What is Flight Time?
Flight time is the total time measured from the moment an aircraft first moves under its own power for the purpose of flight until it comes to rest at the end of that flight. In most regulatory frameworks — including Transport Canada CARs and FAA FAR Part 1 — this definition encompasses the entire period of engine-on, wheels-rolling operation: taxi out, departure, cruise, arrival, and taxi in.
It is important to distinguish flight time from closely related but distinct terms:
- Block time — identical to flight time under most definitions; the time from chocks-out to chocks-in.
- Hobbs time — oil-pressure or master-switch activated; may start before the aircraft moves and stop after shutdown. Often used by flight schools for billing.
- Air time — the period between wheels-off and wheels-on (airborne only). Logged separately in some military and airline contexts.
- Instrument time — the portion of flight time flown under IMC or simulated IMC.
For the purposes of pilot logbooks and currency requirements, flight time is the standard unit used by aviation authorities worldwide.
How to Calculate Flight Time
Calculating flight time is a matter of subtracting your departure time from your arrival time, then converting the result from hours and minutes into decimal hours for your logbook.
Flight Time (decimal) = (Arrival Time − Departure Time) in minutes ÷ 60
The tricky part is handling time arithmetic correctly — particularly when a flight crosses midnight or spans time zones. The safest approach:
- Convert both times to UTC (Zulu time) before subtracting.
- Express both as a 24-hour clock value in total minutes since midnight.
- Subtract departure from arrival. If the result is negative, add 1,440 (the number of minutes in a day) to account for the midnight crossing.
- Divide by 60 to get decimal hours, then round to the nearest tenth.
Most logbooks record flight time to one decimal place (e.g., 1.4 hours). The flight time calculator at the top of this page handles all of this automatically — just enter your off-blocks and on-blocks times.
Step-by-Step Example
Suppose you depart KHWO at 14:32 local (19:32Z) and arrive at KOPF at 15:47 local (20:47Z).
- Convert to UTC: 19:32Z and 20:47Z — both on the same calendar day, no midnight crossing.
- Express in total minutes: 19:32 = (19 × 60) + 32 = 1,172 min. 20:47 = (20 × 60) + 47 = 1,247 min.
- Subtract: 1,247 − 1,172 = 75 minutes.
- Convert to decimal hours: 75 ÷ 60 = 1.25 hours → logged as 1.3 (rounded to nearest tenth).
Now consider a night ferry crossing from CYVR departing 23:40Z and landing CYYJ at 00:15Z the next day:
- Midnight crossing check: arrival (00:15Z = 15 min) − departure (23:40Z = 1,420 min) = −1,405 min. Add 1,440: −1,405 + 1,440 = 35 minutes.
- Convert: 35 ÷ 60 ≈ 0.58 → logged as 0.6 hours.
Use the flight time calculator above to handle these calculations instantly, including decimal rounding and midnight crossings.
Why Accurate Flight Time Matters
Every tenth of an hour you log has downstream consequences across multiple areas of your aviation career:
Licence and rating currency Most recency requirements — such as the FAA's 3-takeoff-and-landing rule (FAR 61.57) or Transport Canada's 5-hour recency requirement — are measured in flight time. An error of even 0.1 hours logged consistently over months can leave you believing you are current when you are not.
Total time milestones Commercial pilots track flight time toward specific minimums (e.g., 250 hours for a Canadian CPL, 1,500 hours for a US ATP). Inaccurate rounding compounded over hundreds of flights produces a meaningful error by the time you apply for a rating upgrade.
Flight school billing Aircraft rental is billed by Hobbs or Tach time, which may differ from logged flight time. Understanding the difference prevents billing disputes and helps you reconcile your logbook with aircraft records.
Airline and charter applications Airlines verify total times, instrument time, and multi-engine time directly from your logbook. Discrepancies discovered during a records audit — even innocent rounding errors — can delay or complicate a hiring process.
Fatigue and duty time management Commercial operators track flight duty periods and cumulative flight time against regulatory limits (e.g., Transport Canada CAR 700.15, FAA Part 117). Accurate time calculations are a safety requirement, not just an administrative one.
Logging correctly from day one removes uncertainty later. Use the flight time calculator at the top of this page for every flight, and let LogLibro carry the totals automatically.
Frequently Asked Questions
- What is a flight time calculator?
- A flight time calculator takes your departure time and arrival time as inputs and returns the total elapsed flight time in decimal hours, correctly handling midnight crossings and time zone differences. It eliminates manual time arithmetic and ensures your logbook entries are rounded consistently to the nearest tenth of an hour.
- Should I log flight time in decimal or hours-and-minutes?
- Most aviation authorities and logbook formats use decimal hours rounded to one decimal place (e.g., 1.4 hours). Some older paper logbooks used hours and minutes (e.g., 1:24). If you are transitioning from a paper logbook to a digital one, convert your historical entries to decimal to keep totals consistent. The standard conversion is minutes ÷ 60, rounded to the nearest 0.1.
- What is the difference between flight time and air time?
- Flight time runs from the moment the aircraft first moves under its own power until it comes to rest at the end of the flight — it includes taxi. Air time (or airborne time) runs only from wheels-off to wheels-on. For most GA pilots logging toward licence requirements, flight time is the correct figure to record. Air time is relevant in certain military contexts and for some maintenance tracking purposes.
- How do I calculate flight time across midnight or time zones?
- Convert both times to UTC before calculating. Express them in total minutes since midnight (hours × 60 + minutes). If the arrival value is less than the departure value, add 1,440 minutes (one full day) before subtracting. Divide the result by 60 for decimal hours. The flight time calculator at the top of this page does this automatically.
- Does Hobbs time equal flight time?
- Not necessarily. Hobbs meters are typically triggered by oil pressure or the aircraft master switch and may run during engine start before the aircraft begins moving, or continue briefly after shutdown. Flight time under most regulatory definitions starts when the aircraft first moves for the purpose of flight. The difference is usually small — a few minutes per flight — but it accumulates over a career. For logbook purposes, always record regulatory flight time, not raw Hobbs time.
- Can LogLibro calculate my flight time automatically?
- Yes. When you enter departure (off-blocks) and arrival (on-blocks) times in your LogLibro logbook entry, the total flight time field is calculated automatically. The result is rounded to one decimal place and carried forward into your running totals for the space, so your cumulative hours are always up to date without manual arithmetic.