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  <xs:element id="algt_FlightAttendantRatificationBonusMember" abstract="true" name="FlightAttendantRatificationBonusMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_SunseekerSpecialChargesMember" abstract="true" name="SunseekerSpecialChargesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_AllegiantTravelCompanyMember" abstract="true" name="AllegiantTravelCompanyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_ComputerHardwareandSoftwareMember" abstract="true" name="ComputerHardwareandSoftwareMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_A320SeriesEngineDomain" abstract="true" name="A320SeriesEngineDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types: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_RewardsPlanNameDomain" abstract="true" name="RewardsPlanNameDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_AllwaysRewardsLoyaltyProgramMember" abstract="true" name="AllwaysRewardsLoyaltyProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <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_AccruedRetentionBonusCurrentPaymentPercentage" abstract="false" name="AccruedRetentionBonusCurrentPaymentPercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="algt_AccruedRetentionBonusMinimumPayCreditHoursPerMonth" abstract="false" name="AccruedRetentionBonusMinimumPayCreditHoursPerMonth" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_AccruedRetentionBonusEmployeeExceptionPercentage" abstract="false" name="AccruedRetentionBonusEmployeeExceptionPercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="algt_NumberOfPointsEarnedForEveryDollarSpent" abstract="false" name="NumberOfPointsEarnedForEveryDollarSpent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_NumberOfPointsEarnedForEveryDollarSpentOverFiveHundredDollars" abstract="false" name="NumberOfPointsEarnedForEveryDollarSpentOverFiveHundredDollars" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <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_AirbusA320AircraftSeriesMember" abstract="true" name="AirbusA320AircraftSeriesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_AircraftAndEnginesMember" abstract="false" name="AircraftAndEnginesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_EquipmentAndLeaseholdImprovementsMember" abstract="false" name="EquipmentAndLeaseholdImprovementsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_InterestCostAbstract" abstract="true" name="InterestCostAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <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_TwoClassMethodWeightedAverageNumberofSharesOutstandingDiluted" abstract="false" name="TwoClassMethodWeightedAverageNumberofSharesOutstandingDiluted" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <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_ResortRevenueMember" abstract="true" name="ResortRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_ThirdPartyProductRevenueMember" abstract="true" name="ThirdPartyProductRevenueMember" 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" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <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_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_ArlineMember" abstract="true" name="ArlineMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <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_RevolvingCreditFacilitiesDue2027Member" abstract="true" name="RevolvingCreditFacilitiesDue2027Member" 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_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_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_SeniorSecuredRevolvingLoanFacilityMember" abstract="true" name="SeniorSecuredRevolvingLoanFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <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_BarclaysBankPLCMember" abstract="true" name="BarclaysBankPLCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_CreditAgricoleCorporateAndInvestmentBankMember" abstract="true" name="CreditAgricoleCorporateAndInvestmentBankMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_DebtInstrumentLiquidationRequirementInterestPercentage" abstract="false" name="DebtInstrumentLiquidationRequirementInterestPercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <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_NumberOfAircraftFinanceLeaseObligation" abstract="false" name="NumberOfAircraftFinanceLeaseObligation" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_FinanceLeasedAssetsNumberOfUnits" abstract="false" name="FinanceLeasedAssetsNumberOfUnits" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_OperatingLeasedAssetsNumberOfUnits" abstract="false" name="OperatingLeasedAssetsNumberOfUnits" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_OperatingLeasedAssetsNumberOfUnitsRemoved" abstract="false" name="OperatingLeasedAssetsNumberOfUnitsRemoved" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_Operatingrightofuseassetnet" abstract="false" name="Operatingrightofuseassetnet" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_TotalRightofUseAsset" abstract="false" name="TotalRightofUseAsset" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_TotalLeaseLiability" abstract="false" name="TotalLeaseLiability" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <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_NonPubliclyHeldDebtMember" abstract="true" name="NonPubliclyHeldDebtMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types: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_EffectiveIncomeTaxRateReconciliationUnrecognizedTaxBenefitsAmount" abstract="false" name="EffectiveIncomeTaxRateReconciliationUnrecognizedTaxBenefitsAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_EffectiveIncomeTaxRateReconciliationUnrecognizedTaxBenefitsPercent" abstract="false" name="EffectiveIncomeTaxRateReconciliationUnrecognizedTaxBenefitsPercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="algt_EmployeeMember" abstract="true" name="EmployeeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_RestrictedStockStockOptionsCashSettledSARsAndEmployeeStockPurchaseProgramMember" abstract="true" name="RestrictedStockStockOptionsCashSettledSARsAndEmployeeStockPurchaseProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalNumberOfSharesAuthorized" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalNumberOfSharesAuthorized" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="algt_ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseDecreaseRestrictedStockCapacity" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardIncreaseDecreaseRestrictedStockCapacity" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="algt_EmployeeStockPurchasePlanExtensionPeriod" abstract="false" name="EmployeeStockPurchasePlanExtensionPeriod" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="algt_UnrecognizedShareBasedPaymentArrangementNoncashExpense" abstract="false" name="UnrecognizedShareBasedPaymentArrangementNoncashExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_WeightedAverageFairValueOfStockPurchaseRightUnderEmployeeStockPurchasePlan" abstract="false" name="WeightedAverageFairValueOfStockPurchaseRightUnderEmployeeStockPurchasePlan" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="algt_AggregateCostOfDiscountOffMarketValueForSharesAvailableUnderEmployeeStockPurchasePlan" abstract="false" name="AggregateCostOfDiscountOffMarketValueForSharesAvailableUnderEmployeeStockPurchasePlan" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="algt_FlightAttendantsMember" abstract="true" name="FlightAttendantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_PilotsMember" abstract="true" name="PilotsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_MaintenanceTechniciansMember" abstract="true" name="MaintenanceTechniciansMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_FlightDispatchersMember" abstract="true" name="FlightDispatchersMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_TotalPercentageofEmployeesMember" abstract="true" name="TotalPercentageofEmployeesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_ConcentrationRiskPercentage" abstract="false" name="ConcentrationRiskPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="algt_NumberOfFullTimeEquivalentEmployee" abstract="false" name="NumberOfFullTimeEquivalentEmployee" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_NumberOfBusinessUnit" abstract="false" name="NumberOfBusinessUnit" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="algt_AllegiantAirMember" abstract="true" name="AllegiantAirMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_SunCountryMember" abstract="true" name="SunCountryMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="algt_BusinessCombinationConsiderationTransferredEquityInterestsIssuedandIssuableCashPaidPerAcquireeShare" abstract="false" name="BusinessCombinationConsiderationTransferredEquityInterestsIssuedandIssuableCashPaidPerAcquireeShare" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="algt_BusinessCombinationConsiderationTransferredEquityInterestsIssuedandIssuableEntitySharesIssuedPerAcquireeShare" abstract="false" name="BusinessCombinationConsiderationTransferredEquityInterestsIssuedandIssuableEntitySharesIssuedPerAcquireeShare" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
</xs:schema>
