Narrative:

Our clearance was orl-J53-crg-J55 sav-J121 chs, orf, swl, sie-vcn-VCN2 phl. Our filed altitude was FL330. Around barbs on J53 the captain programmed in direct chs in the FMC to see what savings it would give us. He did not execute the entry. He called ZJX to see if we could go direct chs. About that same time ZJX said that we could stay at FL270 where we had just leveled and maintain normal cruise speed, or we could climb to FL290 and slow down. They also said that we could not go direct chs because portions of the warning area were active. We decided to stay at FL270 so we could maintain our speed. I programmed the new altitude of FL270 and the speed into the FMC and asked the captain if he was using the FMC. He said no, so I executed the altitude and speed. Unfortunately the direct chs command on the capts FMC control had not been erased and when I executed my input, it also executed direct chs. The airplane made a turn (slight) and shortly thereafter ZJX called and asked if we had made a heading change and for us to make a turn to 330. It was at this point that I noticed the FMC was commanding direct chs instead of J53 to crg. I hd the cruise page up previously and had just switched back to the progress page which shows the next navigation point. The course deviation in our opinion was approximately 4 mi before the correction was made. We did not penetrate the warning area. The only way I can suggest to avoid this type of error is to make sure two people are not programming the FMC simultaneously.

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Original NASA ASRS Text

Title: TRACK DEVIATION FOR ADVTECH ACR MLG.

Narrative: OUR CLRNC WAS ORL-J53-CRG-J55 SAV-J121 CHS, ORF, SWL, SIE-VCN-VCN2 PHL. OUR FILED ALT WAS FL330. AROUND BARBS ON J53 THE CAPT PROGRAMMED IN DIRECT CHS IN THE FMC TO SEE WHAT SAVINGS IT WOULD GIVE US. HE DID NOT EXECUTE THE ENTRY. HE CALLED ZJX TO SEE IF WE COULD GO DIRECT CHS. ABOUT THAT SAME TIME ZJX SAID THAT WE COULD STAY AT FL270 WHERE WE HAD JUST LEVELED AND MAINTAIN NORMAL CRUISE SPD, OR WE COULD CLB TO FL290 AND SLOW DOWN. THEY ALSO SAID THAT WE COULD NOT GO DIRECT CHS BECAUSE PORTIONS OF THE WARNING AREA WERE ACTIVE. WE DECIDED TO STAY AT FL270 SO WE COULD MAINTAIN OUR SPD. I PROGRAMMED THE NEW ALT OF FL270 AND THE SPD INTO THE FMC AND ASKED THE CAPT IF HE WAS USING THE FMC. HE SAID NO, SO I EXECUTED THE ALT AND SPD. UNFORTUNATELY THE DIRECT CHS COMMAND ON THE CAPTS FMC CTL HAD NOT BEEN ERASED AND WHEN I EXECUTED MY INPUT, IT ALSO EXECUTED DIRECT CHS. THE AIRPLANE MADE A TURN (SLIGHT) AND SHORTLY THEREAFTER ZJX CALLED AND ASKED IF WE HAD MADE A HDG CHANGE AND FOR US TO MAKE A TURN TO 330. IT WAS AT THIS POINT THAT I NOTICED THE FMC WAS COMMANDING DIRECT CHS INSTEAD OF J53 TO CRG. I HD THE CRUISE PAGE UP PREVIOUSLY AND HAD JUST SWITCHED BACK TO THE PROGRESS PAGE WHICH SHOWS THE NEXT NAV POINT. THE COURSE DEV IN OUR OPINION WAS APPROX 4 MI BEFORE THE CORRECTION WAS MADE. WE DID NOT PENETRATE THE WARNING AREA. THE ONLY WAY I CAN SUGGEST TO AVOID THIS TYPE OF ERROR IS TO MAKE SURE TWO PEOPLE ARE NOT PROGRAMMING THE FMC SIMULTANEOUSLY.

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.