...was watching over the PLANE.
The Big Bang Theory Season 8, Episode 23
Okay. Now we've got an inclined PLANE.
The Big Bang Theory Season 1, Episode 2
Come on,
I spent an entire PLANE ride with you
The Big Bang Theory Season 10, Episode 22
...by an inclined PLANE
wrapped helically around an axis.
The Big Bang Theory Season 4, Episode 5
The salesman said
it could survive a PLANE crash, so...
The Big Bang Theory Season 10, Episode 23