{"abstract":"Loads placed precisely on the sloped forward boundary are reported FWD.","category":"Aviation weight and balance","checks":13,"contract":"Input [weight lb, CG in, 'normal'|'utility']. Below 1500 lb -> 'ERR_BELOW_EMPTY'. Max weight 2550 normal / 2200 utility -> 'OVERWEIGHT' first. Forward limit 35.0 in up to 1950 lb then linear to 41.0 in at 2550 lb; aft limit 47.3 normal / 40.5 utility. Limits inclusive; else 'FWD','AFT','IN'.","contract_signature":"x","evaluation_group":"w2-aviation-weight-balance-cg-envelope","failed_approach":"Rounding the interpolated limit to a whole inch shifts the sloped boundary instead of making it inclusive.","family":"w2-aviation-weight-balance-cg-envelope-forward-line-inclusive","id":"FA-65866","implementations":{"attempt":{"sha256":"04d4841c91af0c1786cc5820b78612086e344d827a5ab61d4c0dad099c7eb156","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    w, cg, cat = x\n    if w < 1500: return 'ERR_BELOW_EMPTY'\n    maxw = 2550 if cat == 'normal' else 2200\n    if w > maxw: return 'OVERWEIGHT'\n    if w <= 1950:\n        fwd = 35.0\n    else:\n        fwd = 35.0 + (w - 1950) * (41.0 - 35.0) / (2550 - 1950)\n    aft = 47.3 if cat == 'normal' else 40.5\n    if cg < round(fwd): return 'FWD'\n    if cg > aft + 1e-9: return 'AFT'\n    return 'IN'\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['mid-envelope normal', [2110, 42.0, 'normal'], 'IN'], ['on sloped forward line', [2250, 38.0, 'normal'], 'IN'], ['on aft limit utility', [2000, 40.5, 'utility'], 'IN'], ['utility overweight but normal legal', [2301, 42.0, 'utility'], 'OVERWEIGHT'], ['exactly max gross normal', [2550, 41.0, 'normal'], 'IN'], ['forward of sloped line', [2400, 39.1, 'normal'], 'FWD'], ['aft of utility limit', [2100, 41.1, 'utility'], 'AFT'], ['below empty weight', [1499, 40.0, 'normal'], 'ERR_BELOW_EMPTY'], ['exactly empty weight', [1500, 36.0, 'utility'], 'IN'], ['sampled case 1', [2415, 48.96, 'normal'], 'AFT'], ['sampled case 2', [2550, 34.9, 'normal'], 'FWD'], ['sampled case 3', [1950, 42.86, 'utility'], 'AFT'], ['regression: forward limit comparison', [2200, 37.88, 'normal'], 'IN']], [['mid-envelope normal', [2120, 42.0, 'normal'], 'IN'], ['on sloped forward line', [2250, 38.0, 'normal'], 'IN'], ['on aft limit utility', [2000, 40.5, 'utility'], 'IN'], ['utility overweight but normal legal', [2302, 42.0, 'utility'], 'OVERWEIGHT'], ['exactly max gross normal', [2550, 41.0, 'normal'], 'IN'], ['forward of sloped line', [2400, 39.2, 'normal'], 'FWD'], ['aft of utility limit', [2100, 41.2, 'utility'], 'AFT'], ['below empty weight', [1498, 40.0, 'normal'], 'ERR_BELOW_EMPTY'], ['exactly empty weight', [1500, 36.0, 'utility'], 'IN'], ['sampled case 1', [1950, 37.89, 'utility'], 'IN'], ['sampled case 2', [2561, 48.01, 'normal'], 'OVERWEIGHT'], ['sampled case 3', [2550, 45.7, 'normal'], 'IN'], ['regression: forward limit comparison', [2200, 37.87, 'utility'], 'IN']], [['mid-envelope normal', [2130, 42.0, 'normal'], 'IN'], ['on sloped forward line', [2250, 38.0, 'normal'], 'IN'], ['on aft limit utility', [2000, 40.5, 'utility'], 'IN'], ['utility overweight but normal legal', [2303, 42.0, 'utility'], 'OVERWEIGHT'], ['exactly max gross normal', [2550, 41.0, 'normal'], 'IN'], ['forward of sloped line', [2400, 39.3, 'normal'], 'FWD'], ['aft of utility limit', [2100, 41.3, 'utility'], 'AFT'], ['below empty weight', [1497, 40.0, 'normal'], 'ERR_BELOW_EMPTY'], ['exactly empty weight', [1500, 36.0, 'utility'], 'IN'], ['sampled case 1', [1950, 34.67, 'utility'], 'FWD'], ['sampled case 2', [1500, 42.58, 'utility'], 'AFT'], ['sampled case 3', [2200, 48.0, 'utility'], 'AFT'], ['regression: forward limit comparison', [2200, 37.5, 'utility'], 'IN']], [['mid-envelope normal', [2140, 42.0, 'normal'], 'IN'], ['on sloped forward line', [2250, 38.0, 'normal'], 'IN'], ['on aft limit utility', [2000, 40.5, 'utility'], 'IN'], ['utility overweight but normal legal', [2304, 42.0, 'utility'], 'OVERWEIGHT'], ['exactly max gross normal', [2550, 41.0, 'normal'], 'IN'], ['forward of sloped line', [2400, 39.4, 'normal'], 'FWD'], ['aft of utility limit', [2100, 41.4, 'utility'], 'AFT'], ['below empty weight', [1496, 40.0, 'normal'], 'ERR_BELOW_EMPTY'], ['exactly empty weight', [1500, 36.0, 'utility'], 'IN'], ['sampled case 1', [2200, 42.7, 'normal'], 'IN'], ['sampled case 2', [1969, 47.53, 'normal'], 'AFT'], ['sampled case 3', [1500, 48.2, 'normal'], 'AFT'], ['regression: forward limit comparison', [2200, 37.64, 'normal'], 'IN']], [['mid-envelope normal', [2150, 42.0, 'normal'], 'IN'], ['on sloped forward line', [2250, 38.0, 'normal'], 'IN'], ['on aft limit utility', [2000, 40.5, 'utility'], 'IN'], ['utility overweight but normal legal', [2305, 42.0, 'utility'], 'OVERWEIGHT'], ['exactly max gross normal', [2550, 41.0, 'normal'], 'IN'], ['forward of sloped line', [2400, 39.5, 'normal'], 'IN'], ['aft of utility limit', [2100, 41.5, 'utility'], 'AFT'], ['below empty weight', [1495, 40.0, 'normal'], 'ERR_BELOW_EMPTY'], ['exactly empty weight', [1500, 36.0, 'utility'], 'IN'], ['sampled case 1', [1950, 45.06, 'normal'], 'IN'], ['sampled case 2', [2200, 43.63, 'utility'], 'AFT'], ['sampled case 3', [2200, 41.43, 'normal'], 'IN']]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"4e81319dc8b94d4cfd2a4639597cde7baec8f22442f76dc115aabd9d1e47028d","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    w, cg, cat = x\n    if w < 1500: return 'ERR_BELOW_EMPTY'\n    maxw = 2550 if cat == 'normal' else 2200\n    if w > maxw: return 'OVERWEIGHT'\n    if w <= 1950:\n        fwd = 35.0\n    else:\n        fwd = 35.0 + (w - 1950) * (41.0 - 35.0) / (2550 - 1950)\n    aft = 47.3 if cat == 'normal' else 40.5\n    if cg <= fwd: return 'FWD'\n    if cg > aft + 1e-9: return 'AFT'\n    return 'IN'\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['mid-envelope normal', [2110, 42.0, 'normal'], 'IN'], ['on sloped forward line', [2250, 38.0, 'normal'], 'IN'], ['on aft limit utility', [2000, 40.5, 'utility'], 'IN'], ['utility overweight but normal legal', [2301, 42.0, 'utility'], 'OVERWEIGHT'], ['exactly max gross normal', [2550, 41.0, 'normal'], 'IN'], ['forward of sloped line', [2400, 39.1, 'normal'], 'FWD'], ['aft of utility limit', [2100, 41.1, 'utility'], 'AFT'], ['below empty weight', [1499, 40.0, 'normal'], 'ERR_BELOW_EMPTY'], ['exactly empty weight', [1500, 36.0, 'utility'], 'IN'], ['sampled case 1', [2415, 48.96, 'normal'], 'AFT'], ['sampled case 2', [2550, 34.9, 'normal'], 'FWD'], ['sampled case 3', [1950, 42.86, 'utility'], 'AFT'], ['regression: forward limit comparison', [2200, 37.88, 'normal'], 'IN']], [['mid-envelope normal', [2120, 42.0, 'normal'], 'IN'], ['on sloped forward line', [2250, 38.0, 'normal'], 'IN'], ['on aft limit utility', [2000, 40.5, 'utility'], 'IN'], ['utility overweight but normal legal', [2302, 42.0, 'utility'], 'OVERWEIGHT'], ['exactly max gross normal', [2550, 41.0, 'normal'], 'IN'], ['forward of sloped line', [2400, 39.2, 'normal'], 'FWD'], ['aft of utility limit', [2100, 41.2, 'utility'], 'AFT'], ['below empty weight', [1498, 40.0, 'normal'], 'ERR_BELOW_EMPTY'], ['exactly empty weight', [1500, 36.0, 'utility'], 'IN'], ['sampled case 1', [1950, 37.89, 'utility'], 'IN'], ['sampled case 2', [2561, 48.01, 'normal'], 'OVERWEIGHT'], ['sampled case 3', [2550, 45.7, 'normal'], 'IN'], ['regression: forward limit comparison', [2200, 37.87, 'utility'], 'IN']], [['mid-envelope normal', [2130, 42.0, 'normal'], 'IN'], ['on sloped forward line', [2250, 38.0, 'normal'], 'IN'], ['on aft limit utility', [2000, 40.5, 'utility'], 'IN'], ['utility overweight but normal legal', [2303, 42.0, 'utility'], 'OVERWEIGHT'], ['exactly max gross normal', [2550, 41.0, 'normal'], 'IN'], ['forward of sloped line', [2400, 39.3, 'normal'], 'FWD'], ['aft of utility limit', [2100, 41.3, 'utility'], 'AFT'], ['below empty weight', [1497, 40.0, 'normal'], 'ERR_BELOW_EMPTY'], ['exactly empty weight', [1500, 36.0, 'utility'], 'IN'], ['sampled case 1', [1950, 34.67, 'utility'], 'FWD'], ['sampled case 2', [1500, 42.58, 'utility'], 'AFT'], ['sampled case 3', [2200, 48.0, 'utility'], 'AFT'], ['regression: forward limit comparison', [2200, 37.5, 'utility'], 'IN']], [['mid-envelope normal', [2140, 42.0, 'normal'], 'IN'], ['on sloped forward line', [2250, 38.0, 'normal'], 'IN'], ['on aft limit utility', [2000, 40.5, 'utility'], 'IN'], ['utility overweight but normal legal', [2304, 42.0, 'utility'], 'OVERWEIGHT'], ['exactly max gross normal', [2550, 41.0, 'normal'], 'IN'], ['forward of sloped line', [2400, 39.4, 'normal'], 'FWD'], ['aft of utility limit', [2100, 41.4, 'utility'], 'AFT'], ['below empty weight', [1496, 40.0, 'normal'], 'ERR_BELOW_EMPTY'], ['exactly empty weight', [1500, 36.0, 'utility'], 'IN'], ['sampled case 1', [2200, 42.7, 'normal'], 'IN'], ['sampled case 2', [1969, 47.53, 'normal'], 'AFT'], ['sampled case 3', [1500, 48.2, 'normal'], 'AFT'], ['regression: forward limit comparison', [2200, 37.64, 'normal'], 'IN']], [['mid-envelope normal', [2150, 42.0, 'normal'], 'IN'], ['on sloped forward line', [2250, 38.0, 'normal'], 'IN'], ['on aft limit utility', [2000, 40.5, 'utility'], 'IN'], ['utility overweight but normal legal', [2305, 42.0, 'utility'], 'OVERWEIGHT'], ['exactly max gross normal', [2550, 41.0, 'normal'], 'IN'], ['forward of sloped line', [2400, 39.5, 'normal'], 'IN'], ['aft of utility limit', [2100, 41.5, 'utility'], 'AFT'], ['below empty weight', [1495, 40.0, 'normal'], 'ERR_BELOW_EMPTY'], ['exactly empty weight', [1500, 36.0, 'utility'], 'IN'], ['sampled case 1', [1950, 45.06, 'normal'], 'IN'], ['sampled case 2', [2200, 43.63, 'utility'], 'AFT'], ['sampled case 3', [2200, 41.43, 'normal'], 'IN']]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"A deterministic toy loading model with stipulated constants; it is not an approved aircraft flight manual procedure and makes no claim of regulatory conformance. 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.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-aviation-weight-balance-cg-envelope-forward-line-inclusive","generated_at":"2026-09-29T14:47:37.902734+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A category-dependent CG envelope with a sloped forward boundary; limit lines are part of the approved envelope.","root_cause":"The forward check uses <= so the limit line itself is treated as outside the envelope.","sha256":"c0a8aa7657e9fcfc56a781426b5ad8126aa254a96400e983af56f0732e2b0988","title":"A CG exactly on the forward limit line is rejected · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":40.768,"exit_code":1,"observations":[{"actual":"IN","check":"mid-envelope normal","expected":"IN","passed":true},{"actual":"IN","check":"on sloped forward line","expected":"IN","passed":true},{"actual":"IN","check":"on aft limit utility","expected":"IN","passed":true},{"actual":"OVERWEIGHT","check":"utility overweight but normal legal","expected":"OVERWEIGHT","passed":true},{"actual":"IN","check":"exactly max gross normal","expected":"IN","passed":true},{"actual":"FWD","check":"forward of sloped line","expected":"FWD","passed":true},{"actual":"AFT","check":"aft of utility limit","expected":"AFT","passed":true},{"actual":"ERR_BELOW_EMPTY","check":"below empty weight","expected":"ERR_BELOW_EMPTY","passed":true},{"actual":"IN","check":"exactly empty weight","expected":"IN","passed":true},{"actual":"AFT","check":"sampled case 1","expected":"AFT","passed":true},{"actual":"FWD","check":"sampled case 2","expected":"FWD","passed":true},{"actual":"AFT","check":"sampled case 3","expected":"AFT","passed":true},{"actual":"FWD","check":"regression: forward limit comparison","expected":"IN","passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"mid-envelope normal\", \"actual\": \"IN\", \"expected\": \"IN\", \"passed\": true}, {\"check\": \"on sloped forward line\", \"actual\": \"IN\", \"expected\": \"IN\", \"passed\": true}, {\"check\": \"on aft limit utility\", \"actual\": \"IN\", \"expected\": \"IN\", \"passed\": true}, {\"check\": \"utility overweight but normal legal\", \"actual\": \"OVERWEIGHT\", \"expected\": \"OVERWEIGHT\", \"passed\": true}, {\"check\": \"exactly max gross normal\", \"actual\": \"IN\", \"expected\": \"IN\", \"passed\": true}, {\"check\": \"forward of sloped line\", \"actual\": \"FWD\", \"expected\": \"FWD\", \"passed\": true}, {\"check\": \"aft of utility limit\", \"actual\": \"AFT\", \"expected\": \"AFT\", \"passed\": true}, {\"check\": \"below empty weight\", \"actual\": \"ERR_BELOW_EMPTY\", \"expected\": \"ERR_BELOW_EMPTY\", \"passed\": true}, {\"check\": \"exactly empty weight\", \"actual\": \"IN\", \"expected\": \"IN\", \"passed\": true}, {\"check\": \"sampled case 1\", \"actual\": \"AFT\", \"expected\": \"AFT\", \"passed\": true}, {\"check\": \"sampled case 2\", \"actual\": \"FWD\", \"expected\": \"FWD\", \"passed\": true}, {\"check\": \"sampled case 3\", \"actual\": \"AFT\", \"expected\": \"AFT\", \"passed\": true}, {\"check\": \"regression: forward limit comparison\", \"actual\": \"FWD\", \"expected\": \"IN\", \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":42.654,"exit_code":1,"observations":[{"actual":"IN","check":"mid-envelope normal","expected":"IN","passed":true},{"actual":"FWD","check":"on sloped forward line","expected":"IN","passed":false},{"actual":"IN","check":"on aft limit utility","expected":"IN","passed":true},{"actual":"OVERWEIGHT","check":"utility overweight but normal legal","expected":"OVERWEIGHT","passed":true},{"actual":"FWD","check":"exactly max gross normal","expected":"IN","passed":false},{"actual":"FWD","check":"forward of sloped line","expected":"FWD","passed":true},{"actual":"AFT","check":"aft of utility limit","expected":"AFT","passed":true},{"actual":"ERR_BELOW_EMPTY","check":"below empty weight","expected":"ERR_BELOW_EMPTY","passed":true},{"actual":"IN","check":"exactly empty weight","expected":"IN","passed":true},{"actual":"AFT","check":"sampled case 1","expected":"AFT","passed":true},{"actual":"FWD","check":"sampled case 2","expected":"FWD","passed":true},{"actual":"AFT","check":"sampled case 3","expected":"AFT","passed":true},{"actual":"IN","check":"regression: forward limit comparison","expected":"IN","passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"mid-envelope normal\", \"actual\": \"IN\", \"expected\": \"IN\", \"passed\": true}, {\"check\": \"on sloped forward line\", \"actual\": \"FWD\", \"expected\": \"IN\", \"passed\": false}, {\"check\": \"on aft limit utility\", \"actual\": \"IN\", \"expected\": \"IN\", \"passed\": true}, {\"check\": \"utility overweight but normal legal\", \"actual\": \"OVERWEIGHT\", \"expected\": \"OVERWEIGHT\", \"passed\": true}, {\"check\": \"exactly max gross normal\", \"actual\": \"FWD\", \"expected\": \"IN\", \"passed\": false}, {\"check\": \"forward of sloped line\", \"actual\": \"FWD\", \"expected\": \"FWD\", \"passed\": true}, {\"check\": \"aft of utility limit\", \"actual\": \"AFT\", \"expected\": \"AFT\", \"passed\": true}, {\"check\": \"below empty weight\", \"actual\": \"ERR_BELOW_EMPTY\", \"expected\": \"ERR_BELOW_EMPTY\", \"passed\": true}, {\"check\": \"exactly empty weight\", \"actual\": \"IN\", \"expected\": \"IN\", \"passed\": true}, {\"check\": \"sampled case 1\", \"actual\": \"AFT\", \"expected\": \"AFT\", \"passed\": true}, {\"check\": \"sampled case 2\", \"actual\": \"FWD\", \"expected\": \"FWD\", \"passed\": true}, {\"check\": \"sampled case 3\", \"actual\": \"AFT\", \"expected\": \"AFT\", \"passed\": true}, {\"check\": \"regression: forward limit comparison\", \"actual\": \"IN\", \"expected\": \"IN\", \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}