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Altitude Tolerance Survey

What do skydivers judge to be an acceptable error in altitude?

Every jumper has an internal sense of how far off an altitude estimate can be before it becomes unacceptable: a few hundred feet at breakoff, and far less on final approach. Where acceptability ends is a judgment, and not only about safety: it is also about etiquette toward the other jumpers on the load, and about altitude discipline (how tightly one abides by one's planned thresholds). That judgment is what this study attempts to quantify: the tolerance skydivers have for altitude errors at the important thresholds of a skydive; in the survey, skydivers judge short, concrete events on one planned jump, and their judgments, taken together, trace that tolerance.

1planned jump, judged event by event
34judgments per respondent, about eight minutes
7hypotheses, sealed before the first response
Opencollecting responses; results follow the run

Taking part

About eight minutes, anonymous, and no right answers: the data is your judgment. You read about one planned skydive, then see 34 events on it, one at a time, and say whether each is an acceptable deviation from the plan.

Take the survey →

Questions or comments: casey@freefalldatasystems.com.

Why

Tolerance has a computable part and a judged part. Physics sets how much altitude an action consumes; where “acceptable” ends is a judgment, and jumpers disagree about it. A Theory of Skydiving Altitude Indication, the monograph this study belongs to, proposes a model of that tolerance. This study measures the judged tolerance and sets the two side by side. Where they agree, the model holds; where they differ, that is a finding.

How the survey is built and how its answers are analyzed are written down and sealed. They are published with the results, not before, so that nothing on this page steers anyone’s answers.

  • A Theory of Skydiving Altitude IndicationIn preparation The monograph; its section “Quantifying T(A)” will report this study’s result

What we expect

  • Seven hypothesesSealed Oct 15, 2026 Written down before the first response, and kept off this page while the survey is collecting so they cannot steer anyone’s answers. They are published with the results, and the data is free to prove them wrong.

Results

  • The measured tolerance profileTo come The judged boundary at each threshold, drawn over the hypothetical profile
  • What skydivers judge an acceptable altitude error to beTo come The full write-up: method, sample, curves, and what they say about the model

Ethics

The survey is anonymous: no names, emails, USPA numbers or IP addresses. Results are reported only in aggregate. There is no incentive to take part, on purpose: a discount would bring in fast clicks and skew the sample toward people who already own our altimeters. Respondents are reached through instructors, Safety and Training Advisors, and in person at drop zones.

  • Information sheetv0.1 draft What every respondent reads before the first question

Freefall Data Systems LLC · Altitude Tolerance Survey