Pivotal altitude
The pivotal altitude for eights on pylons at your groundspeed, with the knots-squared over 11.3 rule.
Planning and education aid. Not for primary navigation. Full disclaimer
Experimental: not yet fully verified. How results are checked
The pivotal altitude is 885 ft above the ground.
- kt² / 11.3 rule
- Rule error
Provenance
- Computed by
- aviation.performance.pivotal-altitude 1.0.0, core 0.1.0
- Model
- h = V²/g0 (the line of sight to the pylon is parallel to the lateral axis)
- Accuracy
- Exact for level flight at a steady groundspeed. It changes with groundspeed around the pylon.
- Notes
- 1 shown with the answer
- Cites
- Federal Aviation Administration, Airplane Flying Handbook, FAA-H-8083-3C
Something look off?
How we got thisFormula, worked example, sources, and proof
Model: h = V²/g0 (the line of sight to the pylon is parallel to the lateral axis)
Accuracy: Exact for level flight at a steady groundspeed. It changes with groundspeed around the pylon.
Worked example: 100 kt groundspeed. Source: add-aviation-suite pivotal-altitude scenario: about 885 ft AGL (AFH chapter 6: GS²/11.3). It is golden test vector v001, and every build checks the tool still gives its answer within its tolerance.
You enter
- Groundspeed
- 100 kt
You get
- Pivotal altitude
- 885 ft
- kt² / 11.3 rule
- 885 ft
- Rule error
- 0 ft
Review: Not yet independently reviewed by a flight instructor (CFI).
Last verified: 2026-09-18, when a maintainer last confirmed this tool's sources at the issuer. See the sources ledger.
Status: version 1.0.0, core 0.1.0. See this tool in the verification report.
Checked against: 5 golden test vectors (download the test vectors, each with its source and tolerance). See how results are checked and every source.
Sources
- Airplane Flying Handbook, FAA-H-8083-3C, Federal Aviation Administration, FAA-H-8083-3C. Chapter 3 (turns and load factor), Chapter 6 (ground reference maneuvers, pivotal altitude), and Chapter 18 (emergency glides).
Experimental means this tool has not yet met the stable bar: at least 20 golden vectors, differential tests, and an independent worked example.