1. Accident of being locked up in elevators by the Tokyo earthquake
At the Tokyo earthquake on 23rd of April there occurred 78casese in which people who were in elevators were locked in the elevators for some hours and in 73 cases of them the elevators had control equipment which could stop the nearest floor detecting preliminary tremor of an earthquake, but they did not work.
The true cause is still unknown but design changes of the equipment will be inevitably necessary.

2. Relations with design validation of the equipment
The earthquake turned out to be design validation of the equipment.
“ISO9001 for Small Business, What to do; Advice from ISO/TC176” says about 7.3.6 Design and development validation as follows.

“For other types of products and services, validation of the total performance range might not be achieved until the actual conditions occur. The performance at the extremities of the design range might never be validated.”

The makers might do some forms of validation by simulation tests or so. But actual tests were impossible.
The accident has taught us the advice is correct.

3. Design and development validation for non-repetitive product type
Machine makers, who design, make and install machines at customers’ sites, are often finish design and development validation of the design after finishing operation tests at the sites.
Therefore, responsible designers often witness the tests. Some design modifications will happen at the sites. Such modifications should not be handled as customers’ claims, but as design changes.