Light Transport; Low Wing; 2 Turbojet Eng
Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 90; Flight Crew Total 11090; Flight Crew Type 40350
Human-Machine Interface; Training / Qualification; Workload; Distraction
Deviation - Altitude Overshoot; Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance
Flight Crew Became Reoriented; Flight Crew Took Evasive Action; Flight Crew Returned To Clearance
Human Factors; Procedure
On the BACHR1 STAR to Dallas Love field. Fort Worth Center told us to descend and maintain 24;000 feet. We complied and leveled off at our assigned altitude of FL240. Shortly before the ANGST fix we were given descend via the arrival. I then set the lowest altitude on the BACHR1 (RNAV) STAR IN the Altitude select and activated the VNAV I then slowed to the crossing speed restriction of 280kts @FL240. My attention was diverted for no more that a minute. When I saw we had started our descent prematurely and passing below our hard alt of FL240 AT ANGST I disengage the autopilot and stopped the descent. The autopilot and FMS were reset and after that all other fixes were crossed at the appropriate altitudes... (THERE WERE NO TRAFFIC CONFLICTS)..After landing we as a crew discussed what could have been done to prevent this and keep it from ever happening again.
An air taxi jet crew leveled at FL240 on the BACHR1 RNAV to DAL and when cleared VIA before ANGST; the lowest STAR MCP altitude was selected. The aircraft began a descent before the crew realized the error but they recovered to FL240.