Air carrier being vectored for parallel ILS 18L intercept went through the localizer; received TCAS ...

Narrative:

On approach into mem on 18L a vector to join the localizer of 230 degrees at 200 knots with a 7 knot left crosswind. After seeing that we would go through the localizer we started an early turn to join the localizer. The autopilot captured the course and went through the localizer to 1/4 dot deflection. At that time another aircraft was on final for 18R 300 feet above us and descending. We were issued an RA to descend at 1500 feet per minute. We complied and the conflict was resolved. The large intercept angle with the light crosswind and high speed caused the autopilot to not correctly capture the localizer. Approach vectored two aircraft to join parallel runways at the same point setting up the event.

Original NASA ASRS Text

Title: Air carrier being vectored for parallel ILS 18L intercept went through the localizer; received TCAS RA from Runway 18R traffic; reporter claiming large intercept angle; light crosswind and high speed as causal factors.

Narrative: On approach into MEM on 18L a vector to join the localizer of 230 degrees at 200 knots with a 7 knot left crosswind. After seeing that we would go through the localizer we started an early turn to join the localizer. The autopilot captured the course and went through the localizer to 1/4 dot deflection. At that time another aircraft was on final for 18R 300 feet above us and descending. We were issued an RA to descend at 1500 feet per minute. We complied and the conflict was resolved. The large intercept angle with the light crosswind and high speed caused the autopilot to not correctly capture the localizer. Approach vectored two aircraft to join parallel runways at the same point setting up the event.

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.

Attributes
ACN	844291
Time
Date	200907
Local Time Of Day	0601-1200
Place
Locale Reference	MEM.Airport
State Reference	TN
Aircraft 1
Make Model Name	Medium Transport Low Wing 2 Turboprop Eng
Operating Under FAR Part	Part 121
Flight Phase	Initial Approach
Flight Plan	IFR
Person 1
Function	Captain
Experience	Flight Crew Last 90 Days 12 Flight Crew Total 5600 Flight Crew Type 970
Events
Anomaly	Conflict Airborne Conflict Deviation - Procedural Clearance Deviation - Track / Heading All Types

Air carrier being vectored for parallel ILS 18L intercept went through the localizer; received TCAS RA from runway 18R traffic; reporter claiming large intercept angle; light crosswind and high speed as causal factors.