View Single Post
  #3  
Old October 12th 10, 01:41 AM posted to rec.aviation.soaring
Darryl Ramm
external usenet poster
 
Posts: 2,403
Default Aug 6th B738 and Glider Near Miss. Frankfurt

On Oct 11, 4:10*pm, Russell Thorne wrote:
As both an avid glider pilot and also airline pilot, I have never seen
one *jet/glider from the point of view of the other, and I do look, if
I know the other is about. *Transponders are essential if you want to
have any chance of seeing the other at high speed. TCAS is my main
alerter, especially in the US, where I am amazed that that VFR
aircraft have such freedoms in busy airspace, may they continue for
ever. A case in point, last night while on a night departure out of
SFO on climb to 3000ft, there was a Cessna at 3500ft directly in the
departure path doing what he had every right to be doing. According to
TCAS, we passed directly underneath him , thank you TCAS, ATC and on
behalf of *the 315 sitting behind us.
Airlines, and especially Ryanair, will not finance any such fitment of
transponders in gliders, our salvation as glider pilots lies in the
low cost development of ADS-B. In the meantime, I'm off to organise my
bi-annual transponder and altimeter checks.

*As I've said I think it is entirely reasonable to approach

carriers like Ryanair with suggestions for them offsetting your
transponder costs (or take the tricky step of taking that battle
public... does the flying public have a right to know this?). Glider
organizations really need to think through whether to take on this
issue or not, if not when there is eventually a fatal mid-air
collision they just won't have a publicly defensible position. In
areas of high density airline and fast jets and glider traffic, doing
nothing looks to me like a very poor choice.


I know from outside the USA it looks like the whole place is run by a
bunch of cowboys, but I hate to ruin it for you... there is no "just
screwing in" of transponder in the USA. A certified glider requires at
least an IA/A&P sign-off or maybe a 337 field approval, an
experimental one may be done by the pilot. But in either case requires
a RF signal and pressure altimeter check after install and ongoing
biannual RF signal tests. Approved transponder test stations are very
unlikely to just sign off an inspection if they have any concerns
about the transponder install. But.. yes things here are much better
than the silly regulations EASA loads on glider owners in Europe.


Darryl




Russell thanks for adding your airline-pilot voice to this.

But you had me right up until the end point... I worry that waiting
for ADS-B is likely not the answer, and at worse a dangerous
distraction. ADS-B offers many interesting potential capabilities and
benefits but seeing ADS-B offered as an alternative to transponders as
a collision avoidance mechanism near airliners leaves me pretty
concerned.

And I'm awfully curious if your airliner is equipped today with TCAS
II with integrated ADS-B data-in/CDTI?

ADS-B data-out in gliders will not provide an airliner with an RA from
its TCAS II system - something many pilots are not aware of. TCAS
needs a transponder to interrogate to issue an RA. The whole topic
does not get talked about much because it is implicitly assumed that
threat aircraft have transponders or transponders *and* ADS-B data-
out. If your airline has fitted a modern TCAS II that includes ADS-B
data-in and CDTI then you will get traffic display of ADS-B data-out
equipped aircraft but no RA. And you may even have have TCAS II with
ADS-B data-in for TCAS "enhanced surveillance" but still no CDTI/ADS-B
data-in display of traffic at all.

There is no regulatory requirement for airlines or other aircraft to
equip with CDTI, and no regulation likely to happen anytime soon,
since standards are a bit liquid at the moment. Sure there are new
TCAS II systems available that provide CDTI capability, and I expect
some newer transport category aircraft to come so equipped but trying
to understand when a significant fraction of airliners or fast jets
will be so equipped has proven pretty frustrating. If you have an ADS-
B specialist in your airline who could talk about ADS-B data-in/CDTI
adoption plans I would love to talk to them.

As for low-cost, we'll have to wait and see but it may well work out
that the cheapest way to deploy ADS-B data-out is via a Mode S/1090ES
transponder, in which case you get full TCAS compatibility via the
transponder part. Costs may have more to do with market dynamics (like
European Mode S adoption requirements) and worldwide addressable
market vs. engineering a specific UAT product for a part of the USA
low-end GA market. Modern low-cost electronics, FPGAs, high speed CMOS
RF components etc. have also helped to significantly lower Mode S
transponder costs beyond what was probably expected when the FAA and
others started thinking about UAT technology vs. (then very) expensive
Mode S transponders.

Darryl