28 aircraft operating fleet the following table sets forth the number and type of aircraft in service and operated by us as of the dates indicated : replace_table_token_9_th ( 1 ) does not include 11 owned aircraft currently on lease to a european carrier or three other aircraft for which we have taken delivery as of december 31 , 2017 . ( 2 ) does not include two aircraft for which we have taken delivery as of december 31 , 2017 . as of february 2 , 2018 , we are party to forward purchase agreements for 15 airbus a320 series aircraft and have executed lease agreements for 13 airbus a320 series aircraft of which we have not yet taken delivery . we expect delivery of 18 of these aircraft in 2018 and the remaining aircraft in 2019 and 2020. in january 2018 , we took delivery of two aircraft for which we had purchase agreements as of december 31 , 2017. also in january 2018 , we took redelivery of one of our owned aircraft on lease to a european carrier , and also expect redelivery of the remaining 10 aircraft on lease in 2018. refer to part i - item 2 - properties for further detail regarding our aircraft fleet . we continuously consider aircraft acquisitions on an opportunistic basis . network we use profitability management tools to manage capacity and route expansion through optimization of our flight schedule to , among other things , better match demand in certain markets . we continually adjust our network through the addition of new markets and routes , adjusting the frequencies into existing markets , and exiting under-performing markets , as we seek to achieve and maintain profitability on each route we serve . as of february 2 , 2018 and including recent service announcements , we were selling 396 routes . our route network as of december 31 , 2017 represents an 11.4 percent increase in the number of routes flown compared to the end of 2016 , and the number of mid-sized cities served is now up to 22 after we began to initiate service to larger cities in 2014. the following table shows the number of leisure destinations and cities served as of the dates indicated ( includes cities served seasonally ) : replace_table_token_10_th trends continuing with our fleet transition to an all-airbus fleet , we added 19 airbus a320 series aircraft to our operating fleet during 2017. we expect to have fully transitioned by the end of 2018 , based on our plan to add 30 airbus a320 series aircraft into service during 2018. in conjunction with the fleet transition , we retired 10 md-80 aircraft in 2017 as well as our four remaining boeing 757-200 aircraft , and expect to retire our remaining 37 md-80 aircraft by the end of 2018 . 29 as of february 2 , 2018 , we were offering service on 140 medium-sized city routes compared to 96 as of the same date in 2017. we initiated service on 30 new network routes in the fourth quarter of 2017 , including service into two new cities : milwaukee , wisconsin and norfolk , virginia . sunseeker resorts planning and development is ongoing and the land is currently being prepared for construction , with the opening of the resort planned for late 2019 or early 2020. construction of the project and sales efforts are expected to begin in the first half of 2018. our flight attendant group approved their collective bargaining agreement effective in december 2017. we expect the collective bargaining agreement to increase our operating costs by approximately $ 8 million for 2018. our flight dispatchers have also voted for union representation and negotiations are ongoing . any labor actions following an inability to reach collective bargaining agreements with these employee groups , or any other labor groups seeking to organize , could materially impact our operations during the continuance of any such activity . our operating expenses a brief description of the items included in our operating expense line items follows . aircraft fuel expense includes the cost of aircraft fuel , fuel taxes , into plane fees and airport fuel flowage , storage or through-put fees . salary and benefits expense includes wages , salaries , and employee bonuses , sales commissions for in-flight personnel , as well as expenses associated with employee benefit plans , stock compensation expense related to equity grants , and employer payroll taxes . station operations expense includes the fees charged by airports for the use or lease of airport facilities and fees charged by third party vendors for ground handling services , commissary expenses and other related services . maintenance and repairs expense includes all parts , materials and spares required to maintain our aircraft as well as major maintenance costs for our md-80 aircraft . also included are fees for repairs performed by third party vendors . sales and marketing expense includes all advertising , promotional expenses , travel agent commissions and debit and credit card processing fees associated with the sale of scheduled service and air-related ancillary charges , net of credit card fee reimbursement charges collected from customers and treated as a reduction to expense ( program ended in january 2017 ) . aircraft lease rentals expense consists of the cost of leasing aircraft and or engines under operating leases with third parties , as well as costs for sub-service contracted out . depreciation and amortization expense includes the depreciation of all owned fixed assets , including aircraft and engines . story_separator_special_tag under our fixed fee flying contracts , we require customers to prepay for flights , and the cash is escrowed until the flight is completed . prepayments are recorded as restricted cash and a corresponding amount is recorded as air traffic liability . investment securities represent liquid marketable securities which are available-for-sale . during 2017 , our primary source of funds was $ 391.1 million generated by our operations in addition to $ 497.5 million in proceeds from notes payable . our operating cash flows and borrowings have allowed us to return value to shareholders and invest in the growth of our fleet . our future capital needs are primarily for the acquisition of additional aircraft , including our existing airbus a320 series aircraft commitments , as well as potential capital outlay related to sunseeker resorts as well as other travel and leisure initiatives . of the aircraft expected to be placed into service in 2018 , 13 are structured as capital leases and will not require separate financing , and the additional 10 aircraft ( as of february 2 , 2018 ) being returned from lease to a european carrier were purchased in 2014 and have already been paid for . we believe we have more than adequate liquidity resources through our operating cash flows , borrowings , and cash balances , to meet our future contractual obligations . we financed 10 of our new airbus aircraft in 2017 , and expect to finance the remaining two in 2018 in addition to used airbus aircraft under purchase contract , subject to acceptable terms . in addition , we continue to consider raising funds through debt financing on an opportunistic basis . in addition to our recurring quarterly cash dividend , we plan to continue to opportunistically repurchase our stock in the open market subject to availability of cash resources and compliance with our debt covenants . as of december 31 , 2017 , authority under our board-approved stock repurchase program was $ 100.0 million . there is no expiration date for the program . story_separator_special_tag including , but not limited to : ( i ) estimated fair value of the assets ; and ( ii ) estimated future cash flows expected to be generated by those assets , which are based on additional assumptions such as ( but not limited to ) asset utilization , average fare , block hours , fuel costs , length of service the asset will be used in operations , and estimated salvage values . in estimating the useful lives and residual values of our aircraft , we have primarily relied upon actual experience with the same or similar aircraft types , current and projected future market information , and recommendations from other industry sources . subsequent revisions to these estimates could be caused by changing market prices of our aircraft , changes in utilization of the aircraft , and other fleet events . we evaluate these estimates used for each reporting period and adjust when deemed necessary . to the extent a change in estimate for useful lives or salvage values of our property and equipment occurs , there could be an acceleration of depreciation expense associated with the change in estimate . aircraft maintenance and repair costs and major maintenance deferral we account for major maintenance costs of airbus airframes and the related cfm engines using the deferral method . under this method , the cost of major maintenance events is capitalized and amortized as a component of depreciation and amortization expense over the estimated period until the next scheduled major maintenance event . the timing of the next major maintenance event is estimated based on assumptions including estimated cycles , hours and months , required maintenance intervals , and the age/condition of related parts . these assumptions may change based on forecasted aircraft utilization changes , updates to government regulations , and manufacturer maintenance intervals , as well as unplanned incidents causing damage requiring a major maintenance event prior to a scheduled visit . if the estimated timing of the next maintenance event changes , the related amortization period would also change . we account for non-major maintenance and repair costs as well as major maintenance costs of md-80 airframes and the related jt8d-219 engines under the direct expense method . under this method , maintenance and repair costs for owned and leased 37 aircraft are charged to operating expenses as incurred . maintenance and repair costs includes all parts , materials , line maintenance , and non-major maintenance activities required to maintain the company 's fleet types . share-based compensation we recognize share-based compensation expense over the requisite service period using a fair value approach . determining fair value requires judgment , and we use the black-scholes valuation model for stock options and cash-settled sars issued . cash-settled sars are liability-based awards and fair value is updated monthly using the black-scholes valuation model for outstanding awards . judgment is required to establish the assumptions to be used in the model . these assumptions are for the volatility of our common stock price , estimated term over which our stock options and sars will be outstanding , interest rate , and dividend yield to be applied . we use our closing stock price on the grant date as the fair value for issuances of restricted stock . use of non-gaap financial measures total operating expense less fuel and special item eliminates the effect of fuel and the non-cash impairment charge for the accelerated retirement of the md-80 fleet . fuel expense is eliminated because we have limited control over that expense item . the impairment charge is eliminated as it is not reflective of our ongoing operating performance . as such , this is a non-gaap financial measure . the sec has adopted rules ( regulation s-k ( 10e ) ) regulating the use of non-gaap financial measures . because of our use of non-gaap financial measures in this report to

debt our total long-term debt obligations , without reduction for related costs , increased from $ 813.2 million as of december 31 , 2016 to $ 1,171.0 million as of december 31 , 2017 due to borrowings closed to effectively execute the transition of our fleet . as of february 2 , 2018 , we owned 13 unencumbered airbus aircraft , as well as had $ 14.4 million undrawn on our senior secured revolving credit facility . 35 sources and uses of cash operating activities . during 2017 , our operating activities provided $ 391.1 million of cash compared to $ 346.9 million during 2016 . operating cash inflows are primarily derived from providing air transportation and related ancillary products and services to customers , for which the vast majority of tickets are purchased prior to the day travel occurs . the year over year increase in reported cash inflows largely resulted from the increase in earnings after adjustments made for non-cash items such as depreciation and amortization ( $ 16.5 million higher in 2017 ) and the special charge in 2017 ( $ 35.3 million ) , and as a result of a $ 16.2 million increase in air traffic liability . during 2016 , our operating activities provided $ 346.9 million of cash compared to $ 365.4 million in 2015. the year over year decrease in reported cash inflows was impacted by the expenditure of $ 18.9 million related to major maintenance for our airbus airframes and engines . investing activities . during 2017 , cash used for investing activities was $ 618.5 million compared to $ 401.8 million in 2016 . during 2017 , our primary use of cash was for the purchase of property and equipment of $ 580.2 million ( including aircraft pre-delivery deposits and capitalized interest ) . cash was also used for the purchase of investment securities , net of maturities , of $ 43.4 million . during 2016 , our primary use of cash was for the purchase of property and equipment of $ 325.2 million ( including aircraft pre-delivery deposits and capitalized interest ) .


 Write a concise suspicious activity report of the following text delimited by triple backquotes. Return your response as a formal report which covers the key points highlighting the location,dates,entity names and account holder information in chronological order of the text.
     ```debt our total long-term debt obligations , without reduction for related costs , increased from $ 813.2 million as of december 31 , 2016 to $ 1,171.0 million as of december 31 , 2017 due to borrowings closed to effectively execute the transition of our fleet . as of february 2 , 2018 , we owned 13 unencumbered airbus aircraft , as well as had $ 14.4 million undrawn on our senior secured revolving credit facility . 35 sources and uses of cash operating activities . during 2017 , our operating activities provided $ 391.1 million of cash compared to $ 346.9 million during 2016 . operating cash inflows are primarily derived from providing air transportation and related ancillary products and services to customers , for which the vast majority of tickets are purchased prior to the day travel occurs . the year over year increase in reported cash inflows largely resulted from the increase in earnings after adjustments made for non-cash items such as depreciation and amortization ( $ 16.5 million higher in 2017 ) and the special charge in 2017 ( $ 35.3 million ) , and as a result of a $ 16.2 million increase in air traffic liability . during 2016 , our operating activities provided $ 346.9 million of cash compared to $ 365.4 million in 2015. the year over year decrease in reported cash inflows was impacted by the expenditure of $ 18.9 million related to major maintenance for our airbus airframes and engines . investing activities . during 2017 , cash used for investing activities was $ 618.5 million compared to $ 401.8 million in 2016 . during 2017 , our primary use of cash was for the purchase of property and equipment of $ 580.2 million ( including aircraft pre-delivery deposits and capitalized interest ) . cash was also used for the purchase of investment securities , net of maturities , of $ 43.4 million . during 2016 , our primary use of cash was for the purchase of property and equipment of $ 325.2 million ( including aircraft pre-delivery deposits and capitalized interest ) .
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 Suspicious Activity Report : 28 aircraft operating fleet the following table sets forth the number and type of aircraft in service and operated by us as of the dates indicated : replace_table_token_9_th ( 1 ) does not include 11 owned aircraft currently on lease to a european carrier or three other aircraft for which we have taken delivery as of december 31 , 2017 . ( 2 ) does not include two aircraft for which we have taken delivery as of december 31 , 2017 . as of february 2 , 2018 , we are party to forward purchase agreements for 15 airbus a320 series aircraft and have executed lease agreements for 13 airbus a320 series aircraft of which we have not yet taken delivery . we expect delivery of 18 of these aircraft in 2018 and the remaining aircraft in 2019 and 2020. in january 2018 , we took delivery of two aircraft for which we had purchase agreements as of december 31 , 2017. also in january 2018 , we took redelivery of one of our owned aircraft on lease to a european carrier , and also expect redelivery of the remaining 10 aircraft on lease in 2018. refer to part i - item 2 - properties for further detail regarding our aircraft fleet . we continuously consider aircraft acquisitions on an opportunistic basis . network we use profitability management tools to manage capacity and route expansion through optimization of our flight schedule to , among other things , better match demand in certain markets . we continually adjust our network through the addition of new markets and routes , adjusting the frequencies into existing markets , and exiting under-performing markets , as we seek to achieve and maintain profitability on each route we serve . as of february 2 , 2018 and including recent service announcements , we were selling 396 routes . our route network as of december 31 , 2017 represents an 11.4 percent increase in the number of routes flown compared to the end of 2016 , and the number of mid-sized cities served is now up to 22 after we began to initiate service to larger cities in 2014. the following table shows the number of leisure destinations and cities served as of the dates indicated ( includes cities served seasonally ) : replace_table_token_10_th trends continuing with our fleet transition to an all-airbus fleet , we added 19 airbus a320 series aircraft to our operating fleet during 2017. we expect to have fully transitioned by the end of 2018 , based on our plan to add 30 airbus a320 series aircraft into service during 2018. in conjunction with the fleet transition , we retired 10 md-80 aircraft in 2017 as well as our four remaining boeing 757-200 aircraft , and expect to retire our remaining 37 md-80 aircraft by the end of 2018 . 29 as of february 2 , 2018 , we were offering service on 140 medium-sized city routes compared to 96 as of the same date in 2017. we initiated service on 30 new network routes in the fourth quarter of 2017 , including service into two new cities : milwaukee , wisconsin and norfolk , virginia . sunseeker resorts planning and development is ongoing and the land is currently being prepared for construction , with the opening of the resort planned for late 2019 or early 2020. construction of the project and sales efforts are expected to begin in the first half of 2018. our flight attendant group approved their collective bargaining agreement effective in december 2017. we expect the collective bargaining agreement to increase our operating costs by approximately $ 8 million for 2018. our flight dispatchers have also voted for union representation and negotiations are ongoing . any labor actions following an inability to reach collective bargaining agreements with these employee groups , or any other labor groups seeking to organize , could materially impact our operations during the continuance of any such activity . our operating expenses a brief description of the items included in our operating expense line items follows . aircraft fuel expense includes the cost of aircraft fuel , fuel taxes , into plane fees and airport fuel flowage , storage or through-put fees . salary and benefits expense includes wages , salaries , and employee bonuses , sales commissions for in-flight personnel , as well as expenses associated with employee benefit plans , stock compensation expense related to equity grants , and employer payroll taxes . station operations expense includes the fees charged by airports for the use or lease of airport facilities and fees charged by third party vendors for ground handling services , commissary expenses and other related services . maintenance and repairs expense includes all parts , materials and spares required to maintain our aircraft as well as major maintenance costs for our md-80 aircraft . also included are fees for repairs performed by third party vendors . sales and marketing expense includes all advertising , promotional expenses , travel agent commissions and debit and credit card processing fees associated with the sale of scheduled service and air-related ancillary charges , net of credit card fee reimbursement charges collected from customers and treated as a reduction to expense ( program ended in january 2017 ) . aircraft lease rentals expense consists of the cost of leasing aircraft and or engines under operating leases with third parties , as well as costs for sub-service contracted out . depreciation and amortization expense includes the depreciation of all owned fixed assets , including aircraft and engines . story_separator_special_tag under our fixed fee flying contracts , we require customers to prepay for flights , and the cash is escrowed until the flight is completed . prepayments are recorded as restricted cash and a corresponding amount is recorded as air traffic liability . investment securities represent liquid marketable securities which are available-for-sale . during 2017 , our primary source of funds was $ 391.1 million generated by our operations in addition to $ 497.5 million in proceeds from notes payable . our operating cash flows and borrowings have allowed us to return value to shareholders and invest in the growth of our fleet . our future capital needs are primarily for the acquisition of additional aircraft , including our existing airbus a320 series aircraft commitments , as well as potential capital outlay related to sunseeker resorts as well as other travel and leisure initiatives . of the aircraft expected to be placed into service in 2018 , 13 are structured as capital leases and will not require separate financing , and the additional 10 aircraft ( as of february 2 , 2018 ) being returned from lease to a european carrier were purchased in 2014 and have already been paid for . we believe we have more than adequate liquidity resources through our operating cash flows , borrowings , and cash balances , to meet our future contractual obligations . we financed 10 of our new airbus aircraft in 2017 , and expect to finance the remaining two in 2018 in addition to used airbus aircraft under purchase contract , subject to acceptable terms . in addition , we continue to consider raising funds through debt financing on an opportunistic basis . in addition to our recurring quarterly cash dividend , we plan to continue to opportunistically repurchase our stock in the open market subject to availability of cash resources and compliance with our debt covenants . as of december 31 , 2017 , authority under our board-approved stock repurchase program was $ 100.0 million . there is no expiration date for the program . story_separator_special_tag including , but not limited to : ( i ) estimated fair value of the assets ; and ( ii ) estimated future cash flows expected to be generated by those assets , which are based on additional assumptions such as ( but not limited to ) asset utilization , average fare , block hours , fuel costs , length of service the asset will be used in operations , and estimated salvage values . in estimating the useful lives and residual values of our aircraft , we have primarily relied upon actual experience with the same or similar aircraft types , current and projected future market information , and recommendations from other industry sources . subsequent revisions to these estimates could be caused by changing market prices of our aircraft , changes in utilization of the aircraft , and other fleet events . we evaluate these estimates used for each reporting period and adjust when deemed necessary . to the extent a change in estimate for useful lives or salvage values of our property and equipment occurs , there could be an acceleration of depreciation expense associated with the change in estimate . aircraft maintenance and repair costs and major maintenance deferral we account for major maintenance costs of airbus airframes and the related cfm engines using the deferral method . under this method , the cost of major maintenance events is capitalized and amortized as a component of depreciation and amortization expense over the estimated period until the next scheduled major maintenance event . the timing of the next major maintenance event is estimated based on assumptions including estimated cycles , hours and months , required maintenance intervals , and the age/condition of related parts . these assumptions may change based on forecasted aircraft utilization changes , updates to government regulations , and manufacturer maintenance intervals , as well as unplanned incidents causing damage requiring a major maintenance event prior to a scheduled visit . if the estimated timing of the next maintenance event changes , the related amortization period would also change . we account for non-major maintenance and repair costs as well as major maintenance costs of md-80 airframes and the related jt8d-219 engines under the direct expense method . under this method , maintenance and repair costs for owned and leased 37 aircraft are charged to operating expenses as incurred . maintenance and repair costs includes all parts , materials , line maintenance , and non-major maintenance activities required to maintain the company 's fleet types . share-based compensation we recognize share-based compensation expense over the requisite service period using a fair value approach . determining fair value requires judgment , and we use the black-scholes valuation model for stock options and cash-settled sars issued . cash-settled sars are liability-based awards and fair value is updated monthly using the black-scholes valuation model for outstanding awards . judgment is required to establish the assumptions to be used in the model . these assumptions are for the volatility of our common stock price , estimated term over which our stock options and sars will be outstanding , interest rate , and dividend yield to be applied . we use our closing stock price on the grant date as the fair value for issuances of restricted stock . use of non-gaap financial measures total operating expense less fuel and special item eliminates the effect of fuel and the non-cash impairment charge for the accelerated retirement of the md-80 fleet . fuel expense is eliminated because we have limited control over that expense item . the impairment charge is eliminated as it is not reflective of our ongoing operating performance . as such , this is a non-gaap financial measure . the sec has adopted rules ( regulation s-k ( 10e ) ) regulating the use of non-gaap financial measures . because of our use of non-gaap financial measures in this report to

