<SUBMISSION>
<ACCESSION-NUMBER>0000919574-12-002617
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20120329
<FILING-DATE>20120402
<DATE-OF-FILING-DATE-CHANGE>20120402
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>CONWAY RICHARD F
<CIK>0001299904
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-34595
<FILM-NUMBER>12735012
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>C/O LAMPE, CONWAY & CO. LLC
<STREET2>680 FIFTH AVENUE, SUITE 1202
<CITY>NEW YORK
<STATE>NY
<ZIP>10019
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>ATS CORP
<CIK>0001325460
<ASSIGNED-SIC>8742
<IRS-NUMBER>113747950
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>7925 JONES BRANCH DRIVE
<CITY>MCLEAN
<STATE>VA
<ZIP>22102
<PHONE>571-766-2400
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>7925 JONES BRANCH DRIVE
<CITY>MCLEAN
<STATE>VA
<ZIP>22102
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>Federal Services Acquisition CORP
<DATE-CHANGED>20050429
</FORMER-COMPANY>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>LC CAPITAL MASTER FUND LTD
<CIK>0001222051
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-34595
<FILM-NUMBER>12735011
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>C/O LAMPE CONWAY & CO LLC
<STREET2>730 FIFTH AVENUE STE 1002
<CITY>NEW YORK
<STATE>NY
<ZIP>10019-4105
<PHONE>2125818989
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>C/O TRIDENT FUND SERVICES (BVI) LIMITED
<STREET2>PO BOX 146, WATERFRONT DR, WICKHAMS CAY
<CITY>ROAD TOWN, TORTOLA
<STATE>D8
<ZIP>00000
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>LAMPE STEVEN
<CIK>0001260818
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-34595
<FILM-NUMBER>12735013
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>C/O LAMPE, CONWAY & CO. LLC
<STREET2>680 FIFTH AVENUE, SUITE 1202
<CITY>NEW YORK
<STATE>NY
<ZIP>10019
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>LAMPE, CONWAY & CO. LLC
<CIK>0001299982
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-34595
<FILM-NUMBER>12735014
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>680 FIFTH AVENUE, SUITE 1202
<CITY>NEW YORK
<STATE>NY
<ZIP>10019
<PHONE>2125818989
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>680 FIFTH AVENUE, SUITE 1202
<CITY>NEW YORK
<STATE>NY
<ZIP>10019
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>p1279624.xml
<DESCRIPTION>OWNERSHIP DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0305</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-03-29</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001325460</issuerCik>
        <issuerName>ATS CORP</issuerName>
        <issuerTradingSymbol>ATSC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001222051</rptOwnerCik>
            <rptOwnerName>LC CAPITAL MASTER FUND LTD</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TRIDENT FUND SVCS (BVI) LTD</rptOwnerStreet1>
            <rptOwnerStreet2>P.O. BOX 146, WATERFRONT DRIVE</rptOwnerStreet2>
            <rptOwnerCity>ROAD TOWN, TORTOLA</rptOwnerCity>
            <rptOwnerState>D8</rptOwnerState>
            <rptOwnerZipCode></rptOwnerZipCode>
            <rptOwnerStateDescription>VIRGIN ISLANDS, BRITISH</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001299982</rptOwnerCik>
            <rptOwnerName>LAMPE, CONWAY &amp; CO. LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>680 FIFTH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>12TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001260818</rptOwnerCik>
            <rptOwnerName>LAMPE STEVEN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>680 FIFTH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>12TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001299904</rptOwnerCik>
            <rptOwnerName>CONWAY RICHARD F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>680 FIFTH AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>12TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-03-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>U</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2323715</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.20</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-03-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>U</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2323715</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.20</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These securities are owned by LC Capital Master Fund, Ltd., which is a Reporting Person.</footnote>
        <footnote id="F2">These securities may be deemed to be beneficially owned by Lampe, Conway &amp; Co., LLC, the investment manager of LC Capital Master Fund, Ltd. and LC Capital / Capital Z SPV, L.P., Steven G. Lampe, a managing member of Lampe, Conway &amp; Co., LLC and Richard F. Conway, a managing member of Lampe, Conway &amp; Co., LLC. Each such Reporting Person disclaims beneficial ownership of the reported securities except to the extent of his or its pecuniary interest therein, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>LC Capital Master Fund, Ltd. By: /s/Richard F. Conway Name: Richard F. Conway Title: Director</signatureName>
        <signatureDate>2012-04-02</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Lampe, Conway &amp; Co LLC By: /s/Richard F. Conway Name: Richard F. Conway</signatureName>
        <signatureDate>2012-04-02</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>STEVEN LAMPE By: /s/Steven Lampe Name: Steven Lampe</signatureName>
        <signatureDate>2012-04-02</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>RICHARD F. CONWAY By: /s/Richard F. Conway Name: Richard F. Conway</signatureName>
        <signatureDate>2012-04-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
