Interesting thing with transponders

On Mar 6, 8:01*am, "Wayne Paul" wrote:
I find the assertion that military aircraft do not have transponders humorous. *Wasn't it the military that developed the system back in WWII? *Isn't our current system a direct descendant of the original IFF (http://en..wikipedia.org/wiki/Identi..._friend_or_foe) and still uses to original coding system? ("Squawk 1200, etc.)

BTW, I am alive today because of the refusal to allow the USS Long Beach to blindly fire on an aircraft from which it was not receiving a transponder signal. *The aircraft in question turned out to be my A-6A Intruder with an inoperative transponder.

"brian whatcott" wrote in ...

BT wrote:
/snip/
"Transport" military aircraft may or may not have TCAS, it depends on
their vintage, and they do not have an air to air radar to "ping" a
transponder.
" Heavy Bomber" military aircraft may not have TCAS, it depends on their
vintage, and they do not have an air to air radar to "ping" a
transponder.
/snip/

BT "retired military aviator" and one time ATC controller.

I know the C-5 has TCAS. It uses squitter mode and interrogates
transponders.
The KC-135 has TCAS. I am almost certain it too interrogates.
*(I should know this, but I did not update the transponder model for
the KC-135 simulators, and cannot recall. Military aircraft are subject
to continuous performance updates.)

Brian W

You're lucky. I was on the heavy cruiser USS St. Paul watching when
the missile cruiser USS Canberra blasted an AD5 Skyraider out of the
sky with a missile because of an inoperative transponder. The 4-man
A5 crew was lost.

Back to the basic transponder discussion.

It's obvious the US air traffic control system is based on a military
command structure. All information is kicked up the chain of command
for a decision while the ops people at the bottom wait for an answer.
The oxymoron "Military Intelligence" applies.

In a similar way, information on potential air-to-air conflicts is
collected at a 'control center' then, if the situation is deemed
important, the pilots of the conflicted aircraft are notified. The
system assumes a perfect two-way information flow. When closing
speeds exceed 1000 kts, this is a profoundly stupid situation.

I can see no reason why a bunch of civil servants in a concrete bunker
need to know about a potential conflict hundreds of miles away. The
people who need to know are the pilots involved. The pilots have the
most at risk and are the only people in a position to use the
information to save themselves and their passengers. "Controllers"
can talk all they want but the flight paths won't diverge until the
pilots hands move the controls. This is why FLARM and TCAS are so
successful.

It's clear to anyone who understands ADS-B that it undermines the
'central control' idea by providing timely information to pilots thus
putting ground jobs at risk. The painfully slow adoption of ADS-B is
best seen as a labor relations issue.

bildan wrote:
On Mar 6, 8:01 am, "Wayne Paul" wrote:

I find the assertion that military aircraft do not have transponders humorous. Wasn't it the military that developed the system back in WWII?
"Transport" military aircraft may or may not have TCAS, it depends on
their vintage, and they do not have an air to air radar to "ping" a
transponder.
" Heavy Bomber" military aircraft may not have TCAS, it depends on their
vintage, and they do not have an air to air radar to "ping" a

transponder.

BT "retired military aviator" and one time ATC controller.

I know the C-5 has TCAS. It uses squitter mode and interrogates
transponders.
The KC-135 has TCAS. I am almost certain it too interrogates.
(I should know this, but I did not update the transponder model for
the KC-135 simulators, and cannot recall. Military aircraft are subject
to continuous performance updates.)

Brian W


You're lucky. I was on the heavy cruiser USS St. Paul watching when
the missile cruiser USS Canberra blasted an AD5 Skyraider out of the
sky with a missile because of an inoperative transponder. The 4-man
A5 crew was lost.

Back to the basic transponder discussion.

It's obvious the US air traffic control system is based on a military
command structure. All information is kicked up the chain of command
for a decision while the ops people at the bottom wait for an answer.
The oxymoron "Military Intelligence" applies.
That's not the case in eastern Washington State, which has a lot of C17s
running around. The tower at Grant County informs them of potential
conflicts in their area, though nowadays, most/all have TCAS and aren't
dependent on the tower for timely information.

--
Eric Greenwell - Washington State, USA (netto to net to email me)

On Mar 6, 6:31*am, brian whatcott wrote:
BT wrote:

* /snip/
* "Transport" military aircraft may or may not have TCAS, it depends on
* their vintage, and they do not have an air to air radar to "ping" a
* transponder.
* " Heavy Bomber" military aircraft may not have TCAS, it depends on their
* vintage, and they do not have an air to air radar to "ping" a
transponder.
* /snip/

* BT "retired military aviator" and one time ATC controller.

I know the C-5 has TCAS. It uses squitter mode and interrogates
transponders.
The KC-135 has TCAS. I am almost certain it too interrogates.
* (I should know this, but I did not update the transponder model for
the KC-135 simulators, and cannot recall. Military aircraft are subject
to continuous performance updates.)

Brian W

All USAF C5 an KC-10 have TCAS-II/ETCAS (military variant). I
occasionally get to share airspace with KC-10s out of Travis AFB and
glad they have TCAS-II and I have a transponder (and I'm usually on
flight following with Travis approach if close to Travis).

I believe all KC-135s got TCAS-II/ETCAS in the Pacer/CRAG upgrade
program starting back last decade. Maybe some initially got only TCAS-
I.

C-130s have TCAS. And so on. I think the general assumption today
should be that military transport aircraft have TCAS-II. Outside
tactical exercises I expect those TCAS systems to be operating. When
operating normally all these system will interrogate mode C and S
transponders independent of ground radar or other interrogators.

Darryl

On Mar 5, 9:41*pm, "BT" wrote:
As Jim said... but not entirely accurate. And a response by another
responder, not entirely accurate.

"Most" fighter type aircraft can interrogate Mode 3 transponders on their
air to air search radars and get a return.
"Most" fighter type aircraft do not have TCAS. Modern Aircraft might.
"Transport" military aircraft may or may not have TCAS, it depends on their
vintage, and they do not have an air to air radar to "ping" a transponder..
" Heavy Bomber" military aircraft may not have TCAS, it depends on their
vintage, and they do not have an air to air radar to "ping" a transponder..

If a flight of 4 fighters (or more than one) is transitioning airspace
outside of a MOA, ATC will have the wingmen, "Strangle the parrot", so
everyone will only see one transponder return, not four and the ATC radar
will not "go crazy with alerts".

BT "retired military aviator" and one time ATC controller.

Well, yes. A-10s, T-38s, T-45s don't have radars so can't interrogate
(although the latter two may have TCAS - I would hope they do!).
Early F-16s and F-18s didn't have interrogators, but all the later
versions do, as do all F-15s, etc. While fighters do not have TCAS,
I think a lot of trainers do, for obvious operational safety reasons.

Plus, there is Link 16, which lets each fighter in a flight see what
the rest is seeing, and what AWACS is seeing - another way to detect
other aircraft.

But that is just gravy - the important point here is that military
aircraft operating in joint use airspace WILL have a transponder on -
so flight following should work - talk to center if you are going
through a MOA that is hot!! - and if all else fails and you see a
problem developing in a MOA between gliders and military aircraft -
call on Guard (121.5) and they will likely hear you - beats a midair
anyday and you get to talk to your tax money at work, literally.

Kirk
"retired military aviator" and one time interrogator of civilian
transponder traffic in MOAs from the pit of his F-4 (and that was 30
years ago!)

JS wrote:
Apparently two aircraft squawking VFR are visually reported as a
conflict but do not have the same level of alert.
Close to another aircraft could be:
On tow behind a transponder-equipped towplane.
Sharing a thermal.
Pair flying.
Not that gliders ever do any of that.
So as we're all moving toward using radios and transponders to keep
separation, be aware of the havoc we may be wreaking at ATC. Not a
good way to make friends! If you're Mode S, they have your
registration too!
No "havoc" is created by two transponders sqawking 1200 near each other.
It can cause signal scrambling problems so the Mode C altitude data is
not read reliably, but ATC still knows where you are! Mode S
transponders can alleviate this problem.

--
Eric Greenwell - Washington State, USA (netto to net to email me)

" No "havoc" is created by two transponders sqawking 1200 near each
other."

Tell that to the Dutch who fly in the Schiphol area...

On Mar 5, 10:04*pm, Hagbard Celine wrote:
" No "havoc" is created by two transponders sqawking 1200 near each
other."

Tell that to the Dutch who fly in the Schiphol area...

Shiphol had a problem with the back-end processing and display of Mode
S derived traffic data on their display screens. In hindsight this
seems an awfully obvious thing they missed with Mode S transponder
mandates.

Some summary to the problem is at

http://eurocontrol.int/msa/public/st...Procedure.html

Transponders provide visibility for gliders to both ATC and airliner/
fast jets TCAS and are therefore a critical item anywhere we are
mixing those types of aircraft. And I fail to see how a particular
display capacity/planning problem at Shiphol is that relevant to any
general idea of carriage of transponders.

Darryl

JS wrote:
/snip/
As previously suspected, military aircraft do not use transponders
/snip/

Jim


???

I must have been hallucinating during the briefing at Joshua approach.
Time to give up.
Jim

On Mar 7, 10:57*am, JS wrote:
I must have been hallucinating during the briefing at Joshua approach.
Time to give up.
Jim

Jim, I'd be really interested to hear what what is being said in the
Joshua approach briefing. It could be a misunderstanding, or an
actual lack of knowledge between agencies and users on each other's
capabilities - not the first time that has happened.

Has there been a reciprocal briefing of glider operations and
capabilities to Center and AF personnel?

I know when I've worked with the AF on similar issues in the Luke area
(coordinating for regional contest, which would be transiting hot MOAs
during the week), there were often misconceptions (!!) that had to be
cleared up, on both sides.

Cheers,

Kirk
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