A B737 departing sea deviated from the mountain 5 SID because the FMC was improperly programmed.

Attributes
ACN	708477
Time
Date	200609
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : sea.vortac
State Reference	WA
Altitude	msl single value : 4900
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : s46.tracon
Operator	common carrier : air carrier
Make Model Name	B737-700
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	climbout : vacating altitude
Route In Use	departure sid : mountain5
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 173 flight time type : 2210
ASRS Report	708477
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	non adherence : published procedure non adherence : clearance other spatial deviation
Independent Detector	other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : returned to intended or assigned course
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

We were cleared the mountain 5 departure; radar vectors to J90; taking off to the north at seattle. At the gate; I loaded the flight plan which had the first point of normy on the jet route. Thinking I was helping the departure; I inserted the point nezug from the SID (sea 341 degree radial 8 DME) as our first point and then a 070 degree heading off of nezug as a second point followed by normy. My thinking was that we could back ourselves up on the SID. I briefed the captain as to what I had done. Normal departure. After we were cleaned up; the captain selected the autoplt and LNAV to navigation the SID. At approximately 7 DME north of sea; 4900 ft MSL; the autoplt began a right turn to a 070 degree heading; approximately 1 mi early. I verbalized that we were turning early and as the captain was reaching to deselect LNAV we were contacted by departure to turn back to a 341 degree heading. We had turned approximately 30 degrees before we began the turn back to the 341 degree assigned heading. When departure was vectoring us back to the 341 degree heading he explained that before we turned we needed to have both 8 DME/off of the sea 341 degree radial and 4000 ft MSL. This was primarily caused by my programming the 070 degree heading off of nezug into the box. Had I just put nezug in; just used raw data for the point (sea 341 degree radial; 8 DME); or had we not used the autoplt; we would not have turned early I believe.

Original NASA ASRS Text

Title: A B737 DEPARTING SEA DEVIATED FROM THE MOUNTAIN 5 SID BECAUSE THE FMC WAS IMPROPERLY PROGRAMMED.

Narrative: WE WERE CLRED THE MOUNTAIN 5 DEP; RADAR VECTORS TO J90; TAKING OFF TO THE N AT SEATTLE. AT THE GATE; I LOADED THE FLT PLAN WHICH HAD THE FIRST POINT OF NORMY ON THE JET RTE. THINKING I WAS HELPING THE DEP; I INSERTED THE POINT NEZUG FROM THE SID (SEA 341 DEG RADIAL 8 DME) AS OUR FIRST POINT AND THEN A 070 DEG HDG OFF OF NEZUG AS A SECOND POINT FOLLOWED BY NORMY. MY THINKING WAS THAT WE COULD BACK OURSELVES UP ON THE SID. I BRIEFED THE CAPT AS TO WHAT I HAD DONE. NORMAL DEP. AFTER WE WERE CLEANED UP; THE CAPT SELECTED THE AUTOPLT AND LNAV TO NAV THE SID. AT APPROX 7 DME N OF SEA; 4900 FT MSL; THE AUTOPLT BEGAN A R TURN TO A 070 DEG HDG; APPROX 1 MI EARLY. I VERBALIZED THAT WE WERE TURNING EARLY AND AS THE CAPT WAS REACHING TO DESELECT LNAV WE WERE CONTACTED BY DEP TO TURN BACK TO A 341 DEG HDG. WE HAD TURNED APPROX 30 DEGS BEFORE WE BEGAN THE TURN BACK TO THE 341 DEG ASSIGNED HDG. WHEN DEP WAS VECTORING US BACK TO THE 341 DEG HDG HE EXPLAINED THAT BEFORE WE TURNED WE NEEDED TO HAVE BOTH 8 DME/OFF OF THE SEA 341 DEG RADIAL AND 4000 FT MSL. THIS WAS PRIMARILY CAUSED BY MY PROGRAMMING THE 070 DEG HDG OFF OF NEZUG INTO THE BOX. HAD I JUST PUT NEZUG IN; JUST USED RAW DATA FOR THE POINT (SEA 341 DEG RADIAL; 8 DME); OR HAD WE NOT USED THE AUTOPLT; WE WOULD NOT HAVE TURNED EARLY I BELIEVE.

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.