The amount of baggage that does not arrive at Heathrow airport at the same time as its owners has continued to fall, thanks to improved systems.

According to airport operator BAA's results for the six months to 30 June, the baggage misconnect rate at Heathrow has "continued to improve", falling from 20 per 1,000 passengers last year to 17 per 1,000 passengers in 2010. This improvement was in spite of the "effects of prolonged severe winter weather".

In the period covered by BAA's latest results, Heathrow had 30.1 million passengers. This means that around 511,700 passengers were affected by the baggage misconnect in the period, down from 624,000 in 2009.

In June 2009, BAA experienced serious baggage system problems, resulting in the airport not being able to move bags for passengers changing flights at the terminal. IT systems controlling the baggage belts were not ruled out as a cause of the problem.

However, BAA said that baggage misconnect rates have more than halved at Heathrow since 2008.

A spokesperson for the airport operator said: "There are a variety of reasons for this, including the extra capacity created by the opening of Terminal 5 and the relocation of airlines by alliance, reducing the distance transfer bags need to travel. In addition, real-time reporting has enabled better active management of the baggage process."

BAA is investing £900 million in upgrading baggage technology and infrastructure at the airport, so that by 2014, each terminal's baggage systems will be linked via a tunnel. There will also be a new system for the new Terminal 2.

"This will increase the speed and reliability of transfer baggage," the spokesperson said.

In its Capital Investment Plan for 2010, which was published earlier this month, BAA said it was planning to invest £121 million overhauling IT at Heathrow between April 2010 and 2013. As well as upgrading the baggage system, the IT programme includes the vanilla implementation of Oracle E-Business Suite.

The extensive IT changes at Heathrow Airport are part of a £600 million technology transformation programme that also covers its other airports, Stansted, Aberdeen, Southampton, Edinburgh and Glasgow. Last December, it sold Gatwick Airport following a ruling by the competition commission.