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  <xs:element id="algt_LoyaltyProgramLiabilityNoncurrent" abstract="false" name="LoyaltyProgramLiabilityNoncurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_OperatingRevenueAbstract" abstract="true" name="OperatingRevenueAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_ThirdPartyProducts" abstract="false" name="ThirdPartyProducts" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_FixedFeeContractRevenue" abstract="false" name="FixedFeeContractRevenue" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_OtherOperatingRevenue" abstract="false" name="OtherOperatingRevenue" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_AircraftFuel" abstract="false" name="AircraftFuel" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_StationOperations" abstract="false" name="StationOperations" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_AircraftLeaseRental" abstract="false" name="AircraftLeaseRental" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_OtherIncomeExpenseAbstract" abstract="true" name="OtherIncomeExpenseAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_EarningsPerShareToCommonStockholdersAbstract" abstract="true" name="EarningsPerShareToCommonStockholdersAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_WeightedAverageSharesOutstandingUsedInComputingEarningsPerShareToCommonStockholdersAbstract" abstract="true" name="WeightedAverageSharesOutstandingUsedInComputingEarningsPerShareToCommonStockholdersAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_TwoClassMethodWeightedAverageNumberofSharesOutstandingDiluted" abstract="false" name="TwoClassMethodWeightedAverageNumberofSharesOutstandingDiluted" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="algt_StatementOfComprehensiveIncomeAbstract" abstract="true" name="StatementOfComprehensiveIncomeAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_SpecialItemImpairmentcharges" abstract="false" name="SpecialItemImpairmentcharges" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_AircraftPreDeliveryDeposits" abstract="false" name="AircraftPreDeliveryDeposits" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_NonCashTransactionsAbstract" abstract="true" name="NonCashTransactionsAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_PurchasesOfPropertyAndEquipmentInAccruedLiabilities" abstract="false" name="PurchasesOfPropertyAndEquipmentInAccruedLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_SummaryOfSpecialChargesTableTextBlock" abstract="false" name="SummaryOfSpecialChargesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="algt_SunseekerResortsMember" abstract="true" name="SunseekerResortsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_DisposalGroupIncludingDiscontinuedOperationExpendablePartsSuppliesAndFuelNetOfAllowance" abstract="false" name="DisposalGroupIncludingDiscontinuedOperationExpendablePartsSuppliesAndFuelNetOfAllowance" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_DisposalGroupIncludingDiscontinuedOperationValuationAllowance" abstract="false" name="DisposalGroupIncludingDiscontinuedOperationValuationAllowance" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_FacilitySaleMember" abstract="true" name="FacilitySaleMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_WriteDownChargeMember" abstract="true" name="WriteDownChargeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_OrganizationalRestructuringMember" abstract="true" name="OrganizationalRestructuringMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_NumberOfAircraftRetired" abstract="false" name="NumberOfAircraftRetired" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_AirlineMember" abstract="true" name="AirlineMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_NonOperatingSpecialChargeTotal" abstract="false" name="NonOperatingSpecialChargeTotal" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_FlightAttendantRatificationBonus" abstract="false" name="FlightAttendantRatificationBonus" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_SpecialChargesTotal" abstract="false" name="SpecialChargesTotal" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_ProceedsFromBusinessInterruptionInsurance" abstract="false" name="ProceedsFromBusinessInterruptionInsurance" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_ScheduledServiceRevenueMember" abstract="true" name="ScheduledServiceRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_AirrelatedrevenueMember" abstract="true" name="AirrelatedrevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_CobrandRevenueMember" abstract="true" name="CobrandRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_RoomsMember" abstract="true" name="RoomsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_PassengerRevenueMember" abstract="true" name="PassengerRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_ResortRevenueMember" abstract="true" name="ResortRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_ContractwithCustomerLiabilityForwardBookings" abstract="false" name="ContractwithCustomerLiabilityForwardBookings" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="algt_ContractwithCustomerLiabilityCreditVoucherBookings" abstract="false" name="ContractwithCustomerLiabilityCreditVoucherBookings" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="algt_AirTrafficLiabilityRecognized" abstract="false" name="AirTrafficLiabilityRecognized" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_AirTrafficLiabilityRevenueRecognitionPercentage" abstract="false" name="AirTrafficLiabilityRevenueRecognitionPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="algt_Pointsawarded" abstract="false" name="Pointsawarded" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_Pointsredeemed" abstract="false" name="Pointsredeemed" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_ComputerHardwareandSoftware" abstract="false" name="ComputerHardwareandSoftware" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_Landandbuildingsleaseholdimprovements" abstract="false" name="Landandbuildingsleaseholdimprovements" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_NumberOfAircraftCommittedToPurchase" abstract="false" name="NumberOfAircraftCommittedToPurchase" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_FixedRateMember" abstract="true" name="FixedRateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_VariableRateMember" abstract="true" name="VariableRateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_SeniorSecuredNotesDue2027Member" abstract="true" name="SeniorSecuredNotesDue2027Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_ConsolidatedVariableInterestEntitiesDue2029Member" abstract="true" name="ConsolidatedVariableInterestEntitiesDue2029Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_RevolvingCreditFacilitiesDue2027Member" abstract="true" name="RevolvingCreditFacilitiesDue2027Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_SecuredDebtByAircraftEnginesOtherEquipmentAndRealEstateMember" abstract="true" name="SecuredDebtByAircraftEnginesOtherEquipmentAndRealEstateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_ConstructionLoanAgreementDue2032Member" abstract="true" name="ConstructionLoanAgreementDue2032Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_ScheduleofMaturitiesofLongTermDebtAbstract" abstract="true" name="ScheduleofMaturitiesofLongTermDebtAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_UnsecuredCreditFacilityMember" abstract="true" name="UnsecuredCreditFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_FinancingAgreementMember" abstract="true" name="FinancingAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_OtherSecuredDebtMember" abstract="true" name="OtherSecuredDebtMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_DelayedDrawConstructionLoanMember" abstract="true" name="DelayedDrawConstructionLoanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_DebtInstrumentBasisSpreadOnVariableRateTerm" abstract="false" name="DebtInstrumentBasisSpreadOnVariableRateTerm" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="algt_DebtInstrumentNumberOfTranches" abstract="false" name="DebtInstrumentNumberOfTranches" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_AnnualEstimatedEffectiveTaxRatePercent" abstract="false" name="AnnualEstimatedEffectiveTaxRatePercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="algt_LongTermInvestmentsMember" abstract="true" name="LongTermInvestmentsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_EstimatedFairValueofDebtAbstract" abstract="true" name="EstimatedFairValueofDebtAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_NonPubliclyHeldDebtMember" abstract="true" name="NonPubliclyHeldDebtMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_NetIncomeLossAvailableToCommonStockholderBasic" abstract="false" name="NetIncomeLossAvailableToCommonStockholderBasic" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_WeightedAverageNumberOfDilutedSharesOutstandingTreasuryStockMethod" abstract="false" name="WeightedAverageNumberOfDilutedSharesOutstandingTreasuryStockMethod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="algt_SecuritiesExcludedFromComputationOfEarningsPerShareAmounts" abstract="false" name="SecuritiesExcludedFromComputationOfEarningsPerShareAmounts" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="algt_AllegiantAirMember" abstract="true" name="AllegiantAirMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
