At September 30, 2018, the Company leased 28 aircraft under noncancelable operating leases with remaining terms of up to 5.5 years. The Company has the option to terminate certain leases at various times throughout the lease. The Company headquarters and other facility noncancelable operating leases have remaining terms of up to nine years. The leases require the Company to pay all taxes, maintenance, insurance, and other operating expenses. Rental expense is recognized on a straight-line basis over the lease term, net of lessor rebates and other incentives. Aggregate rental expense under all operating aircraft, equipment and facility leases totaled approximately $85.9 million, $83.8 million and $84.8 million for the years ended September 30, 2018, 2017 and 2016, respectively.

Future minimum lease payments as of September 30, 2018, under noncancelable operating leases are as follows (in thousands):

Periods Ending September 30,	Aircraft		Other		Total
2019	$	63,993	$	2,574	$	66,567
2020		45,534		1,594		47,128
2021		44,314		1,367		45,681
2022		29,751		1,339		31,090
2023		12,418		1,308		13,726
Thereafter		11,849		2,704		14,553
Total	$	207,859	$	10,886	$	218,745

The majority of the Company’s leased aircraft are leased through trusts that have a sole purpose to purchase, finance, and lease these aircraft to the Company; therefore, they meet the criteria of a variable interest entity. However, since these are single-owner trusts in which the Company does not participate, the Company is not at risk for losses and is not considered the primary beneficiary. Management believes that the Company’s maximum exposure under these leases is the remaining lease payments.