Narrative:

On the grnpa 1 arrival into las our initial clearance was to cross luxor at 12000 ft and 250 KTS. The constraints for the arrival had been verified in the box. Next; we received the clearance to descend via the arrival. Upon receiving this clearance we set 8000 ft in the altitude selector and continued the descent in a managed mode. During the descent; prior to luxor; we were told to expect a visual to runway 19R. The box was programmed for landing on runway 25L. While reprogramming the box for runway 19R the altitude and speed constraints dropped out of the box and reverted to open descent and selected speed. Before we caught it; we were at 10500 ft and 300 KTS at luxor. We made the correction to cross grnpa at 11000 ft; still slowing on the speed. The next clearance we received was direct trrop intersection down to 8000 ft which was accomplished as directed. No comment was made by ATC regarding our deviation. The problem was 2 pilots trying to reprogram the box instead of 1 pilot flying and 1 pilot programming the box during a critical phase of flight. I believe a procedural change should take place at our airline. The current SOP is the PF programs the box if the airplane is on autoplt. I think the PNF should always be the one programming the box so the PF can do just that -- fly the airplane and not be 'head down' programming the box. Supplemental information from acn 692994: at this point I asked what happened and apparently without advising me the first officer had elected to activate the secondary flight plan in the mcdu which had been programmed by the first officer for runway 19R but apparently without the grnpa 1 arrival and thus when the first officer activated the secondary flight plan all lateral and vertical guidance was lost.

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Original NASA ASRS Text

Title: A319 FLT CREW ON GRNPA RNAV STAR TO LAS LOSES ALT RESTRAINTS IN THE FMS WHEN PROGRAMMING FOR A RWY CHANGE. ALT AND SPD DEVS RESULT.

Narrative: ON THE GRNPA 1 ARR INTO LAS OUR INITIAL CLRNC WAS TO CROSS LUXOR AT 12000 FT AND 250 KTS. THE CONSTRAINTS FOR THE ARR HAD BEEN VERIFIED IN THE BOX. NEXT; WE RECEIVED THE CLRNC TO DSND VIA THE ARR. UPON RECEIVING THIS CLRNC WE SET 8000 FT IN THE ALT SELECTOR AND CONTINUED THE DSCNT IN A MANAGED MODE. DURING THE DSCNT; PRIOR TO LUXOR; WE WERE TOLD TO EXPECT A VISUAL TO RWY 19R. THE BOX WAS PROGRAMMED FOR LNDG ON RWY 25L. WHILE REPROGRAMMING THE BOX FOR RWY 19R THE ALT AND SPD CONSTRAINTS DROPPED OUT OF THE BOX AND REVERTED TO OPEN DSCNT AND SELECTED SPD. BEFORE WE CAUGHT IT; WE WERE AT 10500 FT AND 300 KTS AT LUXOR. WE MADE THE CORRECTION TO CROSS GRNPA AT 11000 FT; STILL SLOWING ON THE SPD. THE NEXT CLRNC WE RECEIVED WAS DIRECT TRROP INTXN DOWN TO 8000 FT WHICH WAS ACCOMPLISHED AS DIRECTED. NO COMMENT WAS MADE BY ATC REGARDING OUR DEV. THE PROB WAS 2 PLTS TRYING TO REPROGRAM THE BOX INSTEAD OF 1 PLT FLYING AND 1 PLT PROGRAMMING THE BOX DURING A CRITICAL PHASE OF FLT. I BELIEVE A PROCEDURAL CHANGE SHOULD TAKE PLACE AT OUR AIRLINE. THE CURRENT SOP IS THE PF PROGRAMS THE BOX IF THE AIRPLANE IS ON AUTOPLT. I THINK THE PNF SHOULD ALWAYS BE THE ONE PROGRAMMING THE BOX SO THE PF CAN DO JUST THAT -- FLY THE AIRPLANE AND NOT BE 'HEAD DOWN' PROGRAMMING THE BOX. SUPPLEMENTAL INFO FROM ACN 692994: AT THIS POINT I ASKED WHAT HAPPENED AND APPARENTLY WITHOUT ADVISING ME THE FO HAD ELECTED TO ACTIVATE THE SECONDARY FLT PLAN IN THE MCDU WHICH HAD BEEN PROGRAMMED BY THE FO FOR RWY 19R BUT APPARENTLY WITHOUT THE GRNPA 1 ARR AND THUS WHEN THE FO ACTIVATED THE SECONDARY FLT PLAN ALL LATERAL AND VERT GUIDANCE WAS LOST.

Data retrieved from NASA's ASRS site as of January 2009 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.