1 EXHIBIT 99.10 [AIRCLAIMS LOGO] Our Ref: 99201/MSH/kw AerFi Group Plc. 21st January, 1999 Aviation House Shannon Ireland Attention: Ms Caroline Jones Dear Sirs, - AERCO PORTFOLIO - BASE VALUE AND CURRENT MARKET VALUATION AS AT 31ST JANUARY, 1999 Further to the instructions of Ms. Caroline Jones, AerFi Group Plc, we are pleased to be able to provide our opinion of the value of each aircraft in the portfolio of AerCo, under Base and Current Market Value scenarios. The aircraft, each of which is subject to a net operating lease, are as indicated in the attached table (ref: 99201/MSH). Our valuation is based on fleet details as provided by Ms. Jones on 30th December 1998, providing the most recent utilisation information available in respect of the aircraft and their respective engines, supplemented with maintenance and specification data obtained or received on previous occasions from Babcock and Brown, GPA Group and GE Capital Aviation Services (GECAS). The point of valuation is 31st January, 1999. As requested by AerFi Group Plc, we have provided our value opinions under CURRENT MARKET and BASE VALUE scenarios. Airclaims believes it to be VERY IMPORTANT that value definitions are understood by all parties and that such values are always considered in conjunction with their definitions. [LOGOS] Airclaims Limited Cardinal Point, Newall Road, Heathrow Airport, London TW6 2AS Telephone (44) 181 897 1066 Facsimile (44) 181 897 0300 Telex 934679 http://www.airclaims.co.uk Registered Head Office as above. Registered in England No. 710284, VAT Reg. No. 224 1906 87 2 [AIRCLAIMS LOGO] BASE VALUE (to ISTAT Definition) The Base Value presented below is based on the definition as outlined by the International Society of Transport Aircraft Trading (ISTAT). ISTAT's definition of Base Value equates in principle to the previously used appraisal term, Fair Market Value. The ISTAT definition is as follows: A Base Value is the Appraiser's opinion of the underlying economic value of an aircraft in an open, unrestricted, stable market environment with a reasonable balance of supply and demand, and assumes full consideration of its "highest and best use". An aircraft's Base Value is founded in the historical trend of values and in the projection of value trends and presumes an arm's length, cash transaction between willing, able and knowledgeable parties, acting prudently, with an absence of duress and with a reasonable period of time available for marketing. In this instance, the Base Value of each aircraft assumes its physical condition is average for an aircraft of its type and age, but has been adjusted to reflect a) the actual utilisation and given maintenance status of airframe, engines and undercarriage where possible (the "Adjusted Base Value") and b) assuming overall "half-life" maintenance condition. The Base Value also assumes that each Aircraft is under a maintenance programme of international airworthiness standards approved by a civil aviation authority, with all airworthiness directives (ADs) and manufacturers service bulletins (SBs) performed in compliance with air carrier rules and regulations. CURRENT MARKET VALUE In Airclaims' considered opinion the CURRENT MARKET VALUE represents that which the aircraft could best achieve under current (i.e. today's) market conditions. Under this scenario each value is intended to reflect what might be expected from the result of an "arms length, single sale" transaction conducted in an orderly manner (for which we consider a period of up to 12 months to come to fruition to be reasonable) between a "willing buyer and willing seller". The value assumes that each aircraft is free of lease or charge, and free of any onerous restrictions in respect of its ownership and title documentation. As part of our valuation process, we have taken into account recent market activity covering open market, financial and lessor sales, the perceived demand for the types, their current market acceptability and availability, and have considered the views of informed industry sources. 3 [AIRCLAIMS LOGO] Further to the above we have also taken account of the data available to us regarding the specification of the subject aircraft, and their accumulated airframe hours and cycles. We have also assumed that the aircraft are in good condition with all Airworthiness Directives (ADs) and significant Service Bulletins (SBs) complied with. In this instance, the Current Market Value of each aircraft assumes its physical condition is average for an aircraft of its type and age, but has been adjusted to reflect the actual utilisation and given maintenance status of airframe, engines and undercarriage where possible (the "Adjusted Current Market Value") and b) under the assumption that each aircraft is in overall "half-life" maintenance conditions (Current Market "Half-Life" Value). The Current Market Value also assumes that each Aircraft is under a maintenance programme of international airworthiness standards approved by a civil aviation authority with all airworthiness directives (ADs) and manufacturers service bulletins (SBs) performed in compliance with air carrier rules and regulations. Whilst the tabulated values provided under this assignment are given as single figures, it must be borne in mind that the determination of such value involves a multiplicity of variables, and that some variation in perceived values must be expected due to, for example, any potential inaccuracies in the data provided. In this case we consider that a tolerance of +/- 4% may reasonably apply to the aforementioned calculated values. Please note that valuations given by Airclaims are valid only as at the date of issue. Subsequent to that date there may be alterations in the world aviation market, or in the status and physical condition of the subject aircraft or other general factors that may affect Airclaims' value opinion. I trust the foregoing is satisfactory and to your requirements. Yours sincerely, /s/ Edward Pieniazek ---------------- Edward Pieniazek Director, Consultancy & Information Services Encl. 4 Current Market and Base Values for AerCo Portfolio as of 31st January 1999, expressed in Million US Dollars Market Values Base Values Type Engines MSN Operator YoB Hours Cycles As at MTOW (lbs) Half Life Adj. Half Life Adj. Airbus CF6-50C2 240 Indian Airlines Feb-83 31,384 18,024 Sep-98 363,765 $8.35M $8.88M $8.70M $9.22M A300-B4-200 Airbus A320-200 CFM56-5A1 85 Air France Oct-89 16,828 17,676 Oct-98 162,041 $26.65M $25.65M $25.81M $24.81M Airbus A320-200 CFM56-5A3 299 Premiair Jan-92 22,553 8,112 Sep-98 166,450 $31.30M $31.36M $38.12M $30.18M Airbus A320-200 CFM56-5A3 391 Monarch Dec-92 21,389 8,253 Sep-98 169.757 $32.60M $32.72M $31.42M $31.54M Airlines Airbus A320-200 CFM56-5A1 403 Canadian Jan-93 17,905 6,581 Oct-98 158,731 $32.20M $31.34M $30.99M $30.13M Airlines International Airbus A320-200 V2500-A1 362 Airlines Sep-92 23,255 8,384 Sep-98 166,450 $32.20M $32.46M $31.02M $31.28M International Boeing 737-300 CFM56-3B1 24465 Philippine Jul-89 18,181 22,102 Oct-98 135,000 $19.73M $19.74M $19.13M $19.14M Airlines Boeing 737-300 CFM56-3B1 24677 Philippine Feb-90 17,106 20,641 Oct-98 135,000 $20.43M $20.97M $19.79M $20.34M Airlines Boeing 737-300 CFM56-3C1(23.5) 24908 Sun Express Feb-91 27,769 12,392 Oct-98 139,500 $23.30M $22.81M $22.63M $22.13M Boeing 737-300 CFM56-3C1(22) 24909 MALEV Feb-91 19,881 11,931 Oct-98 139,500 $22.74M $21.38M $22.07M $20.70M Boeing 737-300 CFM56-3C1(23.5) 26968 China Yannan May-92 20,174 15,556 Dec-98 139,000 $23.97M $23.27M $23.36M $22.66M Airlines Boeing 737-400 CFM56-3C1(23.5) 23868 British Midland Sep-88 24,756 26,812 Oct-98 143,500 $22.24M $21.53M $21.23M $22.52M Airways Boeing 737-400 CFM56-3C1(23.5) 23979 Pegasus Airlines Dec-88 25,184 12,242 Oct-98 143,500 $22.99M $23.36M $22.23M $22.61M Boeing 737-400 CFM56-3C1(23.5) 24685 Futurs Apr-90 29,053 14,213 Oct-98 150,000 $24.86M $24.34M $24.26M $23.75M Boeing 737-400 CFM56-3C1(23.5) 24904 THY - Turkish Jan-91 20,346 11,901 Aug-98 150,000 $25.37M $24.70M $24.65M $23.99M Airlines Boeing 737-400 CFM56-3C1(23.5) 25764 Asiana Airlines May-92 12,923 18,846 Oct-98 143,500 $25,50M $26.02M $24.76M $25.28M Boeing 737-400 CFM56-3C1(23.5) 25765 Asiana Airlines Jan-92 12,617 18,413 Oct-98 143,500 $25.50M $25.15M $24.76M $24.41M Boeing 737-400 CFM56-3C1(23.5) 26066 THY - Turkish May-92 18,212 9,495 Aug-98 150,000 $27.11M $26.36M $26.37M $25.63M Airlines Boeing 737-500 CFM56-3C1(20) 26067 Air Pacific May-92 20,903 9,770 Oct-98 133,500 $22.23M $20.75M $21.56M $20.08M Boeing 747-200D JT9D-7Q 22496 Tower Air Aug-81 51,591 10,879 Oct-98 814,000 $23.67M $26.79M $25.83M $28.95M Boeing 757-200 RB211-535E4 26152 Avianca Jul-92 20,103 8,129 Oct-98 255,000 $37.27M $38.39M $36.09M $37.21M Boeing 757-200 RB211-535E4 26153 China Southwest Jul-92 14,727 8,554 Oct-98 255,000 $37.27M $39.47M $36.09M $38.28M Airlines Boeing 757-200 RB211-535E4 26158 Air 2000 Jan-93 23,603 7,269 Oct-98 255,000 $18.52M $39.48M $37.45M $38.41M Boeing 767-300ER PW4060 24947 LANChile Jan-91 35,574 8,830 Oct-98 407,000 $55.87M $55.59M $57.12M $56.84M Boeing 767-300ER PW4860 24999 Spanair Jan-91 35,122 7,801 Nov-98 407,000 $56.17M $56.38M $57.42M $57.63M Douglas DC-8-71F CFM56-2C1 46840 LANChile Mar-69 69,717 27,234 Jul-98 325,000 $14.50M $16.17M $15.59M $17.26M Douglas DC-8-71F CFM56-2C1 46064 Air Transport May-69 78,000 31,297 Sep-98 325,000 $14.50M $14.97M $15.59M $16.06M International Fokker 100 RB183 Tay 650-15 11341 TAM Brasil Jun-91 13,311 13,053 Oct-98 98,000 $13.52M $12.96M $15.19M $14.63M Fokker 100 RB183 Tay 650-15 11342 Portugalia Jun-91 13,805 13,198 Oct-98 98,000 $13.52M $13.64M $15.19M $15.31M Fokker 100 RB183 Tay 650-15 12350 TAM Brasil Aug-91 16,265 17,300 Oct-98 98,000 $13.62M $13.42M $15.29M $15.09M Fokker 100 RB183 Tay 650-15 11351 TAM Brasil Sep-91 17,021 17,179 Oct-98 98,000 $13.52M $13.29M $15.19M $14.96M MD-83 JT8D-219 49627 Spanair Feb-89 34,470 16,701 Oct-98 160,000 $17.80M $17.89M $17.34M $17.43M MD-83 JT8D-219 49790 Spanair Aug-89 31,958 15,480 Oct-98 160,000 $18.05M $18.41M $17.59M $17.95M MD-83 JT8D-219 49952 Far Eastern Oct-91 23,077 16,366 Oct-98 160,000 $19.87M $19.87M $19.40M $18.61M Air Transport