Dean Wilkinson wrote:

James Robinson wrote:

Dean Wilkinson wrote:

The controller in this case clearly screwed up since he instructed the
Russian jet to descend when the Russian crew told him they had an RA
instructing them to climb.

You might like to wait for the accident report, since that isn't what
the initial review of the CVR and FDR indicated.

Really? I read the initial review, and the CVR transcripts. It
appeared to me that the contoller gave bad advice, and Russian captain
made the mistake of heeding it.

Not exactly. If the controller's advice had been followed in the
absence of TCAS, there likely wouldn't have been a collision, since the
Russian aircraft would have passed under the DHL. The problem was that
TCAS gave the initial RA to ascend just one second before the controller
urgently advised the aircraft to descend. After the controller made a
second urgent request to descend, the Russian crew chose to follow the
controller's instructions rather than TCAS. Meanwhile, the DHL started a
descent to comply with the TCAS RA on their aircraft. Hence both
aircraft descended into a collision.

That was only part of the overall problem, however, since there were
many procedural and technical problems at the control center, which
tends to turn the focus of the investigation on the controller's
employer. The controller was probably put into the position where he
couldn't adequately handle the traffic being offered, which led to his
mistakes.

Beyond that, the sequence of events in your initial post is wrong, based
on the transcripts that were released. The controller did not know the
Russian crew had an RA to climb, and issued his instruction based on the
information he had at hand. The Russian crew received the RA and
controller's instruction at practically the same time, and chose to
follow the controller. Here are a couple of interesting articles that
discuss this issue:

http://www.ainonline.com/issues/08_0...ncollpg16.html
http://www.ainonline.com/issues/09_0...rtcaspg12.html

The TCAS system had warned the Russian crew to climb, but just as they
started to comply, the controller instructed the aircraft to descend.
The Russian crew did not first tell the controller that they had an RA
instructing them to climb, so the controller did not override that
alert.

The DHL crew got an instruction to descend from their TCAS, and
announced that they were doing so.

So, given that the DHL crew told the controller that they were
responding to a TCAS RA, the controller KNEW he had an RA on his hands
and that it applied to BOTH aircraft.

Yes, but the controller only knew after he had issued the descend
instruction to the Russian aircraft. He did not know that either plane
had a TCAS RA up to that point.

I have not seen a report on exactly when the DHL crew supposedly
announced that they were descending to comply with their TCAS RA, but
there is the question of whether the controller heard or understood it.
By the time the DHL aircraft announced he was descending, it was
probably too late for the controller to do anything more. The initial
RA was about 45 seconds before impact, and the Russian plane started to
descend about 15 seconds later, after the controller made a second call.

The Russians don't appear to have given proper training to their
crews regarding the TCAS system because the crew didn't ignore the
controller like they should have and followed the RA.

Again, you don't know what their training is. The pilot didn't follow
the instructions, but he might have done that on his own, contrary to
his training. There has also been some argument that the controller's
instructions should have priority over those of the on-board system.

Actually, when I worked for Boeing it was pretty clear that the
Russians were installing TCAS to comply with the rules for flying in
European airspace, but that they weren't necessarily adopting the TCAS
philosophy...

If you read the second of the two articles cited above, you will see
that while the majority of pilots would follow TCAS, a substantial
percentage would still follow the controller's instructions, or ignore
both when they receive conflicting information. It therefore appears
that the TCAS philosophy was not universally accepted back then. I
wonder if the attitude has changed in the meantime?

Why not wait for the accident report instead of making rash, misinformed
accusations?

It is pretty rash of you to assume that I am misinformed...

You were clearly putting most of the blame on the controller, perhaps
based on an incorrect sequence of events. What other conclusion could I
come to?

There were other things the controller did wrong, such as not giving
separation advice early enough, only notifying one aircraft to take
evasive action, and not notifying the aircraft of where the conflicting
traffic was. As I understand it, he did not, however, knowingly give
instructions to the crews that conflicted with the RAs they each heard.

Given that the cause of the accident was a sequence of events, the
investigators are probably looking at how all of them came together, and
what needs to be done to avoid similar problems in the future. If any
one of the links in the chain of events had been broken, the accident
wouldn't have happened. The controller was not entirely to blame. I'm
not even sure he was mostly to blame. That is what the accident report
should address.