Ambulance London Service - Computer Aided Dispatch (LAS-CAD) project was designed to automate many of the human-intensive processes of manual dispatch systems associated with ambulance services in the UK. The LASCAD system was built as an event-based system using a rule-based approach in interaction with a geographical information system (GIS) running under Microsoft Windows. The GIS communicated with Datatrak's automatic vehicle tracking system. The system ran on a series of network PCs and file severs supplied by Apricot. The major rationale expressed for such computerization was that a number of problems existed with the manual CAD system. The basic functionality of the intended LAS-CAD system was as follows: British Telecom (BT) operators would route all 999 calls concerning medical emergencies as a matter of routine to LAS headquarters. 18 HQ 'receivers' were then expected to record on the system the name, telephone number and address of the caller, and the name, destination address and brief details of the patient. This information would then be transmitted over a local area network and pinpoint the patient's location on a map display of areas within London. The system was expected to continuously monitor the location of every ambulance via radio messages transmitted by each vehicle every 13 seconds. The system would then determine the nearest ambulance to the patient. Experienced ambulance dispatchers would be organized into teams based on three zones (south, north-west and north-east). Ambulance dispatchers would be offered details of the three nearest ambulances by the system and the estimated time each would need to reach the scene. The dispatcher would choose an ambulance and send patient details to a small terminal screen located on the dashboard of the ambulance. The crew would then be expected to confirm that it was on its way. If the selected ambulance was in an ambulance depot then the dispatch message would be received on the station printer. The ambulance crew would always be expected to acknowledge a message. The system would automatically alert HQ of any ambulance where no acknowledgement was made A follow up message would then be sent from HQ. The system would detect from each vehicle's location messages whether an ambulance was heading in the wrong direction. The system would then alert controllers. Further messages would tell HQ when ambulance the crew had arrived, when it was on its way to a hospital and when it was free again. The system was loaded and started-up on 26 October 1992. As the number of ambulance incidents increased that day, the amount of incorrect vehicle information recorded by the IT increased. This had a knock-on effect in that the IT automatically made incorrect allocations on the basis of the data it had. For example, multiple vehicles were sent to the same incident, or the closest vehicle was not chosen for dispatch. As a consequence, the 'receivers' had fewer ambulance
resources to allocate. For some reason the software program began placing calls that had not gone through the appropriate protocol on a waiting list which generated exception messages. The number of exception messages increased to such an extent that the staff were not able to clear the queue of calls. It became increasingly difficult for staff to attend to calls that had scrolled off the screen. The increasing size of the call queue slowed the technology. At the receiving end, patients became frustrated with the delays to ambulances arriving at incidents. This led to an increase in the number of calls made back to the LAS HQ relating to already recorded incidents. The increased volume of calls, together with a slow system and an insufficient number of 'receivers', contributed to significant delays in answering calls which, in turn, caused further delays to patients. At the ambulance end, crews became increasingly frustrated at incorrect allocations. This may have led to an increased number of instances where crews failed to use the technology correctly. Crew frustration also seems to have contributed to a greater volume of voice radio traffic. This in turn contributed to the rising radio communications bottleneck. In addition, it was claimed that a reorganization of sector desks over the preceding weekend may have caused loss of local knowledge. Claims were later made in the press that up to 20-30 people may have died as a result of ambulances arriving too late on the scene. The LAS chief executive, John Wiley, resigned within a couple of days of the events described above. A Public Inquiry Report presented the findings of an investigation into the London Ambulance Service Computer Aided Dispatch System failure (this case is taken and adapted from http://www.lasunofficial.co.uk/cad.html).