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| Date: | Thursday 4 April 1991 |
| Time: | 13:10 LT |
| Type: |  Bell 412SP |
| Owner/operator: | Sun Company Inc. |
| Registration: | N78S |
| MSN: | 33114 |
| Year of manufacture: | 1985 |
| Total airframe hrs: | 2739 hours |
| Engine model: | P&W PT6T |
| Fatalities: | Fatalities: 2 / Occupants: 2 |
| Other fatalities: | 5 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | Merion, PA -
 United States of America
|
| Phase: | Approach |
| Nature: | Executive |
| Departure airport: | Williamsport, PA (IPT) |
| Philadelphia, PA (PHL) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
Piper Aerostar 601, N3645D, was arriving as Bell 412 (helicopter), N78S, was departing. N3645D reported the aircraft's nose gear indicator light did not illuminate to verify the nose gear was down & locked. The crew of N78S heard the communication and saw the Aerostar as they crossed beneath it's approach path. They reported N3645D's nose gear appeared to be extended. The Aerostar flew past the tower and tower personnel also reported the nose gear appeared to be extended. As N3645D was cleared to turn downwind, the Bell offered to join for a closer look. The captain of the Aerostar accepted the offer. During joinup, N78S converged from left rear, then reported they would pass around the right side and look at everything as they went by. They reported that everything looked ok.
Moments later, the 2 aircraft collided and crashed to the ground.
None of the piltos had training for flight in close proximity to another aircraft.
Probable Cause:
The poor judgement by the captain of the airplane to permit the in-flight inspection after he had determined to the best of his ability that the nose landing gear was fully extended, the poor judgment of the captain of the helicopter to conduct the inspection, and the failure of the flightcrew of the helicopter to maintain safe separation.
Accident investigation:
 |
|
Sources:
NTSB DCA91MA031
NTSB PB91-910407
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 24-Oct-2008 10:30 | ASN archive | Added |
| 05-Feb-2013 07:41 | TB | Updated [Source, Narrative, ] |
| 21-Dec-2016 19:24 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency, ] |
| 21-Apr-2024 07:21 | ASN Update Bot | Updated [Time, Cn, Operator, Total fatalities, Total occupants, Other fatalities, Phase, Nature, Departure airport, Destination airport, Source, Narrative, Category, Accident report, ] |
| 29-Jan-2025 18:20 | Leepolonez | Updated [Total fatalities, Total occupants, Source, Narrative, ] |
| 29-Jan-2025 18:27 | ASN | Updated [Cn, Departure airport, Destination airport, Narrative, ] |
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