<PAGE>

                                                                     EXHIBIT 4.4
                                                                     -----------

March 20, 2000

Via Facsimile to 0 63 32-97 20-20
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Herr Fritz Winkler
Winair Winkler & Feyock Gmbh & Co. KG
Flugplatz, Gebaude 324
D-66482 Zweibrucken, Germany

     Re:  Acquisition of Piaggio Avanti P180

Dear Herr Winkler:

This letter evidences the interest of Pinnacle Oil Inc., a Nevada corporation
and a wholly-owned subsidiary of Pinnacle Oil International, Inc. ("Pinnacle")
to purchase a 1992 P180 Piaggio Avanti aircraft, Serial Number 1017, as more
particularly described in paragraph 1(a) of this letter (the "Aircraft"),
together with all documentation and technical publications and records relating
to the Aircraft as more particularly described in paragraph 1(b) of this letter
(the "Records"), from Winair Winkler & Feyock Gmbh & Co. KG ("Seller").   When
executed by you, this Agreement (the "Agreement") is intended as a binding
agreement for the sale of the Aircraft by Seller and the purchase of the
Aircraft by Pinnacle (the "Acquisition").  The following are the material terms
and conditions relating to the Acquisition:

1.   Description of Aircraft and Records.   For purposes of this Agreement, the
     -----------------------------------
     terms Aircraft and Records shall be deemed to include the following:

     (a)  Aircraft.   The Aircraft shall consist of the aircraft body configured
          --------
          in accordance with the floorplan and specifications described in
          Appendix A to this Agreement, together with all engines, equipment,
          avionics and accessories described in Appendix A to this Agreement.

     (b)  Records.   The Records shall include all logbooks, flight logs,
          -------
          technical records, maintenance manual and other technical records
          relating to the Aircraft, including those described in Appendix B to
          this Agreement.

2.   Purchase Price.   The total purchase price for the purchase of the Aircraft
     --------------
     (the "Purchase Price") is U.S. $2,790,000 (two million seven hundred ninety
     thousand U.S. dollars).

3.   Deposit; Escrow.
     ---------------

     (a)  Escrow.   The parties agree that the consummation of the transaction
          ------
          contemplated by this Agreement shall be facilitated through an escrow
          account with Dixie Aire Title Service, Inc., Oklahoma City, USA (the
          "Escrow Agent"). Following execution of this Agreement, the parties
          shall each execute such standard escrow instructions as provided by
          the Escrow Agent.
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Via Facsimile to 0 63 32-97 20-20
---------------------------------

Herr Fritz Winkler
c/o Winair Winkler & Feyock Gmbh & Co. KG
March 20, 2000
Page 2

     (b)  Initial Deposit Into Escrow.   Pinnacle agrees to wire transfer the
          ---------------------------
          sum of $30,000 (thirty thousand U.S. dollars) to the Escrow Agent
          serve as a refundable deposit to be applied against the Purchase Price
          (the "Deposit"). If the Deposit is not paid by March 23, 2000, 5:00
          p.m. Canadian m.s.t., then Seller may terminate this Agreement without
          further obligation. If the Deposit is made by Pinnacle, then it shall
          be remitted to either Pinnacle or Seller under the following
          conditions:

          (i)   If the closing of the Acquisition is consummated pursuant to the
                terms of this Agreement, the Deposit shall be paid to Seller and
                applied to the payment of the Purchase Price.

          (ii)  Subject to paragraph (iv), if the Agreement is terminated due to
                Pinnacle's inability to timely procure financing pursuant to
                paragraph 4 of this letter, then the Deposit shall be remitted
                to Seller as liquidated damages for the termination of this
                Agreement.

          (iii) Subject to paragraph (iv), if the Agreement is terminated due to
                Pinnacle's wrongful failure or inability to consummate the
                Acquisition pursuant to the terms of this Agreement, then the
                Deposit shall be remitted to Seller as liquidated damages for
                the termination of this Agreement.

          (iv)  If the Agreement is terminated for any other reason, including
                the Principals refusal to ratify this Agreement or deliver title
                to the Aircraft to Seller or Seller's wrongful failure or
                inability to perform its covenants or otherwise consummate the
                Acquisition, then the Deposit shall be immediately returned to
                Pinnacle upon its unilateral instructions, and no party hereto
                shall have any further obligations under this Agreement except
                as otherwise contained herein.

     (c)  Balance Of Purchase Price.   Pinnacle agrees to remit the remaining
          -------------------------
          balance of the Purchase Price, including additional costs to be borne
          by Pinnacle and paid by the Escrow Agent under this Agreement, to the
          Escrow Agent by no later than one (1) day before the Closing, unless
          this Agreement has been previously terminated.

4.   Financing Contingency.   Pinnacle shall use its best efforts to procure a
     ---------------------
     commitment for financing the Purchase Price on terms acceptable to it by
     April 14, 2000. If Pinnacle is unable to procure financing notwithstanding
     its best efforts by the Closing, then Pinnacle will state its intentions to
     continue efforts to procure financing or may terminate this transaction, in
     which case the Deposit shall be remitted to Seller pursuant to paragraph
     3(b)(ii), and no party hereto shall have any further obligations under this
     Agreement except as otherwise contained herein.
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Via Facsimile to 0 63 32-97 20-20
---------------------------------

Herr Fritz Winkler
c/o Winair Winkler & Feyock Gmbh & Co. KG
March 20, 2000
Page 3

5.   Closing.   The closing of the Acquisition (the "Closing') shall be April
     -------
     21, 2000, or such earlier date as shall be mutually agreed to by the
     parties, at which time (i) the Escrow Agent shall remit the Purchase Price
     to Seller, (ii) Seller will tender possession of the Aircraft to Pinnacle
     at Zweibrucken Airport, including keys and all Records, and Seller shall
     transfer title to the Aircraft to Pinnacle for re-registry with the United
     States Federal Aviation Administration ("FAA"). Pinnacle shall have the
     right, at a reasonable time in advance of the Closing, without cost, to
     conduct a final inspection flight of not more than one hour's duration,
     with a flight crew designated by Seller, to confirm the proper functioning
     of the Aircraft and its engines, and any items identified as not properly
     function shall be corrected by Seller in accordance with a pre-purchase
     check list either prior to the Closing or, if elected by Pinnacle, after
     the Closing subject to the reservation of an appropriate retention by the
     Escrow Agent for the cost of such repairs.

6.   Covenants and Costs.
     -------------------

     (a)  Each of the parties shall pay all costs and expenses incurred or to be
          incurred by it in negotiating and preparing this Agreement.

     (b)  Seller shall, at its sole cost, perform all maintenance items
          described in Appendix C to this Agreement prior to the Closing by no
          later than April 13, 2000.

     (c)  Seller shall take all actions and shall pay all costs necessary to
          obtain good title to the transfer of the Aircraft (including its
          engines and other equipment and avionics), including taking all
          actions and paying all costs to satisfy and to obtain releases of all
          liens, charges, claims, options, encumbrances, security agreements or
          interests or other liabilities, restrictions or covenants affecting
          title thereto prior to the Closing.

     (d)  Seller shall also take all actions and shall pay all costs necessary
          to de-register the Aircraft in Germany prior to or contemporaneously
          with the Closing.

     (e)  Seller shall also take all actions and shall pay all costs necessary
          to obtain a Export Certificate of Airworthiness necessary for the
          import of the Aircraft into the United States and to qualify for a
          Certificate of Airworthiness with the FAA, including taking all
          actions and paying all costs to (i) validate the compliance of the
          engines with Pratt and Whitney Type Approval Certificate No. E-21 and
          to validate the compliance of the equipment and avionics with USA Type
          Approval Certificate No. A-170 Issue 2, and (ii) to remove the current
          "D" number identification from the aircraft and replacing it with a
          new "N" number reserved by Pinnacle.

     (f)  With the exception of the matters described in subparagraphs (b) and
          (d) above, Pinnacle shall pay all costs to register title to the
          Aircraft in the United States, including costs for a title search,
          title insurance, filing documents with the FAA (excluding lien
          releases), procuring a Certificate of Registration from the FAA,
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Via Facsimile to 0 63 32-97 20-20
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Herr Fritz Winkler
c/o Winair Winkler & Feyock Gmbh & Co. KG
March 20, 2000
Page 4

          obtaining certified copies of documents, and satisfying any conditions
          imposed by any prospective lender.

     (g)  Seller shall pay all German export, sales, income, excise or other
          transactional taxes, fees or duties imposed in connection with the
          Acquisition or the export of the Aircraft from Germany shall be paid
          by Seller, while all United States import, use, sales, excise or other
          transactional taxes, fees or duties imposed in connection with the
          Acquisition or the import of the Aircraft into the United States shall
          be paid by Pinnacle.

     (h)  Pinnacle shall pay all escrow fees incurred by the Escrow Agent.

7.   "As Is" Condition.   Except for (i) the delivery of the Aircraft to
     -----------------
     Pinnacle at the Closing free of all maintenance discrepancies and with all
     A/D's and Mandatory SB's up-to-date; (ii) any repairs or maintenance or
     other matters relating to the condition of the Aircraft which Seller has
     agreed to perform or remedy as a condition of this Agreement, and (iii) any
     material adverse matters relating to the physical condition or operation of
     the Aircraft not recorded in the flight logs for the Aircraft which Seller
     or its agents had actual knowledge and failed to disclose to Pinnacle,
                       ------
     Pinnacle will take possession of the Aircraft at the location of the
     Closing in "As Is" condition and shall be responsible for all further
     repairs and maintenance.

8.   Representations and Warranties by Seller to Pinnacle.   Seller represents
     ----------------------------------------------------
     and warrants to Pinnacle that:

     (a)  Seller is currently the authorized selling agent of T. & I. Lemp
          (collectively, the "Principal"), who is the current owner of the
          Aircraft, and that the Principal is legally bound to sell the Aircraft
          to Seller for sale to Pinnacle in accordance with the terms of this
          Agreement, although registered title will be conveyed by the Principal
          to Seller for purposes of effectuating the transactions contemplated
          by this Agreement.

     (b)  Title to the Aircraft shall be conveyed to Pinnacle free and clear of
          all charges, claims, options, encumbrances, security agreements or
          interests or other liabilities, restrictions or covenants affecting
          title; and

     (c)  Seller has no actual knowledge of any material adverse matter relating
          to the physical condition or operation of the Aircraft other than any
          such adverse matter recorded in the flight logs of the Aircraft and
          other support documents, manuals and maintenance releases provided to
          Pinnacle as part of the Records.

9.   Representations and Warranties by Pinnacle to Seller.   Pinnacle represents
     ----------------------------------------------------
     and warrants to Seller that it has already made application to several
     reputable lenders to finance the
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Via Facsimile to 0 63 32-97 20-20
---------------------------------

Herr Fritz Winkler
c/o Winair Winkler & Feyock Gmbh & Co. KG
March 20, 2000
Page 5

     transactions contemplated by this Agreement, and it has no reason to
     believe that a loan commitment on terms satisfactory to Pinnacle will not
     be timely extended.

10.  Representations and Warranties by Parties to Each Other.   Each of Seller
     -------------------------------------------------------
     and Pinnacle represent and warrant to the other that:

     (a)  Such party, if an entity, is duly organized, validly existing and in
          good standing under the laws of its state, territory or province of
          incorporation or organization, and has all requisite corporate or
          other power and authority to enter into this Agreement;

     (b)  The execution and delivery of this Agreement by such party, and the
          performance by such party of the transactions herein contemplated,
          have, if such party is an entity, been duly authorized by its
          governing organizational documents, and are not prohibited by its
          governing organization documents, and no further corporate or other
          action on the part of such party is necessary to authorize this
          Agreement, or the performance of such transactions;

     (c)  This Agreement has been duly executed and delivered by such party and,
          assuming due authorization, execution and delivery by all of the other
          parties hereto, is valid and binding upon such party in accordance
          with its terms;

     (d)  Such party has the full right, power and authority to consummate the
          transactions contemplated by this Agreement in accordance with its
          terms without obtaining the consent or approval of any other person or
          governmental authority or agency; and

     (e)  Such party shall perform, execute and/or deliver or cause to be
          performed, executed and/or delivered any and all further acts, deeds
          and assurances as may, from time to time, be reasonably required to
          consummate the transactions contemplated in this Agreement.

11.  Conditions to Pinnacle's Performance.   Satisfaction of the following by
     ------------------------------------
     Seller shall be a condition precedent to Pinnacle's obligation to fully
     perform hereunder:

     (a)  The accuracy of Seller's representations and warranties at the time of
          at the Closing;

     (b)  The obtaining of the consent or approval, where required, of all
          government agencies and administrative bodies and third parties; and

     (c)  That there shall not be in existence any proceeding or action or
          threat of such proceeding or action seeking to restrain or enjoin the
          transaction.
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Via Facsimile to 0 63 32-97 20-20
---------------------------------

Herr Fritz Winkler
c/o Winair Winkler & Feyock Gmbh & Co. KG
March 20, 2000
Page 6

12.  Damage or Destruction.   If the Aircraft is destroyed or materially damaged
     ---------------------
     prior to the Closing, Pinnacle may elect to terminate this Agreement, in
     which case all sums tendered by Pinnacle to the Escrow Agent shall be
     returned to it; provided, however, in the event the prospective cost of
     repair (labor and parts) is less than the sum of $50,000 (fifty thousand
     U.S. dollars), and the repairs can be effectuated within thirty (30)
     business days, then Seller shall have the right to effectuate such repairs
     and the Acquisition shall close as soon as possible upon completion of the
     repairs subject to the satisfaction of Pinnacle and its lender as to the
     adequacy of the repairs.

13.  Brokers' Fees.   Neither Pinnacle (including its respective agents or
     -------------
     affiliates) or Seller (including its respective agents or affiliates) has
     incurred any liability or obligation to pay any fees or commissions,
     including to any broker, finder or any other third-party hired or
     contracted by such party in connection with or arising out of the
     transactions contemplated by this Agreement, for which any other party
     could become liable or obligated.

14.  Indemnification.   Seller shall indemnify, defend and hold Pinnacle
     ---------------
     harmless from any and all claims, losses, costs, expenses, damages,
     injuries, recoveries, deficiencies and liabilities, including interest,
     penalties and reasonable attorneys' fees, arising from or on account of (i)
     any breach of Seller's covenants, (ii) in connection the ownership, control
     and operation of the Aircraft before the Closing by Seller or the
     Principal, and (iii) any claims by the Principal relative to Seller's
     authority or actions in selling the Aircraft to Pinnacle pursuant to this
     Agreement. Pinnacle shall indemnify, defend and hold Seller and the
     Principal harmless from any and all such claims, losses, costs, expenses,
     damages injuries, recoveries, deficiencies and liabilities, including
     interest, penalties and reasonable attorneys' fees, arising from or in
     connection with Pinnacle's ownership, control and operation of the Aircraft
     after the Closing.

15.  No Other Negotiations.   Until such time as this Agreement no longer
     ---------------------
     remains in effect, Seller agrees that it will not, and it further agrees
     that it shall use its best efforts to ensure that none of its affiliates,
     nor anyone acting on their behalf, will, solicit from or negotiate with any
     other person or entity to purchase the Aircraft.

16.  Attorneys' Fees.   In the event of any litigation between the parties due
     ---------------
     to breach of this Agreement, the unsuccessful party agrees to pay the
     successful party all costs and expenses of litigation incurred by the
     successful party including, but not limited to, reasonable attorneys' fees
     for all legal counsel, depositions, witness fees and other expenses
     incurred in connection with such litigation, and if the successful party
     shall recover judgment in any action proceeding, the costs, expenses and
     attorneys' fees shall be included as part of the judgment.

17.  Time of the Essence.   It is expressly understood that time of performance
     -------------------
     is of the essence to this Agreement.
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Herr Fritz Winkler
c/o Winair Winkler & Feyock Gmbh & Co. KG
March 20, 2000
Page 7

18.  Binding Effect.   This Agreement shall bind and inure to the benefit of the
     --------------
     parties hereto and their respective heirs, executors, administrators, legal
     representatives, successors and assigns.

19.  Counterparts; Facsimile Signatures.   This Agreement may be executed in
     ----------------------------------
     several counterparts, each of which shall be deemed an original, and all of
     such counterparts together shall constitute one agreement, binding on all
     parties hereto. If a copy or counterpart of this Agreement is originally
     executed and such copy or counterpart is thereafter transmitted
     electronically by facsimile or similar device, such facsimile document
     shall for all purposes be treated as if manually signed by the party whose
     facsimile signature appears.

20.  Severability.   If all or any portion of any of the provisions of this
     ------------
     Agreement shall be invalid, illegal or unenforceable by laws applicable
     thereto, then the performance of said offending provision or provisions
     shall be excused by the parties hereto and such invalidity, illegibility,
     or unenforceability shall not affect any other provision of this Agreement.

21.  No Modifications Except in Writing.   No modification hereof shall be
     ----------------------------------
     binding unless set forth in writing and signed by the party or parties to
     be bound by the modification.

22.  Governing Law.   This Agreement shall be governed by and construed in
     -------------
     accordance with the laws of the Federal Republic of Germany.

23.  Interpretation.   This Agreement is an agreement between financially
     --------------
     sophisticated and knowledgeable parties and is entered into by the parties
     in reliance upon the economic and legal bargains contained herein and shall
     be interpreted and construed in a fair and impartial manner without regard
     to such factors as the party who prepared (or caused the preparation of)
     this instrument or the relative bargaining power of the parties.

24.  Further Assurances.   In addition to the acts and deeds recited herein and
     ------------------
     contemplated to be performed, executed and/or delivered by either Pinnacle
     or Seller, such party shall perform, execute and/or deliver or cause to be
     performed, executed and/or delivered at the Closing, or if necessary, after
     the Closing, any and all further acts, deeds and assurances as may, from
     time to time, be reasonably required to consummate the transactions
     contemplated in this Agreement.

If the terms and conditions of this Agreement are satisfactory, then indicate
your approval by executing and dating this letter below and delivering it to the
undersigned by 5:00 p.m., Canadian m.s.t., on March 21, 2000.  In the event the
terms and conditions described above are not satisfactory, or you have any
question or comments, then please refrain from signing this letter and call me
at your earliest convenience.  Please note that this Agreement will terminate if
the undersigned does not receive delivery of (or a facsimile of) this Agreement
executed draft by the above-mentioned date.
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Via Facsimile to 0 63 32-97 20-20
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Herr Fritz Winkler
c/o Winair Winkler & Feyock Gmbh & Co. KG
March 20, 2000
Page 8

If you are in agreement with the foregoing, please execute and return to us one
copy of this Agreement.

Very truly yours,


/s/ Daniel C. Topolinsky
-------------------------------
Daniel C. Topolinsky, President


By signature below in the space provided, the undersigned hereby evidence their
agreement with the terms of this Agreement as they pertain to them, and their
intention to be legally bound hereby.

Seller :

Winair Winkler & Feyock Gmbh & Co. KG

By:    /s/ Fritz P. Winkler
   ----------------------------------
Title: Managing Director
      -------------------------------
Date:  March 20, 2000
     --------------------------------
<PAGE>

                                  APPENDIX A

                            Description of Aircraft
                            -----------------------

AIRFRAME & EQUIPMENT

Make:..............   Piaggio

Model:.............   P180 Avanti

Serial Number:.....   #1017

Year:..............   1992

First Certificate
of Airworthiness:..   1992

Total Time:........   1600 hrs

Annual:............   2000

Paint:.............   White, Turquoise/Beige

Interior:..........   Taupe Leather, Teal Carpet (Option 1 Arrangement), Wood
                      Veneer, Stereo System, Cabin Display

Options:...........   Freon Air Conditioning Propeller Synchrophaser Cockpit
                      Handles and Curtain Single Point Refueling New style
                      Windscreens Cabin Display Standby Gyro

Autopilot:.........   Collins APS 65 System
                      EFIS 85 B 3-Tube

Avionics:..........   Collins Proline II Package
                      UNS 1 M FMS/GPS
                      Meets ICAO Annex 10 and B-RNAV
                      COMM'S 8,33 KHz spacing

Misc:..............   350 hrs. SHSI, Prop OH 7/97

ENGINES

Make:..............   Pratt and Whitney

Model..............   Two (2) PT 6A-66

Horsepower:........   2 X 850 shp

Serial Numbers:....   Left Engine:        PC-E 104044
                      Right Engine:       PC-E 104047

Engine Time:.......   1600 hrs
<PAGE>

                                  APPENDIX B

               Documentation and Technical Publications/Records
               ------------------------------------------------



             (Include both USA and German documents as applicable)



1.)   Certificate of Conformity

2.)   Standard Democratic Republic of Germany Certificate of Airworthiness

3.)   Aircraft Log with Discrepancies Records

4.)   Pilot's Operating Handbook with Deviation Compass Card

5.)   Maintenance Manual

6.)   Parts Catalogue

7.)   Wiring Manual

8.)   Engine Log (RH)

9.)   Export Certificate

10.)  Engine Log (LH)

11.)  Export Certificate

12.)  Propeller Log (RH)

13.)  Export Certificate

14.)  Hartzell Assembly Report

15.)  PIAGGIO Assembly Report

16.)  Propeller Log (LH)

17.)  Export Certificate

18.)  Hartzell Assembly Report

19.)  PIAGGIO Assembly Report

20.)  Serialized Components List

21.)  Warranty Certificate Application Forms for:

        Avionics (COLLINS);

        Propellers (HARTZELL);

        Engines and miscellaneous

22.)  List of Service Bulletins and Service Letters issued

23.)  List of the warranties remaining lives from Avionics manufacturers
<PAGE>

                                  APPENDIX C

                             Required Maintenance
                             --------------------

1.)    Phase A                              (Due 71 Hrs)

2.)    Phase B                              (Due 118 Hrs)

3.)    1 Year Inspection                    (Due 8 Months)

4.)    3 Year Inspection                    (Due 3 Months)

5.)    450 Flt. Hr. Inspection              (Due 225 Hours)

6.)    Cabin Blower Electro Mech. O/H       (Due 426 Hours)

7.)    Horizontal Tail Trim Actuator        (Due 426 Hours)

8.)    Refrigeration Pack Oil Change        (Due 100 Hours)

9.)    ELT Battery Replacement              (Due 2 Months)

10.)   Replace fuel Filter Cartridge        (Due 150 Hours)

11.)   Engine Oil Filter Replacement

       Ser # 104044                         (Due 138 Hours)

       Ser # 104047                         (Due 138 Hours)

12.)   P3 Filter Replacement

       Ser # 104044                         (Due 239 Hours)

       Ser # 104047                         (Due 239 Hours)

13.)   Fuel Nozzles - Clean/Inspect

       Ser # 104044                         (Due 250 Hours)

       Ser # 104047                         (Due 250 Hours)

14.)   Lube Inboard Flap Jackscrew          (Due 100 Hours)

15)    Six months specials

16)    Oxygen 3-position valve              (Due July 2000)

17)    Oxygen bottle hydro-static test      (Due June 2000)