Holdover Calculator

Holdover Calculator is a pre-departure decision tool for pilots facing winter operations. It returns the applicable anti-icing holdover or allowance time from FAA or Transport Canada published guidance, based on the actual weather, the de/anti-icing fluid applied, and your aircraft configuration.

DESIGNED FOR iOS 26

Built for iOS 26 and its Liquid Glass interface. The pilot answers a sequence of focused questions; the app shows the matching table cell, the published range, and a continuously interpolated estimate within that range.

KEY FEATURES

• Holdover and allowance times from the current FAA Holdover Time Guidelines and Transport Canada HOT Guidelines — and if a correction is published mid-season, the app can pick up the new numbers on its own. Settings shows which set you are calculating with.

• Live weather autofill via the NOAA Aviation Weather Center — closest METAR or any ICAO you search.

• Manual entry always available when stations are out of range or you want to model conditions ahead.

• All four fluid types (Type I through Type IV) with both generic-table and specific-brand selections.

• Active Frost allowance and Ice Pellet allowance with a 90-minute takeoff-window tracker.

• Chart Notes surfaced inline, with active conditions (cold-soaked wing, OAT thresholds, etc.) flagged so you see only the notes that matter right now.

• App Estimated time — a continuous interpolation across OAT and precipitation intensity, shown alongside the FAA Recommended low end of every published range.

• Countdown timer with Live Activity on the Lock Screen, with the wall-clock "Ends at" time always shown to the second.

• Apple Watch companion for the crew member running the timer.

• Cockpit Sync — share one running timer across the flight deck. Link two to four devices over a direct local connection; the captain approves every change. No account, no internet, no server.

• On iPad and the open iPhone Duo, dock the holdover time and countdown beside your questions, on either side.

• Readable on the ramp. Tap any advisory note — or any setting's description — to enlarge it in a comfortable card sized for reading-distance glasses.

• Support & Feedback in one tap. Reach the developer from the menu with a note, a screenshot, and a summary of your session. No account required.

• FAA or Transport Canada as the global default, with per-calculation overrides.

• Local or Zulu time display; 12- or 24-hour clock.

PRE-DEPARTURE DECISION ONLY

This app is an advisor. The pilot in command remains solely responsible for verifying that the selected time is appropriate for the actual conditions, fluid, and aircraft at the moment of departure. Always cross-reference the current published holdover tables.

DATA SOURCES

• FAA Holdover Time Guidelines (current revision)
• Transport Canada Holdover Time Guidelines (current revision)
• NOAA Aviation Weather Center (aviationweather.gov) for live METAR observations

SUBSCRIPTION

Holdover Calculator is an auto-renewable annual subscription, with a free trial for new subscribers. Pricing is shown in the app before you subscribe.

• Payment is charged to your Apple ID at confirmation of purchase.
• The subscription renews automatically unless cancelled at least 24 hours before the end of the current period.
• Your account is charged for renewal within 24 hours before the period ends.
• Manage or cancel anytime in your Apple ID account settings.
• Any unused portion of a free trial is forfeited when you purchase a subscription.

PRIVACY

Location is requested only to identify the nearest weather station; your coordinates are sent solely to NOAA to run that query and are never stored or shared with us. No ads, no analytics, no tracking.

Privacy Policy: https://kilolimallc.github.io/legal/holdover-calculator/privacy.html
Terms of Use (EULA): https://kilolimallc.github.io/legal/holdover-calculator/terms.html
Disclaimer: https://kilolimallc.github.io/legal/holdover-calculator/disclaimer.html