One may involve nitroglycerine gel, a highly explosive substance which could be disguised in shaving or hair gel, and set off using a detonator which could be hidden inside electrical devices like an iPod/MP3 player or cell phone.

However, nitroglycerine is not easily available, and is very unstable.

Another highly potent explosive is triacetone triperoxide, or TATP, which is usually found in the form of a crystalline powder. This powder can be dissolved into a innocent looking liquid that could be carried aboard a plane.

Or, the two chemicals that make TATP could be carried separately and mixed aboard the aircraft.

Other devices that could be used to create a fire or an explosion aboard aircraft are oxidisers used to clean swimming pools or even a combination of ammonium nitrate (used as fertiliser) and diesel fuel.

'There are a lot of homemade mixtures you can concoct from some very common materials that are innocent in themselves,' Andy Oppenheimer, editor, Jane's Nuclear, Biological and Chemical Defence Directory, was quoted as saying in one report.

'We are talking about common, everyday chemicals that are used in perfumes, cosmetics, drain cleaner, batteries, or could for example be stolen from school labs. These materials are easy to obtain and hard to detect, and could be smuggled in small amounts in small containers because it doesn't take much to blow an aircraft up,' he added.

Very few airports in the world have the capability of detecting liquid explosives, particularly if the components are taken aboard separately. Which is why transporting liquids in any form has been banned for passengers travelling to the US from the UK. It is almost certain that this ban will be implemented by airlines the world over very soon.

Clearly, air travel, as we knew it before August 10, will never be the same again.