In the Talking Head of May 19 three authors of a paper presented to a recent World Bank conference in Washington DC likened the current state of defined contribution pension planning to the early stages of airplane design, when poorly understood technology led to crashes. They contrasted it with the present state of planning plane journeys, when safe outcomes are largely assured by the underlying engineering and the focus is on choices the travellers themselves make that best suit their preferences.

Ten years ago, similar observations led us to build a model that integrated the planning, accumulation and decumulation phases of personal pensions - the three phases that Messrs Blake, Curtis and Dowd liken to take-off, cruising and landing. We had our own aborted take-offs commercialising the model but for several years it has been used to plan and manage the capital of private clients assigned to a goal with "defined outcomes", the commonest goal being retirement spending.