The BBC explains the role of the altimeter in the recent crash at Schiphol airport:

At a news conference in The Hague, [Dutch Safety Board chairman] Mr Van Vollenhoven said the plane had been at an altitude of 595m (1950ft) when making its landing approach to Schiphol airport.

But the altimeter recorded an altitude of around ground level.

The plane was on autopilot and its systems believed the plane was already touching down, he said.

The automatic throttle controlling the two engines was closed and they powered down. This led to the plane losing speed, and stalling.

As many times as people ask me if I can generate security products that “automate” controls, I find news like this reminding me that there will always (at least for the foreseeable future) be a place for human oversight by trained professionals. Unfortunately in this case the pilots ignored the alarms and continued to let the autopilot control the engines until it was too late to restart them.