when (someone) arrived at the station
駅に着いた時、乗るつもりの電車が出てしまったことに気付いた。
When I arrived at the station, I realized that the train I intended to take had already left.
私が駅に着いた時、急行がちょうど到着するところだった。
When I arrived at the station, the express train was just arriving.
私達が駅に着いた時に列車はもう出てしまった後だった。
The train had already left by the time we arrived at the station.