SABENA - Belgian World Airlines, 1923 - 2001. 
-         #1/#1a(diff paper),                        #8/#8a(diff paper),                        #5:

  -           #6,                            #12,                         #4,                               #2:

SABRE Airways, Crawley, UK, 1994-2001 renamed as Excel Airways UK(q.v.). 
     
Safarilink Aviation, Nairobi, Kenya, founded 2004.    -   #1:

SAFI Airways, Kabul, Afghanistan (Registered in Dubai), 2007-2016.  - #4,   #5,   #2,   #1: 

SAFIRAN, Tehran, Iran, founded 1990.      -   #1:

Saha Air Lines, Tehran, Iran, founded 1990.    -   #2,         #3:

SAM,  Medellin / Bogota, Colombia, 1945-2010, as of 2004 subsidary of Avianca.   -  #2:

SAMA LelTayaran Co., Riyadh, Saudi Arabia, 2007-2010 merged into Al Arabiya Airlines. -  #2:

Santa Barbara Airlines, Caracas, Venezuela,  1995-2018.     - #1,             #2:

SAS Scandinavian Airlines System, Stockholm, Sweden, founded 1946.
-       #13,                      #5/#5a(diff paper),         #18/#25(diff paper),                   #3:

-      #7,                                  #16,                             #11,                                  #22:                   

        -       #21,                       #26,                                 #28,                          #15new2023:

SATA, Ponto Delgada, Acores, founded 1990.    -  1,   #5(frame 16,3x9cm),   #7a,     #4:

-   #8/#8a(diff cut),                                    #9,                          #10,                 #10a:

Saudi Arabian Airlines, Jeddah, founded 1946.
#5,                                               #1,                                  #4,                                   #19:

#6/#3/#16(diff paper and maker print),   #20/#23/#28/#28a(diff maker + color),   #24,   #25: 

-   #26(flat base, tear off),    #29(sealed base, no tear off):

Saurya Airlines, Kathmandu, Nepal, founded 2014.   -    #1(front and rear):

Scanair, Bromma, Sweden, 1961-1994 merged with Conair DK to form Premiair DK(q.v.). - 2:

SCAT Airlines, Shymkent, Kazakhstan, founded 1997.     #1:

Scibe Airlift Zaire, Kinshasa, D.R. Congo, 1976-1998.    -   #2:

Scoot, Singapore, founded 2011.    -   #1,           #3:

SEAIR South East Asian Airlines, Manila, Philippines, 1995 - June 2013 renamed to Tigerairways.com.
-    #1,                                                                 #4a,                          #2:

Sempati Air, Jakarta, Indonesia, 1969-1998.    #2:

Sepehran Airlines, Shiraz, Iran, founded 2017.   -   #1:

Servivensa, Caracas, Venezuela, 1990 - 2003.          -  #1:

Seven Four Eight Air Services, Nairobi, Kenya, founded 1994.   -   #1:

Shaheen Air, Karachi, Pakistan,  1994 - 2018.           -  #3,         #4:

Shandong Airlines/Shandong Aviation, Jinan, China, founded 1994:
  -           #4,                 #1(normal paper/#1a(glossy paper),                          #5/#5a/#5b:      

-                                #7,                                         #6:

Shanghai Airlines, China, founded 1985.     #1/#3/#7,     and  #9/#10,     #16  and  #17:

      -              # 13,                  # 14,          #15,                                   #18:

Shenzhen Airlines, China, founded 1992.      
-           # 12 in color variations,          #11,                     #15,                          #13: 

  -               #4,                           #14,                                #6,                                 #7: 

-             #16,                                    #17,                                   #21,                             #19:                               

  -           #18,                                   #18a,                                #18b,                              #20:

-             #26:

Shorouk Air, Cairo, Egypt, 1992-2003.  -   #2(glossy paper):

SIA Singapore Airlines, founded 1947.
       -          #9,                            #4/#5/#12(diff base print),              #6/#10(diff base print):

      -        #21/#22(diff. base),                       #27,                          #29/#30(diff. paper) :

      -       #15 / #17,                                               #2 / #16 / #18 :

Sichuan Airline, Chengdu, China, founded 1986.      -  #3,       #2,         #8,        #9:

-                 #7,                             #6,                        #11,                                #10:

-               #13:

Sichuan Airlines Group SCAL #1:

Siem Reap Airways, Phnom Penh, Cambodia, 2000-2008.      - #1,               #2:

SILK AIR, subsidary of SIA, Singapore, founded 1992 by renaming from Tradewinds*1989.
- #2, #6(clean white normal paper)/#7(eggshell white glossy, bold letters rear)/#8(normal paper):
 
  -              #9,                                   #10:

Silver Cloud Air, Speyer, Germany, founded 1982.   -  #1:

Silverstone Air Services, Nairobi, Kenya, 2013-2019.    -  #1:

Simrik Airlines, Kathmandu, Nepal, founded 2009. 
#- #1(front and rear shown),       #3(sticker on a Guna#2-bag. Guna(q.v.) was taken over 2013 by Simrik):

Sita Air, Kathmandu, Nepal, founded 2003.   -  #1:

SK Telekom, Seoul, South-Korea. Company only aircraft A319 reg HL8080, biz jet in vip config since 2015:

SKY Airline, Santiago de Chile, founded 2001.  - #4,       #5,       #6,         #7/#7a(glossy paper):

Sky Airlines, Antalya, Turkey, 2000-2013.  -   #1,   #2/#3/#5(in small variations), #4:

Sky Angkor Airlines, Siem Reap, Cambodia, founded 2014 by renaming from Skywings Asia. -  #1:

Sky Europe, Bratislava, Slovakia - ceased operations August 31, 2009.    #1    and   younger generic bag:

Sky Express, Heraklion, Crete, Greece, founded 2005.   -  #1,   #2,   #4(glossy-)/#5(normal paper):

SkyJet Airlines (Magnum Air), Manila, Philippines, founded 2012.  -  #1:

SKYMARK Airlines, Ota, Tokyo, Japan,  founded 1998.   -  #3,            #4,         #6:

-     #7:

SNA - Skynet Asia Airways, Miyazaki, Japan, 2002-2011,
(Renamed as SOLASEED Air as of July 2011, q.v.)     -    #1:

Skyservice, Toronto, Canada, 1986-2010.     -   #1:

Skyways, Linköping, Sweden,  1993 - 2012.    -  #1 and #3:

Skyward Express, Nairobi, Kenya, founded 2010.  -   #1:

Sky Work Airlines, Bern-Belp, Switzerland,  1983 - 2018.
                 - #1(front and rear shown),                                                       #2: