NTSB Final Report: The Three-Minute Descent of News Helicopter N606HD

An electronic news-gathering helicopter flew normally for most of the mission before drifting off course and descending into the New Jersey forest.

On December 19, 2023, American Eurocopter AS350B2 N606HD was returning to Philadelphiafter an electronic news-gathering assignment in southern New Jersey. The weather was good, there were no clouds or precipitation along the flightpath, and the helicopter had completed the assignment without any reported anomaly. Yet in the final three minutes, the aircraft drifted from its course, began a gradual descent and accelerated until it struck terrain. The NTSB’s final report could reconstruct the flight precisely but could not determine why the descent began.

Accident Facts

A Routine News Mission

The helicopter departed Northeast Philadelphia Airport at about 19:23 with a pilot and a non-pilot videographer. It flew roughly 44 nautical miles to the assignment area, arriving about 20 minutes later. The crew orbited while collecting video for about 10 minutes. There was no reported abnormality during the outbound flight or while working over the scene.

Turning Back to Philadelphia

After completing the assignment, the crew began the return flight. FAA data showed the helicopter climbing to about 1,000 ft while tracking generally toward Philadelphia. At 19:52, the pilot told ATC that they were done and heading back. The controller offered flight following, but the pilot declined. At 19:59, ATC terminated radar service.

The Course Deviation

About two minutes after radar service ended, the helicopter drifted right of its established course and crossed its earlier outbound track. The deviation was the first objective sign that something had changed. At 20:01:54, the helicopter began descending through 775 ft. Nothing in the radio record indicates that the pilot declared an emergency or reported a mechanical problem.

A Descent That Accelerated

The descent was gradual at first, but the aircraft’s speed increased as altitude decreased. At 20:02:16 it was below 700 ft at more than 93 knots. By 20:03:08 it had descended through 400 ft at 103 knots. Seventeen seconds later it was below 250 ft at 107 knots. The final ADS-B return at 20:03:37 showed 115 knots. The helicopter then struck terrain.

The Weather Was Not the Explanation

The accident occurred at night, but weather conditions were favorable. The nearby observation reported clear conditions, no ceiling, five-knot winds and no precipitation. A model sounding indicated a cloud-free atmosphere below 15,000 ft except for a shallow layer of few clouds near 4,200 ft. The NTSB found no evidence that weather, other traffic or a bird strike caused the accident.

The Aircraft Examination

Investigators found no evidence of a preimpact failure or malfunction in the helicopter, engine or systems that would have prevented normal operation. The absence of a mechanical explanation was important because the final flight path could otherwise have been interpreted as an emergency descent. The wreckage did not establish a system failure that preceded the loss of altitude.

The Pilot and Medical Evidence

The pilot was 68 and had an estimated 8,597 total flight hours, including about 3,584 hours in the AS350 model. The NTSB reviewed medical information including treatment for prediabetes and high blood pressure. Toxicology identified several prescribed medications and chlorpheniramine, which can have impairing effects. Investigators could not establish that the pilot was incapacitated, asleep or impaired, although the flight profile was consistent with possible incapacitation or sleep.

The Investigation’s Hard Limit

The key evidence was the mismatch between the measurable flight sequence and the absence of a proven initiating event. Investigators knew exactly when the aircraft crossed its course, exactly when it began descending and how its groundspeed changed. They could not establish whether the pilot became distracted, fell asleep, suffered a medical event or experienced another cockpit problem.

What the Records Show

The NTSB’s probable cause was the helicopter’s gradual descent and impact with terrain for reasons that could not be determined. The investigation therefore deliberately stops short of assigning a medical, mechanical or operational explanation that the evidence could not support.

Conclusion

N606HD is a reminder that a final report can be highly specific without providing a satisfying answer to every question. The accident sequence is clear: normal news mission, return toward Philadelphia, flight-following declined, radar service terminated, course deviation, descent, accelerating groundspeed and terrain impact. What caused the first deviation and descent remains unknown.

Sources & Reconstruction Note

• https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193546/pdf