乗ってた

was riding, was on, was aboard

→ 乗る
乗っ to get on; to ride or take (a vehicle) + て Te-form (conjunctive form) + た Past tense
verb · informal, imperfect tense Rare #31,657
was riding, was on, was aboard Casual contraction of 乗っていた; the exact meaning depends on what was being ridden or boarded.
JA: 昨日はバスに乗ってた。
EN: I was on the bus yesterday.
Conjugation of 乗る
Indicative imperfect
乗ってた

これがトムと私が乗ってた船の写真なのよ。

This is a photo of the boat Tom and I were on.

ずいぶん長く乗ってたんだな

You’ve been riding for quite a long time.

— ロシアン・ブラザー (1997)

昔は毎日乗ってた

I used to ride it every day.

— ワンス・アポン・ア・タイム・イン・ハリウッド (2019)

これはトムと僕が乗ってた船の写真だよ。

This is a photo of the boat Tom and I were on.

君も乗ってたのか!

You were on it too!

— イングリッシュ・ペイシェント (1996)

その船には何人の人が乗ってたんですか?

How many people were on that ship?