| 801 | QTRI | QUALI-T-RUCK SERVICE, INC | | | SCAC3 |
| 802 | QTRI | QUALI-T-RUCK SERVICE INC | | | SCAC4 |
| 803 | QTRK | QUALITY TRUCKING | | | SCAC4 |
| 804 | QTRP | QUINT TRANSPORT INC | | | SCAC3 |
| 805 | QTRP | QUIROGAS TRANSPORT | | | SCAC4 |
| 806 | QTRQ | QT TRANSPORT | | | SCAC4 |
| 807 | QTRT | QUIJANOS TRANSPORT | | | SCAC4 |
| 808 | QTSA | QUALITY TRANSPORTATION SERVICES INC | | | SCAC4 |
| 809 | QTSC | QUALITY TRANSPORT SERVICE LTD | | | SCAC3 |
| 810 | QTSC | QTS INC | | | SCAC4 |
| 811 | QTSI | QUALITY TRANSPORTATION SERVICES INC | | | SCAC3 |
| 812 | QTSI | QUALITY TRANSPORTATION SERVICES INC | | | SCAC4 |
| 813 | QTSJ | QUALITY TRANSPORT SERVICES OF JACKS | | | SCAC3 |
| 814 | QTSJ | QUALITY TRANSPORT SERVICES OF JACKS | | | SCAC4 |
| 815 | QTSO | QUALITY TRANSFER & STORAGE CO | | | SCAC4 |
| 816 | QTSR | QUALITY TRANSPORTATION SERVICES INC | | | SCAC4 |
| 817 | QTSV | QUALITY TRANSPORTATION SERVICES INC | | | SCAC3 |
| 818 | QTTI | QUALITY TOUR TRANSPORT INC | | | SCAC3 |
| 819 | QTTR | QUALITY TRUCK & TRAILER REPAIR | | | SCAC3 |
| 820 | QTTR | QUALITY LOGISTICS INC | | | SCAC4 |
| 821 | QTTX | TTX Co. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 822 | QTTX | Trailer Train Co. | added 10/1964; 7/1965-10/1966; eliminated 10/1967; 4/1970; eliminated 7/1972; 1/1975-1/1980; added 7/1991; eliminated 1/1992 | | NAKINA |
| 823 | QTTX | Trailer Train Co. | added 10/1964 | | NAKINA |
| 824 | QTTX | Trailer Train Co. (FMS flat cars specially equipped to provide for loading of agricultural equipment) | 7/1965-10/1966; eliminated 10/1967 | | NAKINA |
| 825 | QTTX | Trailer Train Co. (same as OTTX) | 4/1970; eliminated 7/1972 | | NAKINA |
| 826 | QTTX | Trailer Train Co. (no definition) | 1/1975-1/1980 | | NAKINA |
| 827 | QTTX | Trailer Train Co./TTX Co. (heavy capacity special type flats AAR mechanical designations FD and FM ranging in capacity from 110-ton to 245-ton of various lengths) | added 7/1991; 10/1991-1/1994 | | NAKINA |
| 828 | QTTX | TTX Co. (heavy capacity special type flats AAR mechanical designations FD and FM ranging in capacity from 105-ton to 370-ton of various lengths, equipped with end of car cush.) | 7/2000 | | NAKINA |
| 829 | QTTX | Trailer Train Co. | Jul-65 | | NRHS |
| 830 | QTTX | Trailer Train Co. (FMS flat cars specially equipped to provide for loading of agricultural equipment) | 10/66; eliminated 10/67 | | NRHS |
| 831 | QTTX | Trailer Train Co. | Apr-70 | | NRHS |
| 832 | QTTX | Trailer Train Co. (no definition) | 1/75-1/80 | | NRHS |
| 833 | QTTX | Trailer Train Co. | added 7/91; eliminated 1/92 | | NRHS |
| 834 | QTTX | TTX Co. | added 1/92 | | NRHS |
| 835 | QTTX | TTX Co. (heavy capacity special type flats AAR mechanical designations FD and FM ranging in capacity from 110-ton to 245-ton of various lengths) | Jan-94 | | NRHS |
| 836 | QTTX | TTX Co. (heavy capacity special type flats AAR mechanical designations FD and FM ranging in capacity from 105-ton to 370-ton of various lengths, equipped with end of car cush.) | Jul-00 | | NRHS |
| 837 | QTTX | TTX CO. | | | PWRC |
| 838 | QTTX | TTX Corporation | | | RSRV |
| 839 | QTTX | TTX COMPANY | | | SCAC4 |
| 840 | QTUI | Q2U INC | | | SCAC4 |
| 841 | QTUK | Q TRUCKING INC | | | SCAC3 |
| 842 | QTUM | QUANTUM TRANSPORTATION LLC | | | SCAC4 |
| 843 | QTX | Quantex Environmental, Inc. | Callsign: Air Quantex, | CDN | AVCODES |
| 844 | QTX | Quantex Environmental | | | ICAO1 |
| 845 | QTX | General American Transportation Corp. | 7/1937-1/1943 | | NAKINA |
| 846 | QTX | Quaker City Tank Line (General American Tank Car Corp.) | 7/1935 | | NAKINA |
| 847 | QTX | Quaker City Tank Line | 7/1930-7/1932 | | NAKINA |
| 848 | QTX | Quaker City Tank Line (General American Transportation Corp.) | Apr-38 | | NRHS |
| 849 | QTX | QUAKER CITY TANK LINE | | | PWRC |
| 850 | QTXI | QUICK TRUX INC | | | SCAC3 |
| 851 | QTXI | QUEST EXPRESS TRUCKING | | | SCAC4 |
| 852 | QTXL | QUALITY TRANSPORT LLC | | | SCAC4 |
| 853 | QTYS | QUIK-TRIP | | | SCAC3 |
| 854 | QU | Uganda Airlines Corp. | ICAO: UGA, Callsign: Uganda, | EAU | AVCODES |
| 855 | QU | Uganda Airlines Holdings Ltd. | ICAO: UGA, Callsign: Uganda, Name changed from Uganda Airlines Corp. Operations restarted. Ceased operations in October 2000 | EAU | AVCODES |
| 856 | QU | Uganda Airlines Corp. | ICAO: UGA, Callsign: Uganda, Name changed to Uganda Airlines Holdings Ltd. Operations restarted. Ceased operations in October 2000 | EAU | AVCODES |
| 857 | QU | East Afrian Airlines Limited | IATA designator change to QU | EAU | AVCODES |
| 858 | QU | East Afrian Airlines Limited | ICAO: UGX, Callsign: Crane, IATA designator changed from QU* | EAU | AVCODES |
| 859 | QU | East Afrian Airlines Limited | ICAO: UGX, Callsign: Crane, IATA designator changed to QU | EAU | AVCODES |
| 860 | QU | Azur Air Ukraine Airlines LLC | ICAO: UTN, Callsign: UT-Ukraine, IATA Prefix: 761, Name changed from Airline Utair - Ukraine w.e.f. October 2015. | UA | AVCODES |
| 861 | QUA | Quassar de Mexico, S.A. de C.V. | Callsign: Quassar, | MEX | AVCODES |
| 862 | QUAB | QUABOAG TRANSFER INC | | | SCAC3 |
| 863 | QUAC | QUAKER CITY FORWARDERS, INC | | | SCAC3 |
| 864 | QUAD | QUAD CITIES SPOTTING SERVICE | | | SCAC3 |
| 865 | QUADR | QUADRUM BVBA | | BE | VKM |
| 866 | QUAE | QUASAR EXPRESS | | | SCAC3 |
| 867 | QUAF | QUICK AIR FREIGHT INC | | | SCAC3 |
| 868 | QUAF | QUICK AIR FREIGHT INC | | | SCAC4 |
| 869 | QUAI | QUALITY MOVING & STORAGE INC | | | SCAC3 |
| 870 | QUAK | QUAKER TRANSPORT, INC | | | SCAC3 |
| 871 | QUAK | QUAKER TRANSPORT INC | | | SCAC4 |
| 872 | QUAM | QUALITY TEAM 1 | | | SCAC4 |
| 873 | QUAN | QUANDT TANK LINES | | | SCAC3 |
| 874 | QUAN | QUANTUM TRANSPORTATION LTD | | | SCAC4 |
| 875 | QUAO | QUALITY CONTAINER TRANSPORT INC | | | SCAC4 |
| 876 | QUAR | QUARRY TRUCK CO INC | | | SCAC3 |
| 877 | QUAS | QUAST TRANSFER, INC | | | SCAC3 |
| 878 | QUAS | QUAY TRANSPORT SERVICES INC | | | SCAC4 |
| 879 | QUASE | Quadrante Servizi S.r.l. | | I | TRAFFIC |
| 880 | QUAT | QUAKER TRANSIT CO INC | | | SCAC3 |
| 881 | QUAX | Redstreak, LLC | 7/2005 (not listed); added 1/2007 | | NAKINA |
| 882 | QUAX | Quality Rail Services, LLC | added 1/2000; 7/2000; eliminated 4/2001 | | NAKINA |
| 883 | QUAX | Quality Rail Services, LLC | added 1/2000; 7/2000; eliminated 4/2001 | | NRHS |
| 884 | QUAX | *QUALITY RAIL SERVICES, LLC | | | PWRC |
| 885 | QUAX | +REDSTREAK, LLC | | | PWRC |
| 886 | QUAX | Quality Rail Services | | | RSRV |
| 887 | QUAX | REDSTREAK LLC | | | SCAC4 |
| 888 | QUAY | QUALITY COURIER&EXPRESS SERVICE | | | SCAC3 |
| 889 | QUAY | QUALITY COURIER & EXPRESS SERVICE | | | SCAC4 |
| 890 | QUBC | QUEBEC PARCEL SERVICE | | | SCAC3 |
| 891 | QUBM | QUALITY BELT MAINTENANCE LTD | | | SCAC4 |
| 892 | QUBR | QUIN BROS CORP | | | SCAC3 |
| 893 | QUBR | QUALITY SOLUTIONS GROUP LLC | | | SCAC4 |
| 894 | QUBT | QUECKBOERNER TRUCKING INC | | | SCAC3 |
| 895 | QUBU | QUBE CONTAINERS LIMITED | | GB | BIC |
| 896 | QUCA | QUALITY CARTAGE, INC | | | SCAC3 |
| 897 | QUCC | QUEEN CARPET CORP | | | SCAC3 |
| 898 | QUCC | QUALITY DRIVE AWAY INC | | | SCAC4 |
| 899 | QUCD | QUICK DELIVERY CO | | | SCAC3 |
| 900 | QUCF | QUAD CITY FREIGHT SERVICE INC | | | SCAC3 |
