Narrative:

Pilots misunderstood clearance on the departure from bzn. Believed clearance to require on runway 30 a climbing left turn to 275 degree heading to intercept the bzn 284 degree radial. The procedure requires a climb to 8000 ft then a turn to the bzn VOR. Pilots did not turn to the bzn VOR, but continued out the 284 degree radial west to clearance limit altitude of 14000 ft. On initial contact with ZLC pilots' were instructed to contact ZLC again at 10 DME from bzn VOR. The call was made and ATC questioned our clearance. ATC then assigned us a vector on course. Contributing factors were pilots' careful attention to terrain avoidance (MEA) and adherence to the believed clearance. The procedure is written in a manner that may lead to confusion. The pilots believed that the procedure ended on course outbound the bzn 284 degree radial because the next sentence starts with the exception to the clearance, wbound aircraft, rather than 'all other' aircraft. Rewriting the departure procedure might help prevent a recurrence. Callback conversation with reporter revealed the following information: this captain was flying a B727- 200 out of bzn when an important portion of the departure procedure was overlooked by the flight crew. This portion of the departure instructions required the flight crew to turn back to the bzn VOR after climbing to 8000 ft. The captain said that he is familiar with mountain flying and with complicated departure instructions, however, he said that he has not seen instructions that address exceptions to the normal route and then further add instructions to the normal route. He said that everyone on the flight crew missed these instructions and he believes that the way that they are written was the primary cause for the error.

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Original NASA ASRS Text

Title: THIS ACR B727-200 FLC MISREAD A PORTION OF THEIR DEP INSTRUCTIONS THAT REQUIRED THEM TO TURN BACK TO THE BZN VOR AFTER CLBING TO 8000 FT. THE RPTR SAID THAT THE INSTRUCTIONS WERE MISLEADING TO HIM SINCE THE EXCEPTIONS TO THE RTE PORTION COMES BEFORE THE REMAINDER OF THE REGULAR RTE INSTRUCTIONS.

Narrative: PLTS MISUNDERSTOOD CLRNC ON THE DEP FROM BZN. BELIEVED CLRNC TO REQUIRE ON RWY 30 A CLBING L TURN TO 275 DEG HDG TO INTERCEPT THE BZN 284 DEG RADIAL. THE PROC REQUIRES A CLB TO 8000 FT THEN A TURN TO THE BZN VOR. PLTS DID NOT TURN TO THE BZN VOR, BUT CONTINUED OUT THE 284 DEG RADIAL W TO CLRNC LIMIT ALT OF 14000 FT. ON INITIAL CONTACT WITH ZLC PLTS' WERE INSTRUCTED TO CONTACT ZLC AGAIN AT 10 DME FROM BZN VOR. THE CALL WAS MADE AND ATC QUESTIONED OUR CLRNC. ATC THEN ASSIGNED US A VECTOR ON COURSE. CONTRIBUTING FACTORS WERE PLTS' CAREFUL ATTN TO TERRAIN AVOIDANCE (MEA) AND ADHERENCE TO THE BELIEVED CLRNC. THE PROC IS WRITTEN IN A MANNER THAT MAY LEAD TO CONFUSION. THE PLTS BELIEVED THAT THE PROC ENDED ON COURSE OUTBOUND THE BZN 284 DEG RADIAL BECAUSE THE NEXT SENTENCE STARTS WITH THE EXCEPTION TO THE CLRNC, WBOUND ACFT, RATHER THAN 'ALL OTHER' ACFT. REWRITING THE DEP PROC MIGHT HELP PREVENT A RECURRENCE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THIS CAPT WAS FLYING A B727- 200 OUT OF BZN WHEN AN IMPORTANT PORTION OF THE DEP PROC WAS OVERLOOKED BY THE FLC. THIS PORTION OF THE DEP INSTRUCTIONS REQUIRED THE FLC TO TURN BACK TO THE BZN VOR AFTER CLBING TO 8000 FT. THE CAPT SAID THAT HE IS FAMILIAR WITH MOUNTAIN FLYING AND WITH COMPLICATED DEP INSTRUCTIONS, HOWEVER, HE SAID THAT HE HAS NOT SEEN INSTRUCTIONS THAT ADDRESS EXCEPTIONS TO THE NORMAL RTE AND THEN FURTHER ADD INSTRUCTIONS TO THE NORMAL RTE. HE SAID THAT EVERYONE ON THE FLC MISSED THESE INSTRUCTIONS AND HE BELIEVES THAT THE WAY THAT THEY ARE WRITTEN WAS THE PRIMARY CAUSE FOR THE ERROR.

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.