Document:

<PAGE>   1
                     Incorporated Under the Laws of Delaware

 Number                                                               Shares
  C-__                          [GRAPHIC OF EAGLE]                 ____________
                         NEXTLINK Communications, Inc.

         Series C Cumulative Convertible Participating Preferred Stock

                            $.01 Par Value Per Share

      THIS IS TO CERTIFY THAT __________________________ is the owner of
__________________________________ fully paid and non-assessable Shares of the
above Corporation transferable only on the books of the Corporation by the
holder hereof in person or by a duly authorized Attorney upon surrender of this
Certificate properly endorsed.

      IN WITNESS WHEREOF, the said Corporation has caused this Certificate to be
signed by its duly authorized officers and to be sealed with the Seal of the
Corporation.

Dated:
      -----------------------    -----------------------------------------
                                    Title:                    Title:

<PAGE>   2

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933 OR THE SECURITIES LAWS OF ANY STATE AND MAY NOT BE
SOLD OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION
STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES LAWS OR AN APPLICABLE
EXEMPTION TO THE REGISTRATION REQUIREMENTS OF SUCH ACT OR SUCH LAWS.

THE SALE, PLEDGE, TRANSFER, ASSIGNMENT OR OTHER DISPOSITION OF THE SHARES
REPRESENTED BY THIS CERTIFICATE IS RESTRICTED BY AND SUBJECT TO THE PROVISIONS
OF A STOCK PURCHASE AGREEMENT DATED AS OF DECEMBER 7, 1999, A COPY OF WHICH IS
AVAILABLE UPON REQUEST FOR INSPECTION AT THE OFFICES OF THE CORPORATION. ANY
SUCH REQUEST SHOULD BE ADDRESSED TO THE SECRETARY OF THE CORPORATION.

THE CORPORATION IS AUTHORIZED TO ISSUE MORE THAN ONE CLASS OR SERIES OF STOCK. A
COPY OF THE PREFERENCES, POWERS, QUALIFICATIONS AND RIGHTS OF EACH CLASS AND
SERIES WILL BE FURNISHED BY THE CORPORATION UPON WRITTEN REQUEST AND WITHOUT
CAUSE.

      The following abbreviations, when used in the inscription on the face of
this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations. Additional abbreviations may also
be used though not in the list.

<TABLE>
<S>                                                          <C>
 TEN COM  -- as tenants in common                            UNIF GIFT MIN ACT--.................Custodian.............. (Minor)
 TEN ENT  -- as tenants by the entireties                                under Uniform Gifts to Minors Act................ (State)
 JT TEN   -- as joint tenants with right of survivorship
             and not as tenants in common
For value received, the undersigned hereby sells, assigns and transfers unto        PLEASE INSERT SOCIAL SECURITY
                                                                                    OR OTHER IDENTIFYING NUMBER OF ASSIGNEE
</TABLE>

--------------------------------------------------------------------------------
(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
Shares represented by the within Certificate, and hereby irrevocably constitutes
and appoints ___________________________________________________________________
__________________________________________________Attorney to  transfer the said
shares on the books of the within-named Corporation with full power of
substitution in the premises.

Dated,-----------------------       --------------------------------------------
          In presence of<PAGE>   1
                     Incorporated Under the Laws of Delaware

Number                                                                Shares
 D-__                          [GRAPHIC OF EAGLE]                  ____________
                        NEXTLINK Communications, Inc.

               Series D Convertible Participating Preferred Stock

                            $.01 Par Value Per Share

      THIS IS TO CERTIFY THAT __________________________ is the owner of
__________________________________ fully paid and non-assessable Shares of the
above Corporation transferable only on the books of the Corporation by the
holder hereof in person or by a duly authorized Attorney upon surrender of this
Certificate properly endorsed.

      IN WITNESS WHEREOF, the said Corporation has caused this Certificate to be
signed by its duly authorized officers and to be sealed with the Seal of the
Corporation.

Dated:
       ----------------------    ---------------------------------------------
                                    Title:                    Title:

<PAGE>   2

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933 OR THE SECURITIES LAWS OF ANY STATE AND MAY NOT BE
SOLD OR OTHERWISE DISPOSED OF EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION
STATEMENT UNDER SUCH ACT AND APPLICABLE STATE SECURITIES LAWS OR AN APPLICABLE
EXEMPTION TO THE REGISTRATION REQUIREMENTS OF SUCH ACT OR SUCH LAWS.

THE SALE, PLEDGE, TRANSFER, ASSIGNMENT OR OTHER DISPOSITION OF THE SHARES
REPRESENTED BY THIS CERTIFICATE IS RESTRICTED BY AND SUBJECT TO THE PROVISIONS
OF A STOCK PURCHASE AGREEMENT DATED AS OF DECEMBER 7, 1999, A COPY OF WHICH IS
AVAILABLE UPON REQUEST FOR INSPECTION AT THE OFFICES OF THE CORPORATION. ANY
SUCH REQUEST SHOULD BE ADDRESSED TO THE SECRETARY OF THE CORPORATION.

THE CORPORATION IS AUTHORIZED TO ISSUE MORE THAN ONE CLASS OR SERIES OF STOCK. A
COPY OF THE PREFERENCES, POWERS, QUALIFICATIONS AND RIGHTS OF EACH CLASS AND
SERIES WILL BE FURNISHED BY THE CORPORATION UPON WRITTEN REQUEST AND WITHOUT
CAUSE.

      The following abbreviations, when used in the inscription on the face of
this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations. Additional abbreviations may also
be used though not in the list.

<TABLE>
<S>                                                          <C>
 TEN COM  -- as tenants in common                            UNIF GIFT MIN ACT--.................Custodian.............. (Minor)
 TEN ENT  -- as tenants by the entireties                                under Uniform Gifts to Minors Act................ (State)
 JT TEN   -- as joint tenants with right of survivorship
             and not as tenants in common
For value received, the undersigned hereby sells, assigns and transfers unto        PLEASE INSERT SOCIAL SECURITY
                                                                                    OR OTHER IDENTIFYING NUMBER OF ASSIGNEE
</TABLE>

--------------------------------------------------------------------------------
(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
Shares represented by the within Certificate, and hereby irrevocably constitutes
and appoints ___________________________________________________________________
__________________________________________________ Attorney to transfer the said
shares on the books of the within-named Corporation with full power of
substitution in the premises.

Dated,
      ---------------------------
            In presence of               ---------------------------------------<PAGE>   1

                          NEXTLINK COMMUNICATIONS, INC.
                                STOCK OPTION PLAN
     (as amended on September 30, 1997, December 31, 1997, February 5, 1998,
     February 4, 1999, May 3, 1999, October 19, 1999 and February 16, 2000)

    SECTION 1.  Purpose. The purpose of this Stock Option Plan (this "Plan") is
to provide a means whereby Nextlink Communications, Inc. (the "Company") or any
parent or subsidiary of the Company, as defined in Subsection 5.9 (the "related
entities"), may continue to attract, motivate and retain selected employees,
officers and independent contractors who can materially contribute to the
Company's growth and success, and to encourage stock ownership in the Company
through granting incentive stock options or nonqualified stock options, or both,
to purchase the Class A Common Stock of the Company (as defined in Section 3),
so that such key employees and other persons and entities will more closely
identify their interests with those of the Company and its shareholders. In
addition, options under this Plan may serve as replacement options for options
issued under the Equity Option Plan sponsored by the Company's predecessor.

    SECTION 2.  Administration. This Plan shall be administered by the Board of
Directors of the Company (the "Board") or, in the event the Board shall appoint
or authorize a committee to administer this Plan, by such committee. The
administrator of this Plan shall hereinafter be referred to as the "Plan
Administrator."

       2.1 Procedures. The Board may designate one of the members of the Plan
Administrator as chairperson. The Plan Administrator may hold meetings at such
times and places as it shall determine. The acts of a majority of the members of
the Plan Administrator present at meetings at which a quorum exists, or acts
reduced to or approved in writing by all Plan Administrator members, shall be
valid acts of the Plan Administrator.

       2.2 Responsibilities. Except for the terms and conditions explicitly
required in this Plan, the Plan Administrator shall have the authority, in its
discretion, to determine all matters relating to the options to be granted under
this Plan, including selection of the individuals to be granted options, the
number of shares to be subject to each option, the exercise price, and all other
terms and conditions of the options. Grants under this Plan need not be
identical in any respect, even when made simultaneously. The interpretation and
construction by the Plan Administrator of any terms or provisions of this Plan
or any option issued under this Plan, or of any rule or regulation promulgated
in connection with this Plan, shall be conclusive and binding on all interested
parties, so long as such interpretation and construction with respect to
incentive stock options correspond to the requirements of Section 422 of the
Internal Revenue Code (the "Code"), as amended, and the regulations thereunder.

       2.3 Section 16(b) Compliance and Bifurcation of Plan. In the event the
Company registers any of its equity securities pursuant to Section 12(b) or
12(g) of the Exchange Act, it is the intention of the Company that this Plan,
and options granted under this Plan, comply in all respects with Rule 16b-3
under the Exchange Act and, if any Plan provision is later found not to be in
compliance with such Section, the provision shall be deemed null and void, and
in all events this Plan shall be construed in favor of its meeting the
requirements of Rule 16b-3.

Page 1 - STOCK OPTION PLAN
<PAGE>   2

Notwithstanding anything in this Plan to the contrary, the Board, in its
absolute discretion, may bifurcate this Plan so as to restrict, limit or
condition the use of any provision of this Plan to participants who are officers
and directors subject to Section 16(b) of the Exchange Act without so
restricting, limiting or conditioning other Plan participants.

    SECTION 3.  Stock Subject to This Plan. The stock subject to this Plan shall
be the Company's Class A Common Stock (the "Class A Common Stock"), presently
authorized but unissued or now held or subsequently acquired by the Company as
treasury shares. Subject to adjustment as provided in Section 7 of this Plan,
the aggregate amount of Class A Common Stock to be delivered upon the exercise
of all options granted under this Plan shall not exceed 41,000,000 shares (the
"Plan Maximum") as such Class A Common Stock was constituted on the effective
date of this Plan. If any option granted under this Plan expires or is
surrendered, canceled, terminated or exchanged for another option for any reason
without having been exercised in full, the unpurchased shares subject to such
option shall again be available for purposes of this Plan, including use as
replacement options that may be granted in exchange for such surrendered,
canceled or terminated options.

    SECTION 4.  Eligibility. An incentive stock option may be granted only to an
individual who, at the time the option is granted, is an employee of the Company
(or a corporate related entity, as described in Section 5.9) and who the Board
may from time to time select for participation in this Plan. Members of the
Board shall not be eligible for grants of incentive stock options unless they
are also employees of the Company. At the discretion of the Plan Administrator,
employees and independent contractors of the Company (including nonemployee
directors) or any related entity may receive nonqualified stock options.
Notwithstanding anything to the contrary herein, the maximum number of shares of
Class A Common Stock with respect to which options may be granted to any
individual in any calendar year shall not exceed the Plan Maximum, as such
number may change from time to time. Any party to whom an option is granted
under this Plan shall be referred to in this Plan as an "Optionee."

    SECTION 5.  Terms and Conditions of Options. Options granted under this Plan
shall be evidenced by written agreements that contain such terms, conditions,
limitations and restrictions as the Plan Administrator shall deem advisable and
which are not inconsistent with this Plan. Notwithstanding the foregoing,
options shall include or incorporate by reference the following terms and
conditions:

       5.1 Number of Shares. The maximum number of shares that may be purchased
pursuant to the exercise of each option, which number shall be as established by
the Plan Administrator.

       5.2 Price of Shares. The price per share at which each option is
exercisable (the "exercise price") shall be as established by the Plan
Administrator, provided that the Plan Administrator shall act in good faith to
establish the exercise price as follows:

              5.2.1 Incentive Stock Options and Nonqualified Stock Options. With
respect to incentive stock options intended to qualify under Section 422 of the
Code, and subject to Subsection 5.2.2 below, the exercise price shall be not
less than the fair market value per share

Page 2 - STOCK OPTION PLAN
<PAGE>   3

of the Class A Common Stock at the time the option is granted, except with
respect to the substitution of a new option for an old option, or an assumption
of an old option, in accordance with Code Section 424(a). With respect to
nonqualified stock options, the exercise price shall be the amount set by the
Plan Administrator.

              5.2.2 Incentive Stock Options to Greater than 10% Shareholders.
With respect to incentive stock options granted to greater than 10% shareholders
of the Company, the exercise price shall be as required by Section 6.

              5.2.3 Fair Market Value. The fair market value per share of the
Class A Common Stock for the purpose of determining the exercise price under
this Section 5.2 shall be determined as follows:

              (a)   if the Common Stock is listed on any established stock
exchange or a national market system including without limitation the National
Market System of the National Association of Securities Dealers, Inc. Automated
Quotation ("NASDAQ") System, the fair market value shall be the closing sales
price for such stock (or the closing bid, if no sales were reported), as quoted
on such system or exchange for the last market trading date prior to the time of
determination as reported in The Wall Street Journal or such other source as the
Plan Administrator deems reliable;

              (b)   if the Common Stock is quoted on the NASDAQ System (but not
on the National Market System thereof) or regularly quoted by a recognized
securities dealer but selling prices are not reported, the fair market value
shall be the mean between the high and low asked prices for the Common Stock on
the last market trading date prior to the day of determination, as reported in
The Wall Street Journal or such other source as the Plan Administrator deems
reliable; or

              (c)   In the absence of an established market for the Common
Stock, fair market value shall be determined by the Plan Administrator in good
faith at the time the option is granted.

       5.3 Term and Maturity. Subject to the restrictions contained in Section 6
with respect to granting incentive stock options to greater than 10%
shareholders of the Company, the term of each incentive stock option shall be 10
years from the date it is granted unless a shorter period of time is established
by the Plan Administrator, but in no event shall the term of any incentive stock
option exceed 10 years. The term of each nonqualified stock option shall be 15
years from the date it is granted, unless a shorter period of time is
established by the Plan Administrator in the individual option agreement. To
ensure that the Company or related entities will achieve the purpose and receive
the benefits contemplated in this Plan, any option granted under this Plan
shall, unless this condition is waived or modified by the Plan Administrator in
the agreement evidencing the option, or by subsequent resolution of the Plan
Administrator, be exercisable according to the following schedule:

Page 3 - STOCK OPTION PLAN
<PAGE>   4

<TABLE>
<CAPTION>

Period of Optionee's Continuous Relationship             Portion of Total Option
With the Company or Related Entity from the                Which is Exercisable
Date the Option is Granted
<S>                                                       <C>
After one year                                                       25%
After two years                                                      50%
After three years                                                    75%
After four years                                                    100%
</TABLE>

       5.4 Exercise. Subject to the vesting schedule described in subsection 5.3
above, if any, and to any additional holding period required by applicable law,
each option may be exercised in whole or in part; provided, however, that only
whole shares will be issued pursuant to the exercise of any option and that the
exercise price shall not be less than the par value per share of the Class A
Common Stock at the time the option is exercised. During an Optionee's lifetime,
any stock options granted under this Plan are personal to him or her and are
exercisable solely by such Optionee, except as provided in Section 5.8. Options
shall be exercised by delivery to the Company of notice of the number of shares
with respect to which the option is exercised, together with payment of the
exercise price.

       5.5 Payment of Exercise Price. Payment of the option exercise price shall
be made in full at the time the notice of exercise of the option is delivered to
the Company and shall be in cash, bank certified or cashier's check or personal
check (unless at the time of exercise the Plan Administrator in a particular
case determines not to accept a personal check) for the Class A Common Stock
being purchased.

       The Plan Administrator can determine at the time the option is granted
for incentive stock options, or at any time before exercise for nonqualified
stock options, that additional forms of payment will be permitted, including
installment payments on such terms and over such period as the Plan
Administrator may determine in its discretion. To the extent permitted by the
Plan Administrator and applicable laws and regulations (including, but not
limited to, federal tax and securities laws and regulations and state corporate
law), an option may be exercised by:

       (a) delivery of shares of stock of the Company held by an Optionee having
a fair market value equal to the exercise price, such fair market value to be
determined in good faith by the Plan Administrator;

       (b) delivery of a full-recourse promissory note executed by the Optionee,
provided that (i) such note delivered in connection with an incentive stock
option shall, and such note delivered in connection with a nonqualified stock
option may, in the sole discretion of the Plan Administrator, bear interest at a
rate specified by the Plan Administrator but in no case less than the rate
required to avoid imputation of interest (taking into account any exceptions to
the imputed interest rules) for federal income tax purposes; (ii) the Plan
Administrator in its sole discretion shall specify the term and other provisions
of such note at the time an incentive stock

Page 4 - STOCK OPTION PLAN
<PAGE>   5

option is granted or at any time prior to exercise of a nonqualified stock
option; (iii) the Plan Administrator may require that the Optionee pledge the
Optionee's shares to the Company for the purpose of securing the payment of such
note and may require that the certificate representing such shares be held in
escrow in order to perfect the Company's security interest; (iv) the note
provides that 90 days following the Optionee's termination of employment with
the Company or a related entity, the entire outstanding balance under the note
shall become due and payable, if not previously due and payable; and (v) the
Plan Administrator in its sole discretion may at any time restrict or rescind
this right upon notification to the Optionee;

       (c) delivery of a properly executed exercise notice, together with
irrevocable instructions to a broker, all in accordance with the regulations of
the Federal Reserve Board, to promptly deliver to the Company the amount of sale
or loan proceeds to pay the exercise price and any federal, state or local
withholding tax obligations that may arise in connection with the exercise;
provided, that the Plan Administrator, in its sole discretion, may at any time
determine that this Subparagraph (c), to the extent the instructions to the
broker call for an immediate sale of the shares, shall not be applicable to any
Optionee who is subject to Section 16(b) of the Exchange Act if such transaction
would result in a violation of Section 16(b), or is not an employee at the time
of exercise;

       (d) delivery of a properly executed exercise notice, together with a
request by the Optionee for the Company to pay the exercise price by withholding
from the shares that would otherwise be issued that number of shares having a
fair market value equal to the option exercise price; provided, the Plan
Administrator retains complete discretion to honor or deny the Optionee's
request for such a method of exercise.

       5.6 Shareholders' Agreement. To the extent required by the Plan
Administrator upon exercise of an option the Optionee shall agree to enter into
and be bound by the agreement then in effect, if any, between the Company and
its shareholders relating to the repurchase by the Company of its outstanding
Class A Common Stock.

       5.7 Withholding Tax Requirement. The Company or any related entity shall
have the right to retain and withhold from any payment of cash or Class A Common
Stock under this Plan the amount of taxes required by any government to be
withheld or otherwise deducted and paid with respect to such payment. At its
discretion, the Company may require an Optionee receiving shares of Class A
Common Stock to reimburse the Company or a related entity for any such taxes
required to be withheld and may withhold any distribution in whole or in part
until the Company, or related entity, is so reimbursed. In lieu of such
withholding or reimbursement, the Company (or related entity) shall have the
right to withhold from any other cash amounts due or to become due from the
Company (or related entity) to the Optionee an amount equal to such taxes or to
retain and withhold a number of shares having a market value not less than the
amount of such taxes required to be withheld as reimbursement for any such taxes
and cancel (in whole or in part) any such shares so withheld.

       5.8 Nontransferability of Option. Options granted under this Plan and the
rights and privileges conferred by this Plan may not be transferred, assigned,
pledged or hypothecated in any manner (whether by operation of law or otherwise)
other than by will or by the applicable

Page 5 - STOCK OPTION PLAN
<PAGE>   6

laws of descent and distribution; provided, with respect to a non-qualified
stock option, an Optionee may transfer the option to a revocable trust created
by the Optionee for the benefit of his or her descendants, to an immediate
family member or to a partnership in which only immediate family members or such
trusts are partners. Options under this Plan shall not be subject to execution,
attachment or similar process. Any attempt to transfer, assign, pledge,
hypothecate or otherwise dispose of any option under this Plan or of any right
or privilege conferred by this Plan, contrary to the Code or to the provisions
of this Plan, or the sale or levy or any attachment or similar process upon the
rights and privileges conferred by this Plan shall be null and void.
Notwithstanding the foregoing, an Optionee may during the Optionee's lifetime,
designate a person who may exercise the option after the Optionee's death by
giving written notice of such designation to the Plan Administrator. Such
designation may be changed from time to time by the Optionee by giving written
notice to the Plan Administrator revoking any earlier designation and making a
new designation.

       5.9 Termination of Relationship. If the Optionee's employment
relationship with the Company or any related entity ceases for any reason other
than termination for cause, death or permanent and total disability, and unless
by its terms the option sooner terminates or expires, then the Optionee may
exercise, for a period of three months after such cessation, that portion of the
Optionee's option which is exercisable at the time of such cessation. The
Optionee's option, however, shall terminate at the end of the three month period
following such cessation as to all Shares for which it has not been exercised,
unless such provision is waived in the agreement evidencing the option or by
resolution adopted by the Plan Administrator. If, in the case of an incentive
stock option, an Optionee's relationship with the Company or related entity
changes (i.e., from employee to nonemployee, such as a consultant), such change
shall constitute a termination of an Optionee's employment with the Company or
related entity and the Optionee's incentive stock option shall terminate in
accordance with this subsection. Upon the expiration of the three month period
following cessation of employment, the Plan Administrator shall have sole
discretion in a particular circumstance to extend the exercise period following
such cessation beyond that specified above. If, however, in the case of an
incentive stock option, the Optionee does not exercise the Optionee's option
within three months after cessation of employment, the option will no longer
qualify as an incentive stock option under the Code.

       Upon an Optionee's termination of employment for cause, all of the
optionee's outstanding (i.e., unexercised) options issued under this Plan shall
immediately expire and no longer be available for exercise. For purposes of this
Section 5.9, a termination shall be considered for "cause" if the termination is
attributable to the Optionee's: (a) Embezzlement; (b) use of illegal drugs or
alcohol that materially impairs the Optionee's ability to fulfill his or her
duties as an employee or independent contractor; (c) willful disclosure of trade
secrets or confidential information of the Company; (d) dishonesty which results
in substantial harm to the Company; or (e) conviction or confession of a
criminal felony.

       If an Optionee's relationship with the Company or any related entity
ceases because of a permanent and total disability, the Optionee's option shall
not terminate, and in the case of an incentive stock option, shall not cease to
be treated as an incentive stock option, until the end of the 12-month period
following such cessation (unless by its terms it sooner terminates

Page 6 - STOCK OPTION PLAN
<PAGE>   7

and expires). As used in this Plan, the term "permanent and total disability"
has the same meaning provided in Code Section 22(e)(3).

       For purposes of this subsection 5.9, a transfer of relationship between
or among the Company and/or any related entity shall not be deemed to constitute
a cessation of relationship with the Company or any of its related entities. For
purposes of this subsection 5.9, with respect to incentive stock options,
employment shall be deemed to continue while the Optionee is on military leave,
sick leave or other bona fide leave of absence (as determined by the Plan
Administrator). The foregoing notwithstanding, employment shall not be deemed to
continue beyond the first 90 days of such leave, unless the Optionee's
reemployment rights are guaranteed by statute or by contract.

       As used in this Plan, the term "related entity," when referring to a
subsidiary, shall mean any business entity (other than the Company) which, at
the time of the granting of the option, is in an unbroken chain of entities
ending with the Company, if stock or voting interests possessing 50% or more of
the total combined voting power of all classes of stock or other ownership
interests of each of the entities other than the Company is owned by one of the
other entities in such chain. When referring to a parent entity, the term
"related entity" shall mean any entity in an unbroken chain of entities ending
with the Company if, at the time of the granting of the option, each of the
entities other than the Company owns stock or other ownership interests
possessing 50% or more of the total combined voting power of all classes of
stock (or other ownership interests) in one of the other entities in such chain.
In addition, with respect to an incentive stock option, the definition of
"related entity" as used in this Plan shall apply by only considering entities
that are corporations.

       5.10 Death of Optionee. If an Optionee dies while he or she has a
relationship with the Company or any related entity or dies within the three
month period (or 12-month period in the case of totally disabled Optionees)
following cessation of such relationship, any option held by such Optionee to
the extent that the Optionee would have been entitled to exercise such option,
may be exercised within one year after his or her death by the personal
representative of his or her estate or by the person or persons to whom the
Optionee's rights under the option shall pass by will or by the applicable laws
of descent and distribution.

       5.11 Status of Shareholder. Neither the Optionee nor any party to which
the Optionee's rights and privileges under the option may pass shall be, or have
any of the rights or privileges of, a shareholder of the Company with respect to
any of the shares issuable upon the exercise of any option granted under this
Plan unless and until such option has been exercised.

       5.12 Continuation of Employment. Nothing in this Plan or in any option
granted pursuant to this Plan shall confer upon any Optionee any right to
continue in the employ of the Company or of a related entity, or to interfere in
any way with the right of the Company or of any related entity to terminate his
or her employment or other relationship with the Company or a related entity at
any time.

       5.13 Modification and Amendment of Option. Subject to the requirements of
Code Section 422 with respect to incentive stock options and to the terms and
conditions and within

Page 7 - STOCK OPTION PLAN
<PAGE>   8

the limitations of this Plan, the Plan Administrator may modify or amend
outstanding options granted under this Plan. The modification or amendment of an
outstanding option shall not, without the consent of the Optionee, impair or
diminish any of his or her rights or any of the obligations of the Company under
such option. Except as otherwise provided in this Plan, no outstanding option
shall be terminated without the consent of the Optionee. Unless the Optionee
agrees otherwise, any changes or adjustments made to outstanding incentive stock
options granted under this Plan shall be made in such a manner so as not to
constitute a "modification" as defined in Code Section 424(h) and so as not to
cause any incentive stock option issued hereunder to fail to continue to qualify
as an incentive stock option as defined in Code Section 422(b).

       5.14 Limitation on Value for Incentive Stock Options. As to all incentive
stock options granted under the terms of this Plan, to the extent that the
aggregate fair market value (determined at the time the incentive stock option
is granted) of the stock with respect to which incentive stock options are
exercisable for the first time by the Optionee during any calendar year (under
this Plan and all other incentive stock option plans of the Company, a related
entity or a predecessor corporation) exceeds $100,000, those options (or the
portion of an option) beyond the $100,000 threshold shall be treated as
nonqualified stock options. The previous sentence shall not apply if the
Internal Revenue Service publicly rules, issues a private ruling to the Company,
any Optionee, or any legatee, personal representative or distributee of an
Optionee or issues regulations changing or eliminating such annual limit.

    SECTION 6.  Greater Than 10% Shareholders.

       6.1 Exercise Price and Term of Incentive Stock Options. If incentive
stock options are granted under this Plan to employees who own more than 10% of
the total combined voting power of all classes of stock of the Company or any
related entity, the term of such incentive stock options shall not exceed five
years and the exercise price shall be not less than 110% of the fair market
value of the Class A Common Stock at the time the incentive stock option is
granted. This provision shall control notwithstanding any contrary terms
contained in an option agreement or any other document.

       6.2 Attribution Rule. For purposes of subsection 6.1, in determining
stock ownership, an employee shall be deemed to own the stock owned, directly or
indirectly, by or for his brothers, sisters, spouse, ancestors and lineal
descendants. Stock owned, directly or indirectly, by or for a corporation,
partnership, estate or trust shall be deemed to be owned proportionately by or
for its shareholders, partners or beneficiaries. If an employee or a person
related to the employee owns an unexercised option or warrant to purchase stock
of the Company, the stock subject to that portion of the option or warrant which
is unexercised shall not be counted in determining stock ownership. For purposes
of this Section 6, stock owned by an employee shall include all stock actually
issued and outstanding immediately before the grant of the incentive stock
option to the employee.

    SECTION 7.  Adjustments Upon Changes in Capitalization. The aggregate number
and class of shares for which options may -be granted under this Plan, the
number and class of shares covered by each outstanding option and the exercise
price per share thereof (but not the total

Page 8 - STOCK OPTION PLAN
<PAGE>   9

price), and each such option, shall all be proportionately adjusted for any
increase or decrease in the number of issued shares of Class A Common Stock of
the Company resulting from a split-up or consolidation of shares or any like
capital adjustment, or the payment of any stock dividend.

       7.1  Effect of Liquidation, Reorganization or Change in Control.

              7.1.1 Cash, Stock or Other Property for Stock. Except as provided
in subsection 7.1.2, upon a merger (other than a merger of the Company in which
the holders of Class A Common Stock immediately prior to the merger have the
same proportionate ownership of Class A Common Stock in the surviving
corporation immediately after the merger), consolidation, acquisition of
property or stock, separation, reorganization (other than a mere reincorporation
or the creation of a holding company) or liquidation of the Company, as a result
of which the shareholders of the Company receive cash, stock or other property
in exchange for or in connection with their shares of Class A Common Stock, any
option granted under this Plan shall terminate. Notwithstanding the foregoing,
the Optionee shall have the right immediately prior to any such merger,
consolidation, acquisition of property or stock, separation, reorganization or
liquidation to exercise such option in whole or in part, to the extent the
vesting requirements set forth in this Plan have been satisfied, unless stated
otherwise in the Optionee's individual option agreement.

              7.1.2  Conversion of Options on Stock for Stock Exchange. If the
shareholders of the Company receive capital stock of another corporation
("Exchange Stock") in exchange for their shares of Class A Common Stock in any
transaction involving a merger (other than a merger of the Company in which the
holders of Class A Common Stock immediately prior to the merger have the same
proportionate ownership of common stock in the surviving corporation immediately
after the merger), consolidation, acquisition of property or stock, separation
or reorganization (other than a mere reincorporation or the creation of a
holding company), all options granted under this Plan shall be converted into
options to purchase shares of Exchange Stock unless the Company and the
corporation issuing the Exchange Stock, in their sole discretion, determine that
any or all such options granted under this Plan shall not be converted into
options to purchase shares of Exchange Stock, but instead shall terminate in
accordance with the provisions of subsection 7.1.1. The amount and price of
converted options shall be determined by adjusting the amount and price of the
options granted under this Plan in the same proportion as used for determining
the number of shares of Exchange Stock the holders of the Class A Common Stock
receive in such merger, consolidation, acquisition of property or stock,
separation or reorganization. Unless accelerated by the Board, the vesting
schedule set forth in the option agreement shall continue to apply for the
Exchange Stock.

              7.1.3  Change in Control.

       (a)    In the event of a "Change in Control", as defined in Section
    7.1.4(b) below, of the Company, except as provided in Section 7.1.3(b) or
    unless otherwise determined by the Board prior to the occurrence of such a
    Change in Control, any options or portions of such options outstanding as of
    the date such a Change in Control is determined to have occurred that are
    not yet fully vested shall not become fully vested merely by the occurrence
    of a Change in Control.

Page 9 - STOCK OPTION PLAN
<PAGE>   10

       (b)    Notwithstanding anything to the contrary in Section 7.1.3(a), each
    outstanding option granted prior to February 16, 2000 (other than those
    options described in Section 7.1.3.(d)) shall be deemed to be amended to
    provide that, and each option granted on or after such date shall provide
    that, unless otherwise expressly determined in a resolution duly adopted by
    the Board on the date of grant or such later date on which the Board may
    ratify such grant, such option shall (1) if the Optionee is a Nonaffiliate
    Director, immediately become fully exercisable upon the occurrence of an
    Acceleration Change of Control of the Company or (2) if the Optionee is
    recognized by the Company or any of the related entities as a regular full
    time employee who is subject to U.S. income tax withholding, immediately
    become fully exercisable upon the termination of the Optionee's employment
    by the Company or any of the related entities without Cause during the
    Accelerated Vesting Period or, in the case of an Optionee who is an
    Executive, upon the termination of the Optionee's employment by the Optionee
    for Good Reason during the Accelerated Vesting Period; provided, however,
    that this Section 7.1.3(b) shall be deemed void ab initio and shall be of no
    force or effect, if it should be determined that any such provision would
    prevent a proposed merger or other business combination that is intended by
    the parties thereto to be accounted for as a pooling of interests from being
    so accounted for.

       (c)    With respect to options that, as of February 16, 2000, incorporate
    a definition of change of control that provides for accelerated vesting
    solely in the event that Craig O. McCaw, or an entity or entities he
    controls, no longer controls a majority of the votes of the Company (or
    language to that effect), Section 7.1.3(b) shall supplement such provision
    and each holder of such an option shall be entitled to the benefits of
    Section 7.1.3(b), but Section 7.1.3(b) shall not be deemed to modify,
    replace or impair such options' existing change of control provisions.

       (d)    Notwithstanding anything to the contrary in Section 7.1.3(b),
    Section 7.1.3(b) shall not apply to the following options granted prior to
    February 16, 2000:

              (i)   options granted to any employee whose employment
       relationship is subject, as of February 16, 2000, to severance in
       connection with the relocation of the Company's headquarters from
       Bellevue, Washington to Reston, Virginia, where such employee is entitled
       to benefits under the NEXTLINK Headquarters Relocation Retention and
       Severance Pay Plan and Summary Plan Description for Headquarters
       Personnel;

              (ii)  options granted to any employee whose employment
       relationship is subject, as of February 16, 2000, to severance in
       connection with the reorganization and restructuring of the Company's
       regional divisions, where such employee is entitled to benefits under the
       NEXTLINK Severance Pay Plan and Summary Plan Description; and

Page 10 - STOCK OPTION PLAN
<PAGE>   11

              (iii) options (A) that, by their terms, incorporate the definition
       of "Change in Control" set forth in Section 7.1.4(b) of this Plan as in
       effect prior to the February 16, 2000 amendment thereto and provide for
       accelerated vesting upon the occurrence of such a "Change in Control", or
       (B) that provide for acceleration upon a change of control pursuant to
       the terms of an employment agreement or otherwise, excluding those
       options referenced in Section 7.1.3(c).

              7.1.4 Definitions.

       (a)    For purposes of Section 7.1.3, the following defined terms shall
    have the following meanings:

       "Acceleration Change of Control" shall mean the occurrence of any of the
following events:

       (A)    The Company is merged or consolidated or reorganized into or with
              another company or other legal entity, other than a merger or
              consolidation or reorganization into or with an entity that is an
              affiliate of Craig O. McCaw, and as a result of such merger,
              consolidation or reorganization less than a majority of the
              combined voting power of the then-outstanding securities of such
              company or person immediately after such transaction is held
              directly or indirectly in the aggregate by the holders of voting
              securities of the Company immediately prior to such sale or
              transfer, including voting securities issuable upon exercise or
              conversion of options, warrants or other securities or rights;

       (B)    The Company sells or otherwise transfers all or substantially all
              of its assets to any other company or other legal entity, other
              than such a sale or transfer to a company or legal entity that is
              an affiliate of Craig O. McCaw, and as a result of such sale or
              other transfer of assets, less than a majority of the combined
              voting power of the then-outstanding securities of such company or
              person immediately after such sale or transfer is held directly or
              indirectly in the aggregate by the holders of voting securities of
              the Company immediately prior to such sale or transfer, including
              voting securities issuable upon exercise or conversion of options,
              warrants or other securities or rights;

       (C)    There is a report filed on Schedule 13D or Schedule 14D-1 (or any
              successor schedule, form or report), each as promulgated pursuant
              to the Securities Exchange Act of 1934, as amended (the "Exchange
              Act"), disclosing that any person (as the term "person" is used in
              Section 13(d)(3) or Section 14(d)(2) of the Exchange Act) other
              than Craig O. McCaw and his affiliates has become the beneficial
              owner (as the term "beneficial owner" is defined under Rule 13d-3
              or any successor rule or regulation promulgated under the Exchange
              Act) of securities representing 50% or more of the voting
              securities of the Company, including voting

Page 11 - STOCK OPTION PLAN
<PAGE>   12

              securities issuable upon exercise or conversion of options,
              warrants or other securities or rights;

       (D)    The Company files a report or proxy statement with the Securities
              and Exchange Commission pursuant to the Exchange Act disclosing in
              response to Form 8-K or Schedule 14A (or any successor schedule,
              form or report or item therein) that a change in control of the
              Company has occurred;

       (E)    Notwithstanding the foregoing provisions of subparagraphs (C) and
              (D) hereof, an "Acceleration Change of Control" shall not be
              deemed to have occurred solely because (x) the Company, (y) an
              entity in which the Company directly or indirectly beneficially
              owns 50% or more of the voting securities, or (z) any
              Company-sponsored employee stock ownership plan or other employee
              benefit plan of the Company, either files or becomes obligated to
              file a report or proxy statement under or in response to Schedule
              13D, Schedule 14D-1, Form 8-K or Schedule 14A (or any successor
              schedule, form or report or item therein) under the Exchange Act,
              disclosing beneficial ownership by it of voting securities,
              whether in excess of 50% or otherwise, or because the Company
              reports that a change of control of the Company has or may have
              occurred or will or may occur in the future by reason of such
              beneficial ownership;

       (F)    Notwithstanding the foregoing provisions of subparagraphs (A)
              through (D) above, no Acceleration Change of Control shall result
              from a merger, consolidation or reorganization of the Company with
              any entity in which Eagle River Investments, L.L.C. has invested
              at least $10,000,000 in equity prior to such merger, consolidation
              or reorganization.

       "Accelerated Vesting Period" means the period beginning on the effective
date of an Acceleration Change of Control and ending on the first anniversary of
such effective date.

       "Cause" means (i) the conviction of a felony involving an intentional act
of fraud, embezzlement or theft in connection with one's duties or otherwise in
the course of one's employment with an Employer, (ii) the intentional and
wrongful damaging of property, contractual interests or business relationships
of an Employer, (iii) the intentional and wrongful disclosure of secret
processes or confidential information of an Employer in violation of an
agreement with or a policy of an Employer, or (iv) intentional conduct contrary
to an Employer's announced policies or practices (including those contained in
the Corporation's Employee Handbook) where either:

       (A)    the nature and/or severity of the conduct or its consequences
              typically would have resulted in immediate termination based on
              the Corporation's established employee termination or disciplinary
              practices in place on the Reference Date; or

Page 12 - STOCK OPTION PLAN
<PAGE>   13

       (B)    the employee has been provided with written notice detailing the
              relevant policy or practice and the nature of the objectionable
              conduct or other violation, and within 20 business days of the
              receipt of such notice the employee has not remedied the violation
              or ceased to engage in the objectionable conduct.

       "Executive" means any individual employed by the Company or any of the
related entities in a position having a salary grade of EX3, EX2 or EX1 (as the
Company's salary grades are established and in existence on February 16, 2000,
and adjusting as appropriate for any changes to the Company's system of
classifying its employees by salary grades implemented subsequent to such date).

       "Good Reason" means that an Executive shall have made a good faith
determination that one or more of the following has occurred:

       (i)    any significant and adverse change in the Executive's duties,
              responsibilities and authority, as compared in each case to the
              corresponding circumstances in place on the Reference Date;

       (ii)   a relocation of the Executive's principal work location as
              established on the Reference Date to a location that is more than
              30 miles away from such location;

       (iii)  a reduction in the Executive's salary or bonus potential that is
              not in either case agreed to by the Executive, or any other
              significant adverse financial consequences associated with the
              Executive's employment as compared to the corresponding
              circumstances in place on the Reference Date; or

       (iv)   a breach by any Employer of its obligations under any agreement to
              which the Employer and the Executive are parties that is not cured
              within 20 business days following the Employer's receipt of a
              written notice from the Executive specifying the particulars of
              such breach in reasonable detail.

       "Nonaffiliate Director" means a person who (i) is serving (or who has
been elected or appointed and has agreed to serve) as a member of the Board,
(ii) is not an officer or employee of the Company or any of the related entities
or a beneficial owner of 10 percent or more of the outstanding common stock of
the Company and (iii) was not elected or appointed as a member of the Board
pursuant to or in connection with any contractual or other commitment on the
part of the Company to cause such person to be elected or appointed, or to
nominate or otherwise advance such person for election or appointment, as a
member of the Board.

       "Reference Date" means the day before the effective date of any
Acceleration Change of Control of the Company.

Page 13 - STOCK OPTION PLAN
<PAGE>   14

       (b)    Solely with respect to options outstanding as of February 16, 2000
    in which the grant agreement evidencing such option incorporates the
    definition of "Change in Control" set forth in this Plan as in effect prior
    to this amendment and provide for accelerated vesting upon the occurrence of
    such a "Change of Control", the following definition shall apply:

       A "Change in Control" shall mean (a) the first approval by the Board or
by the stockholders of the Company of an Extraordinary Event, (b) a Purchase, or
(c) a Board Change.

       An "Extraordinary Event", for purposes of Section 7.1.4(b), shall mean
any of the following actions:

       (i)    any consolidation or merger of the Company in which the Company is
    not the continuing or surviving corporation or pursuant to which shares of
    Class A Common Stock would be converted into cash, securities or other
    property, other than a merger of the Company in which the holders of common
    stock immediately prior to the merger have substantially the same
    proportionate ownership of common stock of the surviving corporation
    immediately after the merger;

       (ii)   any sale, lease, exchange or other transfer (in one transaction or
    a series of related transactions) of all, or substantially all, the assets
    of the Company; or

       (iii)  the adoption of any plan or proposal for liquidation or
    dissolution of the Company.

       A "Purchase", for purposes of Section 7.1.4(b), shall mean the
acquisition by any person (as such term is defined in Section 13(d) of the
Exchange Act) of any shares of Class A Common Stock or securities convertible
into Class A Common Stock) without the prior approval of a majority of the
Continuing Directors (as defined below) of the Company, if after making such
acquisition such person is the beneficial owner (as such term is defined in Rule
13d-3 under the Exchange Act) directly or indirectly of securities of the
Company representing 20% or more of the combined voting power of the Company's
then outstanding securities (calculated as provided in paragraph (d) of such
Rule 13d-3).

       A "Board Change", for purposes of Section 7.1.4(b), shall have occurred
if individuals who constitute the Board of the Company at the time of adoption
of this Plan (the "Continuing Directors") cease for any reason to constitute at
least a majority of the Board, provided that any person becoming a Director
subsequent to the date of adoption of this Plan whose nomination for election
was approved by a vote of at least a majority of the Continuing Directors (other
than a nomination of an individual whose initial assumption of office is in
connection with an actual threatened election contest relating to the election
of the Directors of the Company, as such terms are used in Rule 14a-11 of
Regulation 14A under the Exchange Act) shall be deemed to be a Continuing
Director.

Page 14 - STOCK OPTION PLAN
<PAGE>   15

       7.2 Fractional Shares. In the event of any adjustment in the number of
shares covered by any option, any fractional shares resulting from such
adjustment shall be disregarded and each such option shall cover only the number
of full shares resulting from such adjustment.

       7.3 Determination of Board to Be Final. All Section 7 adjustments shall
be made by the Board, and its determination as to what adjustments shall be
made, and the extent of such adjustments, shall be final, binding and
conclusive. Unless an Optionee agrees otherwise, any change or adjustment to an
incentive stock option shall be made in such a manner so as not to constitute a
"modification" as defined in Code Section 424(h) and so as not to cause his or
her incentive stock option issued under this Plan to fail to continue to qualify
as an incentive stock option as defined in Code Section 422(b).

    SECTION 8.  Securities Regulation. Shares shall not be issued with respect
to an option granted under this Plan unless the exercise of such option and the
issuance and delivery of such shares pursuant to the exercise of such option
shall comply with all relevant provisions of law, including, without limitation,
any applicable state securities laws, the Securities Act of 1933, as amended,
the Exchange Act, the rules and regulations promulgated thereunder, and the
requirements of any stock exchange upon which the shares may then be listed, and
shall be further subject to the approval of counsel for the Company with respect
to such compliance, including the availability of an exemption from registration
for the issuance and sale of any shares under this Plan. Inability of the
Company to obtain from any regulatory body having jurisdiction, the authority
deemed by the Company's counsel to be necessary for the lawful issuance and sale
of any shares under this Plan or the unavailability of an exemption from
registration for the issuance and sale of any shares under this Plan shall
relieve the Company of any liability in respect of the nonissuance or sale of
such shares as to which such requisite authority shall not have been obtained.

       As a condition to the exercise of an option, the Company may require the
Optionee to represent and warrant at the time of any such exercise that the
shares are being purchased only for investment and without any present intention
to sell or distribute such shares if, in the opinion of counsel for the Company,
such a representation is required by any relevant provision of the
aforementioned laws. At the option of the Company, a stop-transfer order against
any shares of stock may be placed on the official stock books and records of the
Company, and a legend indicating that the stock may not be pledged, sold or
otherwise transferred unless an opinion of counsel is provided (concurred in by
counsel for the Company) stating that such transfer is not in violation of any
applicable law or regulation, may be stamped on stock certificates in order to
assure exemption from registration. The Plan Administrator may also require such
other action or agreement by the Optionees as may from time to time be necessary
to comply with the federal and state securities laws. THIS PROVISION SHALL NOT
OBLIGATE THE COMPANY TO UNDERTAKE REGISTRATION OF THE OPTIONS OR STOCK
HEREUNDER.

       Should any of the Company's capital stock of the same class as the stock
subject to options granted under this Plan be listed on a national securities
exchange, all stock issued under this Plan if not previously listed on such
exchange shall be authorized by that exchange for listing on such exchange prior
to the issuance of such stock.

Page 15 - STOCK OPTION PLAN
<PAGE>   16

    SECTION 9.  Amendment and Termination.

       9.1 Board Action. The Board may at any time suspend, amend or terminate
this Plan, provided that except as set forth in Section 7, the approval of the
Company's shareholders is necessary within 12 months before or after the
adoption by the Board of any amendment which will:

              (a) increase the number of shares which are to be reserved for the
issuance of options under this Plan;

              (b) permit the granting of stock options to a class of persons
other than those presently permitted to receive stock options under this Plan;
or

              (c) require shareholder approval under applicable law, including
Section 16(b) of the Exchange Act.

              Any amendment to this Plan that would constitute a "modification"
to incentive stock options outstanding on the date of such amendment shall not
be applicable to outstanding incentive stock options, but shall have prospective
effect only, unless individual Optionees agree otherwise.

       9.2 Automatic Termination. Unless sooner terminated by the Board, this
Plan shall terminate ten years from the earlier of (a) the date on which this
Plan is adopted by the Board or (b) the date on which this Plan is approved by
the shareholders of the Company. No option may be granted after such termination
or during any suspension of this Plan. The amendment or termination of this Plan
shall not, without the consent of the option holder, alter or impair any rights
or obligations under any option previously granted under this Plan.

    SECTION 10. Effectiveness of This Plan. This Plan shall become effective
upon adoption by the Board so long as it is approved by the Company's
shareholders any time within 12 months before or after the adoption of this
Plan.

Page 16 - STOCK OPTION PLAN

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