Narrative:

We were departing sjc runway 30L on the loupe 1 departure. After reviewing the SID we decided to fly the flight director in LNAV to make sure we didn't miss the sjc 1.8 DME. We also had it backed up. It was a visual day. As we climbed out; we turned at 1.8 DME northwest of sjc. The heading bug was set to 120 degree heading. The FMS needle also pointed to 120 degrees. As we were in the turn the aircraft accelerated as our FMS dictated. We were clear of all obstacles and started to level. The aircraft turned past 120 degree heading to a 150 degree heading. We saw this and turned back to 120 degree heading. ATC asked what heading we were on and we said 120 degrees. He then asked if we were on a 150 degree heading and we said yes. He asked what avionics we had. We told him honeywell. He said they have had gulfstreams going through the 120 degree heading; and trying to figure out if it was the same avionics. We later decided to call norcal departure. After talking to them; we found out they need the turn to be kept tight; due to obstacle clearance and class B airspace. Nowhere on the SID does it state a turn radius nor a speed restr. Being VFR we were able to maintain visual separation from all obstacles. I feel they need to put a speed restr on this SID; especially for faster aircraft such as the gulfstream and citation X's. Then as pilots we would be able to know they need a tight turning radius and we would be able to speed intervene the FMS; so as not to accelerate until we are past the 047 degree radial off of sjc or ATC advises. I believe this would help ATC with separation and speed under class B. This also would allow aircraft to still be able to climb at V2 to meet minimum climb gradients in IFR. (It would need to say do not exceed 200 KTS; example.) even being VFR all climb gradients were met. I believe this would help pilots who are unfamiliar and even ATC. Callback conversation with reporter revealed the following information: reporter stated that they were flying the aircraft in the LNAV/FMS mode and the aircraft will only give a 25 degree bank. As it accelerated the aircraft's turn radius was not enough and it did overshoot the FMS depicted departure (magenta line) and was correcting back on a heading of 150 degrees. The reporter had discussed this with the other pilot and they determined that the turn was too tight to fly in the LNAV mode and they agreed they should fly it in the heading select mode or manually.

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Original NASA ASRS Text

Title: CITATION 750 HAS A HDG DEV DURING THE LOUPE1 SID.

Narrative: WE WERE DEPARTING SJC RWY 30L ON THE LOUPE 1 DEP. AFTER REVIEWING THE SID WE DECIDED TO FLY THE FLT DIRECTOR IN LNAV TO MAKE SURE WE DIDN'T MISS THE SJC 1.8 DME. WE ALSO HAD IT BACKED UP. IT WAS A VISUAL DAY. AS WE CLBED OUT; WE TURNED AT 1.8 DME NW OF SJC. THE HDG BUG WAS SET TO 120 DEG HDG. THE FMS NEEDLE ALSO POINTED TO 120 DEGS. AS WE WERE IN THE TURN THE ACFT ACCELERATED AS OUR FMS DICTATED. WE WERE CLR OF ALL OBSTACLES AND STARTED TO LEVEL. THE ACFT TURNED PAST 120 DEG HDG TO A 150 DEG HDG. WE SAW THIS AND TURNED BACK TO 120 DEG HDG. ATC ASKED WHAT HDG WE WERE ON AND WE SAID 120 DEGS. HE THEN ASKED IF WE WERE ON A 150 DEG HDG AND WE SAID YES. HE ASKED WHAT AVIONICS WE HAD. WE TOLD HIM HONEYWELL. HE SAID THEY HAVE HAD GULFSTREAMS GOING THROUGH THE 120 DEG HDG; AND TRYING TO FIGURE OUT IF IT WAS THE SAME AVIONICS. WE LATER DECIDED TO CALL NORCAL DEP. AFTER TALKING TO THEM; WE FOUND OUT THEY NEED THE TURN TO BE KEPT TIGHT; DUE TO OBSTACLE CLRNC AND CLASS B AIRSPACE. NOWHERE ON THE SID DOES IT STATE A TURN RADIUS NOR A SPD RESTR. BEING VFR WE WERE ABLE TO MAINTAIN VISUAL SEPARATION FROM ALL OBSTACLES. I FEEL THEY NEED TO PUT A SPEED RESTR ON THIS SID; ESPECIALLY FOR FASTER ACFT SUCH AS THE GULFSTREAM AND CITATION X'S. THEN AS PLTS WE WOULD BE ABLE TO KNOW THEY NEED A TIGHT TURNING RADIUS AND WE WOULD BE ABLE TO SPD INTERVENE THE FMS; SO AS NOT TO ACCELERATE UNTIL WE ARE PAST THE 047 DEG RADIAL OFF OF SJC OR ATC ADVISES. I BELIEVE THIS WOULD HELP ATC WITH SEPARATION AND SPD UNDER CLASS B. THIS ALSO WOULD ALLOW ACFT TO STILL BE ABLE TO CLB AT V2 TO MEET MINIMUM CLB GRADIENTS IN IFR. (IT WOULD NEED TO SAY DO NOT EXCEED 200 KTS; EXAMPLE.) EVEN BEING VFR ALL CLB GRADIENTS WERE MET. I BELIEVE THIS WOULD HELP PLTS WHO ARE UNFAMILIAR AND EVEN ATC. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THEY WERE FLYING THE ACFT IN THE LNAV/FMS MODE AND THE ACFT WILL ONLY GIVE A 25 DEG BANK. AS IT ACCELERATED THE ACFT'S TURN RADIUS WAS NOT ENOUGH AND IT DID OVERSHOOT THE FMS DEPICTED DEP (MAGENTA LINE) AND WAS CORRECTING BACK ON A HDG OF 150 DEGS. THE RPTR HAD DISCUSSED THIS WITH THE OTHER PLT AND THEY DETERMINED THAT THE TURN WAS TOO TIGHT TO FLY IN THE LNAV MODE AND THEY AGREED THEY SHOULD FLY IT IN THE HDG SELECT MODE OR MANUALLY.

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.