Narrative:

I was the captain on an air carrier flight from iah to ewr. The first officer left the cockpit to visit the lavatory. I received a clearance to cross 55 DME south of kenton at or below 270 to maintain 240. My acknowledgement was blocked and I was asked to repeat it, thus losing some time. I had difficulty entering the fix into the CDU of the IRS (the inertial navigation system on the medium large transport). It kept refusing the fix. At about this time I received a call from one of the F/a's to find out how much time was remaining. Then the first officer knocked to gain admission to the cockpit. I let him in and explained the difficulty I was having with the computer while at the same time trying to tune the eno VOR manually to figure out the distance left to the crossing fix. The IRS programmed 'top of descent' point was indicating less than 20 mi from the crossing point. We finally figured out that the crossing restriction fix was in the wrong sequence in the IRS. (I am quite sure that I loaded it correctly. I don't know why it was wrong). I told him to tell center that it was too late and that we would be unable to comply with the clearance just as they called and said that our mode C showed us still at 370 and that we were approaching our crossing fix. Center then changed our clearance and said that everything was ok in that there was no conflict with other aircraft. I feel that this event should not have happened. I feel that proper cockpit management on my part could have prevented it. My recommendations (and my new procedures) are: 1) continually back up the IRS with the VOR's along the route of flight and not to depend too much on the computer, 2) have crew members make their physiological visits early on so as not to conflict with the busier times, such as approaching dscnts, 3) 'fly first' and answer cabin calls when able, better priority order, 4) return to the 3-MAN crew.

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Original NASA ASRS Text

Title: MISSED CROSSING RESTRICTION DUE TO FO OUT OF COCKPIT, CLRNC GIVEN TO DESCEND AT THAT TIME. CAPT UNABLE TO PROGRAM IRS CORRECTLY AND DISTR FROM FA REQUEST.

Narrative: I WAS THE CAPT ON AN ACR FLT FROM IAH TO EWR. THE F/O LEFT THE COCKPIT TO VISIT THE LAVATORY. I RECEIVED A CLRNC TO CROSS 55 DME S OF KENTON AT OR BELOW 270 TO MAINTAIN 240. MY ACKNOWLEDGEMENT WAS BLOCKED AND I WAS ASKED TO REPEAT IT, THUS LOSING SOME TIME. I HAD DIFFICULTY ENTERING THE FIX INTO THE CDU OF THE IRS (THE INERTIAL NAV SYSTEM ON THE MLG). IT KEPT REFUSING THE FIX. AT ABOUT THIS TIME I RECEIVED A CALL FROM ONE OF THE F/A'S TO FIND OUT HOW MUCH TIME WAS REMAINING. THEN THE F/O KNOCKED TO GAIN ADMISSION TO THE COCKPIT. I LET HIM IN AND EXPLAINED THE DIFFICULTY I WAS HAVING WITH THE COMPUTER WHILE AT THE SAME TIME TRYING TO TUNE THE ENO VOR MANUALLY TO FIGURE OUT THE DISTANCE LEFT TO THE XING FIX. THE IRS PROGRAMMED 'TOP OF DESCENT' POINT WAS INDICATING LESS THAN 20 MI FROM THE XING POINT. WE FINALLY FIGURED OUT THAT THE XING RESTRICTION FIX WAS IN THE WRONG SEQUENCE IN THE IRS. (I AM QUITE SURE THAT I LOADED IT CORRECTLY. I DON'T KNOW WHY IT WAS WRONG). I TOLD HIM TO TELL CENTER THAT IT WAS TOO LATE AND THAT WE WOULD BE UNABLE TO COMPLY WITH THE CLRNC JUST AS THEY CALLED AND SAID THAT OUR MODE C SHOWED US STILL AT 370 AND THAT WE WERE APCHING OUR XING FIX. CENTER THEN CHANGED OUR CLRNC AND SAID THAT EVERYTHING WAS OK IN THAT THERE WAS NO CONFLICT WITH OTHER ACFT. I FEEL THAT THIS EVENT SHOULD NOT HAVE HAPPENED. I FEEL THAT PROPER COCKPIT MGMNT ON MY PART COULD HAVE PREVENTED IT. MY RECOMMENDATIONS (AND MY NEW PROCS) ARE: 1) CONTINUALLY BACK UP THE IRS WITH THE VOR'S ALONG THE ROUTE OF FLT AND NOT TO DEPEND TOO MUCH ON THE COMPUTER, 2) HAVE CREW MEMBERS MAKE THEIR PHYSIOLOGICAL VISITS EARLY ON SO AS NOT TO CONFLICT WITH THE BUSIER TIMES, SUCH AS APCHING DSCNTS, 3) 'FLY FIRST' AND ANSWER CABIN CALLS WHEN ABLE, BETTER PRIORITY ORDER, 4) RETURN TO THE 3-MAN CREW.

Data retrieved from NASA's ASRS site as of August 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.