A319 captain reports entering alpha floor during localizer capture for runway 5R at MMMX; with the a...

Narrative:

The flight was cleared to fly the standard arrival into mexico city (MMMX) to runway 5R. The aircraft was flying with the autopilot and autothrottle engaged; fully configured at final approach speed; in LNAV with the ILS approach armed; turning inbound to final on the arrival and on profile. As the localizer and glideslope became active; the autopilot and autothrottle systems attempted to capture the localizer and glideslope. The autopilot went into an aggressive bank in its attempt to capture the localizer and glideslope while the autothrottle lagged in its power application causing the airplane to enter into alpha floor. The captain intervened and disconnected the autopilot and autothrottle systems and exited alpha floor while continuing to fly a visual approach manually to an uneventful landing on runway 5R.

Original NASA ASRS Text

Title: A319 Captain reports entering Alpha Floor during localizer capture for Runway 5R at MMMX; with the autopilot initiating an aggressive bank. Both autothrust and autopilot are turned off and the approach is completed manually.

Narrative: The flight was cleared to fly the standard arrival into Mexico City (MMMX) to Runway 5R. The aircraft was flying with the autopilot and autothrottle engaged; fully configured at final approach speed; in LNAV with the ILS approach armed; turning inbound to final on the arrival and on profile. As the localizer and glideslope became active; the autopilot and autothrottle systems attempted to capture the localizer and glideslope. The autopilot went into an aggressive bank in its attempt to capture the localizer and glideslope while the autothrottle lagged in its power application causing the airplane to enter into Alpha Floor. The Captain intervened and disconnected the autopilot and autothrottle systems and exited Alpha Floor while continuing to fly a visual approach manually to an uneventful landing on Runway 5R.

Data retrieved from NASA's ASRS site as of July 2013 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	1120231
Time
Date	201310
Place
Locale Reference	MMMX.Airport
State Reference	FO
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	A319
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	IFR
Component
Aircraft Component	Autothrottle/Speed Control
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Other / Unknown

A319 captain reports entering alpha floor during localizer capture for runway 5R at MMMX; with the autopilot initiating an aggressive bank. Both autothrust and autopilot are turned off and the approach is completed manually.