EXHIBIT 3

                                IRREVOCABLE PROXY

         The undersigned agrees to, and hereby grants William F. Mitchell
("Mitchell") an irrevocable proxy pursuant to the provisions of the Pennsylvania
Business Corporation Law to vote, or to execute and deliver written consents or
otherwise act with respect to, all shares of capital stock of Environmental
Tectonics Corporation, a Pennsylvania corporation (the "Corporation"), now owned
or hereafter acquired by the undersigned (collectively, the "Shares") as fully,
to the same extent and with the same effect as the undersigned might or could do
under any applicable laws or regulations governing the rights and powers of
stockholders of a Pennsylvania corporation, as provided in Section 1 of that
certain Stockholders Voting Agreement, dated as of February 18, 2003 (the
"Stockholders Voting Agreement"), among Mitchell, Pete L. Stephens, M.D.,
Emerald Advisors, Inc., ETC Asset Management, LLC and H.F. Lenfest. The
undersigned hereby affirms that this irrevocable proxy is given as a condition
of the Stockholders Voting Agreement and, as such, is coupled with an interest
and is irrevocable. It is further understood by the undersigned that this
irrevocable proxy may be exercised by Mitchell for the period beginning the date
hereof and ending on the earlier of: (i) June 18, 2003; and (ii) the day
immediately following the date of (A) any meeting of the stockholders of the
Corporation at which the stockholders of the Corporation vote to approve the
Transaction (as described in the Stockholders Voting Agreement) or (B) the date
on which the Transaction is otherwise approved by a majority of the stockholders
of the Corporation.

         THIS PROXY SHALL REMAIN IN FULL FORCE AND EFFECT AND BE ENFORCEABLE
AGAINST ANY DONEE, TRANSFEREE OR ASSIGNEE OF THE SHARES.

Dated as of February 18, 2003               /s/ William F. Mitchell
                                            -------------------------------
                                            William F. Mitchell