I know these come and go. Looks like some competition between UA and AA.
UA: only Feb and March
AA: until mid December
AA: HKG-LAX
Interesting points on AA Fare Basis:
1. Fare Basis from HKG -LAX OLE08QN1 258.00(USD) O Fare
2. Fare Basis from LAX-HKG OLX0O8O1 288.00(USD) O Fare (I wasn't able to locate any dates for this one)
AAdvantage earnings for this trip
Executive Platinum
Elite Qualifying 14,520
Dollars (EQDs) 258
Award miles 2,838