Heading deviation. Chart confusion.

Attributes
ACN	94713
Time
Date	198809
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : sfo
State Reference	CA
Altitude	msl bound lower : 7000 msl bound upper : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : oak
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	climbout : intermediate altitude
Route In Use	departure sid : sid
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : flight engineer pilot : commercial pilot : instrument
ASRS Report	94713
Person 2
Affiliation	company : air carrier
Function	flight crew : captain
Qualification	pilot : atp
Events
Anomaly	non adherence : published procedure other anomaly other other spatial deviation
Independent Detector	other controllera
Resolutory Action	flight crew : became reoriented other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation other

Narrative:

Departed sfo on the quiet 1 departure. Clearance was to fly direct to ccr after rebas intersection. Flight crew misread rebas intersection as 11 DME from sfo VOR, therefore turned early toward ccr. Controller asked if we were turning and directed us back on course. Cause of the deviation due to pilots believing rebas was 11 DME from sfo. The incident may be prevented in the future if the chart (sfo 10-30) was more clear in defining rebas, ie, listed a DME from sfo VOR instead of just the distance between an intersection and rebas. Callback conversation with reporter revealed the following: reporter states crew reviewed SID before departure and felt they understood it well. Very disturbed to find interpretation of SID not accurate.

Original NASA ASRS Text

Title: HEADING DEVIATION. CHART CONFUSION.

Narrative: DEPARTED SFO ON THE QUIET 1 DEP. CLRNC WAS TO FLY DIRECT TO CCR AFTER REBAS INTXN. FLT CREW MISREAD REBAS INTXN AS 11 DME FROM SFO VOR, THEREFORE TURNED EARLY TOWARD CCR. CTLR ASKED IF WE WERE TURNING AND DIRECTED US BACK ON COURSE. CAUSE OF THE DEVIATION DUE TO PLTS BELIEVING REBAS WAS 11 DME FROM SFO. THE INCIDENT MAY BE PREVENTED IN THE FUTURE IF THE CHART (SFO 10-30) WAS MORE CLEAR IN DEFINING REBAS, IE, LISTED A DME FROM SFO VOR INSTEAD OF JUST THE DISTANCE BTWN AN INTERSECTION AND REBAS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR STATES CREW REVIEWED SID BEFORE DEP AND FELT THEY UNDERSTOOD IT WELL. VERY DISTURBED TO FIND INTERP OF SID NOT ACCURATE.

Data retrieved from NASA's ASRS site as of August 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.