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                                                                    EXHIBIT 99.4

                FORM OF LETTER TO CLIENTS AND FORM TO INSTRUCTION


                                OFFER TO EXCHANGE
                             NOTES DUE JULY 15, 2025
                           FOR ANY AND ALL OUTSTANDING
                             NOTES DUE JULY 15, 2025
                                       OF
                                  AERCO LIMITED


To Our Clients:

         We are enclosing herewith a Prospectus dated    , of AerCo Limited
("AerCo") and a related Letter of Transmittal (which together constitute the
"Exchange Offer") relating to the offer by AerCo to exchange four subclasses of
its Notes due July 15, 2025 (the "New Notes"), pursuant to an offering
registered under the Securities Act of 1933, as amended (the "Securities Act"),
for a like principal amount of four subclasses of its issued and outstanding
Notes due July 15, 2025 (the "Old Notes") upon the terms and subject to the
conditions set forth in the Exchange Offer.

         PLEASE NOTE THAT THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK
CITY TIME, ON    , UNLESS EXTENDED.

         The Exchange Offer is not conditioned upon any minimum number of Old
Notes being tendered.

         We are the participants in the book-entry transfer facility of Old
Notes held by us for your account. A tender of such Old Notes can be made only
by us as the participant in the book-entry transfer facility and pursuant to
your instructions. The Letter of Transmittal is furnished to you for your
information only and cannot be used by you to tender Old Notes held by us for
your account.

         We request instruction as to whether you wish to tender any or all of
any subclass of Old Notes held by us for your account pursuant to the terms and
conditions of the Exchange Offer. We also request that you confirm that we may
on your behalf make the representations contained in the Letter of Transmittal
that are to be made with respect to you as beneficial owner.

         Pursuant to the Letter of Transmittal, each holder of Old Notes will
represent to AerCo that (i) the New Notes acquired in the Exchange Offer are
being obtained in the ordinary course of business of the person receiving such
New Notes, (ii) the holder of the Old Notes has no arrangement or understanding
with any person to participate in the distribution of such New Notes, (iii) if
the holder is not a broker-dealer or is a broker-dealer but will not receive New
Notes for its own account in exchange for Old Notes, the holder is not engaged
in and does not intend to participate in a distribution of the New Notes and
(iv) the holder is not an "affiliate" of AerCo within the meaning of Rule 405
under the Securities Act. If the tendering holder is a broker-dealer (whether or
not it is also an "affiliate" of AerCo) that will receive New Notes for its own
account pursuant to the Exchange Offer, we will represent on behalf of such
broker-dealer that the Old Notes to be exchanged for the New Notes were acquired
by it as a result of marketing-making activities or other trading activities,
and acknowledge on behalf of such broker-dealer that it will deliver a
prospectus meeting the requirements of the Securities Act in connection with any
resale of such New Notes. By acknowledging that it will deliver and by
delivering a prospectus meeting the requirements of the Securities Act in
connection with any resale of such New Notes, such broker-dealer will not be
deemed to admit that it is an "underwriter" within the meaning of the Securities
Act.



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                                   INSTRUCTION
                       TO BOOK-ENTRY TRANSFER PARTICIPANT
                                  FROM OWNER OF
                                  AERCO LIMITED


                             NOTES DUE JULY 15, 2025



To       Participant of the Book-Entry Transfer Facility:

         The undersigned hereby acknowledges receipt of the Prospectus dated
    (the "Prospectus") of AerCo Limited ("AerCo"), and the accompanying
Letter of Transmittal (the "Letter of Transmittal"), that together constitute
MSAF's offer (the "Exchange Offer"). Capitalized terms used but not defined
herein have the meanings ascribed to them in the Prospectus.

         This will instruct you, the book-entry transfer facility participant,
as to the action to be taken by you relating to the Exchange Offer with respect
to the Old Notes held by you for the account of the undersigned.

         The aggregate face amount of each subclass of Old Notes held by you for
the account of the undersigned is (fill in amount):

         $                 of the Subclass           Notes due July 15, 2025

         With respect to the Exchange Offer, the undersigned hereby instructs
you (check appropriate box):

         [ ] to TENDER the following subclass of Old Notes held by you for the
account of the undersigned (insert principal amount of Old Notes to be tendered,
(if any):

         $                 of the Subclass           Notes due July 15, 2025

         [ ] NOT to tender any Old Notes held by you for the account of the
undersigned.

         If the undersigned instructs you to tender the Old notes held by you
for the account of the undersigned, it is understood that you are authorized to
make, on behalf of the undersigned (and the undersigned, by its signature below,
hereby makes to you), the representations and warranties contained in the Letter
of Transmittal that are to be made with respect to the undersigned as a
beneficial owner, including but not limited to the representations, that (i) the
New Notes acquired pursuant to the Exchange Offer are being obtained in the
ordinary course of business of the undersigned, (ii) the undersigned has no
arrangement or understanding with any person to participate in the distribution
of such New Notes, (iii) if the undersigned is not a broker-dealer, or is a
broker-dealer but will not receive New Notes for its own account in exchange for
Old Notes, the undersigned is not engaged in and does not intend to participate
in the distribution of such New notes and (iv) the undersigned is not an
"affiliate" of AerCo within the meaning of Rule 405 under the Securities Act of
1933, as amended (the "Securities Act"). If the undersigned is a broker-dealer
(whether or not it is also an "affiliate" of AerCo) that will receive New Notes
for its own account pursuant to the Exchange Offer, it represents that such Old
Notes were acquired as a result of market-making activities or other trading
activities, and it acknowledges that it will deliver a prospectus meeting the
requirements of the Securities Act in connection with any resale of such New
Notes. By acknowledging that it will deliver and by delivering a prospectus
meeting the requirements of the Securities Act in connection with any resale of
such New Notes, the undersigned will not be deemed to admit that it is an
"underwriter" within the meaning of the Securities Act.



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                                    SIGN HERE




Name of beneficial owner(s):

Signature(s):

Name(s) (please print):

Address:

Telephone Number:

Taxpayer identification or Social Security Number:

Date: