<PAGE>
 
================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                         ______________________________
                                        
                                  FORM 10-K/A
                               (AMENDMENT NO. 2)

[X]  ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE
     ACT OF 1934

[_]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES
     EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM________ TO_________

FOR THE YEAR ENDED DECEMBER 31, 1997            COMMISSION FILE NUMBER 000-21091
                               ___________________

                          ADVANCED RADIO TELECOM CORP.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

           DELAWARE                                        52-1869023
(STATE OR OTHER JURISDICTION                            (I.R.S. EMPLOYER
OF  INCORPORATION OR ORGANIZATION)                     IDENTIFICATION NO.)
 
         500 108TH AVENUE NE  
               SUITE 2600     
         BELLEVUE, WASHINGTON                                98004
(ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)                   (ZIP CODE)

                                (425) 688-8700
             (REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE)
                                 _____________

          Securities registered pursuant to Section 12(b) of the Act:

                                                       NAME OF EACH EXCHANGE
 TITLE OF EACH CLASS                                    ON WHICH REGISTERED
---------------------                                  ---------------------
     None                                                      None
             

          Securities registered pursuant to Section 12(g) of the Act:

TITLE OF EACH CLASS:                              COMMON STOCK ($.001 PAR VALUE)
------------------- 

Indicate by check mark whether the registrant: (1) has filed all reports
required to be filed by section 13 or 15(d) of the securities exchange act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days: Yes [X] No [_] .

  Indicate by check mark if disclosure of delinquent filers pursuant to item 405
of Regulation s-k is not contained herein, and will not be contained, to the
best of the registrant's knowledge, in the definitive proxy or information
statements incorporated by reference in Part III of this Form 10-K or any
amendment to this Form 10-K [X].

  The aggregate market value of the registrant's voting stock held by non-
affiliates was approximately $324 million on May 1, 1998, Based on the closing
sales price of the registrant's common stock ("Common Stock") as reported on the
NASDAQ National Market as of such date.

  The number of shares outstanding of each of the registrant's classes of Common
Stock as of May 1, 1998 was as follows:

  Common Stock, $.001 par value: 22,237,843

                      DOCUMENTS INCORPORATED BY REFERENCE

  None.  Advanced Radio Telecom Corp. ("ART" or the "Company") hereby amends its
Annual Report on Form 10-K for the year ended December 31, 1997, filed with the
Commission on March 30, 1998, by amending and restating certain information
required by 11 and 12 and Exhibit 99.

                          Exhibit Index is on page 11
================================================================================
                                        
<PAGE>
 
ITEM 11.  EXECUTIVE COMPENSATION.

     The following table sets forth information with respect to compensation
paid to or accrued in each of the last three completed fiscal years, if
applicable, on behalf of the Chief Executive Officer and each of the four other
most highly paid executive officers of the Company who were serving as executive
officers on December 31, 1997 and one other individual who would have been one
of the four most highly paid executive officers of the Company but for the fact
that he was not serving as an executive officer on December 31, 1997 (the "Named
Executive Officers"):

                           SUMMARY COMPENSATION TABLE
<TABLE>
<CAPTION>
 
                                                                              LONG TERM
                                                                             COMPENSATION
                                                                                AWARDS   
                                                                      -----------------------
                                           ANNUAL COMPENSATION        RESTRICTED   SECURITIES 
                                    ---------------------------------   STOCK     UNDERLYING       ALL OTHER
                                     YEAR      SALARY        BONUS     AWARDS   OPTIONS(#)(1)    COMPENSATION
                                    ------  -------------  ----------  -------  --------------  ---------------
<S>                                 <C>     <C>            <C>         <C>      <C>             <C>
 
Henry C. Hirsch (2)...............    1997    $ 54,168(3)     $54,167  100,000     800,000          $300,113(4)
   Chairman, President and Chief      1996          __             __       __          __                __
   Executive Officer                  1995          __             __       __          __                __
 
Vernon L. Fotheringham (5)........    1997    $274,992        $50,000       __          __          $     44(6)
   Vice Chairman                      1996    $250,000             __       __          __                __
                                      1995    $ 90,000             __       __          __                __
Thomas A. Grina...................    1997    $210,600             __       __     228,666          $     26(6)
  Executive Vice President and        1996    $122,190(3)          __       __     181,818          $ 25,000(7)
  Chief Financial Officer             1995          __             __       __          __                __
 
 
James D. Miller,..................    1997    $157,500             __       __      36,364          $    113(6)
  Senior Vice President               1996    $135,000(3)          __       __      36,364                __
  Sales and Marketing                 1995          __             __       __      18,182                __
 
Richard A. Shields, Jr.(8)........    1997    $153,750             __       __      54,545          $     26(6)
  Senior Vice President               1996    $ 93,777(3)          __       __      14,545                __
  Technical Operations                1995          __             __       __          __                __
 
Thomas M. Walker..................    1997    $120,625             __       __      35,000          $     10(6)
  Vice President                      1996    $ 49,482(3)     $10,625       __       7,272          $  2,943(7)
  General Counsel                     1995          __             __       __          __                __
</TABLE>
-----------------------------

(1) On July 31, 1997, the Board of Directors canceled certain options granted
    under the Company's Restated Equity Incentive Plan (the "Equity Incentive
    Plan") and issued new options in lieu thereof with a lower exercise price of
    $7.875, the fair market value of the Common Stock on that date.
(2) Mr. Hirsch joined the Company in November 1997.
(3) Reflects compensation for a partial year.  See "--Employment Agreements."
(4) Reflects payment of term life insurance premiums and moving expenses.
(5) Mr. Fotheringham resigned his position as Chairman, President and Chief
    Executive Officer and was elected Vice Chairman of the Company effective
    November 1997.  He resigned his position as Vice Chairman of the Company
    effective May 1998. Mr. Fotheringham will continue to serve as a director of
    the Company.
(6) Reflects payment of term life insurance premiums.
(7) Reflects the reimbursement of moving expenses.
(8) Mr. Shields ceased being an executive officer of the Company in December
    1997, and his employment with the Company terminated effective January 15,
    1998.

                                      -2-
<PAGE>
 
OPTION GRANTS

     The following table sets forth certain information regarding stock option
grants made to the Named Executive Officers during the fiscal year ended
December 31, 1997.  No grants were made during 1997 to Mr. Fotheringham.

                       OPTION GRANTS IN LAST FISCAL YEAR
                             INDIVIDUAL GRANTS (1)
                       ----------------------------------
<TABLE>
<CAPTION>
 
                                                                                            POTENTIAL REALIZATION VALUE AT   
                              NUMBER OF     PERCENT OF                                          ASSUMED ANNUAL RATES OF       
                             SECURITIES   TOTAL OPTIONS                                      STOCK PRICE APPRECIATION FOR     
                             UNDERLYING     GRANTED TO                                             OPTION TERM (2)            
                               OPTIONS     EMPLOYEES IN   EXERCISE PRICE   EXPIRATION       -------------------------------- 
                               GRANTED     FISCAL YEAR    PER SHARE          DATE                 5%               10%
                              --------    -------------    ------           --------        --------------  ----------------   
<S>                          <C>          <C>             <C>            <C>                <C>             <C>                     

                                                                         
Henry C. Hirsch                  600,000      25.9%       $8.875           10/17/02            $1,471,199       $3,250,966
                                 200,000       8.6%        12.50           10/17/02                     0          358,655
Thomas A. Grina                   46,848       2.0%        7.125            8/21/02                92,221          203,783
                                 181,818       7.8%        7.875            7/30/02               395,585          874,138
James D. Miller                   36,364       1.6%        7.875            7/30/02                79,118          174,830
Richard A. Shields, Jr. (3)       54,545       2.4%        7.875            7/30/02               118,675          262,240
Thomas M. Walker                  35,000       1.5%        7.875            7/30/02                76,150          168,272
</TABLE> 
---------------
(1) On July 31, 1997, the Board of Directors canceled certain options granted
    under the Equity Incentive Plan and issued new options in lieu thereof with
    a lower exercise price of $7.875, the fair market value of the Common Stock
    on that date.
(2) The potential realizable value is calculated based on the term of the option
    at its time of grant. It is calculated by assuming that the stock price on
    the date of grant appreciates at the indicated annual rate, compounded
    annually for the entire term of the option.
(3) In connection with the termination of Mr. Shields employment, 36,545 of
    these options terminated on January 15, 1998 and the remaining 18,000 will
    remain exercisable until January 14, 2000.

                                      -3-
<PAGE>
 
AGGREGATE STOCK OPTION EXERCISES IN LAST FISCAL YEAR AND FISCAL YEAR-END OPTION
VALUES

     The following table sets forth the number and value as of December 31, 1997
of shares underlying unexercised options held by each of the Named Executive
Officers. As of December 31, 1997, Mr. Fotheringham held no options, and no
stock options had been exercised by any of the Named Executive Officers.

                         FISCAL YEAR-END OPTION VALUES

<TABLE>
<CAPTION>
                         NUMBER OF SHARES
                      UNDERLYING UNEXERCISED              VALUE OF UNEXERCISED
                            OPTIONS AT                  IN-THE-MONEY-OPTIONS AT
                         FISCAL YEAR END                   FISCAL YEAR END(1)
                    ---------------------------        --------------------------
NAME                EXERCISABLE   UNEXERCISABLE        EXERCISABLE  UNEXERCISABLE
----                -----------   -------------        -----------  -------------
<S>                 <C>         <C>                   <C>          <C>
                                                     
Henry C. Hirsch            --        800,000                    --        $     0
Thomas A. Grina        45,455        183,211               $ 5,682        $58,037
James D. Miller        20,001         34,545               $38,852        $28,548
Richard A. Shields     13,636         40,908               $ 1,705        $ 5,114
Thomas M. Walker        8,750         26,250               $ 1,094        $ 3,281
</TABLE> 
----------------
(1) Based on the last sales price of the Company's Common Stock reported on the
    Nasdaq National Market on December 31,1997 of $8.00 per share, less the
    exercise price payable upon exercise of such options.


DIRECTOR COMPENSATION

     Each director who is not a full-time employee of the Company or one of its
subsidiaries receives $4,000 per year for services rendered as a director, $500
for each board meeting attended and $500 for each committee meeting attended
("Director Fees").

     Also, non-employee directors are eligible to participate in the 1997 Equity
Incentive Plan for Non-Employee Directors (the "1997 Directors Plan").  The 1997
Directors Plan provides for automatic and discretionary grants of stock options
to directors who are not employees of the Company or one of its subsidiaries and
gives non-employee directors the ability to elect to receive Common Stock in
lieu of their Director Fees.

     Under the 1997 Directors Plan, each eligible director received an initial
grant of options to purchase 20,000 shares of Common Stock, and each newly
elected non-employee director will receive a similar grant upon his or her first
appointment or election to the Board of Directors.   In addition, each non-
employee director will be granted options to purchase 7,000 shares of Common
Stock at each annual meeting at which such director is reelected or is
continuing as a director.  These options have an exercise price equal to the
fair market value of the Common Stock on the date of the grant, expire five
years after the date of grant, and become exercisable on the day before each of
the first, second and third annual stockholders meeting following the date of
grant.

     The 1997 Directors Plan also allows each eligible director to elect
annually in advance  to receive Director Fees in the form of deferred grants of
Common Stock, rather than cash, payable on the earlier of (i) the first business
day of the third January following the date of grant, (ii) a change of control
of the Company or (iii) the date the eligible director ceases to be a director
of the Company.

                                      -4-
<PAGE>
 
EMPLOYMENT AGREEMENTS

     On October 17, 1997, the Company entered into an employment agreement with
Henry C. Hirsch, providing for full-time employment as Chairman, President and
Chief Executive Officer through December 31, 2000 at a salary at the annual rate
of $325,000 for 1997 and 1998, $350,00 for 1999 and $400,000 for 2000.  Under
the agreement, Mr. Hirsch is guaranteed an annual bonus of at least $54,167 for
1997, $325,000 for 1998 and $87,500 for 1999. The agreement further provides
that Mr. Hirsch's annual targeted bonus for years other than 1997 and 1998 will
be not less than 50% of his base salary, and that his maximum incentive bonus
will be 100% of his base salary, pursuant to such bonus or incentive
compensation plan as is available to executives of the Company generally or, if
there is no such plan, as determined by the Board or Directors based on
performance criteria set annually.  Pursuant to the agreement, Mr. Hirsch was
granted five-year stock options under the Equity Incentive Plan for an aggregate
of 800,000 shares of Common Stock, of which 600,000 will be exercisable at
$8.875 per share, the fair market value on the day of the grant, and 200,000
will be exercisable at $12.50 per share.  The Company also granted Mr. Hirsch
100,000 shares of deferred stock deliverable on January 2, 2001.  The Company
also loaned Mr. Hirsch $887,500 to purchase 100,000 shares of Company Common
Stock at $8.875 per share with interest at the minimum applicable federal rate,
payable over five years and secured by the shares purchased.  The Company has
also agreed to pay Mr. Hirsch $300,000 for relocation expenses. The agreement
precludes Mr. Hirsch from competing with the Company for two years after the
cessation of his employment, or a period equal to the length of his employment
up to two years, if he is terminated without cause. The agreement may be
terminated at any time by either party and provides that, if the Company
terminates Mr. Hirsch without cause, Mr. Hirsch's employment is terminated due
to his disability or death, or Mr. Hirsch terminates his employment as a result
of constructive termination, Mr. Hirsch will be entitled to continue to receive
the full amount of his base salary and bonus (at the guaranteed amount for 1997
and 1998 and at the target amounts for 1999 and 2000) for the remainder of the
agreement term or, if Mr. Hirsch is terminated after December 31, 1999, to be
paid his base salary and target bonus in effect for 2000 for twelve months.
Upon such termination, Mr. Hirsch will also be entitled to receive medical and
term life insurance for the remainder of the employment term, but no less than
twelve months and no more than eighteen months following termination.  In
addition, all options granted to Mr. Hirsch not yet vested will vest and remain
exercisable for the lesser of one year or their original term.

     On October 17, 1997, the Company also entered into a Change of Control
Agreement with Mr. Hirsch entitling him to certain benefits if his employment
with the Company is terminated, other than for cause or his disability or death,
or if he resigns for good reason within 24 months of any change of control of
the Company.  Upon such a termination, the agreement provides that: (i) the
Company will pay Mr. Hirsch a cash payment equal to his annual base salary at
the time of termination, to the extent not theretofore paid for the year, plus a
prorated portion of his maximum incentive bonus for the year and any accrued and
unpaid vacation pay; (ii) any stock, stock option or other awards granted to Mr.
Hirsch by the Company will immediately vest and become exercisable in full and
shall remain exercisable for the lesser of four years or their original term;
(iii) the Company will pay to Mr. Hirsch a cash payment equal to the greater of
(a) Mr. Hirsch's aggregate base salary plus maximum incentive compensation for
the period from termination through December 31, 2000 and (b) two times his base
salary rate at the date of termination plus either his maximum incentive
compensation for the year in which termination occurs or his maximum incentive
compensation in effect immediately prior to the change of control, whichever is
higher;  (iv) the Company will continue to insure Mr. Hirsch and his dependents
in the Company's life and medical insurance plans for up to two years after
termination; and (v) Mr. Hirsch will be entitled to return the 100,000 shares of
Common Stock pledged to secure the promissory note described above in full
satisfaction of the promissory note if the fair market value of the Common Stock
is less than the amount due on the note.

     On August 21, 1997, the Company entered into a two-year employment
agreement with Thomas A. Grina, providing for full-time employment as executive
vice president and Chief Operating Officer at an annualized base salary of
$210,000 for 1997, $235,000 for 1998 and $258,000 for 1999. Under the Agreement,
Mr. Grina is eligible for an annual target incentive bonus of not less than 50%
of his annual salary. The agreement precludes Mr. Grina from competing with the
Company for one year after the cessation of his employment. The agreement may be
terminated by either party and provides that, if Mr. Grina's employment is
terminated by the Company other than for cause or by 

                                      -5-
<PAGE>
 
Mr. Grina as a result of constructive termination, Mr. Grina will be entitled to
receive an amount equal to twelve months of his base salary and bonus in effect
at his termination and continuation of benefits to which he would have otherwise
been entitled for a period of twelve months from the date of such termination,
and all options granted to Mr. Grina will vest and remain exercisable for three
years.

     The Company's employment agreement with Mr. Fotheringham provided for his
full-time employment as Vice Chairman at an annualized base salary of $275,000
for 1997 and $300,000 for 1998.  Under an October 1997 amendment to his
employment agreement, Mr. Fotheringham received a guaranteed bonus of $50,000
for 1997.  Mr. Fotheringham resigned his position with the Company in April
1998, and his employment with the Company will terminate in May 1998.  He will
continue to serve as a director of the Company.  The agreement precludes Mr.
Fotheringham from competing with the Company for one year after the cessation of
his employment.

     The Company's employment agreement with James D. Miller provides for full-
time employment at an annual base salary of $150,000 and an annual bonus in
designated amounts based upon the achievement of specified performance goals.
The agreement has a term of three years expiring January 1999 and precludes him
from competing with the Company for one year after the cessation of employment.
The employment agreement may be terminated at any time by the Company or Mr.
Miller and provides that, if the Company terminates Mr. Miller's employment
without cause or his employment is terminated due to his disability or death,
Mr. Miller will receive the full amount of his base salary and any other
benefits to which he would have otherwise been entitled for a period of six
months from the date of such termination.

     The Company's employment agreement with Richard A. Shields provided for
full-time employment at an annual base salary of $110,000 and an annual bonus in
designated amounts based on the achievement of specified performance goals.  The
agreement precludes him from competing with the Company for one year after the
cessation of employment.  Mr. Shields' employment with the Company terminated
effective January 15, 1998.  Mr. Shields is entitled to salary and benefit
continuation for three months from the date of termination.  In connection with
the termination, 36,545 of Mr. Shields' options terminated on January 15, 1998
and the remaining 18,000 will terminate on January 14, 2000.

                                      -6-
<PAGE>
 
ITEM 12.  SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT.

     The following table sets forth certain information with respect to the
beneficial ownership of shares of Common Stock as of May 1, 1998 by (i) the
Named Executive Officers, (ii) each director of the Company, (iii) all executive
officers and directors of the Company as a group and (iv) each person (including
any "group" as that term is used in Section 13(d)(3) of the Exchange Act) known
to the Company to be the beneficial owner of more than five percent of the
outstanding Common Stock.  Except as noted below, each of the persons listed has
sole investment and voting power with respect to the shares indicated:
<TABLE>
<CAPTION>
 
 
                                             BENEFICIAL OWNERSHIP
                                             --------------------
     NAME                                     NUMBER    PERCENT
     ----                                    ---------  --------
<S>                                          <C>        <C>
 
     Advent International Corporation (1)..  1,321,511      5.9%
     Columbia Capital Corporation (2)......  1,338,278      6.0%
     Commco, L.L.C. (3)....................  2,831,677     12.7%
     Landover Holdings Corporation (4).....  2,966,774     13.3%
     James C. Cook (5).....................     58,569        *
     Mark C. Demetree (6)..................    386,942      1.7%
     Andrew I. Fillat (7)..................      5,728        *
     Vernon L. Fotheringham................    974,870      4.4%
     Thomas A. Grina (8)...................     70,455        *
     Henry C. Hirsch.......................    100,000        *
     James D. Miller (9)...................     35,001        *
     James B. Murray, Jr. (10).............    227,643        *
     Alan Z. Senter (11)...................      7,151        *
     Richard A. Shields, Jr.(12)...........     13,636        *
     Thomas M. Walker(13)..................     16,350        *
     WinStar Communications, Inc.(14)......  3,313,864     14.9%
     Laurence S. Zimmerman (4).............  2,966,774     13.3%
     All executive officers and directors
       as a group (15).....................  1,896,345      8.5%
 
</TABLE> 
-----------------------------
Unless otherwise indicated, the business address of each director and executive
officer named above is c/o Advanced Radio Telecom Corp., 500 108th Avenue NE,
Suite 2600, Bellevue, Washington 98004.

*Less than 1.0%.

(1) Includes 1,189,673 shares, 1,149 shares and 58,143 shares of Common Stock,
    and 69,107 shares, 58 shares and 3,381 shares of Common Stock issuable upon
    exercise of warrants, respectively, owned by Global Private Equity II, L.P.,
    Advent International Investors II Limited Partnership and Advent Partners
    Limited Partnership (collectively, the "Advent Partnerships"), each a
    limited partnership whose general partner is controlled by Advent
    International Corporation ("Advent").  Mr. Fillat is an officer of Advent.
    The address of Advent and each of the Advent Partnerships is 101 Federal
    Street, Boston, Massachusetts 02110.
(2) Includes 62,173 shares of Common Stock issuable upon exercise of warrants
    owned by Columbia Capital Corporation ("Columbia Capital") and 357,166
    shares, 116,826 shares and 802,113 shares owned by CCC Millimeter L.P. ("CCC
    Millimeter"), Columbia Millimeter Communications, L.P. ("Millimeter") and
    Columbia Capital, respectively. Columbia Capital, as the sole general
    partner of CCC Millimeter and Millimeter, has the power to vote and dispose
    of the Common Stock held by CCC Millimeter and Millimeter.  Robert Blow,
    Mark J. Kington, David P. Mixer, James B. Murray and Mark R. Warner share
    investment control of the shares held by

                                      -7-
<PAGE>
 
     such entities and may be deemed to beneficially own such shares. Each of
     Messrs. Blow, Kington, Mixer, Murray and Warner disclaims beneficial
     ownership of the shares held by such entities, except to the extent of such
     individual's interest in such entities. The address of each of Columbia
     Capital, CCC Millimeter and Millimeter is 0 Court Square, P.O. Box 1465,
     Charlottesville, VA 22902.
(3)  Includes 54,191 shares of Common Stock issuable upon exercise of warrants.
     The address of Commco, L.L.C. is 4513 Pin Oak Court, Sioux Falls, SD 57103.
(4)  All of such securities are held in the Landover Voting Trust (as defined
     below). Does not include 36,364 shares of Common Stock beneficially owned
     by the wife of and 36,364 shares of Common Stock beneficially owned by a
     family trust of Laurence S. Zimmerman, of which shares Landover Holdings
     Corporation ("LHC") and Mr. Zimmerman disclaim beneficial ownership. LHC is
     controlled by Mr. Zimmerman. See "--Voting Trust Agreement." On April 24,
     1998 LHC entered into an agreement with WinStar Communications, Inc.
     ("WinStar") and certain of its subsidiaries pursuant to which LHC agreed to
     sell 2,758,864 shares of Common Stock to WinStar. The consummation of this
     transaction is subject to the fulfillment or waiver of certain conditions.
     LHC's address is 156 W. 56th Street, Suite 2000, New York, New York 10019.
(5)  Includes 8,000 shares of Common Stock issuable upon exercise of warrants
     and 3,201 shares of Common Stock issuable upon exercise of options
     exercisable within 60 days of May 1, 1998.
(6)  Includes 3,201 shares of Common Stock issuable upon exercise of options
     exercisable within 60 days of May 1, 1998. Does not include 117,999 shares
     of Common Stock issuable upon exercise of warrants or 1,534,964 shares of
     Common Stock beneficially owned in each case by members of Mr. Demetree's
     family or a trust for their benefit, of which he disclaims beneficial
     ownership. Mr. Demetree's address is 3740 Beach Blvd., Suite 306,
     Jacksonville, FL 32207.
(7)  Includes 3,201 shares of Common Stock issuable upon exercise of options
     exercisable within 60 days of May 1, 1998. Does not include shares of
     Common Stock and shares of Common Stock issuable upon exercise of warrants
     held by the Advent Partnerships, of which Mr. Fillat disclaims beneficial
     ownership, except for 2,495 shares of Common Stock and 32 shares issuable
     upon exercise of warrants.
(8)  Includes 70,455 shares of Common Stock issuable upon exercise of options
     exercisable within 60 days of May 1, 1998.
(9)  Includes 35,001 shares of Common Stock issuable upon exercise of an option
     exercisable within 60 days of May 1, 1998.
(10) Includes 1,734 shares of Common Stock issuable upon exercise of options
     exercisable within 60 days of May 1, 1998 Mr. Murray is a Managing Director
     of Columbia Capital Corporation. Excludes shares held by Columbia Capital,
     CCC Millimeter and Millimeter. See Footnote 2. Mr. Murray's address is c/o
     Columbia Capital Corporation, 0 Court Square, P.O. Box 1465,
     Charlottesville, VA 22902.
(11) Includes 7,151 shares of Common Stock issuable upon exercise of options
     exercisable within 60 days of May 1, 1998.
(12) Includes 13,636 shares of Common Stock issuable upon conversion of stock
     options exercisable within 60 days of May 1, 1998.
(13) Includes 16,250 shares of Common Stock issuable upon conversion of stock
     options exercisable within 60 days of May 1, 1998.
(14) On April 24, 1998 WinStar and certain subsidiaries entered into an
     agreement with LHC pursuant to which WinStar agreed to purchase 2,758,864
     shares of Common Stock from LHC.  Also on April 24, 1998, WinStar entered
     into an agreement with another shareholder of the Company pursuant to which
     WinStar agreed to purchase an additional 555,000 shares of Common Stock.
     The consummation of these transactions is subject to the fulfillment or
     waiver of certain conditions.  WinStar's address is 230 Park Ave. Suite
     2700, New York, NY  10169.
(15) Includes 153,830 shares of Common Stock issuable upon exercise of options
     and 10,527 shares of Common Stock issuable upon exercise of warrants
     exercisable within 60 days of May 1, 1998.  Does not include 2,966,774
     shares of Common Stock held in the Landover Voting Trust by trustees, all
     of whom are directors of the Company and do not have beneficial ownership
     of such shares. See "--Voting Trust Agreement."


VOTING TRUST AGREEMENT

     Pursuant to a Voting Trust Agreement dated November 5, 1996,  LHC and the
wife of and a trust for the benefit of the family of Laurence S. Zimmerman
deposited all of their shares of Common Stock in trust (the "Landover Voting
Trust") with Messrs. Demetree, Fillat and Fotheringham as trustees with
irrevocable instructions to vote such shares on all matters submitted to a vote
of the stockholders of the Company in proportion to, or in certain cases,
consistent with the majority of, the vote of other stockholders of the Company.
The voting trust will expire on November 5, 2006, but is subject to early
termination in the event of (i) a business combination in which the Company
stockholders own less than 50%, and the Company directors constitute less than
50% of the Board of Directors, of the combined entity and LHC owns less than 5%
of the voting power of such entity, (ii) the death of Mr. Zimmerman or (iii) the
sale by LHC of such shares to unaffiliated parties.  The 

                                      -8-
<PAGE>
 
trustees of the trust will be indemnified by the Company. LHC retains the right
to pledge or dispose of the Common Stock to third parties. Any such shares of
Common Stock transferred to an affiliate of LHC will remain subject to the terms
of the Landover Voting Trust. Any such shares of Common Stock transferred to
parties not affiliated with LHC will be released from the Landover Voting Trust.
LHC has agreed to sell 2,758,864 shares of Common Stock to WinStar, and LHC and
the beneficiaries under the Landover Voting Trust have agreed to sell the
remaining shares and warrants to other parties, whereupon the Landover Voting
Trust will terminate.

                                      -9-
<PAGE>
 
                                   SIGNATURES

     PURSUANT TO THE REQUIREMENTS OF SECTION 13 OR 15(D) OF THE SECURITIES
EXCHANGE ACT OF 1934, THE REGISTRANT HAS DULY CAUSED THIS REPORT TO BE SIGNED ON
ITS BEHALF BY THE UNDERSIGNED, THEREUNTO DULY AUTHORIZED ON THIS 20TH DAY OF MAY
1998.

                                    Advanced Radio Telecom Corp.

                                    Thomas A. Grina

                                    By: /s/ Thomas A. Grina
                                        --------------------
                                        EXECUTIVE VICE PRESIDENT AND
                                        CHIEF FINANCIAL OFFICER



 

                                      -10-
<PAGE>
 
                                 EXHIBIT INDEX

<TABLE> 
<CAPTION> 



EXHIBIT NO.                                 TITLE                                                      PAGE
-----------                                 -----                                                      ---- 
<S>                    <C>                                                                             <C> 
  3.1                  Amended and Restated Certificate of Incorporation.(11)                                
  3.2                  Restated and Amended Bylaws of Registrant.(11)                                        
  4.1                  Specimen of Common Stock Certificate.(3)                                              
  4.2                  Indenture relating to the Company's 14% Senior Notes                                  
                         due 2007.(10)                                                                       
  4.3                  Specimen of Note (included in Exhibit 4.2).(10)                                       
  4.4                  Collateral Pledge and Security Agreement relating to the Notes.(10)                   
  4.5                  Form of Warrant Agreement in connection with offering of Notes.(10)                   
  4.6                  Specimen of Warrant Certificate in connection with offering of Notes                  
                         of Notes (included in Exhibit 4.5).(10)                                             
  4.7                  Shareholders Rights Agreement.(12)                                                    
  4.8                  Form of Rights Certificate.(12)                                                       
  9.1                  Voting Trust Agreement dated November 5, 1996.(9)                                     
  9.2                  Form of Trustee Indemnification Agreement.(3)                                         
  10.1                 Employment Agreement between the Company and Vernon L. Fotheringham,                  
                         dated December 16, 1995.(1)                                                         
  10.2                 Amendment No. 1 dated October 17, 1997 to Employment Agreement between the            
                         Company and Vernon L. Fotheringham.(13)                                             
  10.3                 Employment Agreement between the Company and Thomas A. Grina dated                  
                         April 26, 1996.(8)                                                                 
  10.4                 Employment Agreement between the Company and Henry C. Hirsch dated                    
                         October 17, 1997.(13)                                                              
  10.5                 Change of Control Agreement between the Company and Henry C. Hirsch                   
                         dated October 17, 1997.(13)                                                        
  10.6                 Form of Director Indemnification Agreement.(1)                                        
  10.7                 Company's Restated Equity Incentive Plan, as amended.(14)                             
  10.8                 Company's 1997 Equity Incentive Plan for Non-Employee Directors.(14)                  
  10.9                 Company's 1996 Non-Employee Directors Incentive Stock Option Plan.(1)                 
  10.10                Second Restated and Amended Registration Rights Agreement dated July 3,               
                         1996 with ART Licensing and the stockholders of each of ART Licensing               
                         and the Company.(2)                                                                 
  10.11                Amendment No. 1 to Registration Rights Agreement dated as of October 16,              
                         1996.(9)                                                                            
  10.12                Form of Indemnity Warrant.(1)                                                         
  10.13                Form of Subscription Agreement dated March 8, 1996, including Forms                   
                         of Bridge Note and Bridge Warrant.(2)                                               
  10.14                Option Agreement dated July 3, 1996 with Commco, L.L.C.(2)                            
  10.15                Form of September Bridge Warrant.(9)                                                  
  10.16                Form of CIBC Warrants.(7)                                                             
  21                   Subsidiaries of the Company.(2)                                                       
  23                   Consent of Independent Accountants.(14)                                               
  27                   Financial Data Schedule.(14)                                                          
  99                   Risk Factors.                                                                      1
</TABLE> 
--------

                                     -11-
<PAGE>
 
(1)  Previously filed with the Company's Registration Statement on Form S-1,
     effective November 5, 1996 (SEC Reg. No. 333-04388) and incorporated by
     reference herein.
(2)  Previously filed with Amendment 1 to the Company's Registration Statement
     on Form S-1, effective November 5, 1996 (SEC Reg. No. 333-04388) and
     incorporated by reference herein.
(3)  Previously filed with Amendment 2 to the Company's Registration Statement
     on Form S-1, effective November 5, 1996 (SEC Reg. No. 333-04388) and
     incorporated by reference herein.
(4)  Previously filed with Amendment 4 to the Company's Registration Statement
     on Form S-1, effective November 5, 1996 (SEC Reg. No. 333-04388) and
     incorporated by reference herein.
(5)  Previously filed with Amendment 6 to the Company's Registration Statement
     on Form S-1, effective November 5, 1996 (SEC Reg. No. 333-04388) and
     incorporated by reference herein.
(6)  Previously filed with Amendment 7 to the Company's Registration Statement
     on Form S-1, effective November 5, 1996 (SEC Reg. No. 333-04388) and
     incorporated by reference herein.
(7)  Previously filed with Amendment 8 to the Company's Registration Statement
     on Form S-1, effective November 5, 1996 (SEC Reg. No. 333-04388) and
     incorporated by reference herein.
(8)  Previously filed with the Company's Registration statement on Form S-1,
     filed May 15, 1996 (SEC Reg. No. 333-03735) and incorporated by reference
     herein.
(9)  Previously filed with the Company's Registration Statement Form S-1,
     effective February 3, 1997 (SEC Reg. No. 333-19295) and incorporated by
     reference herein.
(10) Previously filed with Amendment 2 to the company's Registration Statement
     on Form S-1, effective February 3, 1997 (SEC Reg. No. 333-19295) and
     incorporated by reference herein.
(11) Previously filed with the Company's Annual Report on Form 10-K for the
     fiscal year ended December 31, 1996 and incorporated by reference herein.
(12) Previously filed with the Company's Registration Statement on Form 8-A,
     filed on July 10, 1997 (SEC Reg. No. 000-21091) and incorporated by
     reference herein.
(13) Previously filed with the Company's Quarterly Report on Form 10-Q, dated
     November 14, 1997.  (SEC Reg. No. 000-21091) and incorporated by reference
     herein.
(14) Previously filed with the Company's Annual Report on Form 10-K for the
     fiscal year ended December 31, 1997 and incorporated by reference herein.

                                      -2-