<PAGE>

                                                                   Exhibit 10.15

                                 LOAN AGREEMENT

     THIS LOAN AGREEMENT (the "Agreement") is entered into this 17th day of May,
1994, by and between BARNETT BANK OF PINELLAS COUNTY, a Florida banking
corporation (the "Lender"), AEROSONIC CORPORATION, a Delaware corporation
authorized to do business in the State of Florida ("Aerosonic") and AVIONICS
SPECIALTIES, INC., a Virginia corporation ("Avionics") (Aerosonic and Avionics
will be sometimes collectively referred to below as the "Borrower"), and is made
in reference to the following facts:

     (A) At all times material hereto, Avionics has been the owner of that
certain real property and all improvements thereon located in Albemarle County,
Virginia, and being more particularly described in Exhibit "A" attached hereto
and by this reference made a part hereof (the "Property").

     (B) On or about the date hereof, the Lender has made a secured loan to the
Borrower in the principal amount of ONE MILLION ONE HUNDRED THOUSAND AND NO/100
DOLLARS ($1,100,000.00) (the "Loan"). The Loan is evidence by a deed of trust
note executed by Borrower in favor of Lender (the "Note"). The Loan is secured,
among other things, by a Deed of Trust and other instruments of security which
encumber the Property as a first lien thereon and a first security interest
therein (collectively the "Instruments of Security"). The Note and Instruments
of Security will be sometimes collectively referred to below as the "Loan
Documents".

     (C) The Lender has required the execution of this Agreement as a condition
to making the Loan, and the Borrower is agreeable to such.

     NOW THEREFORE, in consideration of the premises and for other valuable
consideration, the receipt and adequacy of which are hereby acknowledged, the
parties hereto agree as follows:

     1. Recitals. The statements contained in the recitals of fact set forth
above (the "Recitals") are true and correct, and the Recitals are by this
reference made a part hereof.

     2. Exhibits. The exhibit attached to this Agreement is by this reference
made a part hereof.

     3. Abbreviations and Definitions. The following abbreviations and
definitions will be used for purposes of this Agreement.

          (a) The abbreviations of the parties set forth in the Preamble will be
used for purposes of this Agreement;

<PAGE>

          (b) The abbreviations and definitions set forth in the Recitals will
be used for purposes of this Agreement; and

          (c) The term "Agreement" shall mean the Loan Agreement between the
parties in the manner set forth herein.

     4. Financial Information. At all times during the term of the Loan and Loan
Documents, the Borrower shall provide the following financial information to
Lender:

          (a) No later than sixty (60) days following the fiscal quarter end of
Aerosonic, Aerosonic shall provide to Lender a copy of its quarterly 10-Q Report
that is filed with the Securities and Exchange Commission (the "SEC").

          (b) No later than one hundred twenty (120) days following the fiscal
year end of Aerosonic, Aerosonic shall provide to Lender a copy of its 10-K
Report that is filed with the SEC.

          (c) No later than one hundred twenty (120) days following the fiscal
year end of Aerosonic, Aerosonic shall provide to Lender a copy of its audited
financial statement in consolidated and consolidating form, including all
subsidiaries of Aerosonics therein.

Failure of Borrower to provide any of the aforementioned information or
documentation to Lender within the time periods indicated shall constitute a
default under the Loan and Loan Documents, entitling Lender to immediately
accelerate the same, without notice.

     5. Prohibition on Prepayment. The parties hereto acknowledge and agree that
Aerosonic is a debtor under a $1,800,000.00 Industrial Revenue Bond financing
package between, among others, the Pinellas County Industry Council and
Aerosonic, Series 1987, captioned the "Aerosonic Corporation Project" dated
December 17, 1987 (the "Bond Financing"). All instruments, documents and other
items that evidence and/or secure the Bond Financing will be sometimes
collectively referred to below and the "Bond Documents". The parties hereto
acknowledge and agree that the Bond Financing and Bond Documents may not be
prepaid, in whole or in part, so long as the Loan and Loan Documents remain
outstanding. Any attempted prepayment (whether in whole or in part) of the Bond
Financing and Bond Documents without the simultaneous full payoff of the Loan
and Loan Documents shall constitute a default under the Loan and Loan Documents,
and shall entitle Lender to immediately accelerate the same, without notice.

     6. Negative Pledge of Assets. Both entitles comprising the Borrower hereby
covenant to and agree with Lender not to pledge, encumber or grant a security
interest in any or all of their assets at any time during the term of the Loan
and Loan Documents, failing which the same shall constitute a default under the
Loan and Loan Documents, entitling Lender to immediately accelerate the same,
without notice.

                                        2

<PAGE>

     7. Florida Contract. This Agreement shall be deemed a Florida contract and
shall be construed according to the laws of the States of Florida and/or
Virginia (at the sole option of Lender), and shall be enforceable, at the option
of Lender, in any court of competent jurisdiction in the State of Florida,
regardless whether this Agreement is executed by certain of the parties hereto
in other states.

     8. Binding Effect. This Agreement shall bind the successors and assigns of
the parties hereto; it constitutes the entire understanding of the parties and
it may not be modified except in writing.

     9. Counterparts. This Agreement may be execute in several counterparts,
each of which shall be deemed an original.

     10. Execution. This Agreement shall not be effective nor shall it have any
force and effect whatsoever until all the parties hereto have duly executed this
Agreement.

     11. Headings. The headings of the paragraphs contained in this Agreement
are for convenience of reference only and do not form a part hereof and in no
way modify, interpret or construe the meaning of the parties hereto.

 Signed, sealed and delivered              BARNETT BANK OF PINELLAS COUNTY,
 in the presence of:                       a Florida banking corporation


/s/ Peggy E. Morris                        By: /s/ M.P. Freeman
-----------------------------                  ---------------------------------
                                                      its Senior Vice President


/s/ David A. Baldini                                  (CORPORATE SEAL)
-----------------------------
As to Lender


                                           AEROSONIC CORPORATION, a Delaware
                                           corporation authorized to do business
                                           in the State of Florida


/s/ M.P. Freeman                              By: /s/ David S. Goldman
-----------------------------                  ---------------------------------
                                               David S. Goldman, Its President


/s/ David A. Baldini                                 (CORPORATE SEAL)
-----------------------------

                                        3

<PAGE>

                                     AVIONICS SPECIALTIES, INC., a Virginia
                                     corporation


/s/ M.P. Freeman                     By: /s/ David S. Goldman
----------------------------------       ----------------------------------
                                         David S. Goldman, Chairman of the Board

                                                     (CORPORATE SEAL)


/s/ Peggy E. Morris
----------------------------------
As to Borrower

STATE OF VIRGINIA     )
COUNTY OF Albemarle   )

          The foregoing instrument was acknowledged before me this 17th day of
May, 1994 by M. P. Freeman, the Sr. Vice President of BARNETT BANK OF PINELLAS
COUNTY, a Florida banking corporation, who is personally known to me or has
produced (TYPE OF IDENTIFICATION: Florida Drivers License #5 655-555-44-308) as
identification.


                                         /s/ David L. Morris
                                         ----------------------------------
                                                SIGNATURE

                                                David L. Morris
                                                NAME LEGIBLY PRINTED,
                                                TYPEWRITTEN OR STAMPED

    (SEAL)                                      NOTARY PUBLIC
My Commission Expires:
MY COMMISSION EXPIRES JAN. 31, 1997

                                        4

<PAGE>

STATE OF Virginia     )
COUNTY OF Albemarle   )

          The foregoing instrument was acknowledged before me this 17th, day of
May, 1994, by DAVID S. GOLDMAN, the President of AEROSONIC CORPORATION, a
Delaware corporation authorized to do business in the State of Florida, on
behalf of the corporation, who is personally known to me or who has produced
(TYPE OF IDENTIFICATION:                             ) as identification.
                        ----------------------------


                                         /s/ David L. Morris.
                                         ----------------------------------
                                                SIGNATURE

                                                David L. Morris
                                                NAME LEGIBLY PRINTED,
                                                TYPEWRITTEN OR STAMPED

    (SEAL)                                      NOTARY PUBLIC
My Commission Expires:
MY COMMISSION EXPIRES JAN. 31, 1997

STATE OF Virginia     )
COUNTY OF Albemarle   )

          The foregoing instrument was acknowledged before me this 17th day of
Mary 1994, by DAVID S. GOLDMAN, the Chairman of the Board of AVIONICS
SPECIALTIES, INC., a Virginia corporation, on behalf of the corporation, who is
personally known to me or who has produced (TYPE OF IDENTIFICATION: )
                         as identification.
------------------------


                                         /s/ David L. Morris.
                                         ----------------------------------
                                                SIGNATURE

                                                David L. Morris
                                                NAME LEGIBLY PRINTED,
                                                TYPEWRITTEN OR STAMPED

    (SEAL)                                      NOTARY PUBLIC
My Commission Expires:
MY COMMISSION EXPIRES JAN. 31, 1997

                                        5

<PAGE>

                                   EXHIBIT A

                            DESCRIPTION OF PROPERTY

     All that certain parcel or tract of land consisting of 12.037 acres and
depicted on the attached "Plat Showing a Survey of a Proposed Division of the
Teledyne Industries, Inc. Property Located on St. Rt. 743 Southwest of the C/A
Airport in Albemarle Co., VA", prepared by Thomas D. Blue, last revised February
23, 1994.

                                  Page 1 of 3

<PAGE>

                                      [MAP]

                                     [SEAL]

                                  Page 2 of 3

<PAGE>

1.   Property is zoned LI, therefore division rights do not apply.

2.   These lots each have a minimum of 30,000 square feet of contiguous area in
     slopes of less than 25%.

3.   Building set-back limits are those required for the LI Zone.

4.   Property is located in the White Hall Magisterial District.

5.   Tax Map 32, Parcels 88 and 88C, shown in Deed Book 418 page 358 and Deed
     Book 314 page 438, are hereby combined into one parcel and any boundary
     between them is hereby abolished.

6.   A surface drainage easement for the benefit of the 12.037 acre parcel is
     hereby reserved to permit drainage over the 11.451 acre parcel from the
     catch basin located near the northwest corner of the 12.037 acre parcel as
     shown on the attached plat.

                                                                [SEAL]
OWNER'S APPROVAL

     The division of the land described herein is with the free consent and in
accordance with the desire of the undersigned owner. Any reference to future
potential development is to be deemed as theoretical only. All statements
affixed to this plat are true and correct to the best of my knowledge.

                                                OWNER: TELEDYNE INDUSTRIES, INC.


                                                       BY: /s/ Douglas L. Grant
                                                          ----------------------

APPROVED:


/s/ Chairman                                                        3/31/94
------------------------------------------------------         -----------------
Chairman, Albemarle County, Planning Commission                Date


/s/ Designated Agent                                                3/31/94
------------------------------------------------------         -----------------
Designated Agent, Albemarle County, Board of Supervisors       Date

                                   Page 3 of 3