Diversions due to fog YSSY today

[Phil M]

Melbourne is getting a Cat 3B ILS on 16. To be commissioned September I think.

[David Ramsay]

The new Cat III at NZAA is getting a good workout this morning.

ATIS NZAA L 2302
APCH: ILSDME
RWY: 23L
SFC COND: DAMP
OPR INFO: ATC LOW VISIBILITY PROCEDURES ARE IN OPERATION
LANDING AIRCRAFT MUST VACATE AT RUNWAY END VIA TWY A10
WND: VRB04
VIS: 0400 RED 0200
WX: FG
CLD: OVC001
TT: 09
DP: 09
QNH: 1029
2000FT: RCALM

RVR currently 275/275/325

Most of the international flights have got in OK although TN had to hold for a while as the 343 was only Cat II. Domestic stuff is all either grounded or holding.

[Philip Argy]

Originally Posted by Mick F

Phillip, the ILS that is used in Australian airports is only Category 1 type. This does NOT permit landing in zero/zero. The Cat 1 will only permit an approach down to 200ft above ground and requires 800m visibility.

To do a landing in zero/zero you'd need a Category 3C ILS. There are currently none in Australia. They are also extremely expensive and require constant recalibration, and as Nigel has said, for those 10 days of the year when they receive fog, it's simply not viable.

Mick

Thanks, Mick - that's the missing piece of information/explanation that I needed.

[Mark D]

Originally Posted by Philip Argy

Thanks, Mick - that's the missing piece of information/explanation that I needed.

http://en.wikipedia.org/wiki/Instrum...ILS_categories tells you about the categories of ILS.

As stated at the moment all Oz ILS are Cat I - there is considerable expense in maintaining ILSs at higher categories than you "need"

Additionally in Sydney, being so close to the city, the amount of RFI (radio frequency interference) is an issue, keeping the ILS at the current level seems to be hard enough!
Avalon on the other hand would be OK :-)

[Stuart Trevena]

Hi All,

I was surprised to see UA839 diverted to BNE.
Why didn't it just go direct to YMML as it normally does after landing in Sydney?

That flight then becomes UA840 and returns back to Sydney, before continuing to the US.

Stuart

[Tim Bowrey]

You have a good point Stuart. It would have been better to go streight to MEL rather than stopping at 3 destinations, one in which UA doesnt even go to. If QF94 can do LAX-MEL so can it Drop the MEL passengers off 1st then head back up to SYD to drop the early morning arrival passengers off. And its not like you can buy a ticket SYD-MEL or MEL-SYD with UA anyway so they wouldn't have had to pick anyone up.

Tim

[Daniel F]

Originally Posted by Tim Bowrey

And its not like you can buy a ticket SYD-MEL or MEL-SYD with UA anyway so they wouldn't have had to pick anyone up.

Actually they do pick people in Sydney for the SYD-MEL sector. You can't buy a standalone ticket for SYD-MEL, but you can get a ticket involving a trans-Pacific sector that has a stopover in Sydney and then continues onto Melbourne at a later date.

[Andrew McLaughlin]

Originally Posted by Tim Bowrey

You have a good point Stuart. It would have been better to go streight to MEL rather than stopping at 3 destinations, one in which UA doesnt even go to. If QF94 can do LAX-MEL so can it Drop the MEL passengers off 1st then head back up to SYD to drop the early morning arrival passengers off. And its not like you can buy a ticket SYD-MEL or MEL-SYD with UA anyway so they wouldn't have had to pick anyone up.

Tim

They may have only taken on enough fuel for SYD, or they may have encountered unusually strong headwinds meaning they used more fuel than anticipated. Why carry enough fuel to fly an extra 500+nm when you don't need it?

Don't forget the QF jets that usually do LAX-MEL are 747-400ERs or are often payload restricted...UA's jets aren't ERs.

[D Chan]

Originally Posted by Tim Bowrey

You have a good point Stuart. It would have been better to go streight to MEL rather than stopping at 3 destinations, one in which UA doesnt even go to. If QF94 can do LAX-MEL so can it Drop the MEL passengers off 1st then head back up to SYD to drop the early morning arrival passengers off. And its not like you can buy a ticket SYD-MEL or MEL-SYD with UA anyway so they wouldn't have had to pick anyone up.

Tim

I'm sure that if they could they wouldve diverted to Melbourne instead. The Ground staff would surely appreciate it if they had made it to Melbourne and turned the flight around as the 840. Would reduce the delay significantly and avoid a lot of hassles.

But time and time again when there's fog they've diverted to BNE - this suggests they don't have the fuel to make it to Melbourne.