Originally Posted by paperwastage

for a 6am flight, I've entered airside 11pm the night before

explored the airport (the game section is closed during overnight hours, butterflies are sleeping etc), a lot of stores are closed


even if you have bags, your airline may allow early bag checkin (up to 24-48 hours).

for SQ, it explicitly notes that you can only drop bags/enter airside 24 hours before flight, so 48-hour is a misnomer

for UA, no early checkin, though you should be able to get mobile boarding pass? this page from straitstime in 2016 doesnt mention United having mobile option at changi
https://www.straitstimes.com/singapo...rport-security


Departure, GST Refunds, Security - Singapore Changi Airport

Originally Posted by SQTraveller

Really? I didn't realise that.

Maybe I misunderstood the OP, but I think they would be allowed airside as long as they have a valid boarding pass. For SQ, you can check in 48 hours before hand, so I believe you should be able to get airside at that time. I've also read trip reports elsewhere where travellers go to the Private Room the night before and then go sleep in the transit hotel (why?!) and then return to the Private Room the next morning.