SINGAPORE - A Singapore-bound SilkAir flight was forced to return to Chiang Mai International Airport on Tuesday (Jan 8) due to a suspected hairline crack in its cockpit window.

A spokesman for Singapore Airlines (SIA), which operates the regional carrier, said on Wednesday that crew members on flight MI701 decided to turn back as a precautionary measure, so that safety checks on the A320 aircraft could be carried out.

The 146 passengers on board arrived in Chiang Mai, in northern Thailand, at 1.17pm local time (2.17pm Singapore time) on Tuesday, the SIA spokesman said.

The flight was originally scheduled to arrive in Singapore at 3.35pm local time.

The spokesman said that, as engineers on the ground needed time to look at the technical issue, a replacement aircraft left Singapore at 7.34pm local time for Chiang Mai on Tuesday.

The replacement flight, carrying all passengers and crew members, departed Chiang Mai at 10.09pm local time on Tuesday.

It arrived at Singapore's Changi Airport at 2.18am the next day.