Flight Time & Distance Calculator
Aviation E6B time-speed-distance triangulation solver, airport-to-airport distance calculator, and multi-leg NavLog trip builder. Calculate Estimated Time Enroute (ETE), Estimated Time of Arrival (ETA), great-circle distance between airports, required groundspeed, and mandatory 14 CFR § 91.151 / § 91.167 legal fuel reserves with interactive Dalton circular slide rule mechanics and multi-waypoint flight profile visualizers.
Flight Time Inputs
E6B TriangulationEstimated Time Enroute (ETE)
Flight Profile Visualizer
E6B Circular Slide Rule — Time & Speed Computer
Outer Ring = Distance / Speed | Inner Ring = Time (Minutes & Hours)
E6B Slide Rule Principle: Aligning the 60 Index Arrow on the inner time scale with Groundspeed (110 kt) creates a constant ratio along the circumference. Reading opposite 75 NM on the outer scale gives the exact ETE (40.9 min).
Aeronautical Time, Speed & Distance Triangulation Methodology
In aeronautical navigation, the fundamental relationship between time, speed, and distance forms the basis of all dead reckoning and pilotage flight logs. The Dalton E6B circular slide rule operationalizes these relations using logarithmic scales where the 60 Index represents standard hourly rates.
1. Estimated Time Enroute (ETE)
Physical Variables & Aviation Unit Definitions
| Symbol | Parameter | Physical Meaning | Unit |
|---|---|---|---|
| ETE | Estimated Time Enroute | Calculated duration to fly the segment | minutes / hours |
| Distance | Route Distance Supplied | Route distance supplied for the NavLog leg | NM |
| GS | Groundspeed | Speed over the terrain factoring wind component | knots |
| MPM | Miles Per Minute | Groundspeed divided by 60 | NM/min |
2. Distance Flown Over Ground
Physical Variables & Aviation Unit Definitions
| Symbol | Parameter | Physical Meaning | Unit |
|---|---|---|---|
| Distance | Ground Distance | Total ground distance traversed | NM |
| GS | Groundspeed | Aircraft forward speed over ground | knots |
| t_min | Flight Duration | Elapsed flight time | minutes |
3. In-Flight Groundspeed Calculation
Physical Variables & Aviation Unit Definitions
| Symbol | Parameter | Physical Meaning | Unit |
|---|---|---|---|
| GS | Groundspeed | Effective forward velocity | knots |
| Distance | Inter-checkpoint distance | Supplied distance between visual or GPS fixes | NM |
| Time | Elapsed checkpoint time | Stopwatch elapsed time | minutes |
4. Enroute Fuel Burn & Legal Reserves
Physical Variables & Aviation Unit Definitions
| Symbol | Parameter | Physical Meaning | Unit |
|---|---|---|---|
| GPH | Fuel Flow Rate | AFM/POH cruise fuel consumption rate | gallons/hour |
| Day VFR | Day Reserve | 14 CFR § 91.151(a)(1) requirement | +30 min |
| Night VFR | Night Reserve | 14 CFR § 91.151(a)(2) requirement | +45 min |
| IFR | IFR Reserve | 14 CFR § 91.167 requirement (alternate leg if required) | +Alt +45m |
The time, speed, distance, and fuel calculations in this tool operate under the following standard dead-reckoning assumptions:
- Constant Groundspeed: Groundspeed is assumed constant across each defined leg.
- Constant Fuel Flow: Cruise fuel consumption rate (GPH) is assumed uniform throughout flight.
- Supplied Route Distance: Input distance is accepted directly as route/ground track distance (not coordinate-derived geodesic).
- Kinematic Simplifications: Zero acceleration/deceleration transition time between waypoints.
- Phased Fuel Elements: Climb, descent, taxi, holding, and ATC-delay allowances are excluded unless explicitly modeled.
- Steady-State Wind: Wind velocity is assumed invariant across a leg unless groundspeed is updated.
- Reference Clock ETA: ETA is calculated relative to the same time reference as the supplied departure time.
- IFR Alternate Exemption: § 91.167 alternate fuel is added only when an alternate is required under § 91.167(b).
DPE Checkride Oral Exam Prep (Top 5 Questions)
Designated Pilot Examiners (DPEs) frequently evaluate time, speed, distance, and fuel management on private, commercial, and instrument checkrides. Review these high-yield scenarios.
Q1:What are the minimum legal fuel reserve requirements for Day VFR, Night VFR, and IFR flights under 14 CFR Part 91?▼
Under 14 CFR § 91.151 (Fuel requirements for flight in VFR conditions):
- Day VFR: Fly to the first point of intended landing and, assuming normal cruising fuel consumption, fly after that for at least 30 minutes.
- Night VFR: Fly to the first point of intended landing and fly after that for at least 45 minutes.
Under 14 CFR § 91.167 (Fuel requirements for flight in IFR conditions):
- Fly to destination, fly from destination to alternate airport (unless exempt under the § 91.167(b) 1-2-3 weather criteria), and fly after that for 45 minutes at normal cruising fuel consumption.
Q2:How do you quickly calculate Miles Per Minute (MPM) and use it for mental time-distance cross-checks in the cockpit?▼
Miles Per Minute (MPM) is groundspeed divided by 60:
- 60 kt: 1.0 NM/min (60 seconds per nautical mile).
- 90 kt: 1.5 NM/min (40 seconds per nautical mile).
- 120 kt: 2.0 NM/min (30 seconds per nautical mile).
- 150 kt: 2.5 NM/min (24 seconds per nautical mile).
- 180 kt: 3.0 NM/min (20 seconds per nautical mile).
Practical Rule: If you are 10 NM from your checkpoint at 120 kt GS (2.0 MPM), time to checkpoint is simply 10 / 2 = 5 minutes.
Q3:How do you read Time and Distance on the Dalton mechanical E6B slide rule?▼
On the computer side of the E6B:
- Rotate the inner disc until the 60 Rate Index Arrow aligns with your Groundspeed on the outer scale (e.g., 12 for 120 kt).
- Locate your Distance on the outer scale (e.g., 75 for 75 NM).
- Read the Time directly opposite on the middle scale (minutes) or inner scale (hours:minutes). For 75 NM at 120 kt, read 37.5 minutes (0:37:30).
- For fuel consumption, set the 60 Rate Index Arrow to Fuel Flow (GPH) and read total burn opposite the time on the inner scale.
Q4:Why is planned groundspeed different from True Airspeed (TAS), and how does wind effect ETE?▼
TAS is the speed of the aircraft relative to the surrounding airmass. Groundspeed is the actual speed of the aircraft relative to the surface of the earth.
A headwind component reduces groundspeed below TAS, increasing flight time (ETE) and fuel burn. Conversely, a tailwind increases groundspeed, decreasing ETE. Because time is non-linearly related to speed (Time = Distance / Speed), a headwind on an outbound leg increases time more than an equal tailwind on the return leg saves time, resulting in a net increase in round-trip flight duration.
Q5:How do you update your NavLog in flight if you reach your first checkpoint 3 minutes later than planned?▼
1. Record your Actual Time of Arrival (ATA) over the checkpoint.
2. Calculate Actual Groundspeed: Distance flown divided by actual elapsed time in minutes multiplied by 60.
3. Revise your Groundspeed for remaining legs and recalculate remaining ETEs and ETAs.
4. Recalculate Total Trip Fuel Burn using the slower groundspeed to confirm that remaining fuel onboard meets 14 CFR § 91.151 legal reserves. If reserves will be compromised, plan an en-route fuel stop immediately.
Navigation & Time-Distance Variables
Every input and derived parameter is mapped with standard units, provenance classifications, and operational definitions.
| Variable | Symbol | Standard Unit | Data Provenance | Operational Role |
|---|---|---|---|---|
| Route Distance | Dist / D | Nautical Miles (NM) | User Input | Route distance supplied for the NavLog leg along planned ground track. |
| Groundspeed | GS | Knots (NM/hr) | User Input / WCA | Horizontal velocity over the earth's surface factoring winds aloft. |
| Fuel Flow Rate | GPH | Gallons / Hour | AFM/POH Data | Volumetric cruise fuel consumption rate from approved POH tables. |
| Departure Time | Dep | HH:MM | User Input | Reference clock time used as the baseline for leg ETA calculation. |
| Estimated Time Enroute | ETE | Minutes / HH:MM | Kinematic Model | Calculated duration required to traverse segment at planned groundspeed. |
| Estimated Time of Arrival | ETA | HH:MM | Clock Math | Arrival time relative to the supplied departure time reference. |
| Miles Per Minute | MPM | NM / min | Mathematical Constant | Groundspeed divided by 60; standard cockpit mental math factor. |
| Fuel Reserves (Day/Night/IFR) | Reserves | Minutes / Gallons | Regulatory Req | Statutory reserves per 14 CFR § 91.151, § 91.167, and EASA NCO.OP.125. |
* Aircraft preset values (e.g., C172 110 kt / 8.5 GPH, PA-28 120 kt / 9.5 GPH) represent Illustrative Training Profiles. Pilots must always verify exact figures against the serial-number-specific AFM/POH.
Worked NavLog Flight Scenario: Republic (KFRG) to Nantucket (KACK)
Step-by-step cross-country dead reckoning computation for an illustrative Cessna 172 profile cruising at 110 knots Groundspeed with an 8.5 GPH cruise fuel consumption rate.
Step 1: Compute Individual NavLog Leg ETEs
Step 2: Total Route ETE & ETA
Total Route Time = 18.5 + 22.4 + 31.6 = 72.5 minutes (1 hour 13 minutes).
With a 12:00 departure reference, Estimated Time of Arrival (ETA) at Nantucket (KACK) = 13:13.
Step 3: Total Fuel Burn & 14 CFR § 91.151 Compliance
Total Enroute Burn = (72.5 / 60) × 8.5 GPH = 10.3 Gallons.
Aeronautical Flight Time & Distance Quick-Reference Matrix
Standard cross-reference lookup table for Estimated Time Enroute (ETE) and Miles Per Minute across typical General Aviation and Turboprop groundspeeds.
| Groundspeed | MPM | Sec / NM | 25 NM | 50 NM | 75 NM | 100 NM | 150 NM | 200 NM |
|---|---|---|---|---|---|---|---|---|
| 90 kt | 1.50 | 40s | 0:17 | 0:33 | 0:50 | 1:07 | 1:40 | 2:13 |
| 100 kt | 1.67 | 36s | 0:15 | 0:30 | 0:45 | 1:00 | 1:30 | 2:00 |
| 110 kt (C172) | 1.83 | 33s | 0:14 | 0:27 | 0:41 | 0:55 | 1:22 | 1:49 |
| 120 kt (PA-28) | 2.00 | 30s | 0:12 | 0:25 | 0:38 | 0:50 | 1:15 | 1:40 |
| 140 kt | 2.33 | 26s | 0:11 | 0:21 | 0:32 | 0:43 | 1:04 | 1:26 |
| 160 kt (Bonanza) | 2.67 | 23s | 0:09 | 0:19 | 0:28 | 0:38 | 0:56 | 1:15 |
| 200 kt (Twin) | 3.33 | 18s | 0:08 | 0:15 | 0:22 | 0:30 | 0:45 | 1:00 |
| 250 kt (Turboprop) | 4.17 | 14s | 0:06 | 0:12 | 0:18 | 0:24 | 0:36 | 0:48 |
Dual-Jurisdiction Regulatory Fuel Reserves (FAA vs. EASA)
Comparison of statutory fuel reserve standards for non-commercial general aviation flights under United States FAA Part 91 and European Union EASA Part-NCO regulations.
- 14 CFR § 91.151(a)(1) — Day VFR:Fly to first point of intended landing + 30 minutes at normal cruising fuel consumption.
- 14 CFR § 91.151(a)(2) — Night VFR:Fly to first point of intended landing + 45 minutes at normal cruising fuel consumption.
- 14 CFR § 91.167 — IFR Conditions:Fly to destination + fly to alternate airport (unless exempt per § 91.167(b) 1-2-3 rule) + 45 minutes at normal cruise burn.
- VFR Day (Aerodrome Vicinity): 10 minutes at best-range / holding speed.
- VFR Day (Cross-Country): 30 minutes at normal cruising speed.
- VFR Night / IFR: 45 minutes at normal cruising speed (plus alternate routing if alternate required per AMC1 NCO.OP.125(b)).
Operational Limitations & Precedence
1. AFM / POH Precedence: All fuel flow rates (GPH), climb allowances, taxi fuel, and true airspeeds must be obtained from the FAA/EASA-approved Airplane Flight Manual (AFM) or Pilot's Operating Handbook (POH) for your specific aircraft serial number, weight, altitude, and power setting.
2. Headwind Penalties & Non-Linearity: Flight planning assumes steady-state cruise groundspeed. A headwind component increases time and fuel burn on outbound legs more than an equal tailwind reduces them on return legs.
3. Personal Minimums & Legal Floor: Regulatory minimum fuel reserves (30 minutes Day / 45 minutes Night / IFR) represent absolute statutory minimums upon landing, not discretionary cruise fuel. The FAA strongly recommends personal reserve minimums of at least 45 to 60 minutes for cross-country flights.
4. Pilot-in-Command Authority: Per 14 CFR § 91.3 and EASA NCO.GEN.105, the pilot-in-command is directly responsible for, and is the final authority as to, the safe operation and fuel sufficiency of the aircraft.
Frequently Asked Questions
Always enter Groundspeed. Groundspeed accounts for headwind or tailwind drift. If you only know TAS, use the Wind Correction Angle calculator first.
Aviation Workflow Handoffs
Governing Standards & Technical References
Calculations are derived directly from FAA aeronautical flight manuals and statutory fuel regulations, with operational context from general pilot responsibility frameworks.
- • FAA-H-8083-25C Chapter 16: Pilot's Handbook of Aeronautical Knowledge (Dead Reckoning & Navigation).
- • 14 CFR § 91.151: Fuel requirements for flight in VFR conditions (30 min Day / 45 min Night reserve).
- • 14 CFR § 91.167: Fuel requirements for flight in IFR conditions (Destination + Alternate + 45 min).
- • EASA Regulation (EU) No 965/2012 NCO.OP.125 & AMC1/AMC2/AMC3 NCO.OP.125(b): Fuel and oil supply planning and final-reserve protection.
- • 14 CFR § 91.3: Responsibility and authority of the pilot in command.
- • EASA Part-NCO NCO.GEN.105: Pilot-in-command responsibilities, airworthiness, and fuel sufficiency.
- • FAA AC 91-74B: Flight in Icing Conditions and Fuel Planning Considerations.
- • Manufacturer AFM / POH: Section 5 (Performance) Fuel Flow and Cruise Speed Tables.