| Company | Search On | Records | Category | Sub category |
| Israel Aircraft Industries Ltd | IAI | 33 | Aircraft Manufacturers | Non UK |
| International Aeradio Ltd |
IAL | 60 | Airfields | Air Traffic Control |
| International Aviation Services |
IAS | 2 | Air Transport | Airlines |
| IBM UK Ltd | IBM | 1 | Computers | |
| Icelandic Airlines, Loftleidir | Icelandic | 2 | Air Transport | Airlines |
| Imperial Chemical Industries Ltd |
ICI | 117 | Chemicals | Fire Safety |
| I.C.S. International Correspendence Schools | ICS | 16 | Training | Engineering |
| Ilford Ltd | Ilford | 24 | Photography | Film |
| Illingworth & Co Ltd. Thomas | Illingworth | 2 | Photography | Photographic Supplies |
| I.L.O.Oil. W.B.Dick & Co Ltd | ILO | 9 | Lubricant Suppliers | |
| Imber Anti-Fire Tanks Ltd | ImberTanks | 2 | Survival Equipment | Fuel Tanks |
| Imperial Aluminium Co Ltd | Imperial Aluminium | 1 | Manufacturing | Aluminium Alloys |
| Imperial Airways Ltd | ImperialAirways | 116 | Air Transport | Airlines |
| Imperial Light Ltd | ImperialLight | 16 | Airfields | Lighting |
| Impervia Ltd | Impervia | 7 | Manufacturing | Rubber |
| Improved Soldite Company. The | ImprovedSoldite | 1 | Manufacturing | Mouldings |
| Incandescent Heat Company Ltd | Incandescent | 18 | Engineering Equipment | Furnaces |
| Independent Pneumatic Tool Co Ltd | IndependentPneumatic | 8 | Engineering Equipment | Pneumatics |
| Indestructible Paint & Standard Varnish Ltd | Indestructible | 1 | Finishes | Paints |
| British Indestructo Glass Ltd | Indestructo | 3 | Materials | Transparencies |
| Industrial Designs Ltd | IndustrialDesigns | 1 | Fabrication | Jigs |
| Industrial Furnaces Ltd | IndustrialFurnaces | 8 | Engineering Equipment | Furnaces |
| Industrial Rubber Products Ltd | IndustrialRubber | 7 | Materials | Rubber |
| Industrial Tapes Ltd | IndustrialTapes | 6 | Finishes | Paint Spraying |
| Industrial Waste Eliminators Ltd | IndustrialWaste | 4 | Ground Equipment | Recycling |
| Inertia Switch Ltd | InertiaSwitch | 2 | Airfields | Runway |
| Inflight Motion Pictures | Inflight | 2 | Components | Entertainment |
| Infra Red Developments Co Ltd | InfraRed | 1 | Testing | Test Equipment |
| Ingersoll (Mfg.) Ltd | Ingersoll | 2 | Components | Locks |
| Ingham Clark & Co Ltd. Robert | InghamClark | 15 | Finishes | Paints |
| Inner Circle Airlines | InnerCircle | 2 | Air Transport | Airlines |
| Inshaw Accessories Ltd | Inshaw | 3 | Manufacturing | Fairings |
| Instone Air Line | Instone | 9 | Air Transport | Airlines |
| Insulation Equipments Ltd | InsulationEqpt | 17 | Manufacturing | Plastics |
| InsulatorsLtd | Insulators | 1 | Models | Display |
| Insurance. Aviation | Insurance | 5 | Finance | Insurance |
| Intair Ltd | Intair | 2 | Sales & Brokerage | Agency |
| Intava Ltd | Intavia | 15 | Lubricant Suppliers | |
| Integral Auxiliary Equipment Ltd | Integral | 115 | Components | Hydraulics |
| Integral Propeller Co Ltd | IntegralPropeller | 56 | Components | Propellers |
| International Aero Co | InternationalAero | 4 | Aircraft Manufacturers | |
| International Air Lines Ltd | InternationalAirlines | 1 | Air Transport | Airlines |
| International Alloys Ltd | InternationalAlloys | 1 | Materials | Alloys |
| Interocean Airways S.A | Interocean | 2 | Air Transport | Airlines |
| Intra Airways | Intra | 1 | Air Transport | Airlines |
| IOCO Ltd | IOCO | 4 | Materials | Rubber |
| IRA Stephens | IRAStephens | 1 | Engineering Equipment | Hand Tools |
| Irish Air Charter Ltd | IrishAirCharter |
9 | Aircraft Suppliers | Aircraft Sales |
| Irish Biplane. L.E.Bland | IrishBiplane | 1 | Aircraft Manufacturers | |
| Irish Sea Airways | IrishSea | 1 | Air Transport | Airlines |
| Irvin. Irving Air Chute Of Gt Britain Ltd | Irvin | 232 | Survival Equipment | Parachutes |
| Isaacson Engine Company | Isaacson | 3 | Engine Manufacturers | |
| Isopad Ltd | Isopad | 1 | Components | De Icing |
| Iso-Speedic Company | IsoSpeedic | 12 | Components | Controls |
| ITT Federal Laboratories | ITT | 1 | Airfields | Navigation AIds |
| I.V.Pressure Controllers Ltd | IVPressure | 20 | Components | Valves |
