15A
1937-MAR-25 · Upper St. Clair Township, Pennsylvania

Transcontinental & Western Air (TWA) — Flight 15A

TWA Flight 15A crashed during its final approach to Allegheny County Airport after heavy ice accumulation on the wings and control surfaces caused a loss of control. The aircraft entered a series of leftward spirals and struck the ground nose-first in a swampy area of Upper St. Clair Township. All 13 people on board were killed, and responders noted a significant layer of ice on the wreckage despite the absence of a post-crash fire.

Aircraft
Douglas DC-2
Registration
NC13730
Phase
Cause
Souls on Board
13
Fatalities
13
Origin → Dest
Camden Airport, New Jersey → Allegheny County Airport, Pennsylvania
Report

Investigation Summary

Flight 15A departed Camden with extra fuel due to concerns about deteriorating weather in Pittsburgh, a decision that required several passengers to be bumped from the flight to remain within weight limits. The flight proceeded normally until reaching the vicinity of Allegheny County Airport. The crew contacted the tower and was instructed to continue west and descend before turning back for a final approach. During this maneuver, the pilot of another TWA flight in the area observed Flight 15A in level flight at a slightly lower altitude. Instead of completing a standard turn, the aircraft began spiraling to the left. The investigation by the Bureau of Air Commerce focused on the severe icing conditions reported by other pilots in the area that evening. Witnesses at the crash site confirmed that the wings and ailerons were coated in ice, which would have severely degraded the aerodynamic performance and controllability of the DC-2.

Final Conclusions

The Bureau of Air Commerce determined the probable cause to be the accumulation of ice on the aircraft's wings and control surfaces, which led to a loss of control during the approach. The severity of the icing was corroborated by testimony from other pilots operating near Pittsburgh at the time of the accident.

Photographic Evidence (1)

DC-2
© FlugKerl2 · Wikimedia Commons

Video Analysis

No video analysis linked for this case file yet.

Systems & Failure Modes

i

Control Surfaces

The ailerons and other movable surfaces were found coated in ice, which likely jammed or severely restricted the pilot's ability to maintain level flight.

i

Wings

Ice accumulation on the leading edges of the wings altered the airfoil shape, increasing stall speed and reducing lift.

Interesting Facts

  • 01The aircraft was a Douglas DC-2, a prominent airliner of the 1930s.
  • 02All 13 people on board, including 10 passengers and 3 crew members, were killed.
  • 03The crash occurred approximately two miles from the Allegheny County Airport.
  • 04Despite the presence of a large amount of fuel, no fire occurred after the impact.
  • 05Other pilots in the area reported significant ice accumulation on their aircraft during the same period.

Safety Actions & Advisories

Icing Research

The accident contributed to the growing body of evidence regarding the dangers of airframe icing, leading to further development of de-icing systems for commercial transports.

Location

Upper St. Clair Township, Pennsylvania · 40.3300, -80.0672

ACCIDENT SITE · Coordinates taken from the wikidata coordinate.

Case File History

  1. New evidenceUpdated sources.

Related Cases

Case ID · twa-15a-1937Last updated · Filed

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