However, one said arriving late to India wasn't a good look especially as the trip was designed to improve relations between the countries.
Key said he was naturally disappointed, and particularly for the sizeable business delegation on board.
However, he didn't think it was necessary to rush the purchase of new planes, saying the 757s had been reliable during his eight years as Prime Minister.
"It is a little bit [sub-optimal, but] the options aren't great," he said.
Key had been due in Mumbai today, where engagements included the signing of an education agreement. His replacement plane will now fly via Jakarta, as previously scheduled, but then to New Delhi.
Tomorrow he will meet with Indian Prime Minister Narendra Modi to push the case for a free-trade deal.