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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
 Washington, DC 20549
 
 FORM 11-K
  þ
    
    ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
 For the fiscal year ended December 31, 2010
  o
    
    TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
 For the transition period from  to
 Commission file number 001-14141
 AVIATION COMMUNICATION &
SURVEILLANCE SYSTEMS 401(K) PLAN
 (Full title of the plan and the address of the plan,
if different from that of the issuer named below)
 L-3 COMMUNICATIONS HOLDINGS, INC.




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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
Index to Financial Statements and Supplemental Schedule
 PagesReport of Independent Registered Public Accounting Firm
    
    
    2Financial Statements:Statements of Net Assets Available for Benefits as of December 31, 2010 and 2009
    
    
    3Statement of Changes in Net Assets Available for Benefits for the year ended December 31, 2010
    
    
    4Notes to Financial Statements
    
    
    5-13Supplemental Schedule:Schedule H, line 4i*  Schedule of Assets (Held at End of Year)
    
    
    14EX-23
  
 *
    
    Refers to item number in Form 5500 (Annual Return/Report of Employee Benefit Plan) filed
with the Department of Labor for the plan year ended December 31, 2010.Other schedules required by 29 CFR 2520.103-10 of the Department of Labors Rules and
Regulations for Reporting and Disclosure under the Employee Retirement Income Security Act of
1974 have been omitted as the conditions under which they are required are not present.




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Report of Independent Registered Public Accounting Firm
 
   /s/ PricewaterhouseCoopers LLPPricewaterhouseCoopers LLPNew York, New York




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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
 
 STATEMENTS OF NET ASSETS AVAILABLE FOR BENEFITS
 AS OF DECEMBER 31, 2010 AND 2009
 (in thousands)
 2010
    
    
    2009Assets:Investment in Master Trust, at fair value
    
    $
    22,482
    
    
    $
    20,391Receivables:Employer contribution
    
    
    48
    
    
    
    42Participant contributions
    
    
    60
    
    
    
    60Notes receivable from participants
    
    
    506
    
    
    
    489Total receivables
    
    
    614
    
    
    
    591Total assets
    
    
    23,096
    
    
    
    20,982Adjustment from fair value to contract value for interest in collective trust relating to
fully benefit-responsive investment contracts
    
    
    (31
    )
    
    
    35Net assets available for benefits
    
    $
    23,065
    
    
    $
    21,017
  3




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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
 
 STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS
 FOR THE YEAR ENDED DECEMBER 31, 2010
 (in thousands)
 Additions:Contributions:Employer
    
    $
    1,278Participant
    
    
    1,727Rollover
    
    
    56Total contributions
    
    
    3,061Plan interest in the Master Trust net investment income
    
    
    142Interest income on notes receivables from participants
    
    
    23Total additions
    
    
    3,226Deductions:Benefit payments
    
    
    1,159Administrative expenses
    
    
    19Total deductions
    
    
    1,178Net increase
    
    
    2,048Net assets available for benefits, beginning of the year
    
    
    21,017Net assets available for benefits, end of the year
    
    $
    23,065
  4




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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
 
 NOTES TO FINANCIAL STATEMENTS
 1. Plan Description
 General
   Contributions
     Vesting
 th
 5




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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
NOTES TO FINANCIAL STATEMENTS  Continued
 Participant Accounts
  Master Trust Investments
  2. Summary of Significant Accounting Policies
 Investment in Master Trust
   Valuation of Investments
    Basis of Accounting
     6




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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
NOTES TO FINANCIAL STATEMENTS  Continued
  New Accounting Standard Implemented
  Investment Transactions and Investment Income
  Forfeitures
  Benefit Payments
  Plan Expenses
  Risks and Uncertainties
  7




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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
NOTES TO FINANCIAL STATEMENTS  Continued
 3. Master Trust
  Master Trust
    
    
    Plans PortionFund
    
    2010
    
    
    2009
    
    
    2010
    
    
    2009(in thousands)Investments at Fair Value as Determined by
Quoted Market Price:American Funds Growth Fund of America  Class R6*
    
    $
    161,146
    
    
    $
    148,945
    
    
    $
    623
    
    
    $
    469BlackRock High Yield Bond Portfolio. BlackRock
Shares *
    
    
    54,155
    
    
    
    18,860
    
    
    
    436
    
    
    
    96Calamos Growth Fund  Institutional Class*
    
    
    164,913
    
    
    
    136,499
    
    
    
    1,132
    
    
    
    900Davis New York Venture Fund, Inc. Class Y*
    
    
    107,958
    
    
    
    98,246
    
    
    
    367
    
    
    
    311Dodge & Cox Income Fund*
    
    
    160,663
    
    
    
    135,958
    
    
    
    1,162
    
    
    
    809Dodge & Cox Stock Fund*
    
    
    206,320
    
    
    
    183,711
    
    
    
    1,566
    
    
    
    1,425Fidelity Balanced Fund Class K*
    
    
    23,217
    
    
    
    
    
    
    
    78
    
    
    
    Fidelity Balanced Fund*
    
    
    
    
    
    
    13,439
    
    
    
    
    
    
    
    17Fidelity Diversified International Fund Class K*
    
    
    215,256
    
    
    
    
    
    
    
    1,227
    
    
    
    Fidelity Diversified International Fund*
    
    
    
    
    
    
    205,243
    
    
    
    
    
    
    
    1,209Fidelity Freedom K 2000 Fund*
    
    
    14,029
    
    
    
    
    
    
    
    41
    
    
    
    Fidelity Freedom K 2005 Fund*
    
    
    1,079
    
    
    
    
    
    
    
    6
    
    
    
    Fidelity Freedom K 2010 Fund*
    
    
    94,681
    
    
    
    
    
    
    
    246
    
    
    
    Fidelity Freedom K 2015 Fund*
    
    
    19,510
    
    
    
    
    
    
    
    44
    
    
    
    Fidelity Freedom K 2020 Fund*
    
    
    153,798
    
    
    
    
    
    
    
    913
    
    
    
    Fidelity Freedom K 2025 Fund*
    
    
    20,885
    
    
    
    
    
    
    
    64
    
    
    
    Fidelity Freedom K 2030 Fund*
    
    
    105,646
    
    
    
    
    
    
    
    1,174
    
    
    
    Fidelity Freedom K 2035 Fund*
    
    
    10,956
    
    
    
    
    
    
    
    112
    
    
    
    Fidelity Freedom K 2040 Fund*
    
    
    23,562
    
    
    
    
    
    
    
    125
    
    
    
    Fidelity Freedom K 2045 Fund*
    
    
    10,079
    
    
    
    
    
    
    
    1
    
    
    
    Fidelity Freedom K 2050 Fund*
    
    
    15,074
    
    
    
    
    
    
    
    68
    
    
    
    Fidelity Freedom 2000 Fund*
    
    
    
    
    
    
    13,499
    
    
    
    
    
    
    
    34Fidelity Freedom 2005 Fund*
    
    
    
    
    
    
    784
    
    
    
    
    
    
    
    6Fidelity Freedom 2010 Fund*
    
    
    
    
    
    
    91,461
    
    
    
    
    
    
    
    209Fidelity Freedom 2015 Fund*
    
    
    
    
    
    
    9,609
    
    
    
    
    
    
    
    35Fidelity Freedom 2020 Fund*
    
    
    
    
    
    
    130,926
    
    
    
    
    
    
    
    914Fidelity Freedom 2025 Fund*
    
    
    
    
    
    
    8,623
    
    
    
    
    
    
    
    55Fidelity Freedom 2030 Fund*
    
    
    
    
    
    
    82,164
    
    
    
    
    
    
    
    721Fidelity Freedom 2035 Fund*
    
    
    
    
    
    
    4,491
    
    
    
    
    
    
    
    21Fidelity Freedom 2040 Fund*
    
    
    
    
    
    
    15,258
    
    
    
    
    
    
    
    89Fidelity Freedom 2045 Fund*
    
    
    
    
    
    
    3,794
    
    
    
    
    
    
    
    1Fidelity Freedom 2050 Fund*
    
    
    
    
    
    
    8,854
    
    
    
    
    
    
    
    41Fidelity Ginnie Mae Fund*
    
    
    112,228
    
    
    
    107,576
    
    
    
    496
    
    
    
    682Fidelity Magellan Fund Class K*
    
    
    157,418
    
    
    
    
    
    
    
    1,027
    
    
    
    Fidelity Magellan Fund*
    
    
    
    
    
    
    145,240
    
    
    
    
    
    
    
    884Spartan U.S. Equity Index Fund  Advantage Class*
    
    
    139,272
    
    
    
    119,763
    
    
    
    723
    
    
    
    520T. Rowe Price Small-Cap Stock Fund*
    
    
    214,631
    
    
    
    146,418
    
    
    
    937
    
    
    
    613Victory Special Value Fund  Class I*
    
    
    18,826
    
    
    
    9,882
    
    
    
    96
    
    
    
    58Vanguard Inflation  Protected Securities Fund
Investor Shares *
    
    
    10,266
    
    
    
    
    
    
    
    71
    
    
    
    $
    2,215,568
    
    
    $
    1,839,243
    
    
    $
    12,735
    
    
    $
    10,119
 8




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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
NOTES TO FINANCIAL STATEMENTS  Continued
 Master Trust
    
    
    Plans PortionFund
    
    2010
    
    
    2009
    
    
    2010
    
    
    2009(in thousands)Investments at Estimated Fair ValueL-3 Stock Fund
    
    
    656,530
    
    
    
    741,567
    
    
    
    6,622
    
    
    
    7,518Fidelity Managed Income Portfolio II  Class 3**
    
    
    620,050
    
    
    
    608,781
    
    
    
    3,125
    
    
    
    2,7541,276,580
    
    
    
    1,350,348
    
    
    
    9,947
    
    
    
    10,272$
    3,492,148
    
    
    $
    3,189,591
    
    
    $
    22,482
    
    
    $
    20,391
 
 *
    
    Mutual Fund**
    
    Common/Collective Trust Fund  Master Trust
    
    
    Plans Portion(in thousands)Investment Income:Net appreciation in investments
    
    $
    71,335
    
    
    $
    (343
    )Interest and dividend income
    
    
    78,876
    
    
    
    485Net investment income
    
    $
    150,211
    
    
    $
    142
   4. Fair Value Measurements
  Level 1:
    
    Quoted market prices available in active markets for identical
assets or liabilities as of the reporting date. The Plans Level
1 assets include mutual funds, whose fair values are derived from
quoted market prices.Level 2:
    
    Pricing inputs, other than quoted prices in active markets
included in Level 1, which are either directly or indirectly
observable. The Plans Level 2 assets include the L-3 Stock Fund
and the MIP Fund. See Note 5 for the valuation techniques used
by FMTC to measure the fair value of the MIP Funds investment in
fully benefit-responsive investment contracts.Level 3:
    
    Pricing inputs that are generally unobservable and not
corroborated by market data. The Plan does not have any Level 3
investments.
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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
NOTES TO FINANCIAL STATEMENTS  Continued
  Fair Value Measurements Using Input Type2010
    
    
    
    
    
    
    2009Level 1
    
    
    Level 2
    
    
    Level 3
    
    
    Total
    
    
    Level 1
    
    
    Level 2
    
    
    Level 3
    
    
    Total(in thousands)Mutual funds
    
    $
    12,735
    
    
    $
    
    
    
    $
    
    
    
    $
    12,735
    
    
    $
    10,119
    
    
    $
    
    
    
    $
    
    
    
    $
    10,119L-3 Stock Fund
    
    
    
    
    
    
    6,622
    
    
    
    
    
    
    
    6,622
    
    
    
    
    
    
    
    7,518
    
    
    
    
    
    
    
    7,518Common/collective
trust fund
    
    
    
    
    
    
    3,125
    
    
    
    
    
    
    
    3,125
    
    
    
    
    
    
    
    2,754
    
    
    
    
    
    
    
    2,754Total
investments
measured at fair
value
    
    $
    12,735
    
    
    $
    9,747
    
    
    $
    
    
    
    $
    22,482
    
    
    $
    10,119
    
    
    $
    10,272
    
    
    $
    
    
    
    $
    20,391
 5. Benefit-Responsive Investment Contracts
  Wrap Contracts.
   10




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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
NOTES TO FINANCIAL STATEMENTS  Continued
      6. Benefit Payments
 1 2
 1 2 1 2 1 2
 7. Loans
   8. Accounting Standards Issued and Not Yet Implemented
  11




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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
NOTES TO FINANCIAL STATEMENTS  Continued
  9. Tax Status
   10. Related-Party Transactions
   11. Termination Priorities
  12. Subsequent Event
  12




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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
NOTES TO FINANCIAL STATEMENTS  Continued
 13. Reconciliation of Financial Statements to Form 5500
  December 31,2010
    
    
    2009(in thousands)Net assets available for benefits per the financial statements
    
    $
    23,065
    
    
    $
    21,017Less: Adjustment from fair value to contract value for fully benefit-responsive
investment contracts
    
    
    31
    
    
    
    (35
    )Net assets available for benefits per the Form 5500
    
    $
    23,096
    
    
    $
    20,982
 December 31,2010(in thousands)Total investment income per the financial statements
    
    $
    142Add: Adjustment from fair value to contract value for fully benefit-responsive investment
contracts
    
    
    66Total investment income per the Form 5500
    
    $
    208
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AVIATION COMMUNICATION & SURVEILLANCE SYSTEMS 401(K) PLAN
 
 SCHEDULE H, LINE 4i  SCHEDULE OF ASSETS (HELD AT END OF YEAR)
 DECEMBER 31, 2010
 (in thousands)
 Description of Investment
    
    Cost
    
    
    Current ValueParticipant loans*
    
    
    
    
    
    $
    505Total
    
    
    
    
    
    $
    505
 
 *
    
    Consists of participant loans with interest rates from 4.25% to 9.25% maturing through March
2039. 14




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Aviation Communication & Surveillance Systems
401(k) Plan RegistrantDate: June 21, 2011
    
    /s/ Ralph G. DAmbrosioName:
    
    Ralph G. DAmbrosioTitle:
    
    Authorized Signatory,L-3 Benefit Plan Committee