FA-69236 / Tide and marine navigation tables / Open access

Light geographic and visible range: Light elevation is not corrected for the tide · case 01

At low water lights are sighted later than predicted.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Charted elevation above MHWS is used without adding mhws-tide.

THE FAILURE

Charted elevation above MHWS is used without adding mhws-tide.

Unsuccessful approach: Adding tide-mhws lowers the light as the tide falls.

Case contract

Input [he, hl, nominal, mhws, tide]: observer height of eye (m), light elevation charted above MHWS (m), nominal range (nm), MHWS and current tide above datum. Effective light height = hl+(mhws-tide). Geographic range = 2.08*(sqrt(he)+sqrt(effective)). Visible range = min(geographic, nominal); the limit is "geographic" when geographic<nominal else "luminous". Return [geo rounded 1, visible rounded 1, limit].

Why this case matters

Tide tables and passage plans turn published predictions into go/no-go decisions about depth, clearance and timing.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    he,hl,nom,mhws,tide=x
    hle=hl
    geo=2.08*(math.sqrt(he)+math.sqrt(hle))
    vis=min(geo,nom)
    lim='geographic' if geo<nom else 'luminous'
    return [round(geo,1),round(vis,1),lim]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('light geographic and visible range [3, 25, 18, 4.5, 1.0]', [3, 25, 18, 4.5, 1.0], [14.7, 14.7, 'geographic']), ('light geographic and visible range [3, 25, 10, 4.5, 1.0]', [3, 25, 10, 4.5, 1.0], [14.7, 10, 'luminous']), ('light geographic and visible range [9, 64, 23, 5.0, 5.0]', [9, 64, 23, 5.0, 5.0], [22.9, 22.9, 'geographic']), ('light geographic and visible range [1.5, 12, 20, 4.0, 0.5]', [1.5, 12, 20, 4.0, 0.5], [10.7, 10.7, 'geographic']), ('light geographic and visible range [16, 36, 20.8, 3.0, 3.0]', [16, 36, 20.8, 3.0, 3.0], [20.8, 20.8, 'luminous']), ('light geographic and visible range [4, 9, 10.4, 2.0, 2.0]', [4, 9, 10.4, 2.0, 2.0], [10.4, 10.4, 'luminous']), ('light geographic and visible range [2, 40, 15, 4.0, 6.0]', [2, 40, 15, 4.0, 6.0], [15.8, 15, 'luminous'])], [('light geographic and visible range [3, 25, 10, 4.5, 1.0]', [3, 25, 10, 4.5, 1.0], [14.7, 10, 'luminous']), ('light geographic and visible range [1.5, 12, 20, 4.0, 0.5]', [1.5, 12, 20, 4.0, 0.5], [10.7, 10.7, 'geographic']), ('light geographic and visible range [16, 36, 20.8, 3.0, 3.0]', [16, 36, 20.8, 3.0, 3.0], [20.8, 20.8, 'luminous']), ('light geographic and visible range [4, 9, 10.4, 2.0, 2.0]', [4, 9, 10.4, 2.0, 2.0], [10.4, 10.4, 'luminous']), ('light geographic and visible range [2, 40, 15, 4.0, 6.0]', [2, 40, 15, 4.0, 6.0], [15.8, 15, 'luminous']), ('light geographic and visible range [12, 80, 30, 5.0, 2.0]', [12, 80, 30, 5.0, 2.0], [26.2, 26.2, 'geographic']), ('light geographic and visible range [5, 5, 6, 3.0, 1.0]', [5, 5, 6, 3.0, 1.0], [10.2, 6, 'luminous'])], [('light geographic and visible range [1.5, 12, 20, 4.0, 0.5]', [1.5, 12, 20, 4.0, 0.5], [10.7, 10.7, 'geographic']), ('light geographic and visible range [2, 40, 15, 4.0, 6.0]', [2, 40, 15, 4.0, 6.0], [15.8, 15, 'luminous']), ('light geographic and visible range [12, 80, 30, 5.0, 2.0]', [12, 80, 30, 5.0, 2.0], [26.2, 26.2, 'geographic']), ('light geographic and visible range [5, 5, 6, 3.0, 1.0]', [5, 5, 6, 3.0, 1.0], [10.2, 6, 'luminous']), ('light geographic and visible range [25, 100, 28, 4.0, 4.0]', [25, 100, 28, 4.0, 4.0], [31.2, 28, 'luminous']), ('light geographic and visible range [4, 16, 12.48, 3.0, 3.0]', [4, 16, 12.48, 3.0, 3.0], [12.5, 12.5, 'luminous']), ('light geographic and visible range [4, 9.174, 10.48, 2.0, 2.0]', [4, 9.174, 10.48, 2.0, 2.0], [10.5, 10.5, 'geographic'])], [('light geographic and visible range [2, 40, 15, 4.0, 6.0]', [2, 40, 15, 4.0, 6.0], [15.8, 15, 'luminous']), ('light geographic and visible range [25, 100, 28, 4.0, 4.0]', [25, 100, 28, 4.0, 4.0], [31.2, 28, 'luminous']), ('light geographic and visible range [4, 16, 12.48, 3.0, 3.0]', [4, 16, 12.48, 3.0, 3.0], [12.5, 12.5, 'luminous']), ('light geographic and visible range [4, 9.174, 10.48, 2.0, 2.0]', [4, 9.174, 10.48, 2.0, 2.0], [10.5, 10.5, 'geographic']), ('light geographic and visible range [3, 25, 18, 4.5, 1.0]', [3, 25, 18, 4.5, 1.0], [14.7, 14.7, 'geographic']), ('light geographic and visible range [3, 25, 10, 4.5, 1.0]', [3, 25, 10, 4.5, 1.0], [14.7, 10, 'luminous']), ('light geographic and visible range [9, 64, 23, 5.0, 5.0]', [9, 64, 23, 5.0, 5.0], [22.9, 22.9, 'geographic'])], [('light geographic and visible range [12, 80, 30, 5.0, 2.0]', [12, 80, 30, 5.0, 2.0], [26.2, 26.2, 'geographic']), ('light geographic and visible range [3, 25, 18, 4.5, 1.0]', [3, 25, 18, 4.5, 1.0], [14.7, 14.7, 'geographic']), ('light geographic and visible range [3, 25, 10, 4.5, 1.0]', [3, 25, 10, 4.5, 1.0], [14.7, 10, 'luminous']), ('light geographic and visible range [9, 64, 23, 5.0, 5.0]', [9, 64, 23, 5.0, 5.0], [22.9, 22.9, 'geographic']), ('light geographic and visible range [1.5, 12, 20, 4.0, 0.5]', [1.5, 12, 20, 4.0, 0.5], [10.7, 10.7, 'geographic']), ('light geographic and visible range [16, 36, 20.8, 3.0, 3.0]', [16, 36, 20.8, 3.0, 3.0], [20.8, 20.8, 'luminous']), ('light geographic and visible range [4, 9, 10.4, 2.0, 2.0]', [4, 9, 10.4, 2.0, 2.0], [10.4, 10.4, 'luminous'])]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
light geographic and visible range [3, 25, 18, 4.5, 1.0]	`[14.0, 14.0, 'geographic']`	`[14.7, 14.7, 'geographic']`	Failed
light geographic and visible range [3, 25, 10, 4.5, 1.0]	`[14.0, 10, 'luminous']`	`[14.7, 10, 'luminous']`	Failed
light geographic and visible range [9, 64, 23, 5.0, 5.0]	`[22.9, 22.9, 'geographic']`	`[22.9, 22.9, 'geographic']`	Passed
light geographic and visible range [1.5, 12, 20, 4.0, 0.5]	`[9.8, 9.8, 'geographic']`	`[10.7, 10.7, 'geographic']`	Failed
light geographic and visible range [16, 36, 20.8, 3.0, 3.0]	`[20.8, 20.8, 'luminous']`	`[20.8, 20.8, 'luminous']`	Passed
light geographic and visible range [4, 9, 10.4, 2.0, 2.0]	`[10.4, 10.4, 'luminous']`	`[10.4, 10.4, 'luminous']`	Passed
light geographic and visible range [2, 40, 15, 4.0, 6.0]	`[16.1, 15, 'luminous']`	`[15.8, 15, 'luminous']`	Failed

SHA-256 / 3aa9ab081413e0cab3a67fff5db38a30ef8c07b30c98ec16ccc1c878a321c20d

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    he,hl,nom,mhws,tide=x
    hle=hl+(tide-mhws)
    geo=2.08*(math.sqrt(he)+math.sqrt(hle))
    vis=min(geo,nom)
    lim='geographic' if geo<nom else 'luminous'
    return [round(geo,1),round(vis,1),lim]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('light geographic and visible range [3, 25, 18, 4.5, 1.0]', [3, 25, 18, 4.5, 1.0], [14.7, 14.7, 'geographic']), ('light geographic and visible range [3, 25, 10, 4.5, 1.0]', [3, 25, 10, 4.5, 1.0], [14.7, 10, 'luminous']), ('light geographic and visible range [9, 64, 23, 5.0, 5.0]', [9, 64, 23, 5.0, 5.0], [22.9, 22.9, 'geographic']), ('light geographic and visible range [1.5, 12, 20, 4.0, 0.5]', [1.5, 12, 20, 4.0, 0.5], [10.7, 10.7, 'geographic']), ('light geographic and visible range [16, 36, 20.8, 3.0, 3.0]', [16, 36, 20.8, 3.0, 3.0], [20.8, 20.8, 'luminous']), ('light geographic and visible range [4, 9, 10.4, 2.0, 2.0]', [4, 9, 10.4, 2.0, 2.0], [10.4, 10.4, 'luminous']), ('light geographic and visible range [2, 40, 15, 4.0, 6.0]', [2, 40, 15, 4.0, 6.0], [15.8, 15, 'luminous'])], [('light geographic and visible range [3, 25, 10, 4.5, 1.0]', [3, 25, 10, 4.5, 1.0], [14.7, 10, 'luminous']), ('light geographic and visible range [1.5, 12, 20, 4.0, 0.5]', [1.5, 12, 20, 4.0, 0.5], [10.7, 10.7, 'geographic']), ('light geographic and visible range [16, 36, 20.8, 3.0, 3.0]', [16, 36, 20.8, 3.0, 3.0], [20.8, 20.8, 'luminous']), ('light geographic and visible range [4, 9, 10.4, 2.0, 2.0]', [4, 9, 10.4, 2.0, 2.0], [10.4, 10.4, 'luminous']), ('light geographic and visible range [2, 40, 15, 4.0, 6.0]', [2, 40, 15, 4.0, 6.0], [15.8, 15, 'luminous']), ('light geographic and visible range [12, 80, 30, 5.0, 2.0]', [12, 80, 30, 5.0, 2.0], [26.2, 26.2, 'geographic']), ('light geographic and visible range [5, 5, 6, 3.0, 1.0]', [5, 5, 6, 3.0, 1.0], [10.2, 6, 'luminous'])], [('light geographic and visible range [1.5, 12, 20, 4.0, 0.5]', [1.5, 12, 20, 4.0, 0.5], [10.7, 10.7, 'geographic']), ('light geographic and visible range [2, 40, 15, 4.0, 6.0]', [2, 40, 15, 4.0, 6.0], [15.8, 15, 'luminous']), ('light geographic and visible range [12, 80, 30, 5.0, 2.0]', [12, 80, 30, 5.0, 2.0], [26.2, 26.2, 'geographic']), ('light geographic and visible range [5, 5, 6, 3.0, 1.0]', [5, 5, 6, 3.0, 1.0], [10.2, 6, 'luminous']), ('light geographic and visible range [25, 100, 28, 4.0, 4.0]', [25, 100, 28, 4.0, 4.0], [31.2, 28, 'luminous']), ('light geographic and visible range [4, 16, 12.48, 3.0, 3.0]', [4, 16, 12.48, 3.0, 3.0], [12.5, 12.5, 'luminous']), ('light geographic and visible range [4, 9.174, 10.48, 2.0, 2.0]', [4, 9.174, 10.48, 2.0, 2.0], [10.5, 10.5, 'geographic'])], [('light geographic and visible range [2, 40, 15, 4.0, 6.0]', [2, 40, 15, 4.0, 6.0], [15.8, 15, 'luminous']), ('light geographic and visible range [25, 100, 28, 4.0, 4.0]', [25, 100, 28, 4.0, 4.0], [31.2, 28, 'luminous']), ('light geographic and visible range [4, 16, 12.48, 3.0, 3.0]', [4, 16, 12.48, 3.0, 3.0], [12.5, 12.5, 'luminous']), ('light geographic and visible range [4, 9.174, 10.48, 2.0, 2.0]', [4, 9.174, 10.48, 2.0, 2.0], [10.5, 10.5, 'geographic']), ('light geographic and visible range [3, 25, 18, 4.5, 1.0]', [3, 25, 18, 4.5, 1.0], [14.7, 14.7, 'geographic']), ('light geographic and visible range [3, 25, 10, 4.5, 1.0]', [3, 25, 10, 4.5, 1.0], [14.7, 10, 'luminous']), ('light geographic and visible range [9, 64, 23, 5.0, 5.0]', [9, 64, 23, 5.0, 5.0], [22.9, 22.9, 'geographic'])], [('light geographic and visible range [12, 80, 30, 5.0, 2.0]', [12, 80, 30, 5.0, 2.0], [26.2, 26.2, 'geographic']), ('light geographic and visible range [3, 25, 18, 4.5, 1.0]', [3, 25, 18, 4.5, 1.0], [14.7, 14.7, 'geographic']), ('light geographic and visible range [3, 25, 10, 4.5, 1.0]', [3, 25, 10, 4.5, 1.0], [14.7, 10, 'luminous']), ('light geographic and visible range [9, 64, 23, 5.0, 5.0]', [9, 64, 23, 5.0, 5.0], [22.9, 22.9, 'geographic']), ('light geographic and visible range [1.5, 12, 20, 4.0, 0.5]', [1.5, 12, 20, 4.0, 0.5], [10.7, 10.7, 'geographic']), ('light geographic and visible range [16, 36, 20.8, 3.0, 3.0]', [16, 36, 20.8, 3.0, 3.0], [20.8, 20.8, 'luminous']), ('light geographic and visible range [4, 9, 10.4, 2.0, 2.0]', [4, 9, 10.4, 2.0, 2.0], [10.4, 10.4, 'luminous'])]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
light geographic and visible range [3, 25, 18, 4.5, 1.0]	`[13.2, 13.2, 'geographic']`	`[14.7, 14.7, 'geographic']`	Failed
light geographic and visible range [3, 25, 10, 4.5, 1.0]	`[13.2, 10, 'luminous']`	`[14.7, 10, 'luminous']`	Failed
light geographic and visible range [9, 64, 23, 5.0, 5.0]	`[22.9, 22.9, 'geographic']`	`[22.9, 22.9, 'geographic']`	Passed
light geographic and visible range [1.5, 12, 20, 4.0, 0.5]	`[8.6, 8.6, 'geographic']`	`[10.7, 10.7, 'geographic']`	Failed
light geographic and visible range [16, 36, 20.8, 3.0, 3.0]	`[20.8, 20.8, 'luminous']`	`[20.8, 20.8, 'luminous']`	Passed
light geographic and visible range [4, 9, 10.4, 2.0, 2.0]	`[10.4, 10.4, 'luminous']`	`[10.4, 10.4, 'luminous']`	Passed
light geographic and visible range [2, 40, 15, 4.0, 6.0]	`[16.4, 15, 'luminous']`	`[15.8, 15, 'luminous']`	Failed

SHA-256 / 199d634c5fb803dd2e9a18350fe4c78163fdf8126662d209b861c02c9c1de632

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 7 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

Verification & scope

A deterministic toy model with stipulated rules and constants; not certified hydrographic software or a substitute for official tide tables. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:48:09.554623+00:00.

Case digest / a2ad66d75fb2fdbbbb26fa44695788e9a40615cf6fde9135cd7914542307e5a8