Required Ground Speed Calculator (Make-the-Slot)
Invert the time equation: given the miles and the deadline — a slot, sunset, a void time — the ground speed you'd need, and whether it's plausible.
Some deadlines (sunset for a non-night-rated pilot, an IFR void time, fuel) are walls, not targets. Running this arithmetic early converts 'press on faster' temptation into a calm reroute, fuel stop or phone call.
Formula
⚠️ For flight planning and education only — verify with official sources, your POH/AFM and certified equipment. Not for primary navigation.
Disclaimer: This tool is for general informational and estimation purposes only and is not professional financial, tax, accounting or legal advice. All figures are estimates — verify with a qualified professional before making decisions. Read the full disclaimer.
Invert the time equation: given the miles and the deadline — a slot, sunset, a void time — the ground speed you'd need, and whether it's plausible.
About Required Ground Speed Calculator (Make-the-Slot)
Most time-speed-distance tools answer 'how long will it take?' — this one answers the more dangerous question honestly: 'can I make it by then?' Distance and deadline in, required ground speed out, judged against your aircraft's realistic TAS: achievable, needs-a-tailwind, or not-happening. It's get-there-itis arithmetic, designed to move the replanning moment from short final at dusk to the comfort of cruise.
How to use Required Ground Speed Calculator (Make-the-Slot)
- 1Enter — sensible defaults are pre-filled so you see a worked result immediately.
- 2Read the live results: .
- 3Check the "With your numbers" line to see the formula required GS = distance ÷ time × 60; compare against TAS + available wind substituted step by step.
- 4Adjust inputs (or flip the unit toggle) until the scenario matches yours, then copy or share the result.
Why use Required Ground Speed Calculator (Make-the-Slot)?
- ✓Instant, free and private — every calculation runs in your browser, nothing is uploaded
- ✓Built on the published formula required GS = distance ÷ time × 60; compare against TAS + available wind with sources cited on the page
- ✓Some deadlines (sunset for a non-night-rated pilot, an IFR void time, fuel) are walls, not targets. Running this arithmetic early converts 'press on faster' temptation into a calm reroute, fuel stop or phone call.
- ✓Switch units, tweak any input and watch every result update live
Frequently asked questions
What deadlines should this be run against?+
The hard walls: official sunset (plus your night currency status), an IFR clearance void time, fuel-exhaustion time minus reserve, airport closing or curfew, and the passenger connection that actually matters. Soft deadlines (dinner) deserve the math too — but the tool's red verdict matters most when the wall is regulatory or physical.
Why does the verdict cap the plausible tailwind at 25 knots?+
Because at light-aircraft altitudes a 25-kt tailwind component is already a generous day, and planning that requires more than the forecast offers is gambling with a deadline as the stake. If the required wind exceeds what winds-aloft actually promise along the whole route, the honest reading is 'late' — the tool just says it sooner.
What are the alternatives when the answer is 'not happening'?+
In rough order of grace: revise the commitment (a phone call beats a forced approach), land short at a comfortable field and finish in the morning, accept arriving after the soft deadline, or — for the sunset case specifically — divert to the better-lit towered field instead of stretching to the home strip. None of these appear on short final; all of them appear at cruise. That timing is the whole tool.
Does flying faster actually help much?+
Less than instinct claims: pushing a 120-kt airplane to 130 (engine limits permitting) on 100 remaining miles saves under four minutes — while burning notably more fuel, which may pressure the other deadline. The required-GS framing exposes this: when the gap is 5 kt, speed helps; when it's 30, only geometry (shortcuts) or time (the phone call) do.
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