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I.L.A.F.F.T.: The Glide Slope

A faulty glideslope connection fools a pilot into following the instrument's needle almost into the ground.

Credit: Joel Kimmel
Gemini Sparkle

Key Takeaways:

  • A pilot narrowly avoided a crash during an ILS approach when a faulty glideslope indicator, appearing centered, led them astray and nearly into trees.
  • The glideslope malfunction was caused by a disconnected wire during a recent GPS installation, which falsely made the needle appear centered and active.
  • The incident underscores the crucial lesson that the mere appearance of an instrument's needle does not guarantee its validity, emphasizing the need for pilots to understand failure modes and question suspicious indications.
See a mistake? Contact us.

It was 2001, and an IFR-approved panel-mounted GPS had just been installed in my airplane, a Cessna 180. I was anxious to see it in action with its moving map, multitude of functions, and the information it provided. A short 20-minute flight to a nearby airport for breakfast with a friend and some hands-on use of the new equipment was in order.

The weather at the breakfast airport that morning was not VFR because there was a low marine stratus layer. The AWOS reported instrument conditions, with a 300-foot overcast but reasonable visibility of 4 miles below the cloud deck. Because I pride myself by staying instrument current, this would help me stay current.

Alen Hewitt

Alen Hewitt flew U-8s in Vietnam and is a retired electrical engineer who owns a 1966 Cessna 180.

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