Enroute travel time by altitude

I was curious what cruise altitude would allow me to make an Infinite Flight flight in the least amount of time. So, I plotted the maximum groundspeed that could be flown without overspeeding at altitudes FL100 through FL380. I flew it in a “light” A320, no wind, 15 degree air temp. Maximum ground speed (blue line) peaks at FL250, resulting in a travel time about 6 minutes shorter than that possible at FL100 for a 189 nm trip (distance from Honolulu to Hilo).



Very interesting thanks!

That’s pretty cool you did that experiment

Wow that is pretty detailed !

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FL240 is the average altitude for these flights.

No longer applicable on most aircraft due to overspeed violation added.


great work, very intresting.

So blue is for ground speed, what dopes the orange line represent?

Sorry forgot to provide a key. Orange line shows travel time for a 189 nm trip, the scale for travel time is on the right hand side of the plot.

ok great I thought it was something along those lines as saw the time along the side!

Does your research include time to climb to cruise and also descent? I often fly that route (normally go for FL270) which takes about 40 - 45 mins depending on traffic

No, unfortunately it doesn’t include climb and descent time. But you have wisely identified that there may be time tradeoffs associated with climbing and descending to a certain altitude, even if that altitude permits the fastest cruise speed. Maybe next I’ll look into how to look at this question including climb and descent time!

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I typically take cues from real world flights as these are best representation of speed vs economy.

200-300nmi flights tend to be the sweet spot where speed trumps fuel economy due to the simple fact that climbing high (30’s+) brings diminishing returns on fuel economy and that a speedier flight can mean the difference between squeezing an extra return trip out of the flight day and thus more potential revenue.

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There’s real data already put together for these things. It’s cool that you went ahead and did this yourself. I believe most of the manufacturers already supply the data though as a selling point and it’s used in determining the best performance. The airlines fly at certain altitudes for certain trips because you can save on fuel, but it has to be balanced a certain way. It’s really complex and it would be tough for me to explain it all through text, but you can definitely look these things up and find them online. Definitely a good experiment though. Thanks!

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