As of March 31, 2024, we leased 33 aircraft, airport facilities, office space, and other property and equipment under non-cancelable operating and finance leases. The leases generally require us to pay all taxes, maintenance, insurance, and other operating expenses. Operating leased expense is recognized as a rental expense on a straight-line basis over the lease term, net of lessor rebates and other incentives. Finance lease is capitalized and depreciated over the useful life of the asset.

Aggregate rental expense under all aircraft, equipment and facility leases totaled approximately $4.6 million and $3.8 million for the three months ended March 31, 2024 and March 31, 2023, respectively, and $12.6 million and $10.7 million for the six months ended March 31, 2024 and March 31, 2023, respectively.

The components of our lease costs were as follows (in thousands):


	Three Months Ended March 31,				Six Months Ended March 31,
	2024		2023		2024		2023
Operating lease costs	$	1,154	$	1,277	$	2,423	$	5,977
Variable and short-term lease costs		1,672		1,234	$	2,961	$	2,123
Interest expense on finance lease liabilities		1,256		228	$	2,545		502
Amortization expense of finance lease assets		513		1,046		4,636		2,092
Total lease costs	$	4,595	$	3,785	$	12,565	$	10,694

As of March 31, 2024, our operating leases have a remaining weighted average lease term of 6.4 years and our operating lease liabilities were measured using a weighted average discount rate of 5.9%.

Historically, Mesa Airlines, as lessee, entered into the RASPRO Lease Facility, with RASPRO as lessor, for 15 of our CRJ-900 aircraft classified as operating leases. The obligations under the RASPRO Lease Facility are guaranteed by us, and basic rent is paid quarterly on each aircraft. During December 2022, the Company entered into an agreement with RASPRO Trust, reducing the buyout pricing on all 15 aircraft at lease termination by a total of $25 million. Under the terms of the new agreement, the Company reclassified these leases as finance leases.