Delta-V is not an injury measurement
How severely a vehicle was struck and how an occupant was loaded are different questions with different evidence. Restraint hardware answers the second better than any severity number.
Momentum and crush energy: what disagreement between them tells you
Two speed methods with almost no shared inputs. When they converge the result is strong; when they diverge, the divergence is usually telling you something about the collision.
Reading an event data recorder download without overstating it
An EDR is a restraint controller with a short memory, not a flight recorder. What it measured, what it derived, and what it never saw are three different things.
The first week decides a fall case
The spill is mopped in an hour, the shoes go back in a closet, the video overwrites in weeks and the floor is refinished by spring. What preservation actually has to cover.
Trips and stairs are a geometry problem, not a traction problem
A trip is not a slip. Riser uniformity, nosings, handrail continuity and quarter-inch elevation changes are measurable long after any contaminant is gone, and they follow different rules.
Coefficient of friction is a measurement, not a property
A floor does not have a coefficient of friction the way it has a thickness. It has whatever an instrument reported, under one contaminant, with one test foot, on one day.
Reading a derailment: the marks, the geometry and the recorder
A derailment destroys the evidence of its own beginning. What survives — marks on rail and ties, geometry records, the event recorder, and signal and PTC logs — is only as good as the agreement between them.
The pedestrian-case evidence that clears itself away
Scene marks, front-end damage geometry, recorder data, driver-assistance logs and surveillance video all have short lives. What each one answers, what destroys it, and the order preservation should follow.
Conspicuity is a measurement, not an impression
The nighttime pedestrian case turns on detection distance. Contrast against the background, delivered headlamp illumination, lighting uniformity and sightline geometry are all measurable inputs.
What a throw-distance speed estimate can and cannot carry
Throw-distance analysis produces a defensible speed range, not a number. The trajectory family, the friction path and the inferred impact point each move the answer, and each has to be stated.
Stored energy, unexpected startup, and where attribution lands
Energy that was never isolated, came back, or was never recognised as energy at all. How the hierarchy of controls disciplines the argument between machine, procedure and training.
What restarting the line destroys
Controller memory, alarm history, lockout devices and the machine's as-found condition have a short half-life. A working protocol for the first shift after a plant-floor injury.
Reading a defeated guard interlock
A guard fails in one of three distinguishable ways — inadequate by design, removed in service, or defeated at the interlock. Each points at a different party, and each leaves different physical evidence.
Machine, envelope, or rigging: attributing a lift failure
A dropped load can come from a machine defect, from operation outside the chart envelope, or from rigging inadequate for the tension it saw. Each leaves different evidence under different standards.
What recovery destroys at a lift failure scene
Load moment data, rigging hardware, wire rope and the ground beneath the outrigger pads are all perishable. Recovery and site clearance destroy them in a predictable order, and quickly.
What the load chart assumed, and what the ground delivered
A rated capacity chart is a set of conditions, not a number. Configuration, deductions, outrigger reactions and ground bearing capacity each decide whether the figure the crew read off the page applied.
The door that wasn't bolted: Boeing's 737 Max 9 mid-air breach
On January 5, 2024, a door plug blew out of an Alaska Airlines 737 Max 9 at 16,000 feet. The NTSB found four bolts missing — not broken, missing. The case turned a manufacturing defect into a landmark investigation of Boeing's quality-control system.
LaGuardia Runway Collision: A Systems Failure, Not a Material One
On March 22, 2026, a commercial jet collided with a fire truck at LaGuardia Airport, killing two pilots. The NTSB's preliminary report points to a systems gap: emergency vehicles without transponders that an automatic warning system couldn't track.