-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 wAx7aDbQydyqVoYmQT6yvw==

<SEC-DOCUMENT>0000810332-08-000004.txt : 20080117
<SEC-HEADER>0000810332-08-000004.hdr.sgml : 20080117
<ACCEPTANCE-DATETIME>20080117184721
ACCESSION NUMBER:		0000810332-08-000004
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080115
FILED AS OF DATE:		20080117
DATE AS OF CHANGE:		20080117

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MESA AIR GROUP INC
		CENTRAL INDEX KEY:			0000810332
		STANDARD INDUSTRIAL CLASSIFICATION:	AIR TRANSPORTATION, SCHEDULED [4512]
		IRS NUMBER:				850302351
		STATE OF INCORPORATION:			NV
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		410 NORTH 44TH STREET
		STREET 2:		SUITE 700
		CITY:			PHOENIX
		STATE:			AZ
		ZIP:			85008
		BUSINESS PHONE:		6026854000

	MAIL ADDRESS:	
		STREET 1:		410 NORTH 44TH STREET
		STREET 2:		SUITE 700
		CITY:			PHOENIX
		STATE:			AZ
		ZIP:			85008

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MESA AIRLINES INC
		DATE OF NAME CHANGE:	19950426

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ORNSTEIN JONATHAN G
		CENTRAL INDEX KEY:			0001054973

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-15495
		FILM NUMBER:		08537157

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		6082564421

	MAIL ADDRESS:	
		STREET 1:		C/O GAMMAGE & BURNHAM
		STREET 2:		2 NORTH CENTRAL AVENUE 18TH FLOOR
		CITY:			PHOENIX
		STATE:			AZ
		ZIP:			85004
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-01-15</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000810332</issuerCik>
        <issuerName>MESA AIR GROUP INC</issuerName>
        <issuerTradingSymbol>mesa</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001054973</rptOwnerCik>
            <rptOwnerName>ORNSTEIN JONATHAN G</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>410 N 44TH STREET, STE 100</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>PHOENIX</rptOwnerCity>
            <rptOwnerState>AZ</rptOwnerState>
            <rptOwnerZipCode>85008</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Mesa Common</value>
            </securityTitle>
            <transactionDate>
                <value>2008-01-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>12000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.73</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Daughter</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Mesa Common</value>
            </securityTitle>
            <transactionDate>
                <value>2008-01-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>12000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.72</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Son</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Mesa Common</value>
            </securityTitle>
            <transactionDate>
                <value>2008-01-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.75</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Mother</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Mesa Common</value>
            </securityTitle>
            <transactionDate>
                <value>2008-01-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.65</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>243103</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These shares are held by Mr. Ornstein for Jessica Ornstein</footnote>
        <footnote id="F2">These shares are held by Mr. Ornstein as custodian for Jacob Ornstein</footnote>
        <footnote id="F3">These shares are held by Mr. Ornstein for Mona Ornstein</footnote>
        <footnote id="F4">Includes a restricted stock award which shall vest over three years at the rate of one-third on each of the first, second and third anniversaries of the date of grant.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Jonathan Ornstein</signatureName>
        <signatureDate>2008-01-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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