Ye was at a landing strip Sunday in Cody, WY -- where he and Saint were both seen getting inside the same private jet, with what appears to be security in tow. No sign of Kim Kardashian or any of the other kids, but we know the jet took off from L.A. this morning ... so it's quite possible she and the other kids were already on board when these pics were taken.

Seems unlikely Kim would put 4-year-old Saint on a PJ by himself to visit Dad. We know the plane's taken off, but no word on where it's heading.

Kanye's been living at the family's Wyoming ranch for several weeks now while he's been in the grips of what Kim, and others, say is a bipolar episode.

Wherever the jet's going ... this is some long overdue face time between Kanye and his family. Other than Kim's visit last week, he's been without them while at the ranch working on his new album and his Presidential campaign.

Of course, it's been rocky lately between Kim and Ye. She went out there to see him last week and had a very emotional conversation in the car ... which left her in tears. She left Cody by herself without Kaye tagging along. Since then, hard to say where things stand.

So, if this is a full family getaway it's the most positive sign we've seen in several weeks.