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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-06-10</periodOfReport>

    <issuer>
        <issuerCik>0000100517</issuerCik>
        <issuerName>UAL CORP /DE/</issuerName>
        <issuerTradingSymbol>UAUA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001017988</rptOwnerCik>
            <rptOwnerName>OCONNOR JAMES J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 66100 - HDQLD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60666</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Share Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2010-06-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1139.21</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1139.21</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7028.49</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each share unit represents the economic equivalent of one share of common stock.  At time of distribution, Reporting Person will receive a cash payment equal to the number of share units multiplied by the average of the high and low sale prices of a share of the Company's common stock on the date of distribution.</footnote>
        <footnote id="F2">Additional share units accrue when and as dividends are paid on the Company's common stock.  The number of share units accrued will be equal to the dollar amount of dividends that would be payable if the share units were actual shares of common stock, divided by the average of the high and low sale prices of a share of the Company's common stock on the date dividends are paid.</footnote>
        <footnote id="F3">Delivery of a cash payment in settlement of the share units will be made in January of the year following the calendar year in which Reporting Person ceases to be a director of the Company.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Lydia J. Mathas for James J. O'Connor</signatureName>
        <signatureDate>2010-06-14</signatureDate>
    </ownerSignature>
</ownershipDocument>

