Mcdonnell Douglas MD-600N accident near Flagstaff, Arizona, November 21, 1996
On November 21, 1996 at about 4:01 pm local time, a Mcdonnell Douglas MD-600N (helicopter), registered N630N, was substantially damaged in an accident near Flagstaff, Arizona (Flagstaff Pulliam airport). It was a flight of an unrecorded kind under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The pilot's inattention to the altitude and inadvertent late entry into an autorotation maneuver below the established minimum test altitude with a helicopter operating at maximum gross weight in a high density altitude environment that led to a subsequent hard landing. Contributing were the lack of positive communications between ground test personnel and the pilot regarding the low altitude, and the lack of accurate in-flight and ground altimeter equipment.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 21, 1996 · about 4:01 pm local time
- Place
- Flagstaff, Arizona · Flagstaff Pulliam · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Mcdonnell Douglas MD-600N
- Registration
- N630N · registry record · serial 0004F
- Damage
- Substantial damage
- Flight
- Flight of an unrecorded kind · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The helicopter was being flight tested to validate certification criteria for height velocity curves at a maximum gross weight and zero airspeed at a high density altitude airport. On the fourth test profile, the pilot allowed the aircraft to descend below the target altitude of 800 feet agl by almost 70 feet. The ground test engineers observed the drift down and didn't advise the pilot because they assumed he had already begun the autorotation after he had made the 3 second call, and also they believed their ground equipment was inaccurate. The pilot delayed the autorotation for about 8 to 12 seconds and then lowered the collective. The aircraft landed hard exceeding the maximum load for the landing gear system. The horizontal speed at touchdown was 52 knots instead of the target speed of 65 knots. The test helicopter was equipped with standard analog altimeters with pointers that have a lag time instead of the more accurate real time digital altimeters.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: helicopter; instrument: airplane; instrument: helicopter; rotorcraft: glider; rotorcraft: helicopter
- Flight time: 10,342 hours in all; 1,194 in this make and model; 113 in the last 90 days; 56 in the last 30 days; 8,145 as pilot in command; 5,001 on instruments
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 1,985 hours
- Last inspection: annual inspection, April 26, 1996; 88 hours since
- Maximum gross weight: 4,100 lb
- Seats: 2
- Landing gear: fixed
- Engine: Allison 250-C47M (turboshaft); 0 hours total
The flight
- Departed from: FLG at 2:50 pm
- Flight plan: none
- Runway 21, 7,000 ft by 150 ft
Weather at the time
- Light: daylight
- Visibility: 50 statute miles
- Sky: clear
- Temperature: 37°F (3°C), dew point 0°F (-18°C)
- Altimeter: 29.00 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Other NTSB records under N630N the same tail number, which may have belonged to a different aircraft at the time
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.