Socata TB-10 N20BN

Summary

On 23 August 1992 at about 00:00 local time, a Socata TB-10 registered N20BN, operated by General Aviation Company, was involved in an accident near Big Bear, California, United States. 4 people were on board and 4 had minor injuries. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

23 August 1992 at 00:00

Classification

Accident

Location

Big Bear, California, United States

Coordinates

34.2596, -116.8401

Aircraft

Socata TB-10

Registration

N20BN

Category

Airplane

Engines

1

Operator

General Aviation Company

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Unknown → Fullerton

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

LAX92LA360

4 people had minor injuries.

THE PILOTS DECISION TO ATTEMPT CROSSING A RIDGE LINE AT AN ALTITUDE INSUFFICIENT TO ALLOW FOR CONTINGENCY ACTIONS IN THE EVENT OF AN ENCOUNTER WITH DOWN DRAFTS OR TURBULENCE. FACTORS IN THE ACCIDENT WERE THE HIGH DENSITY ALTITUDE AND THE FLIGHT'S ENCOUNTER WITH A DOWN DRAFT.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

IN HIS WRITTEN STATEMENT THE PILOT SAID THAT AFTER DEPARTURE ON RUNWAY 25 HE TURNED IN A SOUTHWEST DIRECTION TO CROSS A RIDGE LINE AT AN ALTITUDE OF ABOUT 7,900 FEET MSL. HE SAID THAT NEAR THE RIDGE LINE THEY ENCOUNTERED A SUDDEN DOWN DRAFT AND HE COULD NOT ARREST THE DESCENT PRIOR TO COLLIDING WITH TREES. AN EYE WITNESS TO THE CRASH SAID THE AIRCRAFT NEVER ACHIEVED MORE THAN ABOUT 300 FEET AGL AT ANY TIME AFTER TAKEOFF. THE WITNESS OBSERVED THE AIRCRAFT IN A NOSE HIGH ATTITUDE BEGIN A RIGHT TURN, THEN IT DESCENDED BELOW THE TOPS OF SOME TREES AND OUT OF VIEW. TWO OTHER WITNESSES REPORTED HEARING THE SOUNDS OF A LOUD AND STRONG ENGINE UNTIL THE SOUNDS OF TREE IMPACTS WERE HEARD. THE AIRPORT IS IN A MOUNTAIN VALLEY AT AN ELEVATION OF 6,750 FEET. MOUNTAIN RIDGES AND PEAKS RISE AN AVERAGE OF 2,000 FEET ABOVE THE VALLEY FLOOR ON ALL SIDES OF THE AIRPORT. THE AIRPORT IS AT THE EAST END OF THE VALLEY AND A LARGE LAKE. A DAM IS AT THE WEST END OF THE VALLEY AT A 'V' NOTCH IN THE SURROUNDING MOUNTAINS. WEST OF THE DAM THE TERRAIN DROPS OFF RAPIDLY TO THE GREATER LOS ANGELES BASIN. THE DENSITY ALTITUDE WAS CALCULATED TO BE ABOUT 9,400 FEET. OTHER PILOTS WHO DEPARTED FROM THE AIRPORT REPORTED THAT TURBULENCE EXISTED OVER THE VALLEY NEAR THE SURROUNDING RIDGES.

Quoted verbatim from the NTSB record.