Narrative:

Leg was flown from boi to las with the following MEL items. Aft lavatory inoperative, APU inoperative, and #2 DME receiver inoperative. After departure from boi, LNAV was used to fly en route to las. Normal NAVAID monitoring was accomplished en route by both pilots and no off course deviations were noted. Approaching las we discovered that LNAV was not to be used with the #2 DME receiver inoperative. We did not notice this MEL restr prior to takeoff from boi. A direct clearance to the las VOR was then received. LNAV procedures were terminated, and normal vectoring for a visual landing to runway 1R at las was accomplished. I believe our failure to fully digest all the MEL implications/restrs, as well as the multiple MEL write-ups on this aircraft (this was the first time I saw more than 1 MEL item on an airplane) caused this oversight. A more thorough review and discussion of all MEL items prior to takeoff, by both pilots, could have prevented this oversight. Supplemental information from acn 564310: one thing that may help is any time there are MEL's that affect other system, put it on the flight release in addition to the supplemental sheets, ie, MEL 34-13 #2 DME (LNAV inoperative) instead of just MEL 34-13 #2 DME.

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Original NASA ASRS Text

Title: WITHOUT LNAV CAPABILITY DUE TO INOP DME, AN ACR CREW USES THE SYS IN ERROR.

Narrative: LEG WAS FLOWN FROM BOI TO LAS WITH THE FOLLOWING MEL ITEMS. AFT LAVATORY INOP, APU INOP, AND #2 DME RECEIVER INOP. AFTER DEP FROM BOI, LNAV WAS USED TO FLY ENRTE TO LAS. NORMAL NAVAID MONITORING WAS ACCOMPLISHED ENRTE BY BOTH PLTS AND NO OFF COURSE DEVS WERE NOTED. APCHING LAS WE DISCOVERED THAT LNAV WAS NOT TO BE USED WITH THE #2 DME RECEIVER INOP. WE DID NOT NOTICE THIS MEL RESTR PRIOR TO TKOF FROM BOI. A DIRECT CLRNC TO THE LAS VOR WAS THEN RECEIVED. LNAV PROCS WERE TERMINATED, AND NORMAL VECTORING FOR A VISUAL LNDG TO RWY 1R AT LAS WAS ACCOMPLISHED. I BELIEVE OUR FAILURE TO FULLY DIGEST ALL THE MEL IMPLICATIONS/RESTRS, AS WELL AS THE MULTIPLE MEL WRITE-UPS ON THIS ACFT (THIS WAS THE FIRST TIME I SAW MORE THAN 1 MEL ITEM ON AN AIRPLANE) CAUSED THIS OVERSIGHT. A MORE THOROUGH REVIEW AND DISCUSSION OF ALL MEL ITEMS PRIOR TO TKOF, BY BOTH PLTS, COULD HAVE PREVENTED THIS OVERSIGHT. SUPPLEMENTAL INFO FROM ACN 564310: ONE THING THAT MAY HELP IS ANY TIME THERE ARE MEL'S THAT AFFECT OTHER SYS, PUT IT ON THE FLT RELEASE IN ADDITION TO THE SUPPLEMENTAL SHEETS, IE, MEL 34-13 #2 DME (LNAV INOP) INSTEAD OF JUST MEL 34-13 #2 DME.

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.