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ASN Wikibase Occurrence # 232993
Last updated: 16 February 2020
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Type:Silhouette image of generic C421 model; specific model in this crash may look slightly different
Cessna 421A
Owner/operator:Knob Hill General Stores, Inc.
Registration: N999MB
C/n / msn: 421A0144
Fatalities:Fatalities: 2 / Occupants: 2
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Location:21 NM N of Nogales, AZ -   United States of America
Phase: En route
Departure airport:Nogales, Arizona
Destination airport:Fresno, California
Investigating agency: NTSB
A Cessna 421A, N999MB, departed Nogales, Arizona, on a noncommercial business flight to Fresno, California. The aircraft crashed in mountainous terrain about 21 nmi north of Nogales. The aircraft was operating on an IFR flight plan.
The pilot was cleared, as filed, to maintain 10,000 ft, to climb VFR until reaching 9,000 ft, and to contact the Tucson departure control. The pilot contacted Tuscon departure control, reported going through 9,000 ft, and stated that he was still VFR. Radar contact had not been established, and the controller cleared the pilot to climb to 11,000 ft in VFR conditions. The pilot stated that he could not climb VFR to that altitude and subsequently stated that he was IFR and would have to descend. Radar contact with the aircraft was then acquired and the controller advised the pilot to turn immediately to avoid the mountain peak in front of him. The pilot stated that he was turning and radar contact was lost shortly thereafter. The aircraft was destroyed and both occupants were killed.

The National Transportation Safety Board determines that the probable cause of the accident was the controllers' issuance of an improper departure clearance, climb restriction,and altitude clearance. The controllers' lack of knowledge and noncompliance with standard ATC procedures placed the aircraft in proximity to high terrain and the pilot lost control of the aircraft for unknown reasons while executing an emergency, controller- directed turn. Contributing to the accident were (1) the inadequacy of official guidelines concerning the use of the published IFR departure procedures, (2) the failure of the departure controller to provide appropriate services, (3) the inability of the flight service specialist to insert the pilot's requested departure route into the ATC fligh t data computer, and (4) the failure of the pilot to check the new departure clearance and route for proper terrain clearance altitudes.



Accident investigation:
Investigating agency: NTSB
Status: Investigation completed
Download report: Final report

Revision history:

16-Feb-2020 11:50 harro Added

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