‘HANG ON… THIS CAN'T POSSIBLY BE RIGHT.’

Many drivers describe the same experience. They glance at the satnav and think: ‘Hang on… this can't possibly be right.’

The device wants them to leave a motorway only to rejoin it later. It suggests a route that appears longer than the original journey. It recalculates repeatedly and offers alternatives that do not seem to make sense.

Online discussions show that these experiences are far from rare. Drivers talk about being sent down narrow country lanes, avoiding perfectly sensible routes, or being offered huge detours to save only a minute or two. Others describe ignoring the device, only for the satnav to stubbornly continue with its original plan.

This does not mean that satnavs are poor tools. Modern navigation systems are remarkable. Live Traffic can identify congestion, estimate delays and suggest alternatives using data gathered from thousands of users.

The difficulty is that information is not the same as judgement.

A satnav cannot know whether a driver is nervous, unfamiliar with the area, towing a trailer, driving a large vehicle or simply prefers a straightforward route over a complicated one. It cannot fully understand local conditions or the confidence of the person behind the wheel.

Perhaps the most important decision occurs when the driver and the satnav disagree.

Do you trust the machine, or do you trust your own judgement?

The best answer is usually neither blind obedience nor complete rejection.

Use the satnav for information. Use your experience for decisions.

Technology has changed dramatically over the past decade, but the underlying principle remains the same: navigation is more than following instructions.

Navigation is more than following instructions.