Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current Assets
Cash and cash equivalents	$ 33,333	$ 37,170
Restricted cash	849	1,449
Marketable securities	153,827	138,370
Accounts receivable, less allowances of $18 as of December 31, 2022 and $40 as of December 31, 2021	40,341	7,422
Notes receivable	19,452	0
Spare parts and supplies, less allowances of $11,764 as of December 31, 2022 and $10,819 as of December 31, 2021	4,579	5,200
Contract costs	143	518
Prepaid expenses and other	3,732	4,174
Total Current Assets	256,256	194,303
Property and Equipment
Flight property and equipment	263,970	259,720
Ground property and equipment	8,055	8,252
Less accumulated depreciation and amortization	(169,766)	(143,313)
Net Property and Equipment	102,259	124,659
Other Assets
Operating lease right-of-use asset	13,480	18,679
Intangibles	5,300	5,300
Long-term deferred tax assets	0	533
Long-term investments	4,275	4,275
Long-term contract costs	0	96
Long-term notes receivable	0	47,568
Other	1,077	3,988
Total Other Assets	24,132	80,439
Total Assets	382,647	399,401
Current Liabilities
Accounts payable	20,165	20,060
Accrued payroll and employee benefits	12,989	14,885
Current portion of operating lease liability	5,091	5,150
Other accrued expenses	137	172
Contract liabilities	1,985	8,098
Deferred revenues	16,561	35,792
Current portion of long-term debt (stated principal amount of $7,000 as of December 31, 2022 and $3,500 as of December 31, 2021)	9,154	5,880
Total Current Liabilities	66,082	90,037
Other Liabilities
Long-term debt (stated principal amount of $48,600 as of December 31, 2022 and $56,000 as of December 31, 2021)	52,068	61,670
Long-term promissory note	4,275	4,275
Deferred tax liability	7,990	688
Long-term operating lease liability	5,849	10,877
Long-term contract liabilities	0	1,326
Deferred revenue, net of current portion	0	9,046
Other	1,977	2,722
Total Long-Term Liabilities	72,159	90,604
Commitments and Contingencies (Note 8)
Mezzanine Equity
Series C Convertible Redeemable Preferred Stock, $0.01 par value, 4,000,000 shares authorized, issued and outstanding at December 31, 2022 and December 31, 2021	13,200	13,200
Stockholders' Equity
Common Stock, $0.01 par value, 100,000,000 shares authorized, 55,481,140 shares issued at December 31, 2022 and December 31, 2021, 45,219,737 shares outstanding at December 31, 2022 and 53,316,299 shares outstanding at December 31, 2021	555	555
Additional paid-in capital	285,668	287,429
Retained deficit	(40,034)	(79,144)
Treasury stock	(14,983)	(3,280)
Total Stockholders' Equity	231,206	205,560
Total Liabilities and Stockholders' Equity	$ 382,647	$ 399,401