GLF5 captain reported a very high workload resulted from a late runway change on arrival to lax.

Attributes
ACN	1352173
Time
Date	201604
Local Time Of Day	0601-1200
Place
Locale Reference	LAX.Airport
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Gulfstream V / G500 / G550
Operating Under FAR Part	Part 135
Flight Phase	Initial Approach
Route In Use	STAR RIIVR2
Flight Plan	IFR
Component
Aircraft Component	FMS/FMC
Person 1
Function	Captain
Qualification	Flight Crew Instrument Flight Crew Multiengine Flight Crew Flight Instructor Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 50 Flight Crew Total 12000 Flight Crew Type 3000
Events
Anomaly	ATC Issue All Types Aircraft Equipment Problem Less Severe

Narrative:

We were cleared the RIIVR2 to runway 25L. At the last minute; over riivr intersection; lax changed runways to runway 24R. When we changed runways in the FMS over riivr; the FMS didn't sequence correctly. After trying to change runways with an incredible amount of step down fixes we were able to get things under control. My advice would be not to change runways on an aircraft at the initial fix due to sequencing in the FMS. We need more time to load the FMS with the proper information before starting an approach.

Original NASA ASRS Text

Title: GLF5 Captain reported a very high workload resulted from a late runway change on arrival to LAX.

Narrative: We were cleared the RIIVR2 to runway 25L. At the last minute; over RIIVR intersection; LAX changed runways to runway 24R. When we changed runways in the FMS over RIIVR; the FMS didn't sequence correctly. After trying to change runways with an incredible amount of step down fixes we were able to get things under control. My advice would be not to change runways on an aircraft at the initial fix due to sequencing in the FMS. We need more time to load the FMS with the proper information before starting an approach.

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.