Reconciling a Hand-Copied Boarding Log
You are the duty watchkeeper on a night shift. At 05:40 you must reconcile the boarding log, which an officer copied by hand onto paper after the tablet battery failed, against the electronic watchlist before handover at 06:00. The watchlist records six vessels of interest by five-digit hull identifier. The log records six boardings, not in the order of the watchlist. Hand-copying is known to introduce transpositions, single-character substitutions and dropped leading zeros. Matching is exact: any character difference is a discrepancy, even where it is obviously a clerical slip. The supervisor does not want a count of errors; she wants each discrepancy named and identified, and a view on which one must be escalated immediately. There is no time to re-board anyone before 06:00.
1. Watchlist: 04712, 13890, 20045, 31876, 44710, 56023. Log as written: 13809, 44701, 56023, 31876, 20054, 04127. List every discrepancy and classify each one.
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| Log entry | Watchlist match | Classification |
|---|---|---|
| 13809 | 13890 | Transposition - final two digits swapped |
| 44701 | 44710 | Transposition - final two digits swapped |
| 20054 | 20045 | Transposition - final two digits swapped |
| 56023 | 56023 | Exact match |
| 31876 | 31876 | Exact match |
| 04127 | none | Unmatched log entry - no watchlist hull resembles it |
| - | 04712 | Unmatched watchlist entry - no boarding recorded |
Two exact matches, three transpositions, one log entry with no counterpart, and one vessel of interest with no boarding. Note the pattern in the transpositions: all three are in the final two digits, which points at one systematic copying habit rather than three independent slips.
2. Which single discrepancy do you escalate first, and why that one rather than the three transpositions?
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Escalate the pair 04127 / 04712.
Reasoning:
- The transpositions are self-correcting. Each has an obvious counterpart on the watchlist and two exact matches confirm the officer's copying is reliable in general. The risk they carry is clerical, and it is bounded.
- The pair carries an unbounded risk. Either (a) hull 04712 was boarded under a misread or false identifier recorded as 04127, meaning a vessel of interest is now at large with a corrupted record, or (b) two separate hulls were involved and 04712 was never boarded at all.
- The two anomalies explain each other, and that correlation is the signal. One unmatched entry alone is noise; an unmatched entry plus an unaccounted vessel of interest is a coherent single event.
Do not assume 04127 is a typo for 04712 - the digits differ in two positions and the match is not clean. Report the discrepancy, and flag that identity of 04712 is unconfirmed.
3. Recommend one change to the process, and state what it must not sacrifice.
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Recommendation: capture identifiers digitally at the point of boarding, with a read-back protocol - the officer reads the hull number digit by digit and the second officer repeats it before it is committed to the record.
What it must not sacrifice: the principle that exact matching governs. The three transpositions here were all in the final two digits, which suggests the copying habit is positional; a read-back attacks position errors directly, whereas a 'near enough' fuzzy-matching rule would silently suppress exactly the discrepancies the watchlist exists to detect. Fix the capture process; do not loosen the matching rule.