<SUBMISSION>
<ACCESSION-NUMBER>0001209191-16-094449
<TYPE>4/A
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20130101
<FILING-DATE>20160201
<DATE-OF-FILING-DATE-CHANGE>20160201
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>PHI INC
<CIK>0000350403
<ASSIGNED-SIC>4522
<IRS-NUMBER>720395707
<STATE-OF-INCORPORATION>LA
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>2001 SE EVANGELINE THRUWAY
<STREET2>-
<CITY>LAFAYETTE
<STATE>LA
<ZIP>70508
<PHONE>(337) 235-2452
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>PO BOX 90808
<CITY>LAFAYETTE
<STATE>LA
<ZIP>70509
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>PETROLEUM HELICOPTERS INC
<DATE-CHANGED>19920703
</FORMER-COMPANY>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Gonsoulin Alton Anthony Jr
<CIK>0001064045
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4/A
<ACT>34
<FILE-NUMBER>000-09827
<FILM-NUMBER>161378018
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>P.O. BOX 16757
<CITY>SUGAR LAND
<STATE>TX
<ZIP>77479
</MAIL-ADDRESS>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>GONSOULIN ALTON ANTHONY JR
<DATE-CHANGED>19980615
</FORMER-NAME>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>doc4a.xml
<DESCRIPTION>FORM 4/A SUBMISSION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2013-01-01</periodOfReport>

    <dateOfOriginalSubmission>2013-01-03</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000350403</issuerCik>
        <issuerName>PHI INC</issuerName>
        <issuerTradingSymbol>PHII</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001064045</rptOwnerCik>
            <rptOwnerName>Gonsoulin Alton Anthony Jr</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>4655 SWEETWATER BLVD.</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>SUGARLAND</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77479</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Voting Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-01-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>30837</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>32.05</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2010865</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This Form 4 is being amended for the purpose of correcting the number of shares withheld to cover taxes (initially overreported by 936 shares).</footnote>
        <footnote id="F2">In addition to these shares of Voting Common Stock, the reporting person owned 787,690 shares of the issuer's Non-Voting Common Stock as of January 1, 2013.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Kenneth J. Najder, on behalf of Al A. Gonsoulin, pursuant to a power of attorney</signatureName>
        <signatureDate>2016-02-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
