Which is longest Oceanic crossing for any commercial flight route? During oceanic crossings, there are limited to no terrestrial radio communications available, so I would think that most flight routes are designed to minimize ocean crossing time. 

Which commercial flight route have the longest oceanic crossing?
For the longest  Oceanic Crossing, the following are the top three contenders:


Sydney to Vancouver
Melbourne to Los Angeles
Auckland to Vancouver


Out of this, 1 and 2 pass over a few islands on their way, 3 does not pass over any landmass.

Have a look at this : www.gcmap.com

Image :


(Image Source: www.gcmap.com)