<PAGE>
 
                                                                    EXHIBIT 3.1

                           CERTIFICATE OF CORRECTION
                                      OF
                          CERTIFICATE OF DESIGNATION
                                      OF
                             WHITTAKER CORPORATION

     Whittaker Corporation, a corporation organized and existing under and by 
virtue of the General Corporation Law of the State of Delaware (the 
"Corporation"), does hereby certify as follows:

     FIRST:  That the Certificate of Designation of Series D Participating 
Convertible Preferred Stock of Whittaker Corporation filed in the office of the 
Secretary of State of Delaware on June 28, 1989 (the "Series D Certificate of 
Designation") has been found to be an inaccurate in certain respects and, 
therefore, requires correction pursuant to Section 103(f) of the General 
Corporation Law of the State of Delaware, 8 Del. C. Section 103(f).

     SECOND:  The Series D Certificate of Designation (i) incorrectly stated in 
Section 2(B) that the quarterly dividend amount was $1.00 per share and (ii) 
failed to specify in Section 2(C) when dividends begin to accrue in the event 
that there is no record date for the first Quarterly Dividend Payment Date. The 
aforementioned Series D Certificate of Designation is hereby corrected 
accordingly to replace Section 2(B) and (C) with the following:

     (B) The Corporation shall declare a dividend or distribution on the 
Preferred Stock as provided in paragraph (A) of this Section immediately after 
it declares a dividend or distribution on the Common Stock (other than as 
described in clauses (i) and (ii) of the second sentence of such paragraph (A));
provided that, in the event no dividend or distribution shall have been declared
on the Common Stock during the period between any Quarterly Dividend Payment 
Date and the next subsequent Quarterly Dividend Payment Date (or, with respect 
to the first Quarterly Dividend Payment Date, the period between the first 
issuance of any share or fraction of a share of the Preferred Stock and such 
first Quarterly Dividend Payment Date), a dividend of $0.25 per share on the 
Preferred Stock shall nevertheless be payable on such subsequent Quarterly 
Dividend Payment Date.
<PAGE>
 
     (C) Dividends shall begin to accrue and the cumulative on outstanding 
shares of Preferred Stock from the Quarterly Dividend Payment Date next 
preceding the date of issue of such shares unless (i) the date of issue of such 
shares is on or prior to the record date for the first Quarterly Dividend 
Payment Date or there is no record date for the first Quarterly Dividend Payment
Date, in either of which events dividends on such shares shall begin to accrue 
from the date of issue of such shares or (ii) the date of issue is a Quarterly 
Dividend Payment Date or is a date after the record date for the determination 
of holders of shares of Preferred Stock entitled to receive a quarterly dividend
and before such Quarterly Dividend Payment Date, in either of which events such 
dividends shall begin to accrue and be cumulative from such Quarterly Dividend 
Payment Date. Accrued but unpaid dividends shall not bear interest. Dividends 
paid on shares of Preferred Stock in an amount less than the total amount of 
such dividends at the time accrued and payable on such shares shall be allocated
pro rata on a share-by-share basis among all shares of Preferred Stock at the 
time outstanding. The Board of Directors may fix a record date for the 
determination of holders of shares of Preferred Stock entitled to receive 
payment of a dividend or distribution declared thereon, which record date shall 
not be more than 60 days prior to the date fixed for the payment thereof.

     IN WITNESS WHEREOF, said Whittaker Corporation has caused its corporate 
seal to be hereunto affixed and this certificate to be signed by Edward R. 
Muller, a Vice President of the Corporation, and Nadine D. Leonsky, an Assistant
Secretary this 7th day of March 1990.

                                       WHITTAKER CORPORATION


                                       By  /s/ Edward R. Muller
                                         ---------------------------------------
                                           Edward R. Muller
                                           Vice President

Attest:

/s/ Nadine D. Leonsky
----------------------------
Assistant Secretary

                                      -2-