1 EXHIBIT 10.5.3 AMENDMENT NO. 3 TO ORBCOMM SYSTEM PROCUREMENT AGREEMENT This Amendment No. 3 ("Amendment No. 3") to the ORBCOMM System Procurement Agreement is entered into this 31st day of March, 1998 between ORBCOMM Global, L.P. ("ORBCOMM Global") and Orbital Sciences Corporation ("Orbital"). WITNESSETH WHEREAS, the parties previously entered into the ORBCOMM System Procurement Agreement dated September 12, 1995 (the "Procurement Agreement") and Amendments No. 1 and No. 2 thereto dated December 9, 1996 and March 24, 1997, respectively; and WHEREAS, the parties wish to set forth their agreement pertaining to a certain claim for equitable price adjustment to the Procurement Agreement for changes made and associated costs incurred by Orbital under the Procurement Agreement through December 31, 1997. NOW THEREFORE, the parties agree as follows: ARTICLE 1 - DEFINITIONS Terms used herein and not otherwise defined shall have the meanings assigned thereto in the Procurement Agreement. ARTICLE 2 - AMENDMENTS Section 2.1 Section 3.1(a) of the Procurement Agreement shall be amended to add a new subparagraph (iv) immediately following subparagraph (iii) that reads as follows: "(iv) Price Adjustment for Changes through $ 3,500,000 December 31, 1997 Outside the General Scope of the Agreement" Section 2.2 Section 3.1(a) of the Procurement Agreement shall be amended to delete the "TOTAL" price of $157,872,143 set forth therein and to replace it with the new "TOTAL" price of $161,372,143. Section 2.3 Section 4.1(b) of the Procurement Agreement shall be deleted in its entirety and replaced with the following: 2 "(b) Monthly Invoicing. (i) Orbital shall be entitled to invoice ORBCOMM Global on a monthly basis for a maximum of 90% of its costs incurred during such month plus, to the extent permitted by Section 4.1(f), such portion of the cost in excess of the maximum amount to be invoiced to ORBCOMM Global in accordance with such Section 4.1(f) and not previously invoiced and paid; provided however that Orbital shall not be entitled to invoice ORBCOMM Global under Section 4.1(a) and this Section 4.1(b)(i) in a cumulative total amount greater than $125,884,929. (ii) Orbital shall be entitled to invoice ORBCOMM Global for costs associated with Section 3.1(a)(iv) as follows: DATE AMOUNT ---- ------ Signing of Amendment No. 3 $1,000,000 July 1, 1998 $2,000,000 October 1, 1998 $ 500,000" Section 2.4 Section 4.1(e) of the Procurement Agreement shall be deleted in its entirety and replaced with the following: "The total amount paid under Section 4.1(a), (b)(i) and (c) shall not exceed $139,872,143 (the "Total Costs"). In the event costs incurred through December 31, 1997, are less than the Total Costs, the parties shall negotiate additional Category B Milestones for payment of the remaining balance of the Total Costs." Section 2.5 The first sentence of Section 4.4 of the Procurement Agreement shall be deleted in its entirety and replaced with the following: "Subject to the foregoing, Orbital shall be entitled to submit to ORBCOMM Global at the address below monthly invoices covering the amounts as described in Subsection 4.1(b)(i), invoices covering the amounts set forth in Subsection 4.1(b)(ii) or invoices for Category A and Category B Milestone payments, in each case certified by the Vice-President and Controller of Orbital or by any other officer designated by the Vice-President and Controller of Orbital in the form provided for in Schedule 4.4." Section 2.6 The parties have mutually agreed to make certain changes outside the general scope of the Procurement Agreement, and have mutually agreed to an equitable adjustment to the Price, as set forth in this Amendment No. 3. The changes made outside the general scope of the Procurement Agreement are set forth in Exhibit A hereto. 2 3 Section 2.7 Section 3.1.1 of Exhibit A, Part 1B Satellite Specifications of the Procurement Agreement shall be deleted in its entirety and replaced with the following: The combined mass of 8 satellites, as launched, plus the adapter and deployment structure, must be injected into orbit according to the parameters stated below. Three or four planes will be launched into different ascending nodes spaced to maximize the coverage of latitudes between 25 and 50 degrees. The launch parameters for the satellites shall be: - ------------------------------------------------------------------------------------------------------------- Parameter Plane A Plane B Plane C - ------------------------------------------------------------------------------------------------------------- Target mean altitude 825 km, circular 810 to 840 km{1} 810 to 840 km{1} Maximum apogee altitude 882 km Target + 15 km Target + 15 km Minimum perigee altitude 767 km Target - 15 km Target - 15 km Target inclination 45 deg. 43 to 46 deg.{2} 43 to 46 deg.{2} Inclination accuracy +/- 0.3 deg. +/- 0.1 deg. +/- 0.1 deg Target right ascension of Unconstrained 120-140 deg. West of Plane A{2} 110-130 deg. East of Plane A{2} ascending nodes Accuracy of ascending N/A +/- 2.5 deg. +/- 2.5 deg. node To the extent possible, the satellite propulsion system shall be used to correct for launch vehicle injection errors. The relative spacing between the ascending or descending nodes of any two planes shall not be less than 30 degrees five years after the launch of plane 3. The phasing of satellites within each plane shall be maintained at 45 degrees +/- 5 degrees. 1 If the actual mean altitude of Plane A is higher than its target mean altitude, the target mean altitude for Planes B and C will be raised to that attained by Plane A, up to 840 km. 2 Target shall be selected by ORBCOMM Global from this range based on actual insertion parameters of previous planes. 3 4 Section 2.8 Section 3.1.1 of Exhibit A, Part 2 Statement of Work and Specification for ORBCOMM Constellation Launch Services of the Procurement Agreement shall be deleted in its entirety and replaced with the following: The Pegasus shall provide a minimum lift capability and injection accuracy to meet the requirements listed in Table 3-1 with 3-sigma probability. - ------------------------------------------------------------------------------------------------------------- Parameter Plane A Plane B Plane C - ------------------------------------------------------------------------------------------------------------- Target mean altitude 825 km, circular 810 to 840 km{1} 810 to 840 km{1} Maximum apogee altitude 882 km Target + 15 km Target + 15 km Minimum perigee altitude 767 km Target - 15 km Target - 15 km Target inclination 45 deg. 43 to 46 deg.{2} 43 to 46 deg.{2} Inclination accuracy +/- 0.3 deg. +/- 0.1 deg. +/- 0.1 deg Target right ascension of Unconstrained 120-140 deg. West of Plane A{2} 110-130 deg. East of Plane A{2} ascending nodes Accuracy of ascending N/A +/- 2.5 deg. +/- 2.5 deg. node Table 3-1 Mission Orbital Requirements 1 If the actual mean altitude of Plane A is higher than its target mean altitude, the target mean altitude for Planes B and C will be raised to that attained by Plane A, up to 840 km. 2 Target shall be selected by ORBCOMM Global from this range based on actual insertion parameters of previous planes. SECTION 3 - MISCELLANEOUS Section 3.1 This Amendment No. 3 shall be construed in accordance with and governed by the laws of the Commonwealth of Virginia, without giving effect to the provisions, policies or principles thereof related to choice or conflict of laws. Section 3.2 No changes to the Procurement Agreement are authorized hereby except as otherwise specified in this Amendment No. 3. 4 5 IN WITNESS WHEREOF, the parties have executed this Amendment No. 3 as of the day and year first above written. ORBCOMM GLOBAL, L.P. By: ------------------------------ Name: Scott L. Webster Title: Chairman & Chief Executive Officer ORBITAL SCIENCES CORPORATION By: ------------------------------ Name: Jeffrey V. Pirone Title: Executive Vice President & Chief Financial Officer 5 6 EXHIBIT A TO AMENDMENT NO. 3