As of March 31, 2023, we leased 18 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 $3.8 million and $11.6 million for the three months ended March 31, 2023 and March 31, 2022, respectively, and 10.7 million and 23.5 million for the six months ended March 31, 2023 and March 31, 2022, respectively.

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


	Three Months Ended March 31,				Six Months Ended March 31,
	2023		2022		2023		2022
Operating lease costs	$	1,277	$	9,663	$	5,977	$	19,144
Variable and short-term lease costs		1,234		1,346	$	2,123	$	3,081
Interest expense on finance lease liabilities		228		87	$	502	$	187
Amortization expense of finance lease assets		1,046		533		2,092		1,066
Total lease costs	$	3,785	$	11,629	$	10,694	$	23,478

As of March 31, 2023, our operating leases have a remaining weighted average lease term of 6.0 years and our operating lease liabilities were measured using a weighted average discount rate of 4.9%.

Due to the impacts of the pilot shortage and the pilot wage increase, we evaluated all asset groups during the fiscal year ended September 30, 2022 and determined that only the asset group associated with the CRJ-900 fleet operating under the American CPA, discussed in Note 7, required impairment.

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.