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Exhibit 10.8 CERTAIN IDENTIFIED INFORMATION HAS BEEN EXCLUDED FROM THE EXHIBIT BECAUSE IT IS BOTH NOT MATERIAL AND IS THE TYPE THAT THE REGISTRANT TREATS AS PRIVATE OR CONFIDENTIAL. OMITTED INFORMATION HAS BEEN REPLACED WITH XXXXXXXXX. Supplemental Agreement No. 4 to Purchase Agreement No. 03776 between The Boeing Company and United Airlines, Inc. Relating to Boeing Model 737-9 Aircraft THIS SUPPLEMENTAL AGREEMENT, entered into as of June 12, 2015, by and between THE BOEING COMPANY (Boeing) and UNITED AIRLINES, INC. (a Delaware corporation formerly known as Continental Airlines, Inc. and successor by merger to United Air Lines, Inc.) (Customer); WHEREAS, the parties hereto entered into Purchase Agreement No. 03776 dated July 12, 2012, as amended and supplemented (Purchase Agreement), relating to the purchase and sale of Boeing model 737-9 aircraft (Aircraft). This Supplemental Agreement is an amendment to the Purchase Agreement; WHEREAS, Boeing and Customer agree to *** the following *** firm model 737-9 Aircraft and *** them with *** new model 737-9 *** Aircraft in the same delivery months: Aircraft Delivery Month MSN *** *** WHEREAS, Boeing and Customer agree to apply *** firm model 737-9 Aircraft *** under this Supplemental Agreement No. 4 *** for the *** new model 737-9 *** Aircraft added under this Supplemental Agreement No. 4 and *** Customer's *** for 737 aircraft. UAL-PA-03776 SA-3 Page 1 BOEING / UNITED AIRLINES, INC. PROPRIETARY �              ! !" ! #    $   !  !"   !    "       #%&'  ( # ) "  ! * ( # )+ ! "" ! ! ! , "  " %!   " * ( # )+ -!"!#!" (, *�./+01  (* ( '+ 23245 67898:;< =>?7@>8AB =>C987D<7EFB G879> :FH 6H@:F9> G:AI>F<C ! "" ! ! ! , "  " %!   " * ( '+ 23245 67898:;< =>?7@>8AB =>C987D<7EFB G879> :FH 6H@:F9> G:AI>F<C -!"!#!" (, *�./+0 J  *    K)...J.'1//+ ! "" ! ! ! , "  " %!   " *    K)...J.'1//+ -!"!#!" (, *�./+0      %! ( ""  ( "   L  !  $!""  #  "   # "   "%! ! ! # #  " #M)KN O NKJO)  #  " , " , #!  % ! ($ PQR STRUVW XTYZ[V\ ]VUPR̂ [U_̀ UVRab UVXcdd   !e fg$, dd h " J "  �!   �!   ,.!.  �! i!  !" j !     "     ! ! KX.x. �./   1STRUVW k ]VUPR̂ [U_̀ UVRab UVXc Z_TZ_URP[_\ �  � �    �    !!"#$  %  "&'(! )  * +  *, -  !! .,# �    /0/ , .123)345  6789�    /: /;  <  /"&=>,#!=#$ #1# ??  �89� @  @# !A#,B/,!C$ D# <D@  <D@E1# :'  :# ,'$$ E1# @@  @;FGGG 'H*  '&H/* : ,$ # ��I  �  J:K4*4L)33M4H4%L3M)3  GGG# J:K4*4L)33M4H4%L3M)N  GGG J:K4*4L)33M4H4%L3M+L  ", # D;(F& J:K4*4L)33M4H4%L3M+)  C$# J:K4*4L)33M4H4%L3M++  C$ /  67J:K4*4L)33M4H4%L3M+M  * ,  '$$  J:K4*4L)33M4H4%L3M+3  '*(#!@>$, J:K4*4L)33M4H4%L3M+5  '$*#0* &# ; J:K4*4L)33M4H4%L3M-L  '$# J:K4*4L)33M4H4%LNL--  GGG J:K4*4L)33M4H4%LN%%  GGG J:K4*4L)33M4H4%LN%)  GGG# J:K4*4L)33M4H4%LN-3  GGG J:K4*4L)33M  .<H@CD:CO.@O.'  '4+*; /% IP �Q R S??�T �  � �  �    �� � !"##$% &'!('") *+,+-./.0120324+0.25+1-615.*7  !"##$% &'!(89$ :; 615.*7  !"##$% &'!('"( 77+/2<.25615.*7  !"##$% &'!(($9 =.-+,.*>???615.*7  % !"#()% &'!#($9 #"#*30@A5+32 0B@75<.257   � CC � � D@EE-.<.251- /*..<.25F3G&  H@2.&#I'!&"D@EE-.<.251- /*..<.25F3G' H12@1*>&)I'!&8D@EE-.<.251- /*..<.25F3G"  61>'$I'!&8JJKLMKNOL PQR  STUUVTW !"##$  ; X%YZ[ZF;YF;D  D )I1/.'34' \ �   PCC �]

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