Date:	Saturday 16 March 1991
Time:	01:43
Type:	Hawker Siddeley HS-125-1A
Owner/operator:	Prestige Tours
Registration:	N831LC
MSN:	25095
Year of manufacture:	1966
Engine model:	Rolls-Royce Viper 522
Fatalities:	Fatalities: 10 / Occupants: 10
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	15 km NE of San Diego-Brown Field Municipal Airport, CA (SDM) -   United States of America
Phase:	En route
Nature:	Private
Departure airport:	San Diego-Brown Field Municipal Airport, CA (SDM/KSDM)
Destination airport:	Amarillo International Airport, TX (AMA/KAMA)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
Because a late night departure was planned, the HS-125 corporate jet had been positioned at Brown Field (SDM) on the outskirts of San Diego due to a noise curfew in effect at San Diego-Lindbergh field. While waiting for his passengers to arrive, the pilot, who was unfamiliar with local procedures and terrain, had three separate conversations with the local Flight Service Station (FSS). During these conversations, the FSS specialist suggested it would save time if the flight departed under visual flight rules and picked up its IFR clearance once airborne. The pilot indicated reluctance to climb through 3000 ft MSL without an IFR clearance, as that would involve flight into the San Diego Terminal Control Area (TCA) whose 'floor' was 3000 ft MSL. The pilot then stated: " so I would be better off if I headed right northeast and stayed down ... below three thousand." The FSS specialist replied "That’ll be fine." This was a fatal mis-communication: the pilot had been referencing 3000 ft MSL, while the FSS specialist understood the pilot’s altitude reference as 3000 ft above ground level.
The flight took off normally and leveled off at approximately 3300 ft MSL. The pilot had filed an IFR flight plan, but due to a delay in takeoff, this flight plan had expired. Without IFR clearance, the flight could not climb into the San Diego TCA without violating flight rules. Responding to the pilot’s request for IFR clearance, the San Diego TRACON controller indicated N831LC’s flight plan had 'clocked out' but that he would "put it right back in." Shortly afterward, the aircraft impacted Otay Mountain, a 3550 ft MSL peak in the San Ysidro Mountains, approximately 8 NM from the takeoff point. Impact occurred approximately 250ft MSL below the summit on a bearing of 050 deg magnetic, while the aircraft was in cruise configuration.
Because terrain in this location is uninhabited and unlit, the crew of N831LC did not see the mountain until it was too late to avoid impact.

PROBABLE CAUSE: "Improper planning/decision by the pilot, the pilot's failure to maintain proper altitude and clearance over mountainous terrain, and the copilot's failure to adequately monitor the progress of the flight. Factors related to the accident were: insufficient terrain information provided by the flight service specialist during the preflight briefing after the pilot inquired about a low altitude departure, darkness, mountainous terrain, both pilot's lack of familiarity with the geographical area, and the copilot's lack of familiarity with the aircraft."

Investigation of Controlled Flight into Terrain : Descriptions of Flight Paths for Selected Controlled Flight into Terrain (CFIT) Aircraft Accidents, 1985-1997 / Robert O. Phillips, U.S. DoT (DOT-TSC-FA9D1-99-01)
NTSB

photo (c) FAA

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