Certain significant amounts included in the Company's consolidated balance sheet as of September 30, 2020 and 2019, consisted of the following (in thousands):

	September 30,			September 30,
	2020			2019
Expendable parts and supplies, net
Expendable parts and supplies	$	27,431		$	25,336
Less obsolescence and other		(4,460	)		(3,999	)
	$	22,971		$	21,337
Prepaid expenses and other current assets
Prepaid aircraft rent	$	—		$	35,786
Deferred offering and reimbursed costs		1,261			2,092
Other		14,806			3,045
	$	16,067		$	40,923
Property and equipment—net
Aircraft and other flight equipment substantially pledged	$	1,596,174		$	1,582,199
Other equipment		5,147			5,122
Leasehold improvements		2,763			2,797
Vehicles		1,032			924
Building		699			699
Furniture and fixtures		302			302
Total property and equipment		1,606,117			1,592,043
Less accumulated depreciation		(393,702	)		(318,458	)
	$	1,212,415		$	1,273,585
Other accrued expenses
Accrued property taxes	$	11,354		$	9,186
Accrued interest		3,268			4,497
Accrued vacation		5,975			6,128
Deferred revenue- current portion		9,389			1,513
Other		24,881			7,564
	$	54,867		$	28,888

The Company monitors for any indicators of impairment of the long-lived fixed assets. When certain conditions or changes in the economic situation such as the current environment brought by COVID-19 exist, the assets may be impaired and the carrying amount of the assets exceed its fair value. The assets need to be tested for recoverability of carrying amount.

To determine whether impairments exist, we group assets at the Capacity Purchase Agreement and fleet-type level (i.e., the lowest level for which there are identifiable cash flows) and then estimate future cash flows based on projections of capacity purchase arrangements, block hours, maintenance events, labor costs and other relevant factors. Due to our reduced flying schedules and projections of future cash flows, we evaluated each of our fleets to determine if any of the fleets are impaired.

Based on our carrying amount recoverability test, we have concluded that no fleet was impaired as of September 30, 2020 as the future cash flows exceeded the carrying value of our long-lived fixed assets. Given the uncertain future amid COVID-19, we will conduct additional tests in first quarter of 2021.

Depreciation expense totaled $80.8 million, $76.2 million and $64.6 million for the years ended September 30, 2020, 2019 and 2018, respectively.

Prior to the Company’s adoption of Topic 842 on October 1, 2019, the Company recorded amortization of the unfavorable lease liability amounting to $5.7 million and $6.6 million for the years ended 2019 and 2018, respectively, as a reduction to lease expense. Upon the Company’s adoption of Topic 842, the unfavorable lease liability is now included in its ROU asset balance and amortized therein. During the year ended 2019 and 2018 the Company wrote off $0.8 million and $1.2 million of unfavorable lease liability related to the lease termination of its aircraft lease facility with Wells Fargo Bank Northwest, National Association, as owner trustee and lessor (the "GECAS Lease Facility"), which was accounted for as lease termination expense.