<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-07-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001089511</issuerCik>
        <issuerName>ALASKA COMMUNICATIONS SYSTEMS GROUP INC</issuerName>
        <issuerTradingSymbol>alsk</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001275968</rptOwnerCik>
            <rptOwnerName>PICHETTE PATRICK</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2660 BAY MEADOW</rptOwnerStreet1>
            <rptOwnerStreet2>ST LAZARE</rptOwnerStreet2>
            <rptOwnerCity>QUEBEC CANADA</rptOwnerCity>
            <rptOwnerState>A8</rptOwnerState>
            <rptOwnerZipCode>00000</rptOwnerZipCode>
            <rptOwnerStateDescription>QUEBEC, CANADA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common stock $.01 par</value>
            </securityTitle>
            <transactionDate>
                <value>2005-07-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F2"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>3296</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.87</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Deferred common stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>9.59</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>20.587</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1007.723</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Deferred common stock in lieu of cash dividend as per Alaska Communications Systems Group, Inc. Dividend Reinvestment and Stock Purchase Plan of March 22, 2005, and the Alaska Communications Systems Group, Inc. 1999 Non-employee Director Stock Compensation Plan, elected by the Director to be deferred until termination of service.</footnote>
        <footnote id="F2">Gift of 3,296 shares to the University of Quebec Foundation to establish a scholarship.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Patrick Pichette</signatureName>
        <signatureDate>2005-08-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
