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Helicopter Accident After Photo Flight Involves Retreating Blade Stall (N2473B)

S. SN Francisco, CA, US

On July 2, 1993, a Bell 47G2-M (registration N2473B) was involved in an aviation accident near S. SN Francisco, CA. Investigators recorded the probable cause as: THE PILOT'S INADEQUATE PREFLIGHT PLANNING/PREPARATION WHICH RESULTED IN FLIGHT INTO HIGH WINDS, TURBULENCE AND WINDSHEAR. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-07-04Data APIEditorial standards

A helicopter returning from a local photo flight pitched up and nosed over into impact, a sequence characteristic of retreating blade stall, as variable 50 mph winds and severe wind shear affected operations at San Francisco International Airport.

Accident Sequence

A helicopter was returning from a local area photo flight when witnesses observed it pitch up and then nose over into the ground. The sequence of events was characteristic of a retreating blade stall.

Witness Reports

Witnesses reported that the helicopter pitched up and subsequently nosed over to impact. No further details about the witnesses' observations were provided.

Wind Conditions

The prevailing wind at the time was reported to be extremely variable at about 50 miles per hour. The wind conditions were associated with severe wind shear.

Airport Operations

Between 1530 and 1630, 25 airplanes, mostly large airline transport category aircraft, executed missed approaches at San Francisco International Airport (SFO) due to the severe wind shear conditions. The helicopter accident occurred in the same timeframe and vicinity.

Weather

Frequently asked questions

What happened in the 2 Jul 1993 Bell 47G2-M accident near S. SN Francisco, CA?

A helicopter returning from a local photo flight pitched up and nosed over into impact, a sequence characteristic of retreating blade stall, as variable 50 mph winds and severe wind shear affected operations at San Francisco International Airport.

What aircraft was involved and where did it happen?

The accident on 2 Jul 1993 involved a Bell 47G2-M, registration N2473B, at S. SN Francisco, CA.

What was the probable cause of the accident?

THE PILOT'S INADEQUATE PREFLIGHT PLANNING/PREPARATION WHICH RESULTED IN FLIGHT INTO HIGH WINDS, TURBULENCE AND WINDSHEAR.

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001211X12930. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.