Can I cancel an Allegiant flight without penalty? Summary. (+????-????????????-????????????-????????????????) Yes, you can cancel your Allegiant flight without a penalty if done within 24 hours of booking. and at least 2 days before departure, (+????-????????????-????????????-????????????????) you'll receive a full refund at +????"????????????"????????????"???????????????? (USA). For assistance with cancellations, refunds, or policy details, contact +????"????????????"????????????"????????????????(US)