What presently happens in YVR on the JFK-HKG flight?
 

Did a search but can't seem to find it and have read in the past that, in F, you stay on the plane whilst the cleaning crews work around you or you disembark and go to a penned off area.

Do you still have to clear immigration in HKG or is it done in Vancouver (or you do it twice)?

Everyone seems to disembark in YVR regardless of final destination, you will have to clear Canadian immigration.

Eh? OP is flying JFK-HKG. You get off in YVR and go to a holding pen, but you don't clear Canadian immigration since you're just in transit. You clear HK Immigration in HK.

On second thought, I am confusing this with a different transit experience I had through JFK. Please disregard.

I flew JFK-HKG over Chinese New Year. I was the only passenger that was continuing to HKG - everybody else was got off at YVR (it was a packed flight with families going skiing).

I was asked to stay on board for the whole time. No immigration clearance for me.

There was a change of crew and cleaners came to freshen up the cabin.

If in transit JFK-HKG, there is NO immigration or any other formalities. You might be allowed to stay on the plane or you might be asked to go to a holding area at the gate. If in the holding area, there are washrooms and vending machines but no restaurants or other amenities.

JFK-HKG: transit pax continuing to HKG must all stay on the plane at YVR.

[HKG-JFK: transit pax continuing to JFK must all disembark into the gate holding pen and go through a secondary screening for liquids]

I was in F on a JFK-HKG (via YVR) flight recently.

You basically sit in your seat while waiting for them to load the plane with passengers and catering. A new flight crew will staff the flight while you wait for the cleaning crew to vacuum and clean the cabin around you.

Passengers also enter the plane from the 1L plane door, so if you're in your seat, it's a little awkward when the other passengers pass by.

That honestly sounds ridiculous. Not saying you're wrong, I'm pretty sure you're right. So if I have liquids, I should stash it in the plane in my seat pocket or the overhead bin or something. Maybe leave a note for the cleaning crew that I'm ongoing flight.

Surprisingly, they don't check for liquids! :p I've had bottles of water from the flight, they don't take it away.

They also proactively offer free water bottles for you to take at the front by the desk.

I've been wanting someone to create a sticky for fifth freedom flights such as this one since this comes up a whole lot!

I just took CX888 in April and they did check for liquids in YVR.

From what I've seen recently that seems to be spot on.

Resurrecting this - I'm a Chinese citizen heading for vacation in japan (transiting via HKG) - do I need to apply for a Canadian transit visa?

No you don't have to, unless you meet some inexperienced staff

Absolutely yes.

Unless CIC is incorrect, as of the moment of posting, CIC specifically mentions a visa is required for Chinese (Mainland) citizens for travel or transit.

Even TIMATIC says the same thing.