Narrative:

Assigned kennedy 1 departure canarsie climb out of jfk. The canarsie climb was selected from the database and checked for accuracy at the gate by both of us and then confirmed just prior to taking runway 31L as part of the before takeoff check by both of us. LNAV was selected as roll mode. At 400 ft AGL the captain initiated a turn direct to cri VOR following the magenta line. The aircraft rolled out direct cri then the lead turn was started following the magenta line; still hand flown. Somewhere in the turn; the FMS produced a discontinuity between cri and the cri 176 radial. Approach asked us what climb we were on. I responded that we were flying the canarsie climb. He notified us we needed a left turn to get back on the radial. At that point we realized there was a discontinuity between the cri VOR and the next point down the 176 radial. We don't exactly know when the discontinuity developed or why; but theorize it developed during the turn to lead the radial; although LNAV remained connected; and no warning lights were displayed. We were off the radial and did not have a magenta line. I think the problem is that the FMS point down the 176 radial is only 2 miles from the VOR and the FMS lead point for the radial positioned the aircraft past that point and a discontinuity was produced un-noticed by either of us.callback conversation with reporter revealed the following information: the reporter stated that the FMS presentation was normal during preflight; takeoff; and initial climb. Shortly after the turn to cri the route discontinuity developed. The reporter reached down to the FMS attempting to program a fix beyond the cri 176/2 which is the end of the programmed departure. After that point the aircraft is expected to fly the 176 degree heading. Before he could enter a new fix the crew was given a heading to intercept the 176 degrees. The reporter does not believe the flight director transitioned to heading hold when the route discontinuity developed but he is not sure because he selected heading select and the vector heading after ATC's vector.

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Original NASA ASRS Text

Title: A B737-800 FLYING THE KENNEDY ONE CANARSIE CLB RECEIVED A RTE DISCONTINUITY AND TRACK DEV AFTER FAILING TO CAPTURE THE 176 DEG R OUTBOUND.

Narrative: ASSIGNED KENNEDY 1 DEP CANARSIE CLB OUT OF JFK. THE CANARSIE CLB WAS SELECTED FROM THE DATABASE AND CHKED FOR ACCURACY AT THE GATE BY BOTH OF US AND THEN CONFIRMED JUST PRIOR TO TAKING RWY 31L AS PART OF THE BEFORE TAKEOFF CHK BY BOTH OF US. LNAV WAS SELECTED AS ROLL MODE. AT 400 FT AGL THE CAPT INITIATED A TURN DIRECT TO CRI VOR FOLLOWING THE MAGENTA LINE. THE ACFT ROLLED OUT DIRECT CRI THEN THE LEAD TURN WAS STARTED FOLLOWING THE MAGENTA LINE; STILL HAND FLOWN. SOMEWHERE IN THE TURN; THE FMS PRODUCED A DISCONTINUITY BETWEEN CRI AND THE CRI 176 RADIAL. APCH ASKED US WHAT CLB WE WERE ON. I RESPONDED THAT WE WERE FLYING THE CANARSIE CLB. HE NOTIFIED US WE NEEDED A L TURN TO GET BACK ON THE RADIAL. AT THAT POINT WE REALIZED THERE WAS A DISCONTINUITY BETWEEN THE CRI VOR AND THE NEXT POINT DOWN THE 176 RADIAL. WE DON'T EXACTLY KNOW WHEN THE DISCONTINUITY DEVELOPED OR WHY; BUT THEORIZE IT DEVELOPED DURING THE TURN TO LEAD THE RADIAL; ALTHOUGH LNAV REMAINED CONNECTED; AND NO WARNING LIGHTS WERE DISPLAYED. WE WERE OFF THE RADIAL AND DID NOT HAVE A MAGENTA LINE. I THINK THE PROB IS THAT THE FMS POINT DOWN THE 176 RADIAL IS ONLY 2 MILES FROM THE VOR AND THE FMS LEAD POINT FOR THE RADIAL POSITIONED THE ACFT PAST THAT POINT AND A DISCONTINUITY WAS PRODUCED UN-NOTICED BY EITHER OF US.CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT THE FMS PRESENTATION WAS NORMAL DURING PREFLT; TKOF; AND INITIAL CLB. SHORTLY AFTER THE TURN TO CRI THE RTE DISCONTINUITY DEVELOPED. THE RPTR REACHED DOWN TO THE FMS ATTEMPTING TO PROGRAM A FIX BEYOND THE CRI 176/2 WHICH IS THE END OF THE PROGRAMMED DEP. AFTER THAT POINT THE ACFT IS EXPECTED TO FLY THE 176 DEG HDG. BEFORE HE COULD ENTER A NEW FIX THE CREW WAS GIVEN A HDG TO INTERCEPT THE 176 DEGS. THE RPTR DOES NOT BELIEVE THE FLT DIRECTOR TRANSITIONED TO HDG HOLD WHEN THE RTE DISCONTINUITY DEVELOPED BUT HE IS NOT SURE BECAUSE HE SELECTED HDG SELECT AND THE VECTOR HDG AFTER ATC'S VECTOR.

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.