Another midair in the pattern

I don't think it is helpful for a guy on the ground to be trying to
act as a one man control tower.......

Cookie

I was number 2 in the pattern, not 'one guy on the ground trying to
act as a one man control tower', but you miss the real issue which is
to keep the ships separated. In my example I had seen red tow near the
airport, but he hadn't called down-wind and I wanted to know where he
was. All of my examples really happened, I'm not making them up. I say
again, any transmission that helps prevent a midair is in no way
misuse of the radio. Asking if anyone is in the pattern at XXX or any
gliders up near YYY may result in no reply 95% of the time, but what
harm has been done? Every now and then the asker will be alerted to
someone he hadn't seen or knew was there. I see this sort of call a
lot from pilots that regularly fly near gliderports. I see no harm in
being extra vigilant.
JJ

On Jan 19, 9:14*am, JJ Sinclair wrote:
I don't think it is helpful for a guy on the ground to be trying to
act as a one man control tower.......

Cookie

I was number 2 in the pattern, not 'one guy on the ground trying to
act as a one man control tower', but you miss the real issue which is
to keep the ships separated. In my example I had seen red tow near the
airport, but he hadn't called down-wind and I wanted to know where he
was. All of my examples really happened, I'm not making them up. I say
again, any transmission that helps prevent a midair is in no way
misuse of the radio. Asking if anyone is in the pattern at XXX or any
gliders up near YYY may result in no reply 95% of the time, but what
harm has been done? Every now and then the asker will be alerted to
someone he hadn't seen or knew was there. I see this sort of call a
lot from pilots that regularly fly near gliderports. I see no harm in
being extra vigilant.
JJ

It irks me when pilots think the AIM is all inclusive and any
transmission not specifically called out in the AIM is a bad idea.
Around our field people listen to the radio and if they haven't heard
a transmission that provides the information they need, they ask. If
I'm wingrunning and I see a non-radio aircraft in the pattern, I'll
call his pattern legs over my handheld to help insure others know of
his presence. When I'm towing and returning to the field and I know
there's aircraft in the pattern, if I can't visually acquire them all
I'll ask for an updated position. If this "extra" AIM unapproved
radio transmission delays someone on the ground announcing he's
taxiing to the fuel pumps--tough.

On Jan 19, 11:29*am, 150flivver wrote:
On Jan 19, 9:14*am, JJ Sinclair wrote:



I don't think it is helpful for a guy on the ground to be trying to
act as a one man control tower.......

Cookie

I was number 2 in the pattern, not 'one guy on the ground trying to
act as a one man control tower', but you miss the real issue which is
to keep the ships separated. In my example I had seen red tow near the
airport, but he hadn't called down-wind and I wanted to know where he
was. All of my examples really happened, I'm not making them up. I say
again, any transmission that helps prevent a midair is in no way
misuse of the radio. Asking if anyone is in the pattern at XXX or any
gliders up near YYY may result in no reply 95% of the time, but what
harm has been done? Every now and then the asker will be alerted to
someone he hadn't seen or knew was there. I see this sort of call a
lot from pilots that regularly fly near gliderports. I see no harm in
being extra vigilant.
JJ

It irks me when pilots think the AIM is all inclusive and any
transmission not specifically called out in the AIM is a bad idea.
Around our field people listen to the radio and if they haven't heard
a transmission that provides the information they need, they ask. *If
I'm wingrunning and I see a non-radio aircraft in the pattern, I'll
call his pattern legs over my handheld to help insure others know of
his presence. *When I'm towing and returning to the field and I know
there's aircraft in the pattern, if I can't visually acquire them all
I'll ask for an updated position. *If this "extra" AIM unapproved
radio transmission delays someone on the ground announcing he's
taxiing to the fuel pumps--tough.

But your examples are not the same as JJ's open questions....."any
gliders in the area?" on thee frequencies....

Or"where is the tow plane?"

If the glider you lost track of, "plays by the rules" It will
announce its position...you shouldn't have to ask. You already knew
he was in the pattern.....If you can't find him then maybe leave the
pattern and re enter.

On Jan 19, 10:14*am, JJ Sinclair wrote:
I don't think it is helpful for a guy on the ground to be trying to
act as a one man control tower.......

Cookie

I was number 2 in the pattern, not 'one guy on the ground trying to
act as a one man control tower', but you miss the real issue which is
to keep the ships separated. In my example I had seen red tow near the
airport, but he hadn't called down-wind and I wanted to know where he
was. All of my examples really happened, I'm not making them up. I say
again, any transmission that helps prevent a midair is in no way
misuse of the radio. Asking if anyone is in the pattern at XXX or any
gliders up near YYY may result in no reply 95% of the time, but what
harm has been done? Every now and then the asker will be alerted to
someone he hadn't seen or knew was there. I see this sort of call a
lot from pilots that regularly fly near gliderports. I see no harm in
being extra vigilant.
JJ

Ok you win.....Maybe you can write up a nice article for Soaring
including all your suggested radio work for safety.

Especially cover the part about turbo aircraft in the vicinity of
glider operations broadcasting on three frequencies...."any gliders?


Cookie

" wrote:
Beyond that, it seems that a transponders/ encoders might still be
required to be able to "see" the other aircraft. At least in the 3D
altitude sense.......

Nothing stops radar from doing vertical sweeps in addition to horizontal
sweeps in order to get the extra dimension. Just not available with existing
marine units, though! (A technology known as phased array can eliminate the
physical movement of the antenna.)

But - my Zaon MRX PCAS, which relies on transponder mode C replies, actually
doesn't issue an alert until the altitude of a target approaches that of the
MRX. This was a deliberate design decision by Zaon. Current radar systems
appear to have vertical beam widths of +/- 30 degrees, which seems reasonable
value to compare with the MRX.

From my personal experience with the MRX, I'd trade the altitude information
in exchange for direction and distance. (The MRX shows altitude difference
and estimated range to a transponder target; the range is estimated based on
signal strength. Several times I've been in the run-up area when a plane
would land 250 feet away and the MRX was telling me it was 1.2 miles away!)

Would a boat type radar work at higher speeds?

I couldn't find an answer to that, but if I understand the technology of
"broadband" (Frequency Modulated Continuous-wave) radar, the speed of
aircraft shouldn't measurably affect it.

Would you be able to
process the information and figure out probable flight paths and
collision courses?

In the realm of the possible, but none of the units I've seen include that
capability today.

It seems to me that GPS works pretty well. I'd put my money on some
universal GPS based system. We're already pretty heavily wired up for
GPS anyway, for navigation, flight recording, and flight computer.

Existing "dependent" systems do indeed have inertia of various kinds behind
them. I wouldn't have mentioned radar except that the subject of collisions
with objects not having appropriate equipment installed (such as birds,
balloons, and anything not having an electrical system) was brought up. Radar
and similar independent active detection systems are pretty much the only
realistic alternatives.

Mike Schumann wrote:
The problem with radar is that you don't get altitude.

True - for current units. But that is a limitation that could be overcome.
(But in my response to twocoolgliders I provide my own personal experience
on the limited value of knowing altitude of targets.)

A FLARM /
ADS-B solution would be much more accurate and elegant, and if
produced in volume, without the artificial certification / aviation
product liability costs, potentially less expensive.

Both ADS-B and FLARM are dependent on external systems and their targets to
be active participants. I do not consider those "elegant" systems precisely
because they are _dependent_ systems. Consider two aircraft, A & B, in one
case both using independent radar systems, and in another case both using
dependent ADS-B or FLARM system:

Let P be the probability that the system on one of the planes fails to
provide an alert before a collision (because it is broken, loss of
electrical power, or whatever,) then the probability that the _dependent_
system successfully averts a collision is given by:

P_success = (1 - P)*(1 - P)

So if P = 0.1 (10% chance of failure) then P_success = 0.81 (81% chance of
averting the collision.)

For an _independent_ system, the probability of averting a collision is
given by:

P_success = 1 - P*P

So if P = 0.1 (10% chance of failure) then P_success = 0.99 (99% chance of
averting the collision.)

The above should seem reasonable, I hope, since the equipment on both
aircraft has to function properly for ADS-B or FLARM to work. You have
twice as many failure points (actually more; the GPS signal may not be
available for many reasons and has several failure points of its own.)

For independent systems each aircraft is self reliant and equipment and
procedures would have to fail on _both_ for the whole system to fail. Even
though each plane exhibits a 10% failure probability, there is only a 1%
chance that both will not be working at any given collision event because
they back each other up.

On Jan 19, 6:12*pm, Jim Logajan wrote:
" wrote:
Beyond that, it seems that a transponders/ encoders might still be
required to be able to "see" the other aircraft. *At least in the 3D
altitude sense.......

Nothing stops radar from doing vertical sweeps in addition to horizontal
sweeps in order to get the extra dimension. Just not available with existing
marine units, though! (A technology known as phased array can eliminate the
physical movement of the antenna.)

But - my Zaon MRX PCAS, which relies on transponder mode C replies, actually
doesn't issue an alert until the altitude of a target approaches that of the
MRX. This was a deliberate design decision by Zaon. Current radar systems
appear to have vertical beam widths of +/- 30 degrees, which seems reasonable
value to compare with the MRX.

From my personal experience with the MRX, I'd trade the altitude information
in exchange for direction and distance. (The MRX shows altitude difference
and estimated range to a transponder target; the range is estimated based on
signal strength. Several times I've been in the run-up area when a plane
would land 250 feet away and the MRX was telling me it was 1.2 miles away!)

Would a boat type radar work at higher speeds?

I couldn't find an answer to that, but if I understand the technology of
"broadband" (Frequency Modulated Continuous-wave) radar, the speed of
aircraft shouldn't measurably affect it.

*Would you be able to
process the information and figure out probable flight paths and
collision courses?

In the realm of the possible, but none of the units I've seen include that
capability today.

It seems to me that GPS works pretty well. *I'd put my money on some
universal GPS based system. We're already pretty heavily wired up for
GPS anyway, for navigation, flight recording, and flight computer.

Existing "dependent" systems do indeed have inertia of various kinds behind
them. I wouldn't have mentioned radar except that the subject of collisions
with objects not having appropriate equipment installed (such as birds,
balloons, and anything not having an electrical system) was brought up. Radar
and similar independent active detection systems are pretty much the only
realistic alternatives.

A radar beam has physical dimensions. Before computers and phased
arrays, the shape of the beam was dependent on the shape of the
antenna. For height finding, you need a beam that is wide in the
horizontal and narrow in the vertical vice versa for azimuth finding.
I don't see the cost of phased or planar array being as affordable as
a typical marine radar that is optimized for finding the azimuth and
range of surface targets only.

On Jan 19, 11:13*am, "
wrote:

If the glider you lost track of, "plays by the rules" *It will
announce its position...you shouldn't have to ask. * You already knew
he was in the pattern.....If you can't find him then maybe leave the
pattern and re enter.

Sure, everyone will eventually announce their position but if I
suspect there is a conflict, I want the information now-- not as I'm
spiralling to my death after a midair collision while waiting for an
"automatic" update at the conflicting aircraft's choosing. Many
pilots report only some of the corners of the pattern. Many's the
time someone calls turning off the crosswind to downwind and stays
silent even though someone announces they're on the 45 to enter--no
call of either seeing or even looking for the other as they converge
at midfield--each thinking that the other must see them or that it's
not a problem--each confident that they complied with the AIM's
suggestion to self announce their position but loath to ask for
confirmation for fear of cluttering up the frequency with "unapproved"
queries.

On 1/19/2011 4:45 PM, Jim Logajan wrote:


For independent systems each aircraft is self reliant and equipment and
procedures would have to fail on _both_ for the whole system to fail. Even
though each plane exhibits a 10% failure probability, there is only a 1%
chance that both will not be working at any given collision event because
they back each other up.

Your math is fine, but it appears an independent system, other than the
eyeball, will have 100% failure probability for many years, as I'm not
aware of any device being considered, much less near the testing phase.

There was another interesting optical system offered for sale a few
years ago, but it disappeared. Too bad - it was small and cheap at $1000
to $2000. It worked by comparing successive images, looking for
something that was getting bigger but not moving otherwise.

So, while the math favors an independent system, the reality is we have
several dependent devices that are in service and working. Inelegance
wins the race.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

What do you think - if radios were mandated, would be be allowed to
use the same kinds of hand helds we do now or we would have to use an
FAA approved radio permanently mounted in the panel? Would these
radios then be part of an inspection and help to the same standards as
standard certificated planes? Or would we hope they would be required
but the government would not tell us what capability or features they
would need? One wonders if the decision to mandate a radio would
imply considerable regulation? Maybe the experts could comment.