PROPERTY AND EQUIPMENT

9 Months Ended

Sep. 30, 2021

Property, Plant and Equipment [Abstract]

Property and equipment consist of the following (in thousands):


	September 30, 2021		December 31, 2020
Aircraft	$	475,769	$	473,509
Software development costs	32,129		22,414
Leasehold improvements	11,703		9,560
Computer equipment	2,147		1,846
Buildings and improvements	1,424		1,424
Furniture and fixtures	1,959		1,321
Tooling	2,890		1,296
Vehicles	800		597
	528,821		511,967

Less: Accumulated depreciation and amortization	(214,835)		(188,877)
Total	$	313,986	$	323,090

Depreciation and amortization expense of property and equipment was $8.4 million and $26.0 million for the three and nine months ended September 30, 2021, respectively, and $10.0 million and $31.0 million for the three and nine months ended September 30, 2020, respectively.

Capitalized costs related to the internal development of software was $3.9 million and $9.6 million for the three and nine months ended September 30, 2021, respectively, and $2.1 million and $5.1 million for the three and nine months ended September 30, 2020, respectively.

Amortization expense related to software development costs, included as part of depreciation and amortization expense of property and equipment, was $1.8 million and $4.8 million for the three and nine months ended September 30, 2021, respectively, and $1.2 million and $3.2 million for the three and nine months ended September 30, 2020, respectively.