A no-BS guide to understanding your flight data without falling asleep
What it is: Add up all your numbers and divide by how many you have. Simple as your pre-flight checklist... or so you think.
The Math (don't panic): Sum of all values ÷ Count of values
The Reality: Like that one pilot who always claims "average conditions" when they actually mean "sketchy as hell but I sent it anyway." The average is your middle-of-the-road number, but it's a terrible liar when you've got outliers.
Why it matters: Your average tells you what "normal" looks like across all your data points, but it's easily fooled by that one epic day when you thermaled to cloud base or that sinking nightmare when you landed in the LZ faster than you planned.
What it is: Line up all your numbers from smallest to biggest and pick the one in the middle. If you've got an even count, average the two middle kids.
The Real Talk: This is your "typical" value that doesn't get drunk on outliers. While the average is out there partying with extreme values, the median is the designated driver keeping things real.
Why pilots love it: When half your flights are epic XC missions and the other half are sled rides, the median tells you what a "normal" flight actually looks like. The average? That liar is somewhere in fantasy land.
What it is: How spread out your data is from the average. Mathematically, it's the average of all the squared differences from the mean.
The Math (just breathe): For each value, subtract the mean, square it, then average all those squared differences.
Translation for Humans: High variance = your flights are all over the map. One day you're bombing out, next day you're tagging clouds. Low variance = you're Mr. Consistent, same altitude, same thermals, same post-flight beer count.
The Catch: Variance is in "squared units" which makes about as much sense as measuring wind in m/s² (looking at you, ICAO). That's why we invented...
What it is: The square root of variance. Finally, numbers we can actually understand!
Why it exists: Because nobody wants to talk about "meters²/second²" when discussing climb rates. Standard deviation gives us back our original units.
The Rule of Thumb:
- About 68% of your values fall within ±1 standard deviation of the mean
- About 95% within ±2 standard deviations
- About 99.7% within ±3 standard deviations
Translation: If your standard deviation is small, you're predictable (boring but safe). If it's huge, you're either a hero or a hazard, depending on the day.
Average Climb Rate:
- What it tells you: Your typical thermal strength across a flight or season
- Example: Average climb of 2.5 m/s sounds great until you realize you spent 10 minutes at 5 m/s and 40 minutes scratching at 0.5 m/s
- Pilot wisdom: "Yeah bro, averaged 3 m/s today!" (spent 2 minutes in a monster thermal and the rest milking dying cores)
Median Climb Rate:
- What it tells you: What you're actually climbing at most of the time
- Example: Median of 1.5 m/s when your average is 2.5 m/s? You spent most of the flight scratching, my friend
- Pilot wisdom: The median doesn't lie about those 45-minute ridge soaring sessions you called "thermals"
Variance & Standard Deviation of Climb Rate:
- What it tells you: How consistent your thermals were
- Low std dev (< 1 m/s): Smooth, consistent lift all day - living the dream
- High std dev (> 2 m/s): Wild ride from sinker city to elevator express - either exciting or terrifying
- Pilot wisdom: High variance day? Better have packed your airsickness bags and your courage
Average Height Gain:
- What it tells you: Mean altitude gained per thermal or per flight
- Example: Average 500m gain per thermal? Nice! But did you top out every thermal or bomb out of most?
- Pilot wisdom: Averaging your climbs is like averaging your landing quality - one great landing doesn't erase three sketchy ones
Median Height Gain:
- What it tells you: The altitude gain you typically get in your thermaling attempts
- Example: Median 300m but average 500m? You're occasionally nailing it but usually bailing early
- Pilot wisdom: If your median is way lower than your average, you're either trigger-happy leaving thermals or your patience ran out (probably both)
Variance & Standard Deviation of Height Gain:
- What it tells you: Consistency in working thermals from bottom to top
- Low variance: You're disciplined, working every thermal to completion - textbook flying
- High variance: Some days you milk it to cloud base, other days you bail at the first hint of sink
- Pilot wisdom: "I gained 1200m that one time" (std dev of 800m means that was your only good climb all month)
Average Wind Speed:
- What it tells you: Mean wind conditions for a flight or a day
- Example: Average 15 km/h sounds flyable until you check the gusts
- Pilot wisdom: Weather apps love reporting average wind while you're getting your face rearranged by 40 km/h gusts
Median Wind Speed:
- What it tells you: The wind speed you experienced most of the time
- Example: Median 12 km/h, average 15 km/h? Fairly consistent with some stronger periods
- Pilot wisdom: When median and average are close, conditions are stable. When they're far apart? Buckle up, buttercup
Variance & Standard Deviation of Wind Speed:
- What it tells you: How much the wind is messing with you
- Low variance (std dev < 5 km/h): Steady Eddie conditions - plan your approach, nail your landing
- High variance (std dev > 10 km/h): Gusty nightmare - landing approach is now a choose-your-own-adventure book
- Pilot wisdom:
- "Light and variable" = high variance, low average (tricky thermals, unpredictable landing)
- "Strong and steady" = low variance, high average (bombing headwinds or tailwinds, but at least you know)
- "Strong and gusty" = high variance, high average (just pack the wing away and go to the pub)
- Climbs: 2.5, 3.0, 2.8, 2.6, 2.7 m/s
- Average: 2.72 m/s
- Median: 2.7 m/s
- Std Dev: 0.19 m/s
- Translation: Consistent thermals all day, every core delivered, you could do no wrong. These are the days we live for.
- Climbs: 0.5, 5.0, 0.8, 1.0, 0.7 m/s
- Average: 1.6 m/s (not bad on paper!)
- Median: 0.8 m/s (oof, the truth hurts)
- Std Dev: 1.71 m/s (chaos incarnate)
- Translation: You caught ONE monster thermal at 5 m/s and spent the rest of the day scratching like a cat on a screen door. Average says "decent day," median says "survival mode," standard deviation says "hot mess."
- Use AVERAGE when: You want the big picture across all your data (season stats, annual totals)
- Use MEDIAN when: You want to know what's actually typical and don't trust outliers (most of the time)
- Use STANDARD DEVIATION when: You want to know if conditions are consistent (low = predictable, high = chaotic)
- Use VARIANCE when: You're writing academic papers or want to confuse your flying buddies
Remember: Data doesn't lie, but averages absolutely will if you let them. The median keeps it real, and standard deviation tells you whether to trust any of these numbers.
Now get out there and make some data worth analyzing!
"In theory, theory and practice are the same. In practice, they're not."
- Every pilot after their first thermal