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This comment in the Arrow vs. Bo thread (and frequently repeated whenever the age-old question of "what plane should I get?' pops up) prompted me to share this.
But the "those few extra knots don't matter much in the real world" argument is only a half-truth, and the half that's not true can be significant, if it comes into play for your mission. It should be thoughtfully considered before being dismissed.
Where it matters is when you're dealing with stiff headwinds, especially combined with long legs. A 30-knot airspeed differential between aircraft plus a 30 kt headwind equals a 60 kt groundspeed differential. (Edit: Not true(!), as has been pointed out in the replies.) Also, the slower your plane's speed is, the more of a bite that headwind takes--a 737's trip time isn't as affected by a 30kt headwind as a J3 Cub.
I knew all this, of course, but was sharply reminded of it during a flight from Houston to El Paso over the Christmas holiday. With no winds, that's a 5.5 hr flight for me--I can really only make it in one leg with some tailwind help. On this day, there were ~25 kt headwinds and it took a little over 7 hrs of flying, with a 45 min fuel stop in Ozona, TX (had a minor mechanical issue). Right about 8 hrs from origin to destination.
About 30-45 min away from El Paso, an A36 came cruising past me. He landed about 10-15 min ahead of me. Later, poking around on Flight Aware, I learned that he took off from San Antonio quite a bit after I took off from my fuel stop--his leg was over 50% longer than mine, he took off later, and he landed before me--he smoked me.
Running the (book) numbers at 65%, he could have made my trip from Houston to El Paso on that day (25 kt headwinds) in 4:30 compared to my 7:10, plus no need for a fuel stop. That's no longer a matter of "a few minutes"--that's pretty huge. (I picked 65% as an arbitrary point of comparison, since that's where I try to cruise. I realize there's lots of flexibility in those numbers, but the point is still valid no matter how you slice them.)
Yes, I know--not fair to compare a Cherokee 180 vs. an A36, but physics doesn't care about fairness.
And yes, that time differential shrinks if your mission is ~250 nm flights instead of 600nm flights, or if you've got tailwinds instead of headwinds. And of course there are all sorts of other pros/cons to one plane vs. another.
But if your mission often requires long legs (not true for a lot of casual pilots) and potentially stiff headwinds (true for almost everyone!), then you should really include some serious flight time math in your process of picking a plane.
Sometimes, those "few extra minutes" really add up.
First off, I don't disagree with any of the other "upgrade trap" stuff. Nicer-looking / faster planes are just waaay more expensive to maintain and operate than slower/simpler planes, and often the only real justification to do it is "because I want to, and I can". Which of course is fine.
But the "those few extra knots don't matter much in the real world" argument is only a half-truth, and the half that's not true can be significant, if it comes into play for your mission. It should be thoughtfully considered before being dismissed.
Where it matters is when you're dealing with stiff headwinds, especially combined with long legs. A 30-knot airspeed differential between aircraft plus a 30 kt headwind equals a 60 kt groundspeed differential. (Edit: Not true(!), as has been pointed out in the replies.) Also, the slower your plane's speed is, the more of a bite that headwind takes--a 737's trip time isn't as affected by a 30kt headwind as a J3 Cub.
I knew all this, of course, but was sharply reminded of it during a flight from Houston to El Paso over the Christmas holiday. With no winds, that's a 5.5 hr flight for me--I can really only make it in one leg with some tailwind help. On this day, there were ~25 kt headwinds and it took a little over 7 hrs of flying, with a 45 min fuel stop in Ozona, TX (had a minor mechanical issue). Right about 8 hrs from origin to destination.
About 30-45 min away from El Paso, an A36 came cruising past me. He landed about 10-15 min ahead of me. Later, poking around on Flight Aware, I learned that he took off from San Antonio quite a bit after I took off from my fuel stop--his leg was over 50% longer than mine, he took off later, and he landed before me--he smoked me.
Running the (book) numbers at 65%, he could have made my trip from Houston to El Paso on that day (25 kt headwinds) in 4:30 compared to my 7:10, plus no need for a fuel stop. That's no longer a matter of "a few minutes"--that's pretty huge. (I picked 65% as an arbitrary point of comparison, since that's where I try to cruise. I realize there's lots of flexibility in those numbers, but the point is still valid no matter how you slice them.)
Yes, I know--not fair to compare a Cherokee 180 vs. an A36, but physics doesn't care about fairness.
And yes, that time differential shrinks if your mission is ~250 nm flights instead of 600nm flights, or if you've got tailwinds instead of headwinds. And of course there are all sorts of other pros/cons to one plane vs. another.
But if your mission often requires long legs (not true for a lot of casual pilots) and potentially stiff headwinds (true for almost everyone!), then you should really include some serious flight time math in your process of picking a plane.
Sometimes, those "few extra minutes" really add up.
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