What is a true statement concerning volcanic ash?

A true statement concerning volcanic ash is that even a thin layer can be detrimental to braking. This is crucial because volcanic ash contains highly abrasive particles that can reduce tire friction on runways. When ash settles on a runway surface, it can create a slippery layer, compromising the ability of aircraft to stop effectively. The small size of the ash particles allows them to infiltrate the braking systems or contact surfaces, further hindering the performance of the brakes, which can lead to safety hazards during landing and takeoff.

In contrast to this correct statement, the other options do not accurately reflect the properties and impacts of volcanic ash. While volcanic ash can impact flight operations at various altitudes, it is particularly concerning at lower levels where aircraft are landing or taking off. The abrasive nature of volcanic ash is generally more severe than sand, which does not account for its hazardous characteristics in aviation contexts. Lastly, managing volcanic ash on runways tends to be complex and challenging, requiring extensive cleanup efforts and specialized equipment to ensure safety.