Glider Crash - Minden?

Yuliy Gerchikov wrote:

The truth is, if you can't see this tiny *motionless* speck ...two miles
away ...in the inversion haze ...on one thermalling turn, then it is going
to hit you before you finish the next.

No. YOU are going to hit it.

Ok, I'll accept "we'll hit each other" but I can't let the arrogance of
"it is going to hit you" pass without comment.

Powered aircraft are only one user of airspace.

GC

Graeme Cant wrote:
Yuliy Gerchikov wrote:

The truth is, if you can't see this tiny *motionless* speck ...two
miles away ...in the inversion haze ...on one thermalling turn, then
it is going to hit you before you finish the next.

No. YOU are going to hit it.

Ok, I'll accept "we'll hit each other" but I can't let the arrogance of
"it is going to hit you" pass without comment.

Powered aircraft are only one user of airspace.

My apologies, Yuliy. I misread your post as coming from a power pilot
with the "How can I possibly be expected to get out of a glider's road?"
point of view. when I re-read your post I'm 180 degrees wrong! Sorry!

GC

GC

Yuliy Gerchikov wrote:

The truth is, if you can't see this tiny *motionless* speck ...two miles
away ...in the inversion haze ...on one thermalling turn, then it is going
to hit you before you finish the next.

Yuliy,

Interesting test, but I don't think it anyway replicates real life.
Airplanes at a distance, co-altitude on the horizon, are going to be
black dots almost all the time. What you have to train yourself to
look for is a moving black dot against the background. Worse, you have
to also find the black dot that isn't moving - because that is the one
on a perfect collision course. That situation is tought, but not
impossible. If you turn at all, you break the collision course, and
generate motion on the canopy.

Plus, 20 seconds is an eternity when it comes to getting out of the
way.

So I don't buy your analogy - it just doesn't correlate with my
personal experience.

See and avoid is not the best solution, but it does work - if everybody
does it correctly. I'm starting to think that many pilots have never
been trained how to look for traffic - the basic physiological and
environmental facts that have to be understood in order to scan
succesfully for traffic. Scary!

These are great discussions, IMHO - makes us all think about how we fly
and how others fly.

And I know I need to spend less time with MCU and even more time
scanning!

Kirk

"kirk.stant" wrote in message
oups.com...

Plus, 20 seconds is an eternity when it comes to getting out of the
way.

I asked this question several times, and never saw a convincing answer:
exactly how do you use even the 20 seconds if you have them to avoid
something coming at you at 300 (or, it was suggested, possibly much more)
knots? If you start in a thermalling glider at minimum sink speed, you can't
seem to run fast enough far enough given the rate of closure -- and the lack
of time to estimate relative motion precisely enough. We don't have
targeting radars in most of the gliders (not sure about Space Shuttle
though).
--
Yuliy

A few additions to Kirk's excellent points - from the background of former
fighter pilot, current airline pilot, and current glider pilot:

1. We often surprise each other in sailplanes with how hard it is to see
each other. Don't expect an airline pilot to be any better at it! The
fighter pilot at least will have good visual acuity and is used to looking
for small targets.

2. Airline pilots don't carry sectionals - at the speeds we operate, there
would be little time to use them anyway. Fighter pilots will carry a low
level map and will have thought about visual traffic conflicts, wires,
terrain, etc in the planning stages. At the speeds they operate, they
aren't looking at those maps very often, once airborne.

3. The busier glider operations are notam'd and often referred to by atc
controllers. If you have an operable transponder, you will *normally* be
called out by atc and if TCAS equipped, airline pilots will be aware of your
location. They would still have to see you to maneuver away from you. (See
note 1.) Big airliners are not very maneuverable (mine - the Boeing 737 -
is limited to 2.5 g!).

4. Fighters are a different case. They don't have TCAS and only some of
them have the ability to interrogate/detect transponder targets. Some of
them have air intercept radar capability, but sailplanes are small radar
targets and will often (usually!) be filtered out because of their low
speeds and altitudes - like highway traffic. If they are at low altitude,
fighters usually operate at high speed (420 - 540 indicated, except the
A-10). As Kirk pointed out they will almost never be alone, but will be in
formations of 2 - 4. When low level (100 to 1500 agl, most commonly 300 -
500agl), they will normally *not* be receiving traffic information from ATC.
When operating in a MOA, there may be intercept controllers who can call out
glider traffic, but again, without a transponder, it is unlikely. The
formations will vary, but most pairs of flight lead and wingman will be
laterally spread by 5000 to 10000 feet, for visual lookout. The flight lead
will be spending quite a bit of his time looking forward for threat
detection and navigation, but the wingman will be spending less time looking
forward because he must maintain formation. If they see you, they have an
excellent capability to avoid you. Head on and tail on, the sailplane has
the tiny visual profile that fighter designers dream of.... In other words,
you are nearly invisible unless you have a wing up in a turn/thermal.

5. As Kirk said, the primary threat is at 6 o'clock, because it is the
hardest to see - essentially, only the overtaking aircraft has a reasonable
chance of avoiding a collision. Therefore, if you know you are operating in
a high threat area: MOA, low level route, approach corridor, VFR flyway,
near an airport etc, I would "belly check" periodically, depending on the
nature of the threat. The timing is based on the amount of time it takes for
the threat aircraft to close from outside visual range to hitting me from
the 6 o'clock position. I use visual ranges of 8nm for airliners, 5 nm for
small commercial jets (corporate and regional jets) and fighters, and 3 nm
for light aircraft - adjust as your visual acuity and experience dictate. I
use worst-case speeds as follows: airliner and small jets - 4 nm/min,
fighters - 8 nm/min, and light aircraft - 2.5 nm/min. Combing detection
ranges and times, I calculate: airliners - 2 min, small jets - 1 min and 15
sec, fighters - roughly 40 sec, and light planes - approx 1 min and 15 sec.
So... if you are straight and level for more than these times, there is
sufficient time for an aircraft to move from outside (my) visual range to
the same airspace as my (your) little pink body. As you would probably
guess, fighters are the worst case because of their relatively small size
and high closure rate. On the positive side, there are typically more
eyeballs with better acuity and better maneuverability involved.
Interestingly, small jets and light aircraft are not that far behind, as far
as detection time is concerned. In my experience they are far less likely
to see you than the fighters. The same is true for airliners, but because
of their size you have more time to see them coming...

6. How to do a belly check: No, I don't hack a stopwatch, but I keep the
above times in mind with respect to the likely threat for my area. My
primary threat is small jet/light aircraft that operate on various
highway/flyways and approach corridors. Away from these specific areas,
traffic density is extremely low. First clear your "new six" - if you are
going to turn left, look to the area behind to the right 4 - 5 oclock
position - this will be your new blind spot. Next clear your new nose
position - this is where you are going to roll out. Finally make a 45 deg
turn to the left and visually clear your "old six", which is now at your
left 7 to 8 o'clock. Often/usually, a belly check can be incorporated into
turns you are going to make anyway, for other reasons. When you visually
clear, make sure you focus on something on the horizon, otherwise you are
only visually clearing out to an arms length. If I really need to hold a
straight line, I do the belly check as a gentle 45 deg turn to each side.

7. In a thermal, periodically check to the outside of your term to clear
your "new six". If there are other sailplanes with you in the thermal, of
course they are the primary threats for midair, but you still need to check
for other aircraft. Fortunately, you are easier to see while turning - as
long as the other pilots are looking...

8. Proximity to clouds. You need to think about what you are doing when
you are near cloudbase, in proximity to likely IFR traffic. If you are 500'
below cloudbase (perfectly legal), and an airliner descends out of the cloud
at 250kt on his descent profile on collision course (perfectly legal), there
may be as little as 20 seconds to impact. If you are tail on when this
happens - good luck. I'm sure no one would ever be right at cloudbase on a
nice day, because that would violate the FARs - more importantly, you are
"rolling the bones" every time you do this on a known approach corridor.

9. Conclusion. If you fly in a high airliner/small jet threat area and
can afford a transponder it will help other people see/avoid you. If your
primary threat comes from military operations in MOAs, I would not spend the
money on a transponder unless I knew those fighters have intercept/atc
controllers passing them information. The various TPAS - type devices will
help your see/avoid efforts and should help in the case of fighters,
although the flight lead is likely the only one squawking in the formation.
Only you/your club knows the primary threats for your particular operating
area and you need to understand what they are. Taylor your altitude
awareness/cloud avoidance and belly check frequency to the nature of your
local area. Don't cede visual lookout/avoidance responsibility to someone
else - ever. Sailplane right-of-way is a myth in most situations and a
comfort only to your survivors/legal counsel.

Hope this helps.

Glen

Thanks for the excellent overview, Glen. Regarding number 3, why would
a TCAS equipped airliner pilot need to see me if the TCAS gives the
resolution? I'm pretty sure most of the airliners vectored around me
never actually see me (although I always
wave ;-)

Ramy

Glen Kelley wrote:
A few additions to Kirk's excellent points - from the background of former
fighter pilot, current airline pilot, and current glider pilot:

1. We often surprise each other in sailplanes with how hard it is to see
each other. Don't expect an airline pilot to be any better at it! The
fighter pilot at least will have good visual acuity and is used to looking
for small targets.

2. Airline pilots don't carry sectionals - at the speeds we operate, there
would be little time to use them anyway. Fighter pilots will carry a low
level map and will have thought about visual traffic conflicts, wires,
terrain, etc in the planning stages. At the speeds they operate, they
aren't looking at those maps very often, once airborne.

3. The busier glider operations are notam'd and often referred to by atc
controllers. If you have an operable transponder, you will *normally* be
called out by atc and if TCAS equipped, airline pilots will be aware of your
location. They would still have to see you to maneuver away from you. (See
note 1.) Big airliners are not very maneuverable (mine - the Boeing 737 -
is limited to 2.5 g!).

4. Fighters are a different case. They don't have TCAS and only some of
them have the ability to interrogate/detect transponder targets. Some of
them have air intercept radar capability, but sailplanes are small radar
targets and will often (usually!) be filtered out because of their low
speeds and altitudes - like highway traffic. If they are at low altitude,
fighters usually operate at high speed (420 - 540 indicated, except the
A-10). As Kirk pointed out they will almost never be alone, but will be in
formations of 2 - 4. When low level (100 to 1500 agl, most commonly 300 -
500agl), they will normally *not* be receiving traffic information from ATC.
When operating in a MOA, there may be intercept controllers who can call out
glider traffic, but again, without a transponder, it is unlikely. The
formations will vary, but most pairs of flight lead and wingman will be
laterally spread by 5000 to 10000 feet, for visual lookout. The flight lead
will be spending quite a bit of his time looking forward for threat
detection and navigation, but the wingman will be spending less time looking
forward because he must maintain formation. If they see you, they have an
excellent capability to avoid you. Head on and tail on, the sailplane has
the tiny visual profile that fighter designers dream of.... In other words,
you are nearly invisible unless you have a wing up in a turn/thermal.

5. As Kirk said, the primary threat is at 6 o'clock, because it is the
hardest to see - essentially, only the overtaking aircraft has a reasonable
chance of avoiding a collision. Therefore, if you know you are operating in
a high threat area: MOA, low level route, approach corridor, VFR flyway,
near an airport etc, I would "belly check" periodically, depending on the
nature of the threat. The timing is based on the amount of time it takes for
the threat aircraft to close from outside visual range to hitting me from
the 6 o'clock position. I use visual ranges of 8nm for airliners, 5 nm for
small commercial jets (corporate and regional jets) and fighters, and 3 nm
for light aircraft - adjust as your visual acuity and experience dictate. I
use worst-case speeds as follows: airliner and small jets - 4 nm/min,
fighters - 8 nm/min, and light aircraft - 2.5 nm/min. Combing detection
ranges and times, I calculate: airliners - 2 min, small jets - 1 min and 15
sec, fighters - roughly 40 sec, and light planes - approx 1 min and 15 sec.
So... if you are straight and level for more than these times, there is
sufficient time for an aircraft to move from outside (my) visual range to
the same airspace as my (your) little pink body. As you would probably
guess, fighters are the worst case because of their relatively small size
and high closure rate. On the positive side, there are typically more
eyeballs with better acuity and better maneuverability involved.
Interestingly, small jets and light aircraft are not that far behind, as far
as detection time is concerned. In my experience they are far less likely
to see you than the fighters. The same is true for airliners, but because
of their size you have more time to see them coming...

6. How to do a belly check: No, I don't hack a stopwatch, but I keep the
above times in mind with respect to the likely threat for my area. My
primary threat is small jet/light aircraft that operate on various
highway/flyways and approach corridors. Away from these specific areas,
traffic density is extremely low. First clear your "new six" - if you are
going to turn left, look to the area behind to the right 4 - 5 oclock
position - this will be your new blind spot. Next clear your new nose
position - this is where you are going to roll out. Finally make a 45 deg
turn to the left and visually clear your "old six", which is now at your
left 7 to 8 o'clock. Often/usually, a belly check can be incorporated into
turns you are going to make anyway, for other reasons. When you visually
clear, make sure you focus on something on the horizon, otherwise you are
only visually clearing out to an arms length. If I really need to hold a
straight line, I do the belly check as a gentle 45 deg turn to each side.

7. In a thermal, periodically check to the outside of your term to clear
your "new six". If there are other sailplanes with you in the thermal, of
course they are the primary threats for midair, but you still need to check
for other aircraft. Fortunately, you are easier to see while turning - as
long as the other pilots are looking...

8. Proximity to clouds. You need to think about what you are doing when
you are near cloudbase, in proximity to likely IFR traffic. If you are 500'
below cloudbase (perfectly legal), and an airliner descends out of the cloud
at 250kt on his descent profile on collision course (perfectly legal), there
may be as little as 20 seconds to impact. If you are tail on when this
happens - good luck. I'm sure no one would ever be right at cloudbase on a
nice day, because that would violate the FARs - more importantly, you are
"rolling the bones" every time you do this on a known approach corridor.

9. Conclusion. If you fly in a high airliner/small jet threat area and
can afford a transponder it will help other people see/avoid you. If your
primary threat comes from military operations in MOAs, I would not spend the
money on a transponder unless I knew those fighters have intercept/atc
controllers passing them information. The various TPAS - type devices will
help your see/avoid efforts and should help in the case of fighters,
although the flight lead is likely the only one squawking in the formation.
Only you/your club knows the primary threats for your particular operating
area and you need to understand what they are. Taylor your altitude
awareness/cloud avoidance and belly check frequency to the nature of your
local area. Don't cede visual lookout/avoidance responsibility to someone
else - ever. Sailplane right-of-way is a myth in most situations and a
comfort only to your survivors/legal counsel.

Hope this helps.

Glen

Ramy,

The problem is that TCAS will display you as a target with altitude unknown
(unless you have mode c with an encoding altimeter). Therefore, TCAS will
only call you out as traffic and display your position without generating a
Resolution Advisory (RA). We see this pretty often as VFR traffic. We will
be looking hard for the traffic, but won't necessarily maneuver the
aircraft, since we can't see altitude/heading.

If in fact, the sailplane does have mode C with an encoding altimeter, then
the RA will be generated and you should see the big bird maneuver to avoid
the conflict. Note that a TCAS RA will direct maneuvering in the vertical
only, since TCAS azimuth is considered too innacurate to generate turn-based
avoidance. Typical RAs would be "Climb,Climb, Climb - Descend, Descend,
Descend - Reduce Climb - Reduce Descent, etc".

I guess I figured most of the gliders with transponders weren't using Mode
C, so good catch.

Glen
"Ramy" wrote in message
ups.com...
Thanks for the excellent overview, Glen. Regarding number 3, why would
a TCAS equipped airliner pilot need to see me if the TCAS gives the
resolution? I'm pretty sure most of the airliners vectored around me
never actually see me (although I always
wave ;-)

Ramy

Glen Kelley wrote:
A few additions to Kirk's excellent points - from the background of
former
fighter pilot, current airline pilot, and current glider pilot:

1. We often surprise each other in sailplanes with how hard it is to see
each other. Don't expect an airline pilot to be any better at it! The
fighter pilot at least will have good visual acuity and is used to
looking
for small targets.

2. Airline pilots don't carry sectionals - at the speeds we operate,
there
would be little time to use them anyway. Fighter pilots will carry a low
level map and will have thought about visual traffic conflicts, wires,
terrain, etc in the planning stages. At the speeds they operate, they
aren't looking at those maps very often, once airborne.

3. The busier glider operations are notam'd and often referred to by atc
controllers. If you have an operable transponder, you will *normally* be
called out by atc and if TCAS equipped, airline pilots will be aware of
your
location. They would still have to see you to maneuver away from you.
(See
note 1.) Big airliners are not very maneuverable (mine - the Boeing
737 -
is limited to 2.5 g!).

4. Fighters are a different case. They don't have TCAS and only some of
them have the ability to interrogate/detect transponder targets. Some of
them have air intercept radar capability, but sailplanes are small radar
targets and will often (usually!) be filtered out because of their low
speeds and altitudes - like highway traffic. If they are at low
altitude,
fighters usually operate at high speed (420 - 540 indicated, except the
A-10). As Kirk pointed out they will almost never be alone, but will be
in
formations of 2 - 4. When low level (100 to 1500 agl, most commonly 300 -
500agl), they will normally *not* be receiving traffic information from
ATC.
When operating in a MOA, there may be intercept controllers who can call
out
glider traffic, but again, without a transponder, it is unlikely. The
formations will vary, but most pairs of flight lead and wingman will be
laterally spread by 5000 to 10000 feet, for visual lookout. The flight
lead
will be spending quite a bit of his time looking forward for threat
detection and navigation, but the wingman will be spending less time
looking
forward because he must maintain formation. If they see you, they have
an
excellent capability to avoid you. Head on and tail on, the sailplane
has
the tiny visual profile that fighter designers dream of.... In other
words,
you are nearly invisible unless you have a wing up in a turn/thermal.

5. As Kirk said, the primary threat is at 6 o'clock, because it is the
hardest to see - essentially, only the overtaking aircraft has a
reasonable
chance of avoiding a collision. Therefore, if you know you are operating
in
a high threat area: MOA, low level route, approach corridor, VFR flyway,
near an airport etc, I would "belly check" periodically, depending on the
nature of the threat. The timing is based on the amount of time it takes
for
the threat aircraft to close from outside visual range to hitting me from
the 6 o'clock position. I use visual ranges of 8nm for airliners, 5 nm
for
small commercial jets (corporate and regional jets) and fighters, and 3
nm
for light aircraft - adjust as your visual acuity and experience dictate.
I
use worst-case speeds as follows: airliner and small jets - 4 nm/min,
fighters - 8 nm/min, and light aircraft - 2.5 nm/min. Combing detection
ranges and times, I calculate: airliners - 2 min, small jets - 1 min and
15
sec, fighters - roughly 40 sec, and light planes - approx 1 min and 15
sec.
So... if you are straight and level for more than these times, there is
sufficient time for an aircraft to move from outside (my) visual range to
the same airspace as my (your) little pink body. As you would probably
guess, fighters are the worst case because of their relatively small size
and high closure rate. On the positive side, there are typically more
eyeballs with better acuity and better maneuverability involved.
Interestingly, small jets and light aircraft are not that far behind, as
far
as detection time is concerned. In my experience they are far less
likely
to see you than the fighters. The same is true for airliners, but
because
of their size you have more time to see them coming...

6. How to do a belly check: No, I don't hack a stopwatch, but I keep
the
above times in mind with respect to the likely threat for my area. My
primary threat is small jet/light aircraft that operate on various
highway/flyways and approach corridors. Away from these specific areas,
traffic density is extremely low. First clear your "new six" - if you
are
going to turn left, look to the area behind to the right 4 - 5 oclock
position - this will be your new blind spot. Next clear your new nose
position - this is where you are going to roll out. Finally make a 45
deg
turn to the left and visually clear your "old six", which is now at your
left 7 to 8 o'clock. Often/usually, a belly check can be incorporated
into
turns you are going to make anyway, for other reasons. When you
visually
clear, make sure you focus on something on the horizon, otherwise you are
only visually clearing out to an arms length. If I really need to hold a
straight line, I do the belly check as a gentle 45 deg turn to each side.

7. In a thermal, periodically check to the outside of your term to clear
your "new six". If there are other sailplanes with you in the thermal,
of
course they are the primary threats for midair, but you still need to
check
for other aircraft. Fortunately, you are easier to see while turning - as
long as the other pilots are looking...

8. Proximity to clouds. You need to think about what you are doing when
you are near cloudbase, in proximity to likely IFR traffic. If you are
500'
below cloudbase (perfectly legal), and an airliner descends out of the
cloud
at 250kt on his descent profile on collision course (perfectly legal),
there
may be as little as 20 seconds to impact. If you are tail on when this
happens - good luck. I'm sure no one would ever be right at cloudbase on
a
nice day, because that would violate the FARs - more importantly, you
are
"rolling the bones" every time you do this on a known approach corridor.

9. Conclusion. If you fly in a high airliner/small jet threat area and
can afford a transponder it will help other people see/avoid you. If
your
primary threat comes from military operations in MOAs, I would not spend
the
money on a transponder unless I knew those fighters have intercept/atc
controllers passing them information. The various TPAS - type devices
will
help your see/avoid efforts and should help in the case of fighters,
although the flight lead is likely the only one squawking in the
formation.
Only you/your club knows the primary threats for your particular
operating
area and you need to understand what they are. Taylor your altitude
awareness/cloud avoidance and belly check frequency to the nature of your
local area. Don't cede visual lookout/avoidance responsibility to
someone
else - ever. Sailplane right-of-way is a myth in most situations and a
comfort only to your survivors/legal counsel.

Hope this helps.

Glen

The proper conclusion is that if you are going to invest in a transponder,
make sure it is a Mode C.

Mike Schumann

"Glen Kelley" wrote in message
news:lmNJg.476$XK4.324@trndny07...
Ramy,

The problem is that TCAS will display you as a target with altitude
unknown (unless you have mode c with an encoding altimeter). Therefore,
TCAS will only call you out as traffic and display your position without
generating a Resolution Advisory (RA). We see this pretty often as VFR
traffic. We will be looking hard for the traffic, but won't necessarily
maneuver the aircraft, since we can't see altitude/heading.

If in fact, the sailplane does have mode C with an encoding altimeter,
then the RA will be generated and you should see the big bird maneuver to
avoid the conflict. Note that a TCAS RA will direct maneuvering in the
vertical only, since TCAS azimuth is considered too innacurate to generate
turn-based avoidance. Typical RAs would be "Climb,Climb, Climb - Descend,
Descend, Descend - Reduce Climb - Reduce Descent, etc".

I guess I figured most of the gliders with transponders weren't using Mode
C, so good catch.

Glen
"Ramy" wrote in message
ups.com...
Thanks for the excellent overview, Glen. Regarding number 3, why would
a TCAS equipped airliner pilot need to see me if the TCAS gives the
resolution? I'm pretty sure most of the airliners vectored around me
never actually see me (although I always
wave ;-)

Ramy

Glen Kelley wrote:
A few additions to Kirk's excellent points - from the background of
former
fighter pilot, current airline pilot, and current glider pilot:

1. We often surprise each other in sailplanes with how hard it is to
see
each other. Don't expect an airline pilot to be any better at it! The
fighter pilot at least will have good visual acuity and is used to
looking
for small targets.

2. Airline pilots don't carry sectionals - at the speeds we operate,
there
would be little time to use them anyway. Fighter pilots will carry a
low
level map and will have thought about visual traffic conflicts, wires,
terrain, etc in the planning stages. At the speeds they operate, they
aren't looking at those maps very often, once airborne.

3. The busier glider operations are notam'd and often referred to by atc
controllers. If you have an operable transponder, you will *normally*
be
called out by atc and if TCAS equipped, airline pilots will be aware of
your
location. They would still have to see you to maneuver away from you.
(See
note 1.) Big airliners are not very maneuverable (mine - the Boeing
737 -
is limited to 2.5 g!).

4. Fighters are a different case. They don't have TCAS and only some
of
them have the ability to interrogate/detect transponder targets. Some
of
them have air intercept radar capability, but sailplanes are small radar
targets and will often (usually!) be filtered out because of their low
speeds and altitudes - like highway traffic. If they are at low
altitude,
fighters usually operate at high speed (420 - 540 indicated, except the
A-10). As Kirk pointed out they will almost never be alone, but will be
in
formations of 2 - 4. When low level (100 to 1500 agl, most commonly
300 -
500agl), they will normally *not* be receiving traffic information from
ATC.
When operating in a MOA, there may be intercept controllers who can call
out
glider traffic, but again, without a transponder, it is unlikely. The
formations will vary, but most pairs of flight lead and wingman will be
laterally spread by 5000 to 10000 feet, for visual lookout. The flight
lead
will be spending quite a bit of his time looking forward for threat
detection and navigation, but the wingman will be spending less time
looking
forward because he must maintain formation. If they see you, they have
an
excellent capability to avoid you. Head on and tail on, the sailplane
has
the tiny visual profile that fighter designers dream of.... In other
words,
you are nearly invisible unless you have a wing up in a turn/thermal.

5. As Kirk said, the primary threat is at 6 o'clock, because it is the
hardest to see - essentially, only the overtaking aircraft has a
reasonable
chance of avoiding a collision. Therefore, if you know you are
operating in
a high threat area: MOA, low level route, approach corridor, VFR flyway,
near an airport etc, I would "belly check" periodically, depending on
the
nature of the threat. The timing is based on the amount of time it takes
for
the threat aircraft to close from outside visual range to hitting me
from
the 6 o'clock position. I use visual ranges of 8nm for airliners, 5 nm
for
small commercial jets (corporate and regional jets) and fighters, and 3
nm
for light aircraft - adjust as your visual acuity and experience
dictate. I
use worst-case speeds as follows: airliner and small jets - 4 nm/min,
fighters - 8 nm/min, and light aircraft - 2.5 nm/min. Combing detection
ranges and times, I calculate: airliners - 2 min, small jets - 1 min
and 15
sec, fighters - roughly 40 sec, and light planes - approx 1 min and 15
sec.
So... if you are straight and level for more than these times, there is
sufficient time for an aircraft to move from outside (my) visual range
to
the same airspace as my (your) little pink body. As you would probably
guess, fighters are the worst case because of their relatively small
size
and high closure rate. On the positive side, there are typically more
eyeballs with better acuity and better maneuverability involved.
Interestingly, small jets and light aircraft are not that far behind, as
far
as detection time is concerned. In my experience they are far less
likely
to see you than the fighters. The same is true for airliners, but
because
of their size you have more time to see them coming...

6. How to do a belly check: No, I don't hack a stopwatch, but I keep
the
above times in mind with respect to the likely threat for my area. My
primary threat is small jet/light aircraft that operate on various
highway/flyways and approach corridors. Away from these specific areas,
traffic density is extremely low. First clear your "new six" - if you
are
going to turn left, look to the area behind to the right 4 - 5 oclock
position - this will be your new blind spot. Next clear your new nose
position - this is where you are going to roll out. Finally make a 45
deg
turn to the left and visually clear your "old six", which is now at your
left 7 to 8 o'clock. Often/usually, a belly check can be incorporated
into
turns you are going to make anyway, for other reasons. When you
visually
clear, make sure you focus on something on the horizon, otherwise you
are
only visually clearing out to an arms length. If I really need to hold
a
straight line, I do the belly check as a gentle 45 deg turn to each
side.

7. In a thermal, periodically check to the outside of your term to
clear
your "new six". If there are other sailplanes with you in the thermal,
of
course they are the primary threats for midair, but you still need to
check
for other aircraft. Fortunately, you are easier to see while turning -
as
long as the other pilots are looking...

8. Proximity to clouds. You need to think about what you are doing
when
you are near cloudbase, in proximity to likely IFR traffic. If you are
500'
below cloudbase (perfectly legal), and an airliner descends out of the
cloud
at 250kt on his descent profile on collision course (perfectly legal),
there
may be as little as 20 seconds to impact. If you are tail on when this
happens - good luck. I'm sure no one would ever be right at cloudbase
on a
nice day, because that would violate the FARs - more importantly, you
are
"rolling the bones" every time you do this on a known approach corridor.

9. Conclusion. If you fly in a high airliner/small jet threat area
and
can afford a transponder it will help other people see/avoid you. If
your
primary threat comes from military operations in MOAs, I would not spend
the
money on a transponder unless I knew those fighters have intercept/atc
controllers passing them information. The various TPAS - type devices
will
help your see/avoid efforts and should help in the case of fighters,
although the flight lead is likely the only one squawking in the
formation.
Only you/your club knows the primary threats for your particular
operating
area and you need to understand what they are. Taylor your altitude
awareness/cloud avoidance and belly check frequency to the nature of
your
local area. Don't cede visual lookout/avoidance responsibility to
someone
else - ever. Sailplane right-of-way is a myth in most situations and a
comfort only to your survivors/legal counsel.

Hope this helps.

Glen

Thanks Glen. I am not aware of any transponder equiped glider not using
mode C. Seems like once you go through the hassle and cost of
installing a transponder, the encoder is the easy part. Mode A sounds
almost useless, more confusing then not. A mode A transponder could
signal an alert to any airline crusing at 30K above.
Which baffles me - Why aren't modern transponders already including
internal encoder??

Ramy

Glen Kelley wrote:
Ramy,

The problem is that TCAS will display you as a target with altitude unknown
(unless you have mode c with an encoding altimeter). Therefore, TCAS will
only call you out as traffic and display your position without generating a
Resolution Advisory (RA). We see this pretty often as VFR traffic. We will
be looking hard for the traffic, but won't necessarily maneuver the
aircraft, since we can't see altitude/heading.

If in fact, the sailplane does have mode C with an encoding altimeter, then
the RA will be generated and you should see the big bird maneuver to avoid
the conflict. Note that a TCAS RA will direct maneuvering in the vertical
only, since TCAS azimuth is considered too innacurate to generate turn-based
avoidance. Typical RAs would be "Climb,Climb, Climb - Descend, Descend,
Descend - Reduce Climb - Reduce Descent, etc".

I guess I figured most of the gliders with transponders weren't using Mode
C, so good catch.

Glen
"Ramy" wrote in message
ups.com...
Thanks for the excellent overview, Glen. Regarding number 3, why would
a TCAS equipped airliner pilot need to see me if the TCAS gives the
resolution? I'm pretty sure most of the airliners vectored around me
never actually see me (although I always
wave ;-)

Ramy

Glen Kelley wrote:
A few additions to Kirk's excellent points - from the background of
former
fighter pilot, current airline pilot, and current glider pilot:

1. We often surprise each other in sailplanes with how hard it is to see
each other. Don't expect an airline pilot to be any better at it! The
fighter pilot at least will have good visual acuity and is used to
looking
for small targets.

2. Airline pilots don't carry sectionals - at the speeds we operate,
there
would be little time to use them anyway. Fighter pilots will carry a low
level map and will have thought about visual traffic conflicts, wires,
terrain, etc in the planning stages. At the speeds they operate, they
aren't looking at those maps very often, once airborne.

3. The busier glider operations are notam'd and often referred to by atc
controllers. If you have an operable transponder, you will *normally* be
called out by atc and if TCAS equipped, airline pilots will be aware of
your
location. They would still have to see you to maneuver away from you.
(See
note 1.) Big airliners are not very maneuverable (mine - the Boeing
737 -
is limited to 2.5 g!).

4. Fighters are a different case. They don't have TCAS and only some of
them have the ability to interrogate/detect transponder targets. Some of
them have air intercept radar capability, but sailplanes are small radar
targets and will often (usually!) be filtered out because of their low
speeds and altitudes - like highway traffic. If they are at low
altitude,
fighters usually operate at high speed (420 - 540 indicated, except the
A-10). As Kirk pointed out they will almost never be alone, but will be
in
formations of 2 - 4. When low level (100 to 1500 agl, most commonly 300 -
500agl), they will normally *not* be receiving traffic information from
ATC.
When operating in a MOA, there may be intercept controllers who can call
out
glider traffic, but again, without a transponder, it is unlikely. The
formations will vary, but most pairs of flight lead and wingman will be
laterally spread by 5000 to 10000 feet, for visual lookout. The flight
lead
will be spending quite a bit of his time looking forward for threat
detection and navigation, but the wingman will be spending less time
looking
forward because he must maintain formation. If they see you, they have
an
excellent capability to avoid you. Head on and tail on, the sailplane
has
the tiny visual profile that fighter designers dream of.... In other
words,
you are nearly invisible unless you have a wing up in a turn/thermal.

5. As Kirk said, the primary threat is at 6 o'clock, because it is the
hardest to see - essentially, only the overtaking aircraft has a
reasonable
chance of avoiding a collision. Therefore, if you know you are operating
in
a high threat area: MOA, low level route, approach corridor, VFR flyway,
near an airport etc, I would "belly check" periodically, depending on the
nature of the threat. The timing is based on the amount of time it takes
for
the threat aircraft to close from outside visual range to hitting me from
the 6 o'clock position. I use visual ranges of 8nm for airliners, 5 nm
for
small commercial jets (corporate and regional jets) and fighters, and 3
nm
for light aircraft - adjust as your visual acuity and experience dictate.
I
use worst-case speeds as follows: airliner and small jets - 4 nm/min,
fighters - 8 nm/min, and light aircraft - 2.5 nm/min. Combing detection
ranges and times, I calculate: airliners - 2 min, small jets - 1 min and
15
sec, fighters - roughly 40 sec, and light planes - approx 1 min and 15
sec.
So... if you are straight and level for more than these times, there is
sufficient time for an aircraft to move from outside (my) visual range to
the same airspace as my (your) little pink body. As you would probably
guess, fighters are the worst case because of their relatively small size
and high closure rate. On the positive side, there are typically more
eyeballs with better acuity and better maneuverability involved.
Interestingly, small jets and light aircraft are not that far behind, as
far
as detection time is concerned. In my experience they are far less
likely
to see you than the fighters. The same is true for airliners, but
because
of their size you have more time to see them coming...

6. How to do a belly check: No, I don't hack a stopwatch, but I keep
the
above times in mind with respect to the likely threat for my area. My
primary threat is small jet/light aircraft that operate on various
highway/flyways and approach corridors. Away from these specific areas,
traffic density is extremely low. First clear your "new six" - if you
are
going to turn left, look to the area behind to the right 4 - 5 oclock
position - this will be your new blind spot. Next clear your new nose
position - this is where you are going to roll out. Finally make a 45
deg
turn to the left and visually clear your "old six", which is now at your
left 7 to 8 o'clock. Often/usually, a belly check can be incorporated
into
turns you are going to make anyway, for other reasons. When you
visually
clear, make sure you focus on something on the horizon, otherwise you are
only visually clearing out to an arms length. If I really need to hold a
straight line, I do the belly check as a gentle 45 deg turn to each side.

7. In a thermal, periodically check to the outside of your term to clear
your "new six". If there are other sailplanes with you in the thermal,
of
course they are the primary threats for midair, but you still need to
check
for other aircraft. Fortunately, you are easier to see while turning - as
long as the other pilots are looking...

8. Proximity to clouds. You need to think about what you are doing when
you are near cloudbase, in proximity to likely IFR traffic. If you are
500'
below cloudbase (perfectly legal), and an airliner descends out of the
cloud
at 250kt on his descent profile on collision course (perfectly legal),
there
may be as little as 20 seconds to impact. If you are tail on when this
happens - good luck. I'm sure no one would ever be right at cloudbase on
a
nice day, because that would violate the FARs - more importantly, you
are
"rolling the bones" every time you do this on a known approach corridor.

9. Conclusion. If you fly in a high airliner/small jet threat area and
can afford a transponder it will help other people see/avoid you. If
your
primary threat comes from military operations in MOAs, I would not spend
the
money on a transponder unless I knew those fighters have intercept/atc
controllers passing them information. The various TPAS - type devices
will
help your see/avoid efforts and should help in the case of fighters,
although the flight lead is likely the only one squawking in the
formation.
Only you/your club knows the primary threats for your particular
operating
area and you need to understand what they are. Taylor your altitude
awareness/cloud avoidance and belly check frequency to the nature of your
local area. Don't cede visual lookout/avoidance responsibility to
someone
else - ever. Sailplane right-of-way is a myth in most situations and a
comfort only to your survivors/legal counsel.

Hope this helps.

Glen

Ramy, I would agree. Mode A isn't completely worthless, since at least the
airliner knows you are around. Clearly Mode C provides more "protection".

Glen
"Ramy" wrote in message
oups.com...
Thanks Glen. I am not aware of any transponder equiped glider not using
mode C. Seems like once you go through the hassle and cost of
installing a transponder, the encoder is the easy part. Mode A sounds
almost useless, more confusing then not. A mode A transponder could
signal an alert to any airline crusing at 30K above.
Which baffles me - Why aren't modern transponders already including
internal encoder??

Ramy

Glen Kelley wrote:
Ramy,

The problem is that TCAS will display you as a target with altitude
unknown
(unless you have mode c with an encoding altimeter). Therefore, TCAS
will
only call you out as traffic and display your position without generating
a
Resolution Advisory (RA). We see this pretty often as VFR traffic. We
will
be looking hard for the traffic, but won't necessarily maneuver the
aircraft, since we can't see altitude/heading.

If in fact, the sailplane does have mode C with an encoding altimeter,
then
the RA will be generated and you should see the big bird maneuver to
avoid
the conflict. Note that a TCAS RA will direct maneuvering in the
vertical
only, since TCAS azimuth is considered too innacurate to generate
turn-based
avoidance. Typical RAs would be "Climb,Climb, Climb - Descend, Descend,
Descend - Reduce Climb - Reduce Descent, etc".

I guess I figured most of the gliders with transponders weren't using
Mode
C, so good catch.

Glen
"Ramy" wrote in message
ups.com...
Thanks for the excellent overview, Glen. Regarding number 3, why would
a TCAS equipped airliner pilot need to see me if the TCAS gives the
resolution? I'm pretty sure most of the airliners vectored around me
never actually see me (although I always
wave ;-)

Ramy

Glen Kelley wrote:
A few additions to Kirk's excellent points - from the background of
former
fighter pilot, current airline pilot, and current glider pilot:

1. We often surprise each other in sailplanes with how hard it is to
see
each other. Don't expect an airline pilot to be any better at it!
The
fighter pilot at least will have good visual acuity and is used to
looking
for small targets.

2. Airline pilots don't carry sectionals - at the speeds we operate,
there
would be little time to use them anyway. Fighter pilots will carry a
low
level map and will have thought about visual traffic conflicts, wires,
terrain, etc in the planning stages. At the speeds they operate, they
aren't looking at those maps very often, once airborne.

3. The busier glider operations are notam'd and often referred to by
atc
controllers. If you have an operable transponder, you will *normally*
be
called out by atc and if TCAS equipped, airline pilots will be aware
of
your
location. They would still have to see you to maneuver away from you.
(See
note 1.) Big airliners are not very maneuverable (mine - the Boeing
737 -
is limited to 2.5 g!).

4. Fighters are a different case. They don't have TCAS and only some
of
them have the ability to interrogate/detect transponder targets. Some
of
them have air intercept radar capability, but sailplanes are small
radar
targets and will often (usually!) be filtered out because of their low
speeds and altitudes - like highway traffic. If they are at low
altitude,
fighters usually operate at high speed (420 - 540 indicated, except
the
A-10). As Kirk pointed out they will almost never be alone, but will
be
in
formations of 2 - 4. When low level (100 to 1500 agl, most commonly
300 -
500agl), they will normally *not* be receiving traffic information
from
ATC.
When operating in a MOA, there may be intercept controllers who can
call
out
glider traffic, but again, without a transponder, it is unlikely. The
formations will vary, but most pairs of flight lead and wingman will
be
laterally spread by 5000 to 10000 feet, for visual lookout. The
flight
lead
will be spending quite a bit of his time looking forward for threat
detection and navigation, but the wingman will be spending less time
looking
forward because he must maintain formation. If they see you, they
have
an
excellent capability to avoid you. Head on and tail on, the sailplane
has
the tiny visual profile that fighter designers dream of.... In other
words,
you are nearly invisible unless you have a wing up in a turn/thermal.

5. As Kirk said, the primary threat is at 6 o'clock, because it is
the
hardest to see - essentially, only the overtaking aircraft has a
reasonable
chance of avoiding a collision. Therefore, if you know you are
operating
in
a high threat area: MOA, low level route, approach corridor, VFR
flyway,
near an airport etc, I would "belly check" periodically, depending on
the
nature of the threat. The timing is based on the amount of time it
takes
for
the threat aircraft to close from outside visual range to hitting me
from
the 6 o'clock position. I use visual ranges of 8nm for airliners, 5
nm
for
small commercial jets (corporate and regional jets) and fighters, and
3
nm
for light aircraft - adjust as your visual acuity and experience
dictate.
I
use worst-case speeds as follows: airliner and small jets - 4 nm/min,
fighters - 8 nm/min, and light aircraft - 2.5 nm/min. Combing
detection
ranges and times, I calculate: airliners - 2 min, small jets - 1 min
and
15
sec, fighters - roughly 40 sec, and light planes - approx 1 min and 15
sec.
So... if you are straight and level for more than these times, there
is
sufficient time for an aircraft to move from outside (my) visual range
to
the same airspace as my (your) little pink body. As you would probably
guess, fighters are the worst case because of their relatively small
size
and high closure rate. On the positive side, there are typically more
eyeballs with better acuity and better maneuverability involved.
Interestingly, small jets and light aircraft are not that far behind,
as
far
as detection time is concerned. In my experience they are far less
likely
to see you than the fighters. The same is true for airliners, but
because
of their size you have more time to see them coming...

6. How to do a belly check: No, I don't hack a stopwatch, but I keep
the
above times in mind with respect to the likely threat for my area. My
primary threat is small jet/light aircraft that operate on various
highway/flyways and approach corridors. Away from these specific
areas,
traffic density is extremely low. First clear your "new six" - if you
are
going to turn left, look to the area behind to the right 4 - 5 oclock
position - this will be your new blind spot. Next clear your new nose
position - this is where you are going to roll out. Finally make a 45
deg
turn to the left and visually clear your "old six", which is now at
your
left 7 to 8 o'clock. Often/usually, a belly check can be incorporated
into
turns you are going to make anyway, for other reasons. When you
visually
clear, make sure you focus on something on the horizon, otherwise you
are
only visually clearing out to an arms length. If I really need to
hold a
straight line, I do the belly check as a gentle 45 deg turn to each
side.

7. In a thermal, periodically check to the outside of your term to
clear
your "new six". If there are other sailplanes with you in the
thermal,
of
course they are the primary threats for midair, but you still need to
check
for other aircraft. Fortunately, you are easier to see while turning -
as
long as the other pilots are looking...

8. Proximity to clouds. You need to think about what you are doing
when
you are near cloudbase, in proximity to likely IFR traffic. If you
are
500'
below cloudbase (perfectly legal), and an airliner descends out of the
cloud
at 250kt on his descent profile on collision course (perfectly legal),
there
may be as little as 20 seconds to impact. If you are tail on when
this
happens - good luck. I'm sure no one would ever be right at cloudbase
on
a
nice day, because that would violate the FARs - more importantly, you
are
"rolling the bones" every time you do this on a known approach
corridor.

9. Conclusion. If you fly in a high airliner/small jet threat area
and
can afford a transponder it will help other people see/avoid you. If
your
primary threat comes from military operations in MOAs, I would not
spend
the
money on a transponder unless I knew those fighters have intercept/atc
controllers passing them information. The various TPAS - type devices
will
help your see/avoid efforts and should help in the case of fighters,
although the flight lead is likely the only one squawking in the
formation.
Only you/your club knows the primary threats for your particular
operating
area and you need to understand what they are. Taylor your altitude
awareness/cloud avoidance and belly check frequency to the nature of
your
local area. Don't cede visual lookout/avoidance responsibility to
someone
else - ever. Sailplane right-of-way is a myth in most situations and
a
comfort only to your survivors/legal counsel.

Hope this helps.

Glen