What is flight log interpretation in aviation?

Flight log interpretation is the process of reading and analyzing the flight planning log to monitor progress, update estimates, and ensure safe and efficient flight operations.

Why must fuel checks be carried out and recorded at regular intervals during flight?

Regular fuel checks and recording are essential to ensure there is sufficient fuel for the remainder of the flight and to detect any discrepancies early.

How do you calculate actual ground speed using a flight log?

Divide the distance flown between two waypoints by the actual time taken to fly that leg, as recorded in the log.

What elements are typically found in an EASA flight log?

Common elements include waypoint names, leg distances, estimated and actual times, headings, ground speeds, fuel required, and fuel on board.

Why is it important to determine aircraft position before descent?

Accurately determining position before descent ensures safe ground clearance and compliance with approach procedures.

Flight Log Interpretation

Hard4 min readFlightplanning

Moderately Examined

Why this matters

Accurate flight log interpretation is essential for real-time fuel management, navigation accuracy, and safety, enabling pilots to adapt to changing conditions and avoid fuel exhaustion or navigation errors.

Flight log interpretation is the process of reading, updating, and analysing a flight planning log to track an aircraft's progress, fuel status, and timing throughout a flight. It involves comparing planned versus actual data for headings, ground speeds, times, and fuel, allowing pilots to make informed decisions in real time. Mastery of this skill ensures safe, efficient, and regulatory-compliant flight operations.

Quick Check

You are overhead waypoint CHARLIE with 4200 kg of fuel on board. The previous leg from BRAVO to CHARLIE took 20 minutes and consumed 200 kg of fuel. If the next leg to DELTA is planned to take 30 minutes under similar conditions, what is your expected fuel on board at DELTA?

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In depth

Explanation

Key Elements of a Flight Log

A flight planning log (or flight log) includes columns for waypoints, headings, distances, estimated and actual times, ground speeds, and fuel data. Typical elements are:

Waypoint/Checkpoint: Named locations along the route.
Heading (HDG): Magnetic direction to fly.
Leg Distance: Nautical miles between waypoints.
Estimated/Actual Times (ETA/ATA): Planned and recorded times over each point.
Ground Speed (GS): Calculated from actual time and distance.
Fuel Required (FUEL REQ): Minimum fuel needed to continue safely.
Fuel On Board (FOB): Actual measured fuel at each point.

How to Read a Flight Log

To interpret a flight log:

Compare ETA and ATA: Spot deviations from plan; if ATA is later than ETA, investigate causes (e.g., headwinds).
Calculate Actual Ground Speed: Use actual time and distance to update GS for each leg.
Monitor Fuel: At each checkpoint, record FOB and compare with planned consumption. Calculate actual fuel flow (fuel used/time elapsed) and project forward.
Update Estimates: Use actual performance to revise ETAs and fuel predictions for subsequent legs.
Position Awareness: Confirm position before descent to ensure terrain clearance and safe arrival.

In-Flight Updates and Decision Making

Regularly update the log in flight—record actual times and fuel at each waypoint. If conditions change (e.g., direct routing, unexpected winds), recalculate leg times, ground speeds, and fuel remaining. This dynamic process supports safe, efficient, and compliant flight management.

The essentials

Key Points

Flight log interpretation tracks actual versus planned flight progress and fuel usage.

ETA (Estimated Time of Arrival) and ATA (Actual Time of Arrival) are compared at each waypoint.

Actual ground speed is calculated using real-time data for accurate navigation and fuel planning.

Fuel checks must be performed at regular intervals and recorded in the log.

Updating the log in flight helps identify deviations early and supports safe decision-making.

Accurate position determination before descent is crucial for terrain clearance.

Flight logs are essential for regulatory compliance and operational safety.

Watch out

Exam Traps & Typical Mistakes

Confusing planned fuel figures with actual fuel on board when calculating fuel remaining.

Using planned ground speed instead of recalculating with actual times and distances.

Forgetting to update ETAs for subsequent waypoints after a deviation is detected.

Assuming fuel flow remains constant without checking actual consumption rates.

Neglecting to account for direct routings or route changes in updated calculations.

Test yourself

Example Exam Questions

Question 2Easy

During flight log interpretation, what is the primary purpose of recording Actual Time of Arrival (ATA) at each waypoint?

Question 3Easy

If your actual ground speed on a leg is higher than planned, what adjustment should you make to your estimated time over the next waypoint in the flight log?

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