Narrative:

On IFR flight plan from isp to mmu, aircraft at 4000 ft proceeding direct to sax VOR (approximately 260 degree heading) at 200 KIAS. Final controller issued a turn to heading 240 degrees, descend to 2000 ft, cleared GPS runway 23 approach. The PF turned the aircraft to 240 degrees and began setting up the FMS for the GPS approach. The PNF dialed in 2000 ft in the altitude select window and asked the PF what heading the controller had assigned. The PNF then read back the clearance. The aircraft remained at 4000 ft because the PF did not hear or acknowledge the altitude change. After about 60 seconds, the controller came back and reissued a descent to 2000 ft stating there was an air carrier at our 12 O'clock position and 5 mi. The PF immediately descended the aircraft to the correct altitude, the rest of the flight was uneventful. This event occurred because: 1) this PF did not hear the altitude change because he was programming the FMS. 2) the PNF did not confirm with the PF that a descent was given. 3) a requested WX graphic became available on the FMS screen at the same time as the clearance was issued and distraction both crew members. Preventing the same problem from happening again: 1) the PF devote most of his attention on flying the aircraft and following ATC instructions. 2) the PNF insure the PF follows ATC instructions.

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Original NASA ASRS Text

Title: G3 FLC CONDUCTING GPS APCH TO MMU ARPT DID NOT IMMEDIATELY DSND FROM 4000 FT TO 2000 FT AND NEEDED TO BE PROMPTED BY THE CTLR BECAUSE OF OPPOSITE DIRECTION TFC.

Narrative: ON IFR FLT PLAN FROM ISP TO MMU, ACFT AT 4000 FT PROCEEDING DIRECT TO SAX VOR (APPROX 260 DEG HDG) AT 200 KIAS. FINAL CTLR ISSUED A TURN TO HDG 240 DEGS, DSND TO 2000 FT, CLRED GPS RWY 23 APCH. THE PF TURNED THE ACFT TO 240 DEGS AND BEGAN SETTING UP THE FMS FOR THE GPS APCH. THE PNF DIALED IN 2000 FT IN THE ALT SELECT WINDOW AND ASKED THE PF WHAT HDG THE CTLR HAD ASSIGNED. THE PNF THEN READ BACK THE CLRNC. THE ACFT REMAINED AT 4000 FT BECAUSE THE PF DID NOT HEAR OR ACKNOWLEDGE THE ALT CHANGE. AFTER ABOUT 60 SECONDS, THE CTLR CAME BACK AND REISSUED A DSCNT TO 2000 FT STATING THERE WAS AN ACR AT OUR 12 O'CLOCK POS AND 5 MI. THE PF IMMEDIATELY DSNDED THE ACFT TO THE CORRECT ALT, THE REST OF THE FLT WAS UNEVENTFUL. THIS EVENT OCCURRED BECAUSE: 1) THIS PF DID NOT HEAR THE ALT CHANGE BECAUSE HE WAS PROGRAMMING THE FMS. 2) THE PNF DID NOT CONFIRM WITH THE PF THAT A DSCNT WAS GIVEN. 3) A REQUESTED WX GRAPHIC BECAME AVAILABLE ON THE FMS SCREEN AT THE SAME TIME AS THE CLRNC WAS ISSUED AND DISTR BOTH CREW MEMBERS. PREVENTING THE SAME PROB FROM HAPPENING AGAIN: 1) THE PF DEVOTE MOST OF HIS ATTN ON FLYING THE ACFT AND FOLLOWING ATC INSTRUCTIONS. 2) THE PNF INSURE THE PF FOLLOWS ATC INSTRUCTIONS.

Data retrieved from NASA's ASRS site as of July 2007 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.