Narrative:

On an IFR flight plan for dfw to ugn, we were cruising at FL390. ZAU cleared us to descend and maintain FL350. I started a descent at 1000 FPM, coupled the autoplt to vertical speed and started down. Passing approximately FL370, center gave a crossing restr of 50 mi south of jot at FL240. The sic read the clearance back, and we both verified it as he set FL240 into the altitude preselect. I then programmed the FMS to cross 50 mi south of jot at FL240, and as always, the pseudo GS appeared on my EFIS display. I didn't bother to do the math in my head to see how fast we had to come down, I chose to rely solely on the FMS -- my first mistake. The GS always pops up deflected all the way up. In other words, it's telling you that you are below the GS. Once I saw that, I told myself 'I don't need to start down yet, I'll wait until the GS needle intercepts, and I'll follow it down -- for the time being, I'll continue my nice 1000 FPM descent.' I then diverted my attention back to the FMS, configuring it for our arrival into ugn. Passing through approximately FL310, I noticed we were only 60 mi out of jot, and realized I had turned my attention away from our crossing restr, had not increased our rate of descent and at that time I increased the rate. At that same time, center inquired if we were given the restr, and what rate were we descending at. We acknowledged and currently were at 2700 FPM and increasing. We were then told to turn right heading 090 degrees and give our best rate down, which I did, and descended at 4000 FPM. To my knowledge we caused no other aircraft to divert, and upon reaching FL240 were cleared back on course. I would say a contributing factor was over automation on my part, and unfamiliarity with the system of a new airplane. With dual FMS's, both the sic and myself were inputting information into our respective units, rather than one of us flying the airplane (myself). Rather, I should have left the programming to the sic and had him xfer the information to mine, a procedure outlined in our SOP. In the future, I will take care of my first priority, flying the airplane. Second, I will follow our SOP, and thirdly leave my practicing till we're on the ground.

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Original NASA ASRS Text

Title: AN H25A CREW, IN DSCNT, UNDERSHOT AN ASSIGNED ALT, MISSING A XING RESTR.

Narrative: ON AN IFR FLT PLAN FOR DFW TO UGN, WE WERE CRUISING AT FL390. ZAU CLRED US TO DSND AND MAINTAIN FL350. I STARTED A DSCNT AT 1000 FPM, COUPLED THE AUTOPLT TO VERT SPD AND STARTED DOWN. PASSING APPROX FL370, CTR GAVE A XING RESTR OF 50 MI S OF JOT AT FL240. THE SIC READ THE CLRNC BACK, AND WE BOTH VERIFIED IT AS HE SET FL240 INTO THE ALT PRESELECT. I THEN PROGRAMMED THE FMS TO CROSS 50 MI S OF JOT AT FL240, AND AS ALWAYS, THE PSEUDO GS APPEARED ON MY EFIS DISPLAY. I DIDN'T BOTHER TO DO THE MATH IN MY HEAD TO SEE HOW FAST WE HAD TO COME DOWN, I CHOSE TO RELY SOLELY ON THE FMS -- MY FIRST MISTAKE. THE GS ALWAYS POPS UP DEFLECTED ALL THE WAY UP. IN OTHER WORDS, IT'S TELLING YOU THAT YOU ARE BELOW THE GS. ONCE I SAW THAT, I TOLD MYSELF 'I DON'T NEED TO START DOWN YET, I'LL WAIT UNTIL THE GS NEEDLE INTERCEPTS, AND I'LL FOLLOW IT DOWN -- FOR THE TIME BEING, I'LL CONTINUE MY NICE 1000 FPM DSCNT.' I THEN DIVERTED MY ATTN BACK TO THE FMS, CONFIGURING IT FOR OUR ARR INTO UGN. PASSING THROUGH APPROX FL310, I NOTICED WE WERE ONLY 60 MI OUT OF JOT, AND REALIZED I HAD TURNED MY ATTN AWAY FROM OUR XING RESTR, HAD NOT INCREASED OUR RATE OF DSCNT AND AT THAT TIME I INCREASED THE RATE. AT THAT SAME TIME, CTR INQUIRED IF WE WERE GIVEN THE RESTR, AND WHAT RATE WERE WE DSNDING AT. WE ACKNOWLEDGED AND CURRENTLY WERE AT 2700 FPM AND INCREASING. WE WERE THEN TOLD TO TURN R HDG 090 DEGS AND GIVE OUR BEST RATE DOWN, WHICH I DID, AND DSNDED AT 4000 FPM. TO MY KNOWLEDGE WE CAUSED NO OTHER ACFT TO DIVERT, AND UPON REACHING FL240 WERE CLRED BACK ON COURSE. I WOULD SAY A CONTRIBUTING FACTOR WAS OVER AUTOMATION ON MY PART, AND UNFAMILIARITY WITH THE SYS OF A NEW AIRPLANE. WITH DUAL FMS'S, BOTH THE SIC AND MYSELF WERE INPUTTING INFO INTO OUR RESPECTIVE UNITS, RATHER THAN ONE OF US FLYING THE AIRPLANE (MYSELF). RATHER, I SHOULD HAVE LEFT THE PROGRAMMING TO THE SIC AND HAD HIM XFER THE INFO TO MINE, A PROC OUTLINED IN OUR SOP. IN THE FUTURE, I WILL TAKE CARE OF MY FIRST PRIORITY, FLYING THE AIRPLANE. SECOND, I WILL FOLLOW OUR SOP, AND THIRDLY LEAVE MY PRACTICING TILL WE'RE ON THE GND.

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.