In the past we've had to rely on rather subjective information from passengers who are often quite ill

Jacqueline Mundell, Virgin Atlantic

She told the BBC: "We can now transmit live medical data down to the ground in real time.

"In the past we've had to rely on rather subjective information from passengers who are often quite ill passing on verbal information to our cabin crew who have to deal with a medical emergency in a very isolated environment."

The equipment, developed by Hampshire-based Remote Diagnostic Technologies (RDT), can monitor pulse, temperature, blood pressure and blood oxygen as well as sending back video pictures of the patient.

The company says non-medical staff can be trained in a few hours.

Direct data

RDT's marketing director, Kate Murphy, says the system will allow ground-based medics to make a reliable diagnosis.

She said: "It allows them to be able to know confidently exactly what is happening in the aircraft and therefore offer a lot more help and guidance to the crew - in terms of very simple things they can do, to either make them more comfortable or actually help the passenger."

Many airlines can already call on advice from the ground by radio or satellite link.

But the new equipment will give doctors direct access to vital data at first hand.

The system will be linked to an international telemedicine centre operated by Medaire in Phoenix, Arizona.

The centre has a database of airports and emergency medical facilities around the world.

British Airways is to install remote cardiac monitors on its long-haul fleet this summer.

American Airlines, the first to trial the transmission of live vital signs, on a test flight from Chicago to Los Angeles in 1997, still has some doubts.

Its spokesman Philip Fleming said: "Until such time as constant communication signals can be guaranteed, American Airlines does not want a passenger's urgent response system based on a programme that has not currently proven to be 100% reliable."

But RDT says it is confident its system can provide reliable global coverage via satellite telephone and says there are only a few small areas, over the poles, where satellite communications will not be able to send back the data.

Virgin Atlantic plans to install the first monitors in April.