AT, TAT, MAT?

Just a clarification for those that might be mis-interpreting some of
my comments: I'm not dismissing information or ignoring it or having
it go "over my head"... I just never stop asking questions or digging
for deeper understanding - sometimes in new directions, sometimes by
trying to refine previous answers or by trying to define special cases
or exceptions to general rules. :-)

Thanks for the continuing good info,

--Noel

What skills do we need to fly a MAT or TAT? As you know it's a wormy
little problem involving several variables; time, distance, altitude
required, wind, speed-to-fly and where's the stinking lift? We are
required to choose the final-turn point (or point-to-turn in a TAT) so
that the final leg will consume the rest of the alloted time with
sufficient altitude to traverse the remaining distance home into an
unknown wind and get there on time! These tasks involve a very
difficult navigation problem; Controlled ETA to a destination in an
aircraft with no visable means of support. Wow! I don't know how we
do it and frankly I couldn't do it very well without my trusty SN-10.
It gives me reliable winds and a running display of time remaining,
distance remaining and altitude required to finish any task I have
dialed in. How do we get better at flying TAT's and MAT's? Practice,
Practice, Practice, and get the best airborne computer available, not
cheap but worth every penny.
JJ

noel.wade wrote:
Just a clarification for those that might be mis-interpreting some of
my comments: I'm not dismissing information or ignoring it or having
it go "over my head"... I just never stop asking questions or digging
for deeper understanding - sometimes in new directions, sometimes by
trying to refine previous answers or by trying to define special cases
or exceptions to general rules. :-)

Thanks for the continuing good info,

--Noel

What skills do we need to fly a MAT or TAT? As you know it's a wormy
little problem involving several variables; time, distance, altitude
required, wind, speed-to-fly and where's the stinking lift?
..... Practice,
Practice, Practice, and get the best airborne computer available, not
cheap but worth every penny.
JJ


I hate to even think of mentioning it, but adding 15 minuites to
everybody's time makes this whole business of trying to nail the
finish time much less important.
Flame suit on -- no, don't worry, I don't imagine it will ever come
back

John Cochrane

On Oct 13, 1:58*pm, BB wrote:
What skills do we need to fly a MAT or TAT? As you know it's a wormy
little problem involving several variables; time, distance, altitude
required, wind, speed-to-fly and where's the stinking lift?
.... Practice,
Practice, Practice, and get the best airborne computer available, not
cheap but worth every penny.
JJ

I hate to even think of mentioning it, but adding 15 minuites to
everybody's time makes this whole business of trying to nail the
finish time much less important.
Flame suit on -- no, don't worry, *I don't imagine it will ever come
back

John Cochrane

I'm right behind you John - about 50 feet behind. ;-)

9B

On Oct 13, 1:58*pm, BB wrote:

I hate to even think of mentioning it, but adding 15 minuites to
everybody's time makes this whole business of trying to nail the

John Cochrane

John -

I don't understand - if you add 15 minutes, what's to stop people from
trying to come in 14 minutes and 59 seconds sooner? Doesn't that just
shift the "minimum task time" without affecting the racing (if not,
what's the logic I'm missing)?

--Noel

Bravo Bravo's giving you his little secret on how to never end up
early.......start home when your computer tells you your 15 minutes
over time and you should never get there early. Usually works, but I
once turned 15 minutes late on a day where I had been flying with M/C
of 2.5 (remember time-to-go changes with M/C setting) Well I started a
100 mile final glideinto what developed into cloud street and I ended
up 10 minutes early. lesson learned, set M/C for expected conditions
on final leg which should have been 4 in the above example.
JJ



noel.wade wrote:
On Oct 13, 1:58�pm, BB wrote:

I hate to even think of mentioning it, but adding 15 minuites to
everybody's time makes this whole business of trying to nail the

John Cochrane

John -

I don't understand - if you add 15 minutes, what's to stop people from
trying to come in 14 minutes and 59 seconds sooner? Doesn't that just
shift the "minimum task time" without affecting the racing (if not,
what's the logic I'm missing)?

--Noel

I don't understand - if you add 15 minutes, what's to stop people from
trying to come in 14 minutes and 59 seconds sooner? *Doesn't that just
shift the "minimum task time" without affecting the racing (if not,
what's the logic I'm missing)?

--Noel

I'm guilty of being too obscure. A few years ago the US experimented
with the following rule. To determine your speed for scoring, we take
(Time + 15 minutes)/distance. Time still had to be greater than
minimum time.

The effect of this change is to offset the fact that you get one fast
final glide, or equivalently one fee thermal to the top of the start
gate, per flight, and therefore remove the critical importance of
finishing close to the minimum time.

For example, suppose you fly 50 mph through the air -- top of start
gate to top of last thermal -- and then do a 15 minute, 100 mph
final glide on a 2:00 hour turn area task. If you fly it perfectly and
finish in two hours, you go (50 x 1.75 + 100 x 0.25 )/2 = 56.2 mph.
If you blow it and do a 2:30 flight, you go (50 x 1.25 + 100 x 0.25) /
2.5 = 55 mph or 972 points. That is a huge difference in contest
soaring, so no wonder pilots invest in thousands of dollars of
computers.

If you add 15 minutes to each time, though, you get scored for 50 mph
in each case! The 15 minute time addition exactly offsets the one-
glide-per-flight effect and makes it unimportant how long you stay
out, so long as you end above minium time and fly fast.

I wish I could say that this was overturned by the evil conspiracy of
flight computer manufacturers. Pilot confusion and poor salesmanship
by its advocates did in a very pretty idea.

And I am not trying to revive it -- lost cause!

John Cochrane

On Oct 13, 4:25*pm, BB wrote:

I'm guilty of being too obscure. A few years ago the US experimented
with the following rule. To determine your speed for scoring, we take
(Time + 15 minutes)/distance. Time still had to be greater than
minimum time.

The effect of this change is to offset the fact that you get one fast
final glide, or equivalently one fee thermal to the top of the start
gate, per flight, and therefore remove the critical importance of
finishing close to the minimum time.

For example, suppose you fly 50 mph through the air -- top of start
gate to top of last thermal -- *and then *do a 15 minute, 100 mph
final glide on a 2:00 hour turn area task. If you fly it perfectly and
finish in two hours, you go (50 x 1.75 + *100 x 0.25 )/2 = 56.2 mph.
If you blow it and do a 2:30 flight, you go (50 x 1.25 + 100 x 0.25) /
2.5 = 55 mph * or 972 points. That is a huge difference in contest
soaring, so no wonder pilots invest in thousands of dollars of
computers.

*If you add 15 minutes to each time, though, you get scored for 50 mph
in each case! The 15 minute time addition exactly offsets the one-
glide-per-flight effect and makes it unimportant how long you stay
out, so long as you end above minium time and fly fast.

I wish I could say that this was overturned by the evil conspiracy of
flight computer manufacturers. Pilot confusion and poor salesmanship
by its advocates *did in a very pretty idea.

And I am not trying to revive it -- lost cause!

John Cochrane

OK, got it. Not sure it works in all cases (though it worked OK in a
few random-number cases I threw at it), but I understand it now. My
newbie brain works better when this is phrased "add 15 minutes at 0mph
on to the end of your flight" (this also jives with your "free
thermal" explanation, since if there's no wind your speed along the
course is effectively zero when you're thermalling straight up).
*shrug* Maybe I'm just weird.

I still don't see how this changes the problem with people coming in
under-time, if the raw time (before adding 15 minutes) still has to be
greater than the minimum task time...

BTW there's a little typo in your example numbers. The longer-flight
pilot spent 2.25 hours at 50mph, not 1.25. :-)

--Noel

On Oct 13, 4:41*pm, "noel.wade" wrote:
On Oct 13, 4:25*pm, BB wrote:





I'm guilty of being too obscure. A few years ago the US experimented
with the following rule. To determine your speed for scoring, we take
(Time + 15 minutes)/distance. Time still had to be greater than
minimum time.

The effect of this change is to offset the fact that you get one fast
final glide, or equivalently one fee thermal to the top of the start
gate, per flight, and therefore remove the critical importance of
finishing close to the minimum time.

For example, suppose you fly 50 mph through the air -- top of start
gate to top of last thermal -- *and then *do a 15 minute, 100 mph
final glide on a 2:00 hour turn area task. If you fly it perfectly and
finish in two hours, you go (50 x 1.75 + *100 x 0.25 )/2 = 56.2 mph..
If you blow it and do a 2:30 flight, you go (50 x 1.25 + 100 x 0.25) /
2.5 = 55 mph * or 972 points. That is a huge difference in contest
soaring, so no wonder pilots invest in thousands of dollars of
computers.

*If you add 15 minutes to each time, though, you get scored for 50 mph
in each case! The 15 minute time addition exactly offsets the one-
glide-per-flight effect and makes it unimportant how long you stay
out, so long as you end above minium time and fly fast.

I wish I could say that this was overturned by the evil conspiracy of
flight computer manufacturers. Pilot confusion and poor salesmanship
by its advocates *did in a very pretty idea.

And I am not trying to revive it -- lost cause!

John Cochrane

OK, got it. *Not sure it works in all cases (though it worked OK in a
few random-number cases I threw at it), but I understand it now. *My
newbie brain works better when this is phrased "add 15 minutes at 0mph
on to the end of your flight" (this also jives with your "free
thermal" explanation, since if there's no wind your speed along the
course is effectively zero when you're thermalling straight up).
*shrug* Maybe I'm just weird.

I still don't see how this changes the problem with people coming in
under-time, if the raw time (before adding 15 minutes) still has to be
greater than the minimum task time...

BTW there's a little typo in your example numbers. *The longer-flight
pilot spent 2.25 hours at 50mph, not 1.25. *:-)

--Noel- Hide quoted text -

- Show quoted text -

On Oct 13, 4:41*pm, "noel.wade" wrote:

I still don't see how this changes the problem with people coming in
under-time, if the raw time (before adding 15 minutes) still has to be
greater than the minimum task time...


Apples and oranges - the (now defunct) 15 minute rule flattened out
the points awarded as a function of time on course OVER AND ABOVE the
minimum time. It was an attempt to reverse out an implicit scoring
penalty due to the dilution of final glide speed into sustained cross-
country speed - longer flights got penalized more as the dilution
effect decreased.

The second topic has to do with flight management - being on time but
not under. The penalty for being under time is much more severe than
the hidden penalty for being over - you get marked to minimum time,
which is like averaging in zero speed for the time you are under.

Hope that makes sense to people.

9B