SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/ifr-approach-lights-100

Using only the approach lights as your visual reference, how low may you descend below DA?

To 100 feet above the touchdown zone elevation.

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  1. 50 feet above touchdown zone elevation
  2. Down to the runway threshold
  3. 100 feet above touchdown zone elevation ✔

Why: 91.175(c)(3) says you cannot go below 100 feet above the touchdown zone elevation using the approach lights as your reference. To go lower, you must also see the red terminating bars or red side row bars.

Huh, didn't know that: The approach lights are just one item on the list of acceptable visual references in 91.175.

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'Sarasota Tower, National 123 with you, guess where?' The controller switched off every airport light: 'National 123, Sarasota Tower, guess where?'
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References

Answer: 100 feet above touchdown zone elevation. 91.175(c)(3) says you cannot go below 100 feet above the touchdown zone elevation using the approach lights as your reference. To go lower, you must also see the red terminating bars or red side row bars.

  1. 14 CFR 91.175 Takeoff and landing under IFR www.law.cornell.edu/cfr/text/14/91.175
    the pilot may not descend below 100 feet above the touchdown zone elevation
    Checked 2026-10-10.

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Test yourself in the game

FlyingA decision altitude (DA) on an approach chart is measured relative to what?FlyingThe authorized DA/DH or MDA for an approach is which of the available values?FlyingBelow DA, which condition must you meet to continue to land?

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