The Downwind Turn Revisited

In 2018, a Junkers Ju 52 crashed in the Swiss Alps while attempting to cross a 10,000-foot saddle from south to north amid gusting winds.

Peter Garrison

Monday, November 05, 2018 at 11:39 PM ET

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The fatal August crash of a Junkers Ju 52 brings to mind some aspects of downwind turns that are worth discussing. JU-Air

Key Takeaways:

The article debunks the common misconception that an airplane loses airspeed when making a downwind turn in a steady wind, asserting that airspeed is unaffected by steady wind.
The 2018 Ju 52 crash in the Swiss Alps, while its cause is still pending, prompts a discussion on the real dangers posed by strong gusts and turbulence, particularly in mountainous environments.
The actual hazard stems from strong gusts, especially vertical or angled ones relative to the aircraft in a banked turn, which can rapidly increase the angle of attack, potentially leading to a stall.
Pilots should be mindful that steeply banked turns, especially when combined with gusting winds, significantly reduce the stall margin and increase the risk of a gust-induced stall, regardless of whether the turn is "downwind."

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In August 2018, a sightseeing flight crashed in the Swiss Alps, killing all 20 aboard. The airplane, a Junkers Ju 52, was attempting to cross a 10,000-foot saddle from south to north. The wind was out of the north, gusting to 25 knots. Witnesses said the airplane approached the saddle, then banked sharply to the left and suddenly dived to the ground, “as if following a plumb line.”

The official analysis of the accident will not emerge for some time. I don’t have an opinion as to what actually caused it. But the accident did bring to mind some aspects of downwind turns that are worth discussing.