So-called runway incursions, or two planes mistakenly ending up on the same strip, "most likely account for the largest single safety problem in front of us, " said Mark Rosenker, another former safety board member.

WSJ: The New Frontier in Air Safety

Valarmadhy inches forward, using small tools to clear a strip 1m (40in) wide, digging down to 6in - the accepted safety depth - to ensure there are no mines between herself and the nearest visible mine.

BBC: The women clearing Sri Lanka's mines