Altitude selection

Sorry if I was making it too complicated. Should have said, all typical issues being no factor what altitude do you prefer?

I have flights like this all the time, I usually go for 5-6,000 for such a short trip just because it doesn’t make sense to me to spend nearly as much time in a climb or descent as I am at cruise. Although it’s bumpy out as it seems to be for me every flight this spring it’s up up up in hopes of finding a better ride.
 
cowman said:
This isn't an FAR question more of a preference question.

Say you're planning a flight that is going to take around 1hr. Conditions all along the route are sky clear and terrain is <1000' along that route. Winds are light at most altitudes and won't make a significant impact on your time enroute at any available altitude. There's no airspace of any note along the route either. No reports of turbulence or any airmets.

For simplicity's sake we'll say the direction of flight is westerly and you're flying a typical single engine unpressurized aircraft with no O2 and we're going to be going VFR. What altitude would you plan on using?
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Generally speaking, the fastest and most efficient flights are those where half or more of the flight is spent in cruise.

Let's say this "1-hr" flight is 150nm. With no wind and below 10K or so, it takes me 2 miles per 1000 feet to climb and 6 miles per 1000 feet to descend. With 8 miles per 1000 feet spent in climb and descent, I want to be traveling about 16 miles per 1000 feet of cruise altitude, or in this case about 9000 feet. If I'm VFR westbound, that means I'm at 8500 or 10,500. As a bonus, those are altitudes where normally aspirated airplanes do very well, able to maintain 65% power while still being high enough to get the best true airspeed for that power setting.
 
High enough to find smooth air. I'd probably start at 6500 and if that wasn't comfortable, then 8500. Usually smoother higher. It's not worth bouncing around, even for an hour. Typically, things smooth out a little bit above 6000 or so. The downside is you can get high enough to find smooth air, only to find that winds aloft have reduced your groundspeed to double digits. I HATE it when trucks are passing me on the Thruway. :)
 
For a short trip like this, I'd probably go 6500, if the weather is nice, all else being equal.

I fly out of Tucson; in the summer, 8500 or 10500 is often quite a bit more comfortable (cooler!) in my Cherokee greenhouse though. Can also be smoother, though you never know. And, the higher you are, the more significant the winds aloft are likely to be, so it might depend on what that looks like for the day.
 
Altitude is indeed our friend. I lost the engine-driven fuel pump on my RV-9A on Saturday, on the way back from a fly-in at Ramona. I was at 5500' over south OC, about to cross the mountains between Saddleback and Lake Elsinore when it coughed...and stopped! Such a helpless feeling when moving the throttle and mixture controls doesn't do a thing. I did a quick 90-degree left toward lower terrain and found a nice wide toll road (the 241) as an emergency landing spot, trimmed for best glide and then went about checking the usual suspects. First the fuel selector; switched tanks and no joy. Then the boost pump--bingo! It re-lit and I was able to make it back to Cable, staying high and overflying as many airports as possible en route.

So nice that we have two pumps! I probably would've been fine if this happened at 2500' agl, but that extra altitude gave me the luxury of having more time to to trouble-shoot.

A good experience to have an actual engine stoppage in flight. New pump was $454 including tax, and Aircraft Spruce (a half-hour drive away in Corona) had one left in stock. Put it in yesterday and flew again this morning, and she's her same ol' self once more.
 
Whatever Foreflight recommends. It has aircraft performance values built in. It factors in quite a bit. It will usually become apparent why it chose what altitude for you.
 
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