I'm trying to save battery but I need my alarm in the morning. Will it still go off if on airplane mode?
p.s. I have an HTC Inspire.
Yes. Airplane mode (flight mode) only disables your phone's signal transmitting functions, not the functions that don't require a signal to function.
Your alarm will still work.
As @Jasir says. Your alarm will still work in Airplane mode.
Be careful as there is another setting on your phone.
Clock > Alarms > Menu > Settings > 'Alarm in silent mode'
You will need this ticked if you put your phone in silent (saving more battery) and still want the alarm to go off!