Originally Posted by
narvik
The issue with United -and this a relatively recent development- is P fare class availability. It seems random and unpredictable (to me).
I need to fly EWR-PEK once a month, but need to get creative nowadays in order to bring costs down and find P fares. This resulted in routings such as BDL-SFO-PEK and BDL-EWR-PEK (!) and ZFV (Amtrak station in Philadelphia)-EWR-PEK.
Spend much more time booking flights these days to find reasonable fares, and hope for equal success in 2019....we will see.
In the case of EWR-HKG, there are no P fare filings at all. Even if there is P bucket available, there's no P fare to go with it and the lowest you can get is a Z fare. However, UA does have P fare filings for PHL-HKG route and fares are as low as $4K roundtrip from there (your ZFV trick also works), so OP might want to consider flying from there.