Incident Overview

Date: Saturday 28 December 1946
Aircraft Type: Lockheed L-049 Constellation
Owner/operator: Transcontinental & Western Air – TWA
Registration Number: NC86505
Location: 1,5 km WNW of Shannon Airport (SNN) – ÿ Ireland
Phase of Flight: Approach
Status: Destroyed, written off
Casualties: Fatalities: 9 / Occupants: 23
Component Affected: Aircraft’s primary flight control system (altimeter and static system).Aircraft’s primary flight control system (altimeter and static system).
Investigating Agency: CABCAB
Category: Accident
On TWA’s Constellation ‘Cairo Skychief’, a flight from Paris-Orly to New York via Shannon and Gander experienced a catastrophic crash due to an altitude loss caused by a low hill obstructing the pilot’s view. The aircraft lost approximately 150 feet of altitude and struck the ground during a left-hand turn to final approach.On TWA’s Constellation ‘Cairo Skychief’, a flight from Paris-Orly to New York via Shannon and Gander experienced a catastrophic crash due to an altitude loss caused by a low hill obstructing the pilot’s view. The aircraft lost approximately 150 feet of altitude and struck the ground during a left-hand turn to final approach.

Description

TWA’s Constellation “Cairo Skychief” departed Paris-Orly at 23:16 on a flight to New York via Shannon and Gander. The en route portion of the flight was uneventful and at 02:00 Shannon control tower cleared the aircraft for approach to runway 14. At 02:06 the flight reported over the range station at 1,200 feet at which time Shannon Tower advised it that Shannon was reporting 10/10 cloud cover at 400 feet, 4/10 at 250 feet, visibility 1 mile, wind 120 degrees, 5 knots. While turning to the left for final approach to runway 14, the aircraft passed behind a low hill which blocked the airport lights from the pilot’s vision. At the end of a left hand turn to final. During this turn the aircraft lost at least 150 feet of altitude and the left wing tip struck the ground. The plane crashed and caught fire. PROBABLE CAUSE: “An error in altimeter indication, the primary reason for which was the reversal of the primary and alternative static source lines which led the pilot to conduct his approach to the airport at a dangerously low altitude. A contributing factor was the negligence of maintenance personnel in certifying to the satisfactory functioning of the static system although the tests required to determine such a condition were not accomplished. A further contributing factor was the restriction of vision from the cockpit resulting from fogging of the unheated windshield panels.”

Primary Cause

Reversed static source lines leading to an incorrect altitude indication, exacerbated by a lack of testing and certification of the static system.Reversed static source lines leading to an incorrect altitude indication, exacerbated by a lack of testing and certification of the static system.

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