Although best known for investigating airplane crashes, the National Transportation Safety Board is an independent federal agency charged with investigating accidents and making safety recommendations in various transportation modes. Problems on the ground are definitely part of its mission — and one of the most glaring examples is motorcycle fatalities.

Last week, the NTSB issued recommendations to federal agencies and states in the face of an alarming trend. Since 1997, the NTSB reported, motorcycle fatalities nationally have increased by 127 percent. Last year, 4,810 motorcyclists died in crashes, which accounted for more than 10 percent of all motor-vehicle crash fatalities. This is an astounding figure, given that the number of registered motorcycles is a small fraction of the total registered vehicles on the road — roughly 2.5 percent.

To make matters worse, more states have abandoned or relaxed their safety helmet laws — Pennsylvania is one of them — and at the same time motorcycle riding has been gaining in popularity. With the number of fatalities outstripping the increase in ridership, the shame of motorcycle tragedies is that many are avoidable.

This is not rocket science: Head injuries are a leading cause of death in motorcycle crashes — and wearing an approved safety helmet can give riders in a crash a fighting chance of survival. Non-helmeted riders are much more likely to suffer a brain injury compared with those who ride protected.

The NTSB recommendations were all to do with the importance of encouraging helmet use. Unfortunately, only 20 states and the District of Columbia have laws requiring all riders to wear a helmet. Some 27 states have partial laws forcing minors and/or passengers to wear a helmet (Pennsylvania requires them only for novice riders). Three states have no helmet laws at all.

Pennsylvania rescinded its full helmet law in 2003. The number of motorcycle fatalities has risen from 156 in 2003 to 187 last year (although this was down slightly from 2005, when 205 riders died in the state; perhaps Steelers quarterback Ben Roethlisberger’s near-tragedy on a bike scared a few people straight).

The alleged right to ride unprotected by a helmet is usually couched in terms of individual freedom, but often a needless death takes a group toll and a public cost. Police, paramedics and emergency-room physicians are strained; children, surviving spouses and parents grieve. And all because legislators across the country are cowed to offend a vocal minority who want the freedom to be stupid.

The NTSB’s recommendations should be heeded. An agency that often investigates plane crashes sees folly taking off on the ground.