A321 flight crew reported they overshot a crossing restriction on approach to lax when they failed t...

Narrative:

On riivr two arrival into lax for runway 25L in managed descent mode. Just outside riivr; ATC directed us to change runway to 24R. ATC had left us high on the arrival due to some previously induced constraints; also said all altitudes could be 'at or above'. I was the pilot flying and flew while the captain reprogrammed the mcdu for runway 24R. We both verified the new runway; waypoints and step down altitudes. At skoll I noticed we were below the required 10;000 ft altitude at about 9;600 ft; and leveled off. We also noticed that the descent mode had changed at some point from a managed descent to an open descent which had allowed the aircraft to descend below the 10;000 ft constraint. After passing skoll I reselected managed descent and continued the approach and landing.although we had complied quickly with all speed constraints issued by ATC; we were directed to sidestep to 24L due to insufficient spacing between us and commuter airplane that ATC had sequenced in from the north. Due to heavy radio congestion we never notified ATC nor did the controller ever query us about our altitude.factors contributing to this situation: last minute runway change; radio congestion; sun in our face; both pilots new in airbus (first officer 3 months; captain 1 month).

Original NASA ASRS Text

Title: A321 flight crew reported they overshot a crossing restriction on approach to LAX when they failed to notice the autoflight mode had gone from 'managed descent' to 'open descent.' Crew cited a late runway change as contributory.

Narrative: On RIIVR TWO arrival into LAX for Runway 25L in managed descent mode. Just outside RIIVR; ATC directed us to change runway to 24R. ATC had left us high on the arrival due to some previously induced constraints; also said all altitudes could be 'at or above'. I was the pilot flying and flew while the Captain reprogrammed the MCDU for runway 24R. We both verified the new runway; waypoints and step down altitudes. At SKOLL I noticed we were below the required 10;000 FT altitude at about 9;600 FT; and leveled off. We also noticed that the descent mode had changed at some point from a managed descent to an open descent which had allowed the aircraft to descend below the 10;000 FT constraint. After passing SKOLL I reselected managed descent and continued the approach and landing.Although we had complied quickly with all speed constraints issued by ATC; we were directed to sidestep to 24L due to insufficient spacing between us and commuter airplane that ATC had sequenced in from the north. Due to heavy radio congestion we never notified ATC nor did the controller ever query us about our altitude.Factors contributing to this situation: Last minute runway change; radio congestion; sun in our face; both pilots new in Airbus (First Officer 3 months; Captain 1 month).

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.

Attributes
ACN	1231521
Time
Date	201501
Local Time Of Day	1201-1800
Place
Locale Reference	LAX.Airport
State Reference	CA
Aircraft 1
Make Model Name	A321
Operating Under FAR Part	Part 121
Flight Phase	Descent
Route In Use	STAR RIIVR TWO
Component
Aircraft Component	FMS/FMC
Person 1
Function	First Officer Pilot Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Person 2
Function	Captain Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP)
Events
Anomaly	Deviation - Altitude Crossing Restriction Not Met Deviation - Altitude Overshoot Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

A321 flight crew reported they overshot a crossing restriction on approach to lax when they failed to notice the autoflight mode had gone from 'managed descent' to 'open descent.' crew cited a late runway change as contributory.