<< >> NASA ASRS Report 1442730, April 2017

B737 flight crew reported diverting to a VFR alternate after their autoflight system malfunctioned twice on the bwi runway 10 ILS.

Attributes
ACN	1442730
Time
Date	201704
Local Time Of Day	1201-1800
Place
Locale Reference	BWI.Airport
State Reference	MD
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Make Model Name	B737 Next Generation Undifferentiated
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Component
Aircraft Component	Autoflight System
Person 1
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 188
Person 2
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 154
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Track / Heading All Types

Narrative:

While intercepting the localizer course for ILS runway 10 bwi approach from the north and just outside of the final approach fix; VOR/localizer captured and then the aircraft made an abrupt continuous right turn away from the inbound course. The localizer was rapidly moving through half scale deflection to the left and the first officer disengaged the autopilot to begin a go-around. At that time; assuming because of the aircraft position; the approach controller asked if we would like to be vectored back around for another ILS. We said we would and proceeded to come around for another approach. On our second attempt at the ILS 10 bwi approach; upon VOR/localizer capture the same automation error occurred with the same abrupt right turn. The PF went around; and during the maneuver the aircraft crossed over the final approach course to the north and we were given radar vectors by ATC for the remainder of the missed approach. The crew then made the decision to proceed to our alternate; which was VFR; due to the weather conditions in bwi and the unexpected behavior of the aircraft.

Related reports:

• A C560 flight crew failed to level at their cleared altitude...
• B737 captain reported autoflight system malfunctioned errone...
• B737-500 autoflight functions abnormal during initial portio...
• An A300 flight crew suffered a cftt incident when the autofl...

	Enter your search terms Submit search form
	Web www.37000feet.com

Original NASA ASRS Text

Title: B737 flight crew reported diverting to a VFR alternate after their autoflight system malfunctioned twice on the BWI Runway 10 ILS.

Narrative: While intercepting the localizer course for ILS Runway 10 BWI Approach from the north and just outside of the final approach fix; VOR/LOC captured and then the aircraft made an abrupt continuous right turn away from the inbound course. The localizer was rapidly moving through half scale deflection to the left and the First Officer disengaged the autopilot to begin a go-around. At that time; assuming because of the aircraft position; the Approach Controller asked if we would like to be vectored back around for another ILS. We said we would and proceeded to come around for another approach. On our second attempt at the ILS 10 BWI Approach; upon VOR/LOC capture the same automation error occurred with the same abrupt right turn. The PF went around; and during the maneuver the aircraft crossed over the final approach course to the north and we were given radar vectors by ATC for the remainder of the missed approach. The crew then made the decision to proceed to our alternate; which was VFR; due to the weather conditions in BWI and the unexpected behavior of the aircraft.

Data retrieved from NASA's ASRS site 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.