The speed distance time test is aviation arithmetic in its natural habitat: 25 problems, 25 seconds each, no calculator, and every question shaped like something a controller actually computes between two transmissions. The entire test folds into one reflex, converting knots into miles per minute, and everything else is built on top of it. This guide covers the problem families, the conversion habit, and the estimation discipline that rescues the hard ones.
What is the Speed Distance Time Test?
The test measures applied numeracy at operational tempo. The formula is the one everyone knows, distance equals speed times time; the skill is running it in your head in aviation units while a timer drains. A controller judging whether a 420 knot aircraft reaches the boundary before the crossing traffic does exactly this, in about the same number of seconds this test allows.
The golden key: knots divided by 60 gives NM per minute. A 300 knot aircraft covers 5 NM a minute; twenty minutes means 100 NM, no long division required. The session opens with pure D equals S times T questions and climbs into two-aircraft comparisons, catch-up closures where the difference of speeds does the work, descent geometry on the 3 NM per 1000 ft rule, and fuel burn projections. It is the applied twin of the mental arithmetic test: same muscle, aviation units.
Which Exams Include the Speed Distance Time Test?
Aviation-unit rate problems are everywhere in selection. Candidates commonly report this test type in:
- FEAST and related ATC selection batteries, where SDT items are a named fixture
- DLR screenings, in applied math stages
- COMPASS and Advanced COMPASS by EPST, in the aviation math sections
- PACE, in airline and cadet programme assessments
- ADAPT and Aon / cut-e batteries, in applied numeracy scales
Providers change their content without notice and publish no official syllabus, so treat this as candidate-reported guidance.
How the Test Works: Format and Rules
The frame:
- 25 problems, about 25 seconds each, four options per question, no calculator.
- Question families ramp from single-aircraft D, S, T through comparisons, closures, descent gradients and fuel burn.
- Two of speed, distance and time are given; the third is the answer, wrapped in an operational story.
The canonical example: an aircraft does 300 knots, how far does it travel in 20 minutes? Convert first, 300 divided by 60 is 5 NM per minute; multiply, 5 times 20 gives 100 NM. This is exactly how it looks in the test:
The distractors are engineered slips: 80 for a botched conversion, 120 for a wrong operation, 150 for a half-remembered shortcut. The timer bar underneath is part of every question:
Knots over 60. Say it until it is not a calculation anymore, just a reading.
Scoring: What a Good Result Looks Like
One point per correct option with time recorded. The wrong options mirror specific mistakes, so assessors can often name your error from your answer: the forgotten divide-by-60 is the classic. Strong candidates convert instantly, hold accuracy through the closure and descent families, and use rounding deliberately on the final seconds rather than freezing. Ninety percent with steady timing marks a prepared candidate.
How to Prepare: Strategies That Actually Work
- Memorize the speed table. 240 knots is 4 NM a minute, 300 is 5, 360 is 6, 420 is 7, 480 is 8. Most questions become single-digit multiplication the moment the table is reflex.
- For closures, subtract speeds first. Two aircraft at 420 and 360 close at 60 knots, one mile a minute. The gap divided by closure speed is the answer; never track both aircraft separately.
- Own the descent rule. Three NM per 1000 ft: losing 8000 ft needs about 24 NM. Half the descent questions are this rule wearing different numbers.
- Round, compute, correct. At 17 minutes, compute 20 minutes and shave; the options are spaced widely enough that disciplined rounding lands the right one.
- Estimate before you pick. A one-second magnitude check kills the trap options, which are usually off by the exact factor your slip would produce.
- Keep the raw arithmetic warm. Daily minutes on the mental arithmetic test keep the multiplication table underneath this test frictionless.
Common Mistakes to Avoid
- Working in knots and minutes without converting, the divide-by-60 omission the distractors are waiting for.
- Computing both aircraft's positions in a closure instead of using the speed difference.
- Burning twenty seconds on exact arithmetic when the options are 40 NM apart.
- Misreading units, minutes versus hours, on the fuel burn questions.
Practice This Skill
Rate math becomes automatic with aviation-unit repetitions, and automatic is what the 25 second clock demands. Train with the Speed Distance Time module, which reproduces the problem families, the engineered distractors and the per-question timer exactly as described here. Level 1 is free, and the guided tutorial walks you through the format before your first attempt.