Picking Optimal Altitudes

McGregor wrote:
: Lazy people (like me) ask their computer. FlightStar from Jepp has an
: "optimize altitude" function that is pretty handy. Once it has downloaded
: DUATs weather it will display groundspeed and fuel burn for all altitudes
: and highlight the optimal flight level.

Although I can do it by hand, I find it much more convenient to have DUATS do
it for me. Since I fly a non-turbo'd Cherokee, I'm effectively relegated to 10kft or
less. A quick check of winds aloft, and maybe two or three altitudes with DUATS flight
planner (it corrects for current wind) and see where I end up. On the fly, I pretty
much figure I need about 5 kt difference in wind to counteract a 2000' climb/descent.
Unfortunately, the nicer the weather (this time of year in particular), the higher the
pressure and bigger the headwind for a westly flight is. Even skimming the trees at
1000' AGL doesn't usually help, so I end up climbing for smoothness and happy engine at
6-10k.

-Cory


--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

I went to Jeppeson's website and looked up flitestar. Looks like a nice
software package. What I could not find is pricing information for the
software or the subscription service to keep the charts updated and
such. Can you give your view on the software and let us know what it
retails for (including any subscriptions). Thanks.

-Sami

McGregor wrote:
Lazy people (like me) ask their computer. FlightStar from Jepp has an
"optimize altitude" function that is pretty handy. Once it has downloaded
DUATs weather it will display groundspeed and fuel burn for all altitudes
and highlight the optimal flight level.

"O. Sami Saydjari" wrote in message
...

When planning a flight against the wind, how to you pick the best
altitude when trying to minimize flight time?

If I read my performance charts correctly, my aircraft (Piper Turbo
Arrow III -- service ceiling 20,000 ft) seems to gain about 2 nts of
*true* airspeed for every 1000 feet you go up. Firstly, does that sound
about right to folks? I assume that this effect is from the decrease in
air friction at high altitudes (even though the prop also has less air
to "push on").

So, unless there is some other factor, I think this means that if the
winds increase at anything higher than 2 nts per 1000 feet, I am best
off staying at the Minimum Enroute Altitude. Is that right?

My experience thus far suggests that most of the time, the winds aloft
speed increase far faster then 2 nts per 1000 feet, so, in general, it
is unlikely that I will do much better than staying at the absolute
minimum altitude. Is that consistent with other folks' experience?

-Sami

O. Sami Saydjari wrote:
: I went to Jeppeson's website and looked up flitestar. Looks like a nice
: software package. What I could not find is pricing information for the
: software or the subscription service to keep the charts updated and
: such. Can you give your view on the software and let us know what it
: retails for (including any subscriptions). Thanks.

For me, personally, I don't run Winders, so any downloadable packages don't
help me. That's why I use DUATS... web-based so it works everywhere. Oh, and it's
"free" (for AOPA members). Me the cheap *******...

-Cory

--
************************************************** ***********************
* The prime directive of Linux: *
* - learn what you don't know, *
* - teach what you do. *
* (Just my 20 USm$) *
************************************************** ***********************

wrote:

For me, personally, I don't run Winders, so any downloadable packages don't
help me. That's why I use DUATS... web-based so it works everywhere. Oh, and it's
"free" (for AOPA members). Me the cheap *******...

Just for the record, you don't need to be an AOPA member to get DUAT for free.

http://www.duats.com DynCorp DUAT
http://www.duat.com DTC DUAT

If you like telnet access: "telnet direct.duats.com". Easy to create a text log
of your DUAT session that you can edit, so it's easier to print selected parts
of the briefing to take with you.

http://www.enflight.com gives you some html post-formatting of the DUAT output
that I find useful. Actually I think this is what AOPA uses under-the-covers.

All are free.

Dave (another Winders avoider and cheap *******)
Remove SHIRT to reply directly.

AOPA has an dumbed-down internet version of FlightStar that you can download
for free at:
http://www.aopa.org/flight_planner/intro.html

The Jepp North American IFR version of Flightstar V9.0 costs $239. I'm
running 8.0 and have never purchased the map or chart revision service. My
flight planning skills have atrophied as a result of using this thing. It
calculates flight times very accurately. But I like it best for long
x-country flights. You can draw a great circle between take-off and landing
and then drag your flight path up or down for fuel stops or VOR fly-overs or
to parallel victor airways if the weather sucks.


"O. Sami Saydjari" wrote in message
...
I went to Jeppeson's website and looked up flitestar. Looks like a nice
software package. What I could not find is pricing information for the
software or the subscription service to keep the charts updated and
such. Can you give your view on the software and let us know what it
retails for (including any subscriptions). Thanks.

-Sami

McGregor wrote:
Lazy people (like me) ask their computer. FlightStar from Jepp has an
"optimize altitude" function that is pretty handy. Once it has
downloaded
DUATs weather it will display groundspeed and fuel burn for all
altitudes
and highlight the optimal flight level.

"O. Sami Saydjari" wrote in message
...

When planning a flight against the wind, how to you pick the best
altitude when trying to minimize flight time?

If I read my performance charts correctly, my aircraft (Piper Turbo
Arrow III -- service ceiling 20,000 ft) seems to gain about 2 nts of
*true* airspeed for every 1000 feet you go up. Firstly, does that sound
about right to folks? I assume that this effect is from the decrease in
air friction at high altitudes (even though the prop also has less air
to "push on").

So, unless there is some other factor, I think this means that if the
winds increase at anything higher than 2 nts per 1000 feet, I am best
off staying at the Minimum Enroute Altitude. Is that right?

My experience thus far suggests that most of the time, the winds aloft
speed increase far faster then 2 nts per 1000 feet, so, in general, it
is unlikely that I will do much better than staying at the absolute
minimum altitude. Is that consistent with other folks' experience?

-Sami

Yes, I just tried the free version. It is quite nice (compared to the
one at DTC DUATS).

Thanks for the info on flitestar.

-Sami

McGregor wrote:
AOPA has an dumbed-down internet version of FlightStar that you can download
for free at:
http://www.aopa.org/flight_planner/intro.html

The Jepp North American IFR version of Flightstar V9.0 costs $239. I'm
running 8.0 and have never purchased the map or chart revision service. My
flight planning skills have atrophied as a result of using this thing. It
calculates flight times very accurately. But I like it best for long
x-country flights. You can draw a great circle between take-off and landing
and then drag your flight path up or down for fuel stops or VOR fly-overs or
to parallel victor airways if the weather sucks.


"O. Sami Saydjari" wrote in message
...

I went to Jeppeson's website and looked up flitestar. Looks like a nice
software package. What I could not find is pricing information for the
software or the subscription service to keep the charts updated and
such. Can you give your view on the software and let us know what it
retails for (including any subscriptions). Thanks.

-Sami

McGregor wrote:

Lazy people (like me) ask their computer. FlightStar from Jepp has an
"optimize altitude" function that is pretty handy. Once it has

downloaded

DUATs weather it will display groundspeed and fuel burn for all

altitudes

and highlight the optimal flight level.

"O. Sami Saydjari" wrote in message
...


When planning a flight against the wind, how to you pick the best
altitude when trying to minimize flight time?

If I read my performance charts correctly, my aircraft (Piper Turbo
Arrow III -- service ceiling 20,000 ft) seems to gain about 2 nts of
*true* airspeed for every 1000 feet you go up. Firstly, does that sound
about right to folks? I assume that this effect is from the decrease in
air friction at high altitudes (even though the prop also has less air
to "push on").

So, unless there is some other factor, I think this means that if the
winds increase at anything higher than 2 nts per 1000 feet, I am best
off staying at the Minimum Enroute Altitude. Is that right?

My experience thus far suggests that most of the time, the winds aloft
speed increase far faster then 2 nts per 1000 feet, so, in general, it
is unlikely that I will do much better than staying at the absolute
minimum altitude. Is that consistent with other folks' experience?

-Sami

I was looking at flight star, is it as good as jepp says it is?

McGregor wrote:

Lazy people (like me) ask their computer. FlightStar from Jepp has an
"optimize altitude" function that is pretty handy. Once it has downloaded
DUATs weather it will display groundspeed and fuel burn for all altitudes
and highlight the optimal flight level.

"O. Sami Saydjari" wrote in message
...
When planning a flight against the wind, how to you pick the best
altitude when trying to minimize flight time?

If I read my performance charts correctly, my aircraft (Piper Turbo
Arrow III -- service ceiling 20,000 ft) seems to gain about 2 nts of
*true* airspeed for every 1000 feet you go up. Firstly, does that sound
about right to folks? I assume that this effect is from the decrease in
air friction at high altitudes (even though the prop also has less air
to "push on").

So, unless there is some other factor, I think this means that if the
winds increase at anything higher than 2 nts per 1000 feet, I am best
off staying at the Minimum Enroute Altitude. Is that right?

My experience thus far suggests that most of the time, the winds aloft
speed increase far faster then 2 nts per 1000 feet, so, in general, it
is unlikely that I will do much better than staying at the absolute
minimum altitude. Is that consistent with other folks' experience?

-Sami

I generally run several flight plans at different altitudes, accounting for
the differences in true air speed, wind speeds, and time to climb and
descend. More often than not, I find that the extra time to climb uses up
the gains in TAS at altitude, and winds are the only factor that make a
significant difference. If the flight is long, say 3-4 hours, then the
climb can be worth it, but for less than a couple of hours, it usually is
not. I fly behind a turbocharged engine and have built-in oxygen, so I can
go anywhere up to 18-20K, but usually stay below 12K or so unless there is a
net advantage due to wind. I like to stay high enough to keep from having
to switch from centers to approach controls all the time and to get above
the haze layer for a smoother ride. But sometimes the high winds just force
you down into the turbulence and traffic at 3-4K.

Stan

"O. Sami Saydjari" wrote in message
...
When planning a flight against the wind, how to you pick the best
altitude when trying to minimize flight time?

If I read my performance charts correctly, my aircraft (Piper Turbo
Arrow III -- service ceiling 20,000 ft) seems to gain about 2 nts of
*true* airspeed for every 1000 feet you go up. Firstly, does that sound
about right to folks? I assume that this effect is from the decrease in
air friction at high altitudes (even though the prop also has less air
to "push on").

So, unless there is some other factor, I think this means that if the
winds increase at anything higher than 2 nts per 1000 feet, I am best
off staying at the Minimum Enroute Altitude. Is that right?

My experience thus far suggests that most of the time, the winds aloft
speed increase far faster then 2 nts per 1000 feet, so, in general, it
is unlikely that I will do much better than staying at the absolute
minimum altitude. Is that consistent with other folks' experience?

-Sami

Stan, It guess I was too lazy to try to compute the flight plan several
different ways. Your note, and one other made me dust off the math
knowledge and do some of that there fancy ciphering (hearing "weeeee
dogies" in the background...said with hillbilly accent, of course).

For a mythical plane that climbs 1000 fpm at 100 nm/hr and cruises at
150 nm/hr and a service ceiling of 20,000 ft. Comparing flight at 1000
ft agl versus 18,000 agl....for a 100nm trip one's tailwind would have
to be about 40nm better at 18,000 compared to 1000 ft. For a trip
distance of 200, the tailwind would only need ot be about 14nm/hr more
favorable. For a 700 mile trip (one that I will be making fairly
often), the winds only need to be about 3nm/hr more favorable.

Now, I just hope the mythical heater is powerful enough so that I do not
freeze my butt off at those altitudes.

-Sami

Stan Prevost wrote:
I generally run several flight plans at different altitudes, accounting for
the differences in true air speed, wind speeds, and time to climb and
descend. More often than not, I find that the extra time to climb uses up
the gains in TAS at altitude, and winds are the only factor that make a
significant difference. If the flight is long, say 3-4 hours, then the
climb can be worth it, but for less than a couple of hours, it usually is
not. I fly behind a turbocharged engine and have built-in oxygen, so I can
go anywhere up to 18-20K, but usually stay below 12K or so unless there is a
net advantage due to wind. I like to stay high enough to keep from having
to switch from centers to approach controls all the time and to get above
the haze layer for a smoother ride. But sometimes the high winds just force
you down into the turbulence and traffic at 3-4K.

Stan

"O. Sami Saydjari" wrote in message
...

When planning a flight against the wind, how to you pick the best
altitude when trying to minimize flight time?

If I read my performance charts correctly, my aircraft (Piper Turbo
Arrow III -- service ceiling 20,000 ft) seems to gain about 2 nts of
*true* airspeed for every 1000 feet you go up. Firstly, does that sound
about right to folks? I assume that this effect is from the decrease in
air friction at high altitudes (even though the prop also has less air
to "push on").

So, unless there is some other factor, I think this means that if the
winds increase at anything higher than 2 nts per 1000 feet, I am best
off staying at the Minimum Enroute Altitude. Is that right?

My experience thus far suggests that most of the time, the winds aloft
speed increase far faster then 2 nts per 1000 feet, so, in general, it
is unlikely that I will do much better than staying at the absolute
minimum altitude. Is that consistent with other folks' experience?

-Sami

O. Sami Saydjari wrote:
When planning a flight against the wind, how to you pick the best
altitude when trying to minimize flight time?

If I read my performance charts correctly, my aircraft (Piper Turbo
Arrow III -- service ceiling 20,000 ft) seems to gain about 2 nts of
*true* airspeed for every 1000 feet you go up. Firstly, does that sound
about right to folks? I assume that this effect is from the decrease in
air friction at high altitudes (even though the prop also has less air
to "push on").

So, unless there is some other factor, I think this means that if the
winds increase at anything higher than 2 nts per 1000 feet, I am best
off staying at the Minimum Enroute Altitude. Is that right?

My experience thus far suggests that most of the time, the winds aloft
speed increase far faster then 2 nts per 1000 feet, so, in general, it
is unlikely that I will do much better than staying at the absolute
minimum altitude. Is that consistent with other folks' experience?

-Sami


Yes, generally lower is better in high wind conditions such as winter
across much of the US. However, you need to balance speed against
turbulence which also tends to be worse at low altitudes, at least over
mountainous regions.

Matt