Error Checking in ATC Selection: Speed, Accuracy and How to Train

Error checking — sometimes called speed and accuracy or perceptual speed — is assessed in several ATC aptitude batteries including the Eurocontrol FEAST selection. It measures one of the most fundamental skills in air traffic control: the ability to compare data accurately and quickly, spotting discrepancies before they cause problems.

Why Error Checking Is Assessed

Air traffic controllers work with data constantly — strip data, radar labels, flight plan information, coordination messages. In busy operational environments, this data is updated frequently and must be verified against other sources. A misread callsign, a transposed altitude, or a missed squawk code change can have serious consequences.

The error checking test measures your natural speed and precision at this task before you have been trained in any specific procedure. It is a strong predictor of how accurately you will monitor data at an operational position.

What the Test Involves

In a typical error checking test you are presented with two versions of the same data — a reference and a check — and must decide as quickly as possible whether they match or contain a discrepancy.

The data types commonly used are deliberately aviation-flavoured:

**Flight numbers** (e.g. BA2394 vs BA2349 — transposed digits in the number)

**Times** (e.g. 14:35 vs 14:53 — transposed digits)

**ICAO codes** (e.g. EGLL vs EGLI — last letter changed)

**Gate identifiers** (e.g. Gate B7 vs Gate B17 — number changed)

**Radio frequencies** (e.g. 128.450 vs 128.405 — transposed decimal digits)

**Squawk codes** (e.g. 4372 vs 4732 — transposed octal digits)

Errors are designed to be subtle: a single transposed digit, a changed letter, or a one-unit difference. The test is timed, so speed matters as much as accuracy.

The Speed-Accuracy Trade-off

The core challenge is managing the trade-off between speed and accuracy. Answering too fast causes errors from hasty misreads. Answering too slowly leaves many pairs unanswered when time runs out. The optimal strategy — which improves with practice — is to develop a fast, consistent scanning pattern that catches errors without requiring a full character-by-character comparison on every pair.

Scanning Techniques

**Anchor on structure, not content.** On flight numbers, check the airline code (letters) and number separately — two quick checks rather than a single complex comparison. On times, check hours then minutes. Structured scanning is faster than free-form visual comparison.

**Expect errors.** Roughly half of pairs in the test contain an error. If you subconsciously expect pairs to match, you will miss errors that should be obvious. Maintain active scepticism with every pair.

**Use peripheral vision.** For short strings (squawk codes, frequencies), train yourself to take in the whole string at once rather than scanning left-to-right. This improves with practice.

**Do not second-guess correct rejections.** One of the most common accuracy errors is changing a correct "different" answer back to "same" after a second look. If you spotted something, trust your initial perception.

How to Improve

Error checking performance improves substantially with focused practice — unlike some cognitive abilities, this skill responds quickly to targeted training. The keys are:

**Volume.** Speed comes from repetition. The comparison process needs to become semi-automatic rather than effortful.

**Immediate feedback.** After each answer, knowing whether you were right reinforces correct scanning patterns and corrects bad habits.

**Consistent conditions.** Practise at the pace you intend to work — not comfortably slow, not recklessly fast. Build speed gradually while keeping accuracy above 90%.

**Mixed data types.** Don't just practise one format. The ability to switch quickly between flight numbers, times, codes and frequencies under time pressure is a specific skill worth training directly.

The Broader Context

Error checking is not the most glamorous test in an ATC aptitude battery — it lacks the novelty of spatial reasoning or the challenge of the dual-task simulation. But it is a genuine predictor of operational accuracy, and it is one of the few areas where focused short-term practice reliably improves test scores. Candidates who prepare specifically for this test type consistently outperform those who treat it as an afterthought.