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Old 30th May 2006, 15:56
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Irish Steve
 
Join Date: Mar 1999
Location: Ashbourne Co Meath Ireland
Age: 72
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Slight digression, and before I get too far in, this did happen a good while ago, so hopefully things have changed enough that it can't happen again.

I get VERY uncomfortable when I read about transponder code suppression, and here's why.

As I warned, a long time ago, I was training at Shoreham, and on this occasion, we were doing VOR holds, using Midhurst VOR, at 2400 Ft, just under the base of the TMA at that time, with a radar service from Dunsfold. We were merrily doing our thing, which was slightly harder than usual as it was twin training, and we were doing single engine work, when we suddenly got a call from Dunsfold, with a slightly raised level of decibels and anxiety, "opposite direction traffic range 1 mile height unknown!". We looked out, as we were near enough VFR, to see a large commercial jet at very close to our altitude, and started taking suitable avoiding action. As we did so, it turned, and we saw clearly that it was a Dan Air 1-11. had we been of a mind to, we could have waved it was that close.

Turned out it was at 2500 Ft, the base of the TMA, postioning visually back to LGW from Lasham after maintenance. We spoke with the controller at Dunsfold, who also was not happy at how close it had been, and he made inquiries etc, and subsequently filed the relevant miss paperwork. Transpired that the 1-11 was under Gatwick control, and the reason he'd been given the routing and level he was at was that the LGW controller had supressed the returns from aircraft outside of "his" airspace, so we came within a couple of hundred feet of a mid air with a 1-11 as a result.

You will undertand why I get very uncomfortable when I read about transponder returns being supressed on a screen!!! OK, on the larger aircraft, you've now got TCAS, which would (should) have warned the 1-11 about us, but if I still had the twin, I doubt I would have fitted TCAS in it, for all sorts of reasons, so we still would not know about the other aircraft if the same sceanrio was repeated today.

Thought provoking.
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