They schedule it, but usually fly over the top. Its just written in the schedule in case the winds are bad
Are you saying there are times when PAL does not land there? I thought if it is a scheduled stop then they have to land? They would have taken off from LAX with fuel that gets them to Guam. Surely winds can never be so good that they saved 3 hours worth of fuel that can get them all the way to Manila??
I think I have the answer so tell me what you think:
On Google Earth, the QA LAX-SYD flight is approximately 800nm further than the PAL LAX-Manila flight.
I noticed that there are many alternative airfields in the S. Hemisphere towards Australia so if winds are bad, they can land.
However for the PAL flight, once you pass Hawaii, the only alternate airfield is Guam. And Guam is 3 hours from Philippines. So it make sense for a PAL flight to stop at Guam but a Qantas flight to sydney does not need a techincal stop.
Have I made an educated guess?