The leave-by method
A leave-by alert is the exact moment Composed tells you to walk out the door, calculated on iPhone from real travel time rather than a guess. It pulls drive time from Google Maps and Apple MapKit, works backward from when the event starts, adds the right buffer for the event type, and lands on a single answer to the only question that matters in the rush before leaving: when do I actually need to go. For a domestic flight it folds in a 2-hour airport buffer; for an international one, 3 hours.
This is the feature that ends the “ran out the door without my keys” genre of morning. The reason that morning keeps happening isn’t that you can’t read a clock — it’s that the mental math of “the appointment is at 2, it’s twenty minutes away, but parking, but the elevator, but I should leave a cushion” is genuinely hard to do well while you’re also getting dressed and finding your shoes. The leave-by method does that arithmetic for you, correctly, in the background.
Real travel time, not distance
The leave-by time is built on real travel time, not straight-line distance, and the difference is the whole reliability of the feature. Eight miles can be twelve minutes on an empty Sunday or fifty in weekday traffic, and a planner that treats them the same will confidently send you out the door with no margin to spare. Composed’s departure tracking queries Google Maps and Apple MapKit for the actual estimated drive from your current location to the event’s location, then works backward from the start time.
Two honest limits keep this trustworthy. It uses current conditions, not a future-traffic prediction — it doesn’t claim to know what the freeway will look like in three hours, only what it looks like when it calculates. And it needs location permission to know where you’re starting from; without it, Composed falls back to a distance-based estimate rather than refusing to help. Knowing those edges is part of trusting the number, which connects directly to the how-to on always leaving on time.
Airport buffer discipline
For flights, the leave-by math adds a fixed airport buffer on top of drive time — 2 hours for a domestic flight, 3 hours for an international one. This is the detail that separates a leave-by alert from a generic “your event is soon” reminder, because the drive to the airport is the smallest part of catching a plane. Check-in, the bag drop, the security line, the walk to a gate that’s somehow always the farthest one: that’s where the real time goes, and it’s the time people systematically underestimate.
Composed detects international flights by reading the IATA airport codes from your flight details, so the buffer chooses itself — you don’t tell it which kind of trip this is. The reason the buffer is a flat rule rather than a clever estimate is, again, trust: a flat 3 hours for international is a number a frequent traveler can sanity-check at a glance and rely on, where a “smart” buffer that varied unpredictably would be one more thing to second-guess at 5am.
The recalculation rule
The leave-by time refreshes every time you open Composed within eight hours of the event, so the number you see is never stale. Traffic that built up since this morning, a meeting that ran long, the fact that you’re now starting from the office instead of home — all of it gets folded in the moment you glance at the app. The eight-hour window exists because beyond that range a precise leave-by time isn’t meaningful yet; conditions will change too much before it matters.
This recalculation is quiet and automatic. You don’t pull to refresh or tap recalculate; opening the app within range is the trigger. The practical effect is that the leave-by alert is always answering “when do I leave from here, now,” not “when would I have left if conditions were what they were when I created the event.” A departure time that silently keeps itself current is one you can act on without re-checking — which is the same trust loop as the rest of Section 3.
Live Journey Activity
Once you’re inside the final window, the leave-by method hands off to Live Journey Activity, a Lock Screen and Dynamic Island presence that keeps the departure visible without opening the app. It shows the current event with a progress bar and an ETA, and a five-tier status that reads from “Ahead of schedule” through “Composed,” “Right on time,” “Cutting it close,” and the honest end of the scale. It ends on its own when GPS detects you’ve arrived.
What Live Journey Activity is not is a navigation app — it tracks time-based progress, not your live position on a map, and it links out to Apple Maps for actual turn-by-turn. That boundary keeps it calm: it’s an ambient sense of “am I on pace,” glanceable from the Lock Screen, rather than a second navigation screen competing for your attention while you drive. For travelers stringing together flights, the flight intelligence card plays the same role across the phases of a trip.
When to override the math
The leave-by math is a strong default, not a command, and there are real reasons to leave earlier than it says. The two big ones: your own anxiety, and prep the math can’t see. If arriving early settles your nerves enough to make the difference between a calm morning and a frantic one, that’s a legitimate input the algorithm doesn’t have — leave when you need to leave, and treat the calculated time as the latest defensible departure, not the target.
The second case is real-world prep the route can’t account for: you need gas, you’re dropping a kid somewhere first, you want to grab coffee, the parking structure at the destination is its own adventure. Composed calculates door-to-door travel plus buffer; it doesn’t know about the errands you’ve stacked around the trip. The right mental model is that the leave-by alert tells you the last responsible moment to walk out assuming a clean trip — and you adjust earlier for everything you know that it doesn’t. A fuller travel-planning walkthrough lives in how to plan travel on iPhone.
The practice this week: the next time Composed gives you a leave-by time, notice whether you trust it enough to keep doing what you’re doing until it tells you to go. The first time you do — and arrive on time anyway — is the moment the door-rush morning starts to disappear.
Next: Floating things without times — the difference between fixed events and the things that just need doing.