Re: Near miss Australia

From:         rado1@ibm.net (Mark Radovich)
Date:         22 Jun 95 03:07:33 
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The Nut <smukherj@metz.une.edu.au> wrote:
>It was reported yesterday, Tue June 6th, that there was a near miss over
>the Australian desert between a British Airways B747 and a domestic
>Qantas B737. It was reported that the aircraft closed to within 150
>metres of each other and that the B747 "filled the windscreen" of the
>smaller jet. The computer generated pictures were very dramatic.
>The B747 was at 31,000 ft and in a standard Sydney-Bangcock(sp?) airway,                                                                                                    >while the B737 was on a domestic flight from Alice Springs to Sydney >and
Bangkok
>was at 29,000 ft. It requested 33,000 ft and was cleared by the
>controller to climb to the new altitude, this is when the incident occured.

>My question is, I know that this B747 had a collision avoidance radar and
>that the B737 did not. The first question is do all B747 have these
>radars or is it only the -400 ?
The systems are known as Traffic alert and Collission Avoidance
Systems-(TCASII)  The II designates a system which is capable of
providing resolution advisories in the vertical plane.  It is an
avionics system that uses interrogation of and replies from airborne
radar beacon transponders and provides traffic advisories and
resolution advisories.  Only if it is a regulatory requirement or the
airline can afford it,  is TCASII fitted.  (See answer lower down)

> The second question is, what is the range
>that the radar works at, that is how close does another plane have to get
>to a B747 before the warning is sounded and how long do the pilots have
>to react?
Range is dependant on speed.  I don't know particularly about the ones
fitted to B747-400's however the ones fitted to Qantas B767 and
B747-classics start to look at traffic some 35-45secs away.

>And finally, why are more planes not fitted with this radar?
They are an expensive piece if equipment $200,000 plus per aircraft an
unless it is a regulatory requirement as it is in the USA,  airlines
obviously feel they cannot afford to spend that sort of money on an
entire fleet.  (See Dick Smith for a debate on affordable safety as I
don't wish to go into it here.)

>Being a pilot myself, I know that closing to within 150 metres would
>scare me brainless.
And shitless

Mark Radovich
rado1@ibm.net