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© Alex Borten 2026
PRETAKEOFF.COM
Runway
Remaining
Advisory runway-remaining monitor. Runway data and weather are pulled live from the FAA; your position never leaves the device.
iPadOS requires a tap before it will release motion data.
© Alex Borten 2026 · all code original
Acquiring position…
Nearest airports
Waiting for a position fix…
Open any US airport
Type a 3 or 4 character identifier. Two letters lists a state, e.g. PA.
Weather
Runways · wind components
Armed · holding short
Holding short
GS 0 kt
Datum Stop on the threshold — your stopped position becomes the start of the runway.
Wind on runway
Est. ground roll
Rotate VR
Headwind
Crosswind
Last chance — before you roll 0 of 6
Tracking starts by itself at 15 kt ground speed.
Simulate
ADEQUATET+0.0s
100%
RUNWAY REMAINING
FEET REMAINING
GROUND SPEED
ROTATE AT
CONSIDER ABORT IF SAFE
THRESHOLDDEPARTURE END
Takeoff log
Runway used
Aircraft & thresholds
Rotation speed (VR)
kt
Weight & performance estimate
One number off your performance chart: ground roll at max gross, sea level, standard day, no wind. The estimate below scales from it — replace the preset figures with your own aeroplane's.
Acceleration gate (the 50/70 rule)
Be at 70% of rotation speed by 50% of the ground roll, or abort. It runs alongside the runway-remaining percentage — not instead of it — and a failed gate floods the screen red on its own.
Measure that distance from
Adequate — green at or above50%
Caution — yellow at or above35%
Below the caution figure the screen floods red and the abort advice flashes.
Display & alerts
© Alex Borten 2026 · all code original
Advisory only. VR and the thresholds are yours to set from the AFM. The app does not compute takeoff performance, weight and balance, or contaminated-surface corrections.
Sensors & data
What the monitor is reading, and how it degrades when an input is missing
Monitor status
Lift-off confirmation
Takeoff is confirmed only when a sustained positive rate of climb is fitted through the last 2.0 s of GPS altitude and the runway rumble in the accelerometer drops away. A single bump, a seam impact or a soft-field skip cannot trigger it: the detector regresses over the whole window, requires a minimum total altitude gain, and extends the window when vibration is heavy.
Build v— · the app shell is fetched fresh on every launch.
Where the data comes from
Runway geometry, lengths, widths, surfaces, headings and threshold coordinates come from the OurAirports public-domain dataset, converted by build.php into static JSON on this server — so search is instant and works with no signal. Weather comes from the FAA METAR feed through api/metar.php, cached server-side, falling back to the nearest reporting station. AirNav is not used: it serves no cross-origin headers and its terms prohibit scraping.