UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                  SCHEDULE 13G


                    Under the Securities Exchange Act of 1934
                                (Amendment No. 1)

                                 WHITTAKER CORP.

                                  COMMON STOCK
                         (Title of Class of Securities)

                                    966680407
                                 (CUSIP Number)

                                October 31, 1998
             (Date of Event Which Requires Filing of this Statement)

Check the  appropriate box to designate the rule pursuant to which this Schedule
is filed:

         |X|      Rule 13d-1(b)
         |_|      Rule 13d-1(c)
         |_|      Rule 13d-1(d)

The  remainder  of this cover page shall be filled out for a reporting  person's
initial filing on this form with respect to the subject class of securities, and
for any  subsequent  amendment  containing  information  which  would  alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the  Securities  Exchange  Act of
1934 ("Act") or otherwise  subject to the liabilities of that section of the Act
but  shall be  subject  to all other  provisions  of the Act  (however,  see the
Notes).

CUSIP No. 966680407                         13G               Page 1 of 6 Pages

1        NAMES OF REPORTING PERSONS
         I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS
                  EIN 23-2856392
                  SCHNEIDER CAPITAL MANAGEMENT CORPORATION




2        CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
                                                                  (a)  |_|
                                                                  (b)  |_|

3        SEC USE ONLY

4        CITIZENSHIP OR PLACE OF ORGANIZATION
                  Pennsylvania

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

                  5        SOLE VOTING POWER
                                    None

                  6        SHARED VOTING POWER
                                    None

                  7        SOLE DISPOSITIVE POWER
                                    425,200

                  8        SHARED DISPOSITIVE POWER
                                    None

9        AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                  425,200

10       CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN 
         SHARES |_|

11       PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9
                  3.75%

12       TYPE OF REPORTING PERSON
                  IA

                              GENERAL INSTRUCTIONS

Item 1.
         (a)  Name of Issuer
                  WHITTAKER CORP.


         (b)      Address  of  Issuer's  Principal  Executive  Offices  
                  1955  N. Surveyor Ave.
                  Simi Valley, CA  93063

Item 2.
         (a)  Name of Person Filing
                  SCHNEIDER CAPITAL MANAGEMENT CORPORATION

         (b)  Address of Principal Business Office or, if none, Residence
                  480 E. Swedesford Road, Suite 1080
                  Wayne, PA 19087

         (c)  Citizenship
                  PENNSYLVANIA

         (d)  Title of Class of Securities
                  COMMON STOCK

         (e)  CUSIP Number
                  966680407

Item 3.  If this statement is filed pursuant to Rules ss.240.13d-1(b), or
         240.13d-2(b) or (c), check whether the person filing is a:

         (a)  |_|  Broker or Dealer registered under Section 15 of
         the Act

         (b) |_| Bank as defined in section 3(a)(6) of the Act

         (c) |_| Insurance Company as defined in section 3(a)(19) of the Act

         (d) |_| Investment Company registered under section 8 of the Investment
         Company Act of 1940

         (e) |X| An Investment Adviser in accordance with
         ss.240.13d-1(b)(1)(ii)(E)

         (f) |_| An employee benefit plan or endowment fund in accordance with
         ss.240.13d-1(b)(1)(ii)(F)

         (g) |_| A parent holding company or control person,  in accordance with
         ss.240.13d-1(b)(1)(ii)(G)



         (h) |_| A savings association as defined in Section 3(b) of the Federal
         Deposit Insurance Act

         (i) |_| A  church  plan  that is  excluded  from the  definition  of an
         investment company under Section 3(c)(14) of the Investment Company Act
         of 1940

         (j)  |_| Group in accordance with ss.240.13d-1(b)(1)(ii)(J)

Item 4.  Ownership.
         (a)  Amount Beneficially Owned
                  425,200

         (b)  Percent of Class
                  3.75%

         (c)      Number of shares as to which the person has: (i) Sole power to
                  vote or to direct the vote
                           None

                  (ii)  Shared power to vote or to direct the vote
                           None

                  (iii)    Sole power to dispose or to direct the disposition of
                           425,200

                  (iv)     Shared power to dispose or to direct the  disposition
                           of None

Item 5.  Ownership of Five Percent or Less of a Class
         If this statement is being filed to report the fact that as of the date
         hereof the reporting  person has ceased to be the  beneficial  owner of
         more than five percent of the class of securities,  check the following
         |X|.

Item 6.  Ownership of More than Five Percent on Behalf of Another Person.
                  None

Item 7.  Identification and Classification of the Subsidiary Which Acquired the
         Security Being Reported on By the Parent Holding Company.

                  Not Applicable

Item 8.  Identification and Classification of Members of the Group.
                  Not Applicable



Item 9.  Notice of Dissolution of Group.
                  Not Applicable

Item 10. Certification.
         By  signing  below I  certify  that,  to the best of my  knowledge  and
belief,  the  securities  referred  to above were  acquired  and are held in the
ordinary  course  of  business  and were not  acquired  and are not held for the
purpose of or with the effect of  changing  or  influencing  the  control of the
issuer of the  securities  and were not acquired and are not held in  connection
with or as a participant in any transaction having that purpose or effect.

                                    SIGNATURE

After  reasonable  inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.

                                            11/10/98
                                            Date

                                            GARY P. SOURA, JR.
                                            Signature

                                            GARY P. SOURA, JR.
                                            ASSISTANT VICE PRESIDENT
                                            Name/Title

         The original  statement  shall be signed by each person on whose behalf
the  statement is filed or his  authorized  representative.  If the statement is
signed  on behalf of a person by his  authorized  representative  other  than an
executive  officer or general  partner of the  filing  person,  evidence  of the
representative's  authority to sign on behalf of such person shall be filed with
the  statement,  provided,  however,  that a power of attorney  for this purpose
which is already on file with the Commission may be  incorporated  by reference.
The name and any title of each person who signs the statement  shall be typed or
printed beneath his signature.

         Attention: Intentional misstatements or omissions of fact constitute
Federal criminal violations (See 18 U.S.C. 1001).