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  <xs:element id="algt_SeniorSecuredNotesDue2027Member" abstract="true" name="SeniorSecuredNotesDue2027Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <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_InterestCostAbstract" abstract="true" name="InterestCostAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_DeferredMaintenanceCostsNetNoncurrent" abstract="false" name="DeferredMaintenanceCostsNetNoncurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_OperatingLeasedAssetsNumberOfUnits" abstract="false" name="OperatingLeasedAssetsNumberOfUnits" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_CobrandRevenueMember" abstract="true" name="CobrandRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_DeferredTotalIncomeTaxExpenseBenefit" abstract="false" name="DeferredTotalIncomeTaxExpenseBenefit" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_FlightDispatchersMember" abstract="true" name="FlightDispatchersMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_AllegiantTravelCompanyMember" abstract="true" name="AllegiantTravelCompanyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_PreopeningExpense" abstract="false" name="PreopeningExpense" 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-types1:domainItemType"/>
  <xs:element id="algt_SunseekerResortsMember" abstract="true" name="SunseekerResortsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <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_SpecialItemImpairmentcharges" abstract="false" name="SpecialItemImpairmentcharges" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_CapitalizedInterestCost" abstract="false" name="CapitalizedInterestCost" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_DeferredCostsForHeavyMaintenance" abstract="false" name="DeferredCostsForHeavyMaintenance" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_Expendablepartssuppliesandfuelreserve" abstract="false" name="Expendablepartssuppliesandfuelreserve" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_RestrictedStockStockOptionsCashSettledSARsAndEmployeeStockPurchaseProgramMember" abstract="true" name="RestrictedStockStockOptionsCashSettledSARsAndEmployeeStockPurchaseProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_EmployeeMember" abstract="true" name="EmployeeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_NumberOfFullTimeEquivalentEmployee" abstract="false" name="NumberOfFullTimeEquivalentEmployee" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_StockIssuedDuringPeriodSharesStockOptionsSARsExercised" abstract="false" name="StockIssuedDuringPeriodSharesStockOptionsSARsExercised" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="algt_FlightAttendantsMember" abstract="true" name="FlightAttendantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_MaintenanceTechniciansMember" abstract="true" name="MaintenanceTechniciansMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_BNPParibasAndJacksonSquareAviationMember" abstract="true" name="BNPParibasAndJacksonSquareAviationMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_BarclaysBankPLCMember" abstract="true" name="BarclaysBankPLCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_ConsolidatedVariableInterestEntityMember" abstract="true" name="ConsolidatedVariableInterestEntityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_PilotsMember" abstract="true" name="PilotsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_NumberOfAircraftFinanceLeaseObligation" abstract="false" name="NumberOfAircraftFinanceLeaseObligation" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <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_AircraftPreDeliveryDeposits" abstract="false" name="AircraftPreDeliveryDeposits" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" 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_ScheduleOfFutureMinimumPaymentsOfLeaseLiabilitiesTableTextBlock" abstract="false" name="ScheduleOfFutureMinimumPaymentsOfLeaseLiabilitiesTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="algt_EquipmentAndLeaseholdImprovementsMember" abstract="false" name="EquipmentAndLeaseholdImprovementsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_RewardsPlanNameAxis" abstract="true" name="RewardsPlanNameAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" 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_EffectiveIncomeTaxRateReconciliationExecutiveCompensationAmount" abstract="false" name="EffectiveIncomeTaxRateReconciliationExecutiveCompensationAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_RewardsPlanNameDomain" abstract="true" name="RewardsPlanNameDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_LongTermInvestmentsMember" abstract="true" name="LongTermInvestmentsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <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_WeightedAverageNumberofDilutedSharesOutstandingTreasuryStockMethod" abstract="false" name="WeightedAverageNumberofDilutedSharesOutstandingTreasuryStockMethod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="algt_LongTermDebtAndOtherLongTermLiabilitiesAbstract" abstract="true" name="LongTermDebtAndOtherLongTermLiabilitiesAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_OtherComprehensiveIncomeLossAbstract" abstract="true" name="OtherComprehensiveIncomeLossAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_HurricaneIdaliaMember" abstract="true" name="HurricaneIdaliaMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_NonCashTransactionsAbstract" abstract="true" name="NonCashTransactionsAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_SecuredDebtByAircraftEnginesOtherEquipmentAndRealEstateMember" abstract="true" name="SecuredDebtByAircraftEnginesOtherEquipmentAndRealEstateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_NumberOfAircraftsIncludedAsCollateral" abstract="false" name="NumberOfAircraftsIncludedAsCollateral" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <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_AircraftAndEnginesMember" abstract="false" name="AircraftAndEnginesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_AirrelatedrevenueMember" abstract="true" name="AirrelatedrevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_LandesbankHessenThuringenGirozentraleMember" abstract="true" name="LandesbankHessenThuringenGirozentraleMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_RevolvingCreditFacilitiesDue2027Member" abstract="true" name="RevolvingCreditFacilitiesDue2027Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_SecuritiesExcludedFromComputationOfEarningsPerShareAmounts" abstract="false" name="SecuritiesExcludedFromComputationOfEarningsPerShareAmounts" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="algt_ContractWithCustomerLiabilityCreditVoucherBookings" abstract="false" name="ContractWithCustomerLiabilityCreditVoucherBookings" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_InsuranceProceedsFromSaleOfPropertyPlantAndEquipment" abstract="false" name="InsuranceProceedsFromSaleOfPropertyPlantAndEquipment" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_CapitalizedInterest" abstract="false" name="CapitalizedInterest" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_AllegiantAirMember" abstract="true" name="AllegiantAirMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_MUFGBankLtdMember" abstract="true" name="MUFGBankLtdMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_StatementOfComprehensiveIncomeAbstract" abstract="true" name="StatementOfComprehensiveIncomeAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="algt_FixedRateMember" abstract="true" name="FixedRateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_DelayedDrawConstructionLoanMember" abstract="true" name="DelayedDrawConstructionLoanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="algt_VariableRateMember" abstract="true" name="VariableRateMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
</xs:schema>
