Exhibit 5.1

May 13, 2002


Airborne, Inc.
3101 Western Avenue
Seattle, Washington 98111

Ladies and Gentlemen:

We have acted as counsel for (i) Airborne, Inc., a Delaware corporation (the
"Company"), and (ii) Airborne Express, Inc., a Delaware corporation, ABX Air,
Inc., a Delaware corporation, Sky Courier, Inc., a Delaware corporation,
Wilmington Air Park, Inc., an Ohio corporation, Airborne FTZ, Inc., an Ohio
corporation, Aviation Fuel, Inc., an Ohio corporation, and Sound Suppression,
Inc., an Ohio corporation, each a direct or indirect wholly owned subsidiary of
the Company (collectively, the "Guarantors"), in connection with the
Registration Statement on Form S-3 (the "Registration Statement") filed by the
Company and the Guarantors with the Securities and Exchange Commission (the
"Commission") under the Securities Act of 1933, as amended (the "Act"), relating
to the resale by certain selling security holders of up to $150,000,000
aggregate principal amount of 5.75% Convertible Senior Notes due April 1, 2007
("the Notes"), an indeterminate number of shares of common stock, par value
$1.00 (the "Common Stock"), of the Company, issuable upon conversion of the
Notes (the "Conversion Shares"), and the guarantees by the Guarantors of the
Notes (the "Guarantees"). The Notes were issued under an Indenture (the
"Indenture") dated as of March 25, 2002 among the Company, the Guarantors and
The Bank of New York (the "Trustee").

The Notes were initially sold by the Company in reliance on Section 4(2) of the
Act and may be resold or delivered from time to time as set forth in the
Registration Statement, any amendment thereto and the prospectus contained
therein (the "Prospectus") pursuant to Rule 415 under the Act.

We have examined the Registration Statement, the Indenture, the global note
evidencing the Notes and a form of certificate for the Common Stock, copies of
which have been filed with the Commission as exhibits to the Registration
Statement. We also have examined the originals, or duplicates or certified or
conformed copies, of such records, agreements, instruments and other documents
and have made such other and further investigations as we have deemed relevant
and necessary in connection with the opinions expressed herein. As to questions
of fact material to this opinion, we have relied upon certificates of public
officials and of officers and representatives of the Company and the Guarantors.

In rendering the opinions set forth below, we have assumed the genuineness of
all signatures, the legal capacity of natural persons, the authenticity of all
documents



Airborne, Inc.
May 13, 2002
Page 2

submitted to us as originals, the conformity to original documents of all
documents submitted to us as duplicates or certified or conformed copies, and
the authenticity of the originals of such latter documents. We have also assumed
that the Indenture is the valid and legally binding obligation of the Trustee.

Based upon the foregoing, and subject to the qualifications and limitations
stated herein, we are of the opinion that:

1.   The Notes have been duly authorized, executed and issued by the Company
and, assuming that they have been duly authenticated by the Trustee, constitute
valid and legally binding obligations of the Company, enforceable against the
Company in accordance with their terms.

2.   The Conversion Shares have been duly authorized and, when issued and
delivered in accordance with the provisions of the Notes and the Indenture, will
be validly issued, fully paid and nonassessable.

3.   The Guarantees have been duly authorized, executed and issued by the
respective Guarantors and, assuming due authentication of the Notes by the
Trustee, constitute valid and legally binding obligations of the respective
Guarantors enforceable against the respective Guarantors in accordance with
their terms.

Our opinions set forth in paragraphs 1 and 3 above are subject to (i) the
effects of bankruptcy, insolvency, fraudulent conveyance, reorganization,
moratorium and other similar laws relating to or affecting creditors' rights
generally, (ii) general equitable principles (whether considered in a proceeding
in equity or at law) and (iii) an implied covenant of good faith and fair
dealing.

We are members of the Bars of the State of Washington and the State of New York,
and we do not express any opinion herein concerning any law other than the
Delaware General Corporation Law (including statutory provisions, all applicable
provisions of the Delaware Constitution and reported judicial decisions
interpreting the foregoing), the law of the State of Washington and the State of
New York and the federal law of the United States.

We hereby consent to the filing of this opinion as Exhibit 5.1 to the
Registration Statement and to the use of our name under the caption "Legal
Matters" in the Prospectus. In giving such consent, we do not thereby admit that
we are in the category of persons whose consent is required under Section 7 of
the Act.

Sincerely,

/s/ Riddell Williams P.S.

RIDDELL WILLIAMS P.S.