<Page> Exhibit 10.33(d) FOURTH AMENDMENT TO OFFICE LEASE AGREEMENT WITH CHAUTAUQUA AIRLINES, INC. THIS FOURTH AMENDMENT, made and entered into this 3 day of September, 1999. by and between the Indianapolis Airport Authority, (hereinafter referred to as "AUTHORITY"), and Chautauqua Airlines, Inc., a New York corporation, authorized to do business in the state of Indiana, (hereinafter referred to as "LESSEE"). W I T N E S S E T H: WHEREAS, AUTHORITY and LESSEE previously entered into a Lease Agreement dated June 17, 1994 for certain space located in the Administration Building at Indianapolis International Airport: and WHEREAS, AUTHORITY and LESSEE amended the Lease Agreement on July 17, 1998, October 2, 1998 and November 6, 1998; and WHEREAS, LESSEE desires to rent additional office space on the fourth floor of the Administration Building commonly known as Room H415B, Room H415D, and a portion of Hallway H411; NOW, THEREFORE, in consideration of the foregoing and the mutual covenants contained herein, the Parties hereby agree that Article 1., LEASED PREMISES, Article 2., TERM, Article 3., RENTAL, LEASED PREMISES and Article 3., RENTAL. RENTAL SCHEDULE are hereby deleted and the following are substituted: 1. LEASED PREMISES The term "Leased Premises" shall consist of 9,749.1 square feet on the third floor and 5,184.65 square feet on the fourth floor of the Administration Building of <Page> which the entire leased space is more particularly shown on Exhibit "A" dated August 25, 1999 attached hereto. The third floor square footage includes the Men's and Woman's restrooms, however no rental is being charged for this square footage 2. TERM LESSEE shall have a different term for each floor it shall occupy. The revised term and rental for the third floor Leased Premises commenced on August 1, 1998 and shall expire on July 31, 2001. The term for the fourth floor Leased Premises, except for Rooms H415A, H415C, H413, H413A, H415B, H415D and a portion of Hallway H411 commenced on August 1, 1998 and shall expire on July 31, 2000. The term for Rooms H415A and H415C commenced on September 23, 1998 and shall expire on July 31, 2000. The term for Room H413 and H413A commenced on October 23, 1998 and shall expire on July 31, 2000. The term for Rooms H415B, H415D and a portion of Hallway H411 commenced on August 1, 1999 and shall expire on July 31, 2000. LESSEE shall have an option to extend this Lease for an additional term of three (3) years upon the rental terms outlined in Article 3.B. LESSEE shall have a different term for each floor it shall occupy. The option term for the third floor shall commence August 1, 2001 and shall terminate July 31, 2004. The option term for the fourth floor shall commence on August 1, 2000 and shall expire on July 31, 2003. LESSEE may exercise the option by mailing or delivering to AUTHORITY written notice of such intention not later than six (6) months prior 2 <Page> to the date of expiration of the primary terms and the first option terms. Notification date on the third floor shall be on or before February 1, 2001. Notification date on the fourth floor shall be on or before February 1, 2000. 3. RENTAL A. LEASED PREMISES Rental for the use of said Leased Premises and appurtenances thereto, LESSEE agrees to pay per annum in accordance with the following rental schedules payable in advance in twelve (12) equal payments on the first day of each calendar month effective on the first day of occupancy. Rental Schedule -Primary Term THIRD FLOOR AUGUST 1, 1998 THROUGH JULY 31, 2001 9,749.1 square feet X $10.50 p.s.f. = $102,365.55 per year payable at $8,530.46 per month FOURTH FLOOR OCTOBER 23, 1998 THROUGH JULY 31, 1999 4,411 square feet X $10.50 p.s.f. = $46,317.08 per year payable at $3,859.76 per month AUGUST 1, 1999 THROUGH JULY 31, 2000 5,184.65 square feet X $10.50 p.s.f. = $54,438.83 per year payable at $4,536.57 per month Any partial month of rent shall be prorated. Said rent shall be payable at the office of the AUTHORITY or such other place as AUTHORITY may from time to time designate. 3 <Page> B. RENTAL SCHEDULE - OPTION PERIODS THIRD FLOOR AUGUST 1, 2001 THROUGH JULY 31, 2002 9,749.1 square feet X $11.00 p.s.f. = $107,240.10 per year payable at $8,936.68 per month AUGUST 1, 2002 THROUGH JULY 31, 2003 9,749.1 square feet X $11.50 p.s.f. = $112,114.65 per year payable at $9,342.89 per month AUGUST 1, 2003 THROUGH AUGUST 31, 2004 9,749.1 square feet X $12.00 p.s.f. = $116,989.20 per year payable at $9,749.10 per month FOURTH FLOOR AUGUST 1, 2000 THROUGH JULY 31, 2001 5,184.65 square feet X $11.00 p.s.f. = $57,03.15 per year payable at $4,752.60 per month AUGUST 1, 2001 THROUGH JULY 31, 2002 5,184.65 square feet X $11.50 p.s.f. = $59,623.48 per year payable at $4,968.62 per month AUGUST 1, 2002 THROUGH JULY 31, 2003 5,184.65 square feet X $12.00 p.s.f. = $62,215.80 per year payable at $5,184.65 per month 4 <Page> THIS FOURTH AMENDMENT shall be effective this ___________ day of ____________________, 1999 and all other terms of the basic Lease dated June 17, 1994, shall remain the same. IN WITNESS WHEREOF, the parties hereto have caused this instrument to be executed as of the date first above mentioned. INDIANAPOLIS AIRPORT AUTHORITY By /s/ Michael W. Wells ------------------------------------- Michael W. Wells, President By /s/ Gordon St. Angelo ------------------------------------- Gordon St. Angelo, Vice-President By /s/ Gene P. Haflich ------------------------------------- Gene P. Haflich, Secretary By /s/ H. Patrick Callahan ------------------------------------- H. Patrick Callahan, Member By /s/ Richard L. Cunningham ------------------------------------- Richard L. Cunningham, Member By /s/ [SEAL OF ABSENT] ------------------------------------- Max L. Siegel, Member By /s/ David E. Mansfield ------------------------------------- David E. Mansfield, Member AUTHORITY CHAUTAUQUA AIRLINES, INC. By /s/ [ILLEGIBLE] ------------------------- Title Executive V.P. & COO ---------------------- 5