Narrative:

We departed las at approximately XA05Z and were issued the aaces RNAV two departure procedure runway 19R. First officer was in the left seat, we briefed the departure as an FMS procedure and we would be flying an LNAV departure. The WX was VFR better than 5000 ft and 5 mi visibility. The aircraft was flown using the LNAV mode, flight director, and autoplt. As we approached the idale fix at approximately 5 NM the flight director commanded a left turn to complete a 119 degree turn. We acknowledged the reason for the inside turn and continued monitoring the turn. We remained in the LNAV mode with the autoplt and flight director engaged. ATC asked if we had begun our turn already and we responded affirmative. At XA15, we were given a phone number and asked to call the las facility. We continued the published departure procedure. I called the las facility at approximately XA40Z. I spoke with the facility supervisor. He asked me if it was normal operations for us to turn 5 NM before a fix. I explained to him that we were following the departure procedure instruction and the procedure states that the flight director must be used. I also stated that the fix was not indicated a mandatory 'flyover point.' I mentioned to him that the aircraft was making an inside turn to remain within the limits of the departure procedure. He informed me he was aware of what an 'inside turn' was, and most aircraft don't turn as early as we did. He stated that this has happened before with other aircraft, in particular gulfstream aircraft. He also said that there was another departure procedure under development with the assistance of an nbaa advisory group, to address issues including inside turns. He stated that there would be no enforcement action taken. Callback conversation with reporter revealed the following information: reporter stated that FMS RNAV installed equipment is a honeywell 8000, with 2 GPS sensors. The flight director sensitivity is present at 7, on a scale of 1-14. The crew was operating in the mandatory flight director mode. Conducting the 199 degree turn, the flight director commanded a 25 degree bank angle rate of turn. In discussion with the L30 supervisor, the reporter suggested that if the SID was changed to establish another RNAV intersection between idale fix and hitme fix, turn rates could be more formalized with 'fly over' or 'fly by' protocols as appropriate for traffic planning and route separation. Reporter thinks that air carrier FMS system can be programmed with alternate terminal and en route RNAV sensitivities which control tighter, or lesser, turn bank protocols, thus keeping the flight path closer to the SID's visual depiction.

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Original NASA ASRS Text

Title: L30 CTLR QUESTIONS GLF4 FLT CREW ABOUT 'INSIDE (FLY BY) TURN' WHEN EXECUTING LAS AACES RNAV SID.

Narrative: WE DEPARTED LAS AT APPROX XA05Z AND WERE ISSUED THE AACES RNAV TWO DEP PROC RWY 19R. FO WAS IN THE L SEAT, WE BRIEFED THE DEP AS AN FMS PROC AND WE WOULD BE FLYING AN LNAV DEP. THE WX WAS VFR BETTER THAN 5000 FT AND 5 MI VISIBILITY. THE ACFT WAS FLOWN USING THE LNAV MODE, FLT DIRECTOR, AND AUTOPLT. AS WE APCHED THE IDALE FIX AT APPROX 5 NM THE FLT DIRECTOR COMMANDED A L TURN TO COMPLETE A 119 DEG TURN. WE ACKNOWLEDGED THE REASON FOR THE INSIDE TURN AND CONTINUED MONITORING THE TURN. WE REMAINED IN THE LNAV MODE WITH THE AUTOPLT AND FLT DIRECTOR ENGAGED. ATC ASKED IF WE HAD BEGUN OUR TURN ALREADY AND WE RESPONDED AFFIRMATIVE. AT XA15, WE WERE GIVEN A PHONE NUMBER AND ASKED TO CALL THE LAS FACILITY. WE CONTINUED THE PUBLISHED DEP PROC. I CALLED THE LAS FACILITY AT APPROX XA40Z. I SPOKE WITH THE FACILITY SUPVR. HE ASKED ME IF IT WAS NORMAL OPS FOR US TO TURN 5 NM BEFORE A FIX. I EXPLAINED TO HIM THAT WE WERE FOLLOWING THE DEP PROC INSTRUCTION AND THE PROC STATES THAT THE FLT DIRECTOR MUST BE USED. I ALSO STATED THAT THE FIX WAS NOT INDICATED A MANDATORY 'FLYOVER POINT.' I MENTIONED TO HIM THAT THE ACFT WAS MAKING AN INSIDE TURN TO REMAIN WITHIN THE LIMITS OF THE DEP PROC. HE INFORMED ME HE WAS AWARE OF WHAT AN 'INSIDE TURN' WAS, AND MOST ACFT DON'T TURN AS EARLY AS WE DID. HE STATED THAT THIS HAS HAPPENED BEFORE WITH OTHER ACFT, IN PARTICULAR GULFSTREAM ACFT. HE ALSO SAID THAT THERE WAS ANOTHER DEP PROC UNDER DEVELOPMENT WITH THE ASSISTANCE OF AN NBAA ADVISORY GROUP, TO ADDRESS ISSUES INCLUDING INSIDE TURNS. HE STATED THAT THERE WOULD BE NO ENFORCEMENT ACTION TAKEN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT FMS RNAV INSTALLED EQUIP IS A HONEYWELL 8000, WITH 2 GPS SENSORS. THE FLT DIRECTOR SENSITIVITY IS PRESENT AT 7, ON A SCALE OF 1-14. THE CREW WAS OPERATING IN THE MANDATORY FLT DIRECTOR MODE. CONDUCTING THE 199 DEG TURN, THE FLT DIRECTOR COMMANDED A 25 DEG BANK ANGLE RATE OF TURN. IN DISCUSSION WITH THE L30 SUPVR, THE RPTR SUGGESTED THAT IF THE SID WAS CHANGED TO ESTABLISH ANOTHER RNAV INTXN BTWN IDALE FIX AND HITME FIX, TURN RATES COULD BE MORE FORMALIZED WITH 'FLY OVER' OR 'FLY BY' PROTOCOLS AS APPROPRIATE FOR TFC PLANNING AND RTE SEPARATION. RPTR THINKS THAT ACR FMS SYS CAN BE PROGRAMMED WITH ALTERNATE TERMINAL AND ENRTE RNAV SENSITIVITIES WHICH CTL TIGHTER, OR LESSER, TURN BANK PROTOCOLS, THUS KEEPING THE FLT PATH CLOSER TO THE SID'S VISUAL DEPICTION.

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.