway whether we're in triple runway departures or not. This becomes very confusing to pilots and controllers alike.