(3) Long‑term Debt

Long‑term debt consisted of the following as of December 31, 2016 and 2015 (in thousands):


	December 31,		December 31,
	2016		2015
Notes payable to banks, due in semi-annual installments, variable interest based on LIBOR, or with interest rates ranging from 2.64% to 2.82% through 2017 to 2020, secured by aircraft	$	63,408	$	108,348
Notes payable to a financing company, due in semi-annual installments, variable interest based on LIBOR, or with interest rates ranging from 2.27% to 3.25% through 2017 to 2021, secured by aircraft		146,266		217,341
Notes payable to banks, due in semi-annual installments plus interest at 6.06% to 6.51% through 2021, secured by aircraft		86,052		108,069
Notes payable to a financing company, due in semi-annual installments plus interest at 5.78% to 6.23% through 2017, secured by aircraft		8,854		17,208
Notes payable to banks, due in monthly installments plus interest of 2.68% to 6.86% through 2025, secured by aircraft		426,389		479,170
Notes payable to banks, due in monthly installments, plus interest at 6.05% through 2020, secured by aircraft		8,998		11,304
Notes payable to banks, due in monthly installments, plus interest at 3.44% through 2019, secured by aircraft		3,280		4,615
Notes payable to banks, due in quarterly installments plus interest at 3.39% to 4.68% through 2028, secured by aircraft		1,806,981		966,156
Notes payable to banks, due in monthly installments, plus interest based on LIBOR at 3.54% through 2017, secured by aircraft		4,666		14,538
Notes payable to banks due in monthly installments, interest at 3.30% through 2019, secured by spare engines		16,010		22,054
Long-term debt	$	2,570,904	$	1,948,803
Less current maturities		(308,945)		(272,027)
Long-term debt, net of current maturities	$	2,261,959	$	1,676,776

The Company adopted guidance ASU 2015-03 on January 1, 2016. As a result, the unamortized debt issuance costs that had been included in Other assets line on the consolidated balance sheets as of December 31, 2015 are now presented as direct deductions from the carrying amounts of the related debt liabilities as shown below as of December 31, 2016 and 2015 (see Note 1 Nature of Operations and Summary of Significant Accounting Policies) (in thousands):



	December 31, 2016		December 31, 2015
Current portion long-term debt	$	308,945	$	272,027
Long-term debt net of current maturities		2,261,959		1,676,776
Total long-term debt (including current portion)	$	2,570,904	$	1,948,803
Unamortized debt issue cost, net		(25,393)		(20,902)
Total long-term debt, net of debt issue costs	$	2,545,511	$	1,927,901

During the year ended December 31, 2016, the Company acquired 41 new E175 aircraft. Approximately 85% of the aircraft purchase price was financed through the issuance of debt and 15% of the aircraft purchase price was paid with cash.

As of December 31, 2016 and 2015, the Company had $2.6 billion and $1.9 billion, respectively, of long‑term debt obligations primarily related to the acquisition of aircraft and certain spare engines. The average effective interest rate on the debt related to those long-term debt obligations at December 31, 2016 and 2015, was approximately 3.8% and 3.7%, respectively.

During the year ended December 31, 2016, the Company used $16.5 million in cash to extinguish $18.4 million in debt early. The payment resulted in a pre-tax gain of $1.3 million, reflected as other income in the consolidated statements of comprehensive income (loss). During the year ended December 31, 2015, the Company used $110.8 million in cash to pay off $145.4 million in debt. The payment resulted in a pre-tax gain of $33.7 million, reflected as other income in the consolidated statements of comprehensive income (loss).

The aggregate amounts of principal maturities of long‑term debt as of December 31, 2016 were as follows (in thousands):


2017	$	308,945
2018		286,164
2019		286,266
2020		251,265
2021		236,896
Thereafter		1,201,368
	$	2,570,904

During the year ended December 31, 2016, the Company increased its line of credit with a bank from $25 million to $75 million. The line of credit includes minimum liquidity and profitability covenants and is secured by certain assets. As of December 31, 2016, the Company was in compliance with the line of credit covenants and had no borrowings outstanding under the facility. However, at December 31, 2016, the Company had $6.5 million in letters of credit issued under the facility which reduced the amount available under the facility to $68.5 million. The facility expires on June 1, 2018 and has a variable interest rate of LIBOR plus 2.5% (3.3% at December 31, 2016).

As of December 31, 2016 and 2015, the Company had $87.7 million and $88.9 million, respectively, in letters of credit and surety bonds outstanding with various banks and surety institutions.