A B737-500 flight crew had a track deviation when their attempt to program a 'direct to a fix with i...

Attributes
ACN	952769
Time
Date	201106
Local Time Of Day	0001-0600
Place
Locale Reference	ZBW.ARTCC
State Reference	NH
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737-500
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 307
Person 2
Function	Pilot Not Flying First Officer
Experience	Flight Crew Last 90 Days 231 Flight Crew Type 10000
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Track / Heading All Types

Narrative:

ATC vectored us to 030 degrees for traffic; then re-cleared us direct bowen. I selected 'bowen; Page1; abeam points; execute (I saw the abeam points repopulated) then LNAV; and VNAV switches down.' the aircraft turned back onto course 30 degrees back to heading prior to 30 degree vector. This was the wrong direction. What I believe happened is the FMC did not receive the 'execute' command either because I did not hit it or it did not accept the bowen abeam points. Regardless; the aircraft turned the wrong direction when I selected LNAV. ATC queried our turn. We again line selected bowen without the abeam points and turned back direct bowen. I was not spatially aware that bowen was another 30 degrees to the left of course; so when the aircraft turned right; it did not raise my suspicions because I thought we were turning back on course toward our previous heading. Since I believed I hit all the right buttons and saw the abeams populate to bowen; when the aircraft turned; I felt I was turning in the correct direction. I need to confirm the heading to the next point I line select to the top of page 1 and before hitting abeam point note the heading to ensure the aircraft turns to the correct heading.

Original NASA ASRS Text

Title: A B737-500 flight crew had a track deviation when their attempt to program a 'direct to a fix with intervening abeam points' went awry. The lack of a moving map Navigation Display was cited as a contributing factor.

Narrative: ATC vectored us to 030 degrees for traffic; then re-cleared us direct BOWEN. I selected 'BOWEN; Page1; ABEAM POINTS; Execute (I saw the abeam points repopulated) then LNAV; and VNAV switches down.' The aircraft turned back onto course 30 degrees back to heading prior to 30 degree vector. This was the wrong direction. What I believe happened is the FMC did not receive the 'execute' command either because I did not hit it or it did not accept the BOWEN abeam points. Regardless; the aircraft turned the wrong direction when I selected LNAV. ATC queried our turn. We again line selected BOWEN without the abeam points and turned back direct BOWEN. I was not spatially aware that BOWEN was another 30 degrees to the left of course; so when the aircraft turned right; it did not raise my suspicions because I thought we were turning back on course toward our previous heading. Since I believed I hit all the right buttons and saw the abeams populate to BOWEN; when the aircraft turned; I felt I was turning in the correct direction. I need to confirm the heading to the next point I line select to the top of Page 1 and before hitting abeam point note the heading to ensure the aircraft turns to the correct heading.

Data retrieved from NASA's ASRS site as of April 2012 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.

A B737-500 flight crew had a track deviation when their attempt to program a 'direct to a fix with intervening abeam points' went awry. The lack of a moving map navigation display was cited as a contributing factor.