"Wild Blue Yonder"

Not only does Potsie get Fonzie and Roger up in a prop plane with an unreliable pilot, but he says all the wrong things when everyone worries at the Cunninghams'.  No wonder Jenny calls him an idiot and Howard ushers him out the door.  So I'm boosting this from a C to a C+.

Notes:

• Flip jokes that Jenny won't finish high school while she's a teenager, but it's not exactly a joke.
• Catherine Gilmour, who's Teresa here, would soon be Patti on Laverne & Shirley.
• Skier William Woff was Bill Ziegler on Joanie Loves Chachi.
• Martin Ferrero would return as the pilot Omar, so I guess his parachute worked.
• There are four writers this time, and they still manage to bring up a possible party and then quickly drop that thread.  Francis X. Feighan has absolutely no other IMDB credits, and Michael O'Mahony wrote more things but nothing else for HD, while Richard Gurman wrote five other HD scripts and Larry Strawther two others.