Stupid transponder question, or, stumped by the wife

"John Kirksey" wrote in message
news:_0YVe.24770$8h6.7135@trnddc09...

So we were watching "Seconds From Disaster" on NGC last night, which
happened to be on AA 77. When they mentioned that seconds after gaining
control of the aircraft the hijackers turned off the transponder (along
with
a brief explanation of what the transponder does), my wife simply says:

"That's stupid, why does something like that even have an on/off switch?"

I honestly never thought about it and couldn't answer her question. Does
anyone know?


So it can be turned off when need be, like when it's providing erroneous
information.

"Peter R." wrote in message
...

Isn't this true with GA formation flying as well?


Yes.

Steve Foley wrote:
Can you picture the radar screen in Boston/New York/Chicago/LAX when all the
planes on the ground are showing up? The radar sweeps by and shows 23 planes
lines up for the departure runway, superimposed on whoever is flying
overhead.

Irrelavant. The radar computer has software that will not show any
target within the user specified distance from the radar antenna. We
set ours to 1 mile. There are also altitude filters that can be set.
There is no good reason to ever turn your transponder off or to STBY
unless ATC asks you to or you somehow know it's not working properly.

"Newps" wrote in message
...

Irrelavant. The radar computer has software that will not show any target
within the user specified distance from the radar antenna. We set ours to
1 mile. There are also altitude filters that can be set.

Facilities that do radar approaches don't tend to filter out these targets.



There is no good reason to ever turn your transponder off or to STBY
unless ATC asks you to or you somehow know it's not working properly.


ASR on the field is good reason to turn your transponder off or to STBY
without ATC request.

JohnH wrote:

"That's stupid, why does something like that even have an on/off
switch?"


For the very reason many men wished thier wives had one.



Oh man... that's brutal.

But oh so true in some cases. (we love our wives)

"kontiki" wrote in message
...
JohnH wrote:

"That's stupid, why does something like that even have an on/off
switch?"


For the very reason many men wished thier wives had one.

Oh man... that's brutal.

Newps writes:

Can you picture the radar screen in Boston/New York/Chicago/LAX
when all the planes on the ground are showing up? The radar sweeps
by and shows 23 planes lines up for the departure runway,
superimposed on whoever is flying overhead.

Irrelavant. The radar computer has software that will not show any
target within the user specified distance from the radar antenna.
[...]

Maybe, but it is still a problem for aircraft with TCAS, who
receive false alarms due to the ground traffic.

- FChE

Then why doesn't the stall warning horn have one?

Jim

Every electric device needs an on-off switch.

In article ,
(Frank Ch. Eigler) wrote:


Maybe, but it is still a problem for aircraft with TCAS, who
receive false alarms due to the ground traffic.

not if their radio altimeter is working.

--
Bob Noel
no one likes an educated mule

"RST Engineering" wrote in message ...
Then why doesn't the stall warning horn have one?

Jim

Every electric device needs an on-off switch.



Isn't it good to have these electronic devices turned off when the plane is started to save them from all the surges on
the DC buss?