Originally Posted by HAWK21M @ 23rd Mar 2011 11:04
Why did the related CB not trip?.
There isn't one in the usual sense of the term. Normally cb's are not employed in the usual way we think. There are two WHC, (Windshield Heat Computer) cb's in the cockpit. The QRH drill is:
COCKPIT WINDSHIELD/WINDOW ARCING
– Affected WINDSHIELD/WINDOW WHC reset button ............................... PULL
In case of electrical arcing, pull the the Window Heat Computer reset button that is located on the affected side.
• WINDSHIELD/WINDOW LEFT SIDE - WHC 1 (261 VU).
• WINDSHIELD/WINDOW RIGHT SIDE - WHC 2 (262 VU)
Clearly there was something more seriously wrong, and the crew dealt with the problem.
In the broader sense of fault sensing, warning and "triage", the Airbus faults are sensed by a number of computer systems which take action such as selecting an alternate system or component, turning systems or a system component off, etc, while presenting ECAM messages, illuminating caution or warning lights and sounding auditory attention-getters of various kinds.
It is part of this extensive warning and maintenance system which generates the ACARS messages. Most cb's on the Airbus are used to re-boot computers, an SOP which is done from the QRH. The L1011 was something like this though most of its cb's were the kind we usually expect.
If a system wasn't functioning as expected, cycling the cb would often fix the problem. In any case, there are very few cb's in the A330/A340 cockpit - just a few on the rear overhead to re-boot FMGECs, CIDS, etc. All other cb's are under the cockpit in the EE bay and one simply doesn't go down there, not, at least, without exceptional reason.
As for this event, there is not nearly enough information to know what actually happened. An arcing windshield can turn into a serious event but arcing and/or shattering windshields, (outer pane only) is not as uncommon as we may believe.
I understand the crew followed SOPs transferring control to the pilot with the clear windshield.
Fire is serious under all circumstances. This ended well and now the investigation will determine why the event escalated from arcing to fire.
QANTAS can't f_rt these days without the media trying to sell more newspapers squawking about the next near-death experience. If there is organizational stress, QANTAS' reputation is that they are eminently qualified to determine same and deal with it without the media's assistance.