Originally Posted by
zzap
Considering you have no checked luggage, could you not do online check-in with AirAsia to receive a digital boarding pass, and then just walk from T3 to T1? I believe all terminals at Changi are connected airside, allowing you to just walk from your arrival gate at T3 to departure gate in T1.
You can walk from T3 to T1, or you can take the airside tram (which runs parallel to a landside tram).
All terminals are connected airside except T4 and Jewel.