Heading and track deviation occurs when flight crew activated an unwanted waypoint in the FMC.

Attributes
ACN	138536
Time
Date	199002
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : bty
State Reference	NV
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tracon : las tower : rno
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude cruise other
Route In Use	departure other departure sid : sid enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 37 flight time total : 8000 flight time type : 4000
ASRS Report	138536
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	non adherence : clearance other anomaly other other spatial deviation
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

On the las oasis departure, we were given a heading to intercept the beatty 126 degree right. The FMC was programmed and everything verified. I plugged hiden intersection into the FMC to see where it was on the EFIS map. At that time we had a frequency change to center. As I was changing the radios and checking in the first officer changed some data in his FMC and executed the entry. This also executed my hiden intersection entry and the aircraft turned toward hiden. By the time we realized what happened, started the turn to our original heading, went from automatic-tuning to manually tuning bty, switched from map mode to VOR and the 126 degree right, we had crossed the radial by 5.0 mi as shown on the FMC. The time lag, when a computer flown aircraft does something, to when the crew notices, idents and corrects the problem, may be enough to compromise safety.

Original NASA ASRS Text

Title: HEADING AND TRACK DEVIATION OCCURS WHEN FLT CREW ACTIVATED AN UNWANTED WAYPOINT IN THE FMC.

Narrative: ON THE LAS OASIS DEP, WE WERE GIVEN A HDG TO INTERCEPT THE BEATTY 126 DEG R. THE FMC WAS PROGRAMMED AND EVERYTHING VERIFIED. I PLUGGED HIDEN INTXN INTO THE FMC TO SEE WHERE IT WAS ON THE EFIS MAP. AT THAT TIME WE HAD A FREQ CHANGE TO CENTER. AS I WAS CHANGING THE RADIOS AND CHKING IN THE F/O CHANGED SOME DATA IN HIS FMC AND EXECUTED THE ENTRY. THIS ALSO EXECUTED MY HIDEN INTXN ENTRY AND THE ACFT TURNED TOWARD HIDEN. BY THE TIME WE REALIZED WHAT HAPPENED, STARTED THE TURN TO OUR ORIGINAL HDG, WENT FROM AUTO-TUNING TO MANUALLY TUNING BTY, SWITCHED FROM MAP MODE TO VOR AND THE 126 DEG R, WE HAD CROSSED THE RADIAL BY 5.0 MI AS SHOWN ON THE FMC. THE TIME LAG, WHEN A COMPUTER FLOWN ACFT DOES SOMETHING, TO WHEN THE CREW NOTICES, IDENTS AND CORRECTS THE PROB, MAY BE ENOUGH TO COMPROMISE SAFETY.

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.