<TABLE>
<S>     <C>    <C>    <C>    <C>    <C>    <C>


EXHIBIT 10.23(b)
                                             SECOND AMENDMENT
                                                    TO
                                       LOAN AND SECURITY AGREEMENT

         THIS SECOND  AMENDMENT  TO LOAN AND SECURITY  AGREEMENT  ("Amendment"),
dated as of the 31st day of December, 1997, made by and between

         FLEET CAPITAL  CORPORATION,  a Rhode Island  corporation  (successor by
merger with Fleet  Capital  Corporation,  a Connecticut  corporation,  which was
formerly known as Shawmut Capital Corporation) (the "Lender"),

         ATLANTIC COAST AIRLINES, a California corporation (the "Borrower"), and

         ATLANTIC COAST AIRLINES,  INC., a Delaware  corporation  (the "Parent";
the Borrower and the Parent being collectively called the "Loan Parties");

         to the  Loan  and  Security  Agreement,  dated  October  12,  1995,  as
previously  amended by First  Amendment  thereto,  dated June 1, 1997 (the "Loan
Agreement"). All capitalized terms used herein without definition shall have the
meanings ascribed to such terms in the Loan Agreement.

                                    RECITALS
         RECITALS RECITALS RECITALS
         A.  Pursuant to the Loan  Agreement,  and upon the terms and subject to
the conditions  contained therein, the Lender has made available to the Borrower
a $20,000,000 revolving line of credit evidenced by the Loan Agreement.

         B. The Loan Parties have  requested  that the Loan Agreement be further
amended to (a) increase the aggregate amount of the Letter of Credit Obligations
which may be  outstanding  at any time from the sum of $10,500,000 to the sum of
$13,500,000,  and (b)  reduce  the  amount  of the Fixed  Bond  Letter of Credit
Guaranty Reserve,  and the Lender has agreed to such requests,  provided,  among
other things,  the Loan  Agreement  and the other Loan  Documents are amended as
herein provided.

         C. To  accomplish  the  foregoing  purposes,  the  parties  hereto  are
mutually desirous of further amending the Loan Agreement as set forth herein.

                                    STATEMENT OF AGREEMENT

         NOW,  THEREFORE,  in  consideration  of the premises and other good and
valuable  consideration,  the  receipt  and  sufficiency  of  which  are  hereby
expressly acknowledged, the Loan Parties and the Lender hereby agree as follows:


<PAGE>



                                                    36



                                    ARTICLE I

                          AMENDMENTS TO LOAN AGREEMENT

         The Loan Agreement is hereby amended as follows:

         1.1  Letters of Credit;  Letter of Credit  Guaranties.  Section  1.4.1,
Issuance of Letters of Credit and Letter of Credit Guaranties, is amended in its
entirety to read as follows:

                  "1.4.1.  Issuance  of  Letters  of Credit and Letter of Credit
         Guaranties.  Lender  agrees,  for so long as no  Default  or  Event  of
         Default  exists and subject to the  provisions  of Section 9 below,  to
         issue its, or cause to be issued its Affiliate's, Letters of Credit and
         Letter of Credit Guaranties,  provided that the aggregate amount of the
         Letter of Credit  Obligations  outstanding at any time shall not exceed
         $13,500,000 and, without the prior written consent of Lender, no Letter
         of Credit or Letter of Credit Guaranty may have an expiration date that
         is  after  the  last day of the  Original  Term or the then  applicable
         Renewal Term."

         1.2 Letter of Credit and Letter of Credit Guaranty Fees. Section 2.2.3,
Letter of Credit and Letter of Credit  Guaranty Fees, is amended in its entirety
to read as follows:

                  "2.2.3.  Letter of Credit and Letter of Credit  Guaranty  Fees.  Borrower shall
         pay the  following  fees for all  Letters  of Credit  and  Letter  of Credit  Guaranties
         issued by Lender and its Affiliates pursuant to Section 1.4.1 hereof:

                           (i) Upon  issuance  of the Bond  Letter of Credit and
                  the  Bond  Letter  of  Credit  Guaranty,  fees  to Bank in the
                  amounts  and on the dates as set forth in Section  2.03 of the
                  Reimbursement Agreement;

                           (ii) Upon issuance of each other Letter of Credit and
                  Letter of Credit Guaranty:



<PAGE>


                                    (a)  an  issuance  fee  to  Lender  for  the
                           account of both Lender and its Affiliate  that issues
                           such other  Letter of Credit equal to (1) in the case
                           of  those  three  (3)  Letters  of  Credit,   numbers
                           9721204,  9721205  and  9721206,  issued  by  Bank on
                           December  31,  1997 in favor of  NationsBanc  Leasing
                           Corporation as  beneficiary  in the original  undrawn
                           amounts   of   $750,000,   $750,000   and   $875,000,
                           respectively,  and the  Letter of  Credit  Guaranties
                           issued  by  Lender  with  respect  thereto,  one  and
                           one-quarter  percent (1.25%) per annum of the undrawn
                           amount of each such Letter of Credit,  and (2) in the
                           case of each  other  Letter of Credit  and  Letter of
                           Credit  Guaranty,  the greater of (a) $500 or (b) one
                           and one-half  percent (1.5%) per annum of the undrawn
                           amount of such other  Letter of Credit,  in each case
                           payable in advance  upon the  issuance  of each other
                           Letter of Credit and Letter of Credit Guaranty and on
                           each extension of the stated termination date thereof
                           for so long as such other Letter of Credit and Letter
                           of Credit Guaranty is outstanding; and

                                    (b) the  reasonable  and  customary  charges
                           from time to time of the issuer of such other  Letter
                           of Credit with respect to the issuance, notification,
                           amendment, transfer, administration, cancellation and
                           conversion of, and drawings under,  such other Letter
                           of  Credit,  all of which  shall be payable to Lender
                           for the account of such issuer.

                  All issuance fees in connection with each Letter of Credit and
         Letter of Credit  Guaranty  as set forth in Sections  2.2.3  (i)(a) and
         (ii)(a)  hereof  shall be deemed  fully earned upon the issuance of the
         Letter of Credit and Letter of Credit Guaranty and shall not be subject
         to rebate or proration  upon the  termination of this Agreement for any
         reason."

         1.3      Fixed Bond Letter of Credit Guaranty Reserve.        The   definition   of  "Fixed  Bond
Letter of Credit Guaranty  Reserve" set forth in Appendix A, General  Definitions,  to the Loan Agreement,
is amended in its entirety to read as follows:

                  "Fixed Bond Letter of Credit Guaranty Reserve - for so long as
         the Bond  Letter of Credit and the Bond  Letter of Credit  Guaranty  is
         outstanding,   a  reserve  established  by  Lender  in  the  amount  of
         $1,980,000."

                                                ARTICLE II

                                      REPRESENTATIONS AND WARRANTIES

         The Loan  Parties  each hereby  represents  and  warrants to the Lender
that:



<PAGE>


         2.1 Compliance with the Loan Agreement and Other Loan Documents.  As of
the execution of this Amendment,  each of the Loan Parties is in compliance with
all of the terms and provisions set forth in the Loan Agreement and in the other
Loan  Documents to be observed or performed by each of the Loan Parties,  except
where the  failure of the Loan  Parties to comply has been  waived in writing by
the Lender.

         2.2.  Representations  in Loan Agreement and other Loan Documents.  The
representations  and  warranties  of the  Loan  Parties  set  forth  in the Loan
Agreement  and the other Loan  Documents  are true and  correct in all  material
respects  except  for  changes  in the  nature  of a Loan  Party's  business  or
operations that would render the information in any exhibit attached to the Loan
Agreement either inaccurate, incomplete or misleading, so long as the Lender has
consented to such changes or such changes are not  expressly  prohibited  by the
Loan Agreement.

         2.3.     No Event of Default.  No Default or Event of Default exists.

                                               ARTICLE III

                      MODIFICATION OF LOAN DOCUMENTS; ACKNOWLEDGMENT OF OBLIGATIONS

         3.1  Modification  of Loan Document The Loan  Agreement and each of the
other Loan  Documents  are  amended to provide  that any  reference  to the Loan
Agreement in the Loan  Agreement or any of the other Loan  Documents  shall mean
the Loan Agreement as amended by this Amendment,  and as it is further  amended,
restated, supplemented or modified from time to time.

         3.2. Acknowledgments by the Loan Parties. To induce the Lender to enter
into this  Amendment,  each Loan Party  acknowledges  and agrees with the Lender
that as of the opening of business on December 31, 1997, the aggregate principal
balance owing on the Revolving Loans outstanding under the Loan Agreement was in
the sum of zero,  and the  aggregate  amount of  Letters of Credit and Letter of
Credit Guaranties outstanding was in the sum of $12,485,932.00 and that all such
Obligations  outstanding  are owed to the Lender without any offset,  deduction,
defense or counterclaim of any nature in favor of either Loan Party.

                                                ARTICLE IV

                                                 GENERAL

         4.1.  Full Force and Effect.  As  expressly  amended  hereby,  the Loan
Agreement  shall  continue  in full  force  and  effect in  accordance  with the
provisions  thereof.  As used in the Loan  Agreement,  "hereinafter",  "hereto",
"hereof"  or words of  similar  import,  shall,  unless  the  context  otherwise
requires, mean the Loan Agreement as amended by this Amendment.

         4.2 Applicable  Law. This Amendment  shall be governed by and construed
in  accordance  with the internal  laws and  judicial  decisions of the State of
North Carolina.


<PAGE>


                  Consolidated Adjusted Net
                  Earnings From Operations                                         Per Annum Fee


         4.3  Counterparts.  This  Amendment  may be  executed  in  one or  more
counterparts,  each of which shall constitute an original, but all of which when
taken together shall constitute but one and the same instrument.

         4.4  Expenses.   The  Borrower  shall  reimburse  the  Lender  for  all
reasonable  fees and  expenses  (legal or  otherwise)  incurred by the Lender in
connection  with the  preparation,  negotiation,  execution and delivery of this
Amendment  and  all  other  agreements  and  documents  referred  to  herein  or
contemplated hereby.

         4.5.     Headings.  The  headings in this  Amendment  are for the purpose of  reference  only and
shall not affect the construction of this Amendment.

         4.6 Waiver of Jury Trial. TO THE FULLEST EXTENT PERMITTED BY APPLICABLE
LAW,  THE LOAN  PARTIES AND THE LENDER EACH WAIVES THE RIGHT TO TRIAL BY JURY IN
ANY ACTION,  SUIT,  PROCEEDING  OR  COUNTERCLAIM  OF ANY KIND  ARISING OUT OF OR
RELATED TO THIS AMENDMENT, THE LOAN AGREEMENT OR THE OTHER LOAN DOCUMENTS OR THE
TRANSACTIONS RELATED HERETO OR THERETO.


<PAGE>


         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
executed and delivered on the date first above written.

                                    Borrower:

                                                     ATLANTIC COAST AIRLINES


                                                     By:________________________________________
                                                          Title:__________________________________
ATTEST:

----------------------------
_________ - Secretary

[CORPORATE SEAL]
                                     Parent:

                                                     ATLANTIC COAST AIRLINES, INC.


                                                     By:________________________________________
                                                          Title:__________________________________
ATTEST:

----------------------------
_________ - Secretary

[CORPORATE SEAL]
                                                     Accepted in Charlotte, North Carolina

                                     Lender:

                                                     FLEET CAPITAL CORPORATION


                                                     By:_______________________________________
                                                          Title:___________________________________



<PAGE>
</TABLE>