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-   -   Perth to London (https://www.pprune.org/australia-new-zealand-pacific/606917-perth-london.html)

neville_nobody 25th Jan 2019 03:15


Originally Posted by cessnapete (Post 10370055)

Aren’t QF 787 Cat IIIC. No cloud base,100m vis as most LHR Operators?

You still need an alternate, which may have been the flight planning problem.

CurtainTwitcher 25th Jan 2019 03:34

I'm hearing that the new flight planning system (constellation) takes quite a bit of time to run each version of the plan.
Pure and utter uncorroborated scuttlebutt (this is a rumour network) is the flight planners don't have good visibility into the "internals" of the plan in progress to see where it is trending to add manual tweaks. Basically it spits out a complete plan. If the plan isn't suitable for whatever reason (read reduced payload), the planners have to completely re-run the plan (about 30 min) with the tweaks to see what pops out. Wash rinse and repeat.

maggot 25th Jan 2019 04:12

Bonuses all round then!

Tuner 2 25th Jan 2019 04:27

QF 787 is CAT3B (0' RA / 75m) and can make use of reduced alternate weather criteria to use alternates below standard alternate criteria but above CAT1 RVR/vis.

Qanchor 25th Jan 2019 05:40


If that was the case they'd reduce the payload, not cancel the flight!
Fathom,
Full tanks are full tanks, reducing payload/blocking seats doesn’t miraculously produce more fuel when the tanks are already full.
What I was implying, (perhaps a little too subtly), was that maybe with the enroute winds and TAF for arrival, full tanks was less than the min op fuel required, even with no pax/freight.
RD got it.

knobbycobby 25th Jan 2019 05:52

Itís not a question of aircraft capability. Itís the fuel policy and also flight time limitations.
If both Heathrow and Gatwick are below CAT 1 visibility you cannot take advantage of the reduced alternate weather criteria.
Unsurprinsingly during winter itís not uncommon for many airports to all be under CAT 1 visibility in the morning hours.

Capt Fathom 25th Jan 2019 09:51


Originally Posted by Qanchor (Post 10370109)

Full tanks are full tanks, reducing payload/blocking seats doesnít miraculously produce more fuel when the tanks are already full.

No, but the lower fuel burn produces more range. But you knew that already! :=

cessnapete 25th Jan 2019 11:05


Originally Posted by knobbycobby (Post 10370112)
Itís not a question of aircraft capability. Itís the fuel policy and also flight time limitations.
If both Heathrow and Gatwick are below CAT 1 visibility you cannot take advantage of the reduced alternate weather criteria.
Unsurprinsingly during winter itís not uncommon for many airports to all be under CAT 1 visibility in the morning hours.

Planning on a forecast that is 17 hours old when you arrive? In my airline on ULR flights plan for somewhere en route that is forecast to be above CAT l and reflightplan if possible with actuals nearest your planned destination?

Qanchor 25th Jan 2019 11:15

So why didn’t the flight depart?

UnderneathTheRadar 25th Jan 2019 11:26


Originally Posted by cessnapete (Post 10370336)


Planning on a forecast that is 17 hours old when you arrive? In my airline on ULR flights plan for somewhere en route that is forecast to be above CAT l and reflightplan if possible with actuals nearest your planned destination?

I think we've already established that for QF9/10 to work - its LHR or LGW only due to the disruption factor of going elsewhere - departing for an alternate and betting the sheep station on an improvement is very different to departing better than CAT1 and running the risk of a deterioration to the point that no CAT3B is possible (I'm not a flyer for a living - out of curiosity, what are the rules if an airfield goes below CAT1 when enroute for a ULR flight? Must re-plan including fuel to an alternate - enough fuel to miss then divert or, if not enough for that, must divert?)

Doesn't explain why it didn't depart though - the good ol'fashion rumour about a new flight planning software sounds pretty Qantas-like also.

cessnapete 25th Jan 2019 20:27


Originally Posted by UnderneathTheRadar (Post 10370346)
I think we've already established that for QF9/10 to work - its LHR or LGW only due to the disruption factor of going elsewhere - departing for an alternate and betting the sheep station on an improvement is very different to departing better than CAT1 and running the risk of a deterioration to the point that no CAT3B is possible (I'm not a flyer for a living - out of curiosity, what are the rules if an airfield goes below CAT1 when enroute for a ULR flight? Must re-plan including fuel to an alternate - enough fuel to miss then divert or, if not enough for that, must divert?)

Doesn't explain why it didn't depart though - the good ol'fashion rumour about a new flight planning software sounds pretty Qantas-like also.

All airlines will have their own rules at replanning en route. From my experience in Uk and based at Lhr, vis lower than CatIII happens very infrequently, cloud base is not a factor. So unless there are long ATC delays you are guaranteed to land with the reliability of modern avionics. Most of the LR flights on my airline arrived between 0500 0700 as QF Perth, so no long ATC delays at that time, and of course 2 Cat III parallel landing runways available, 3 if you include LGW which is approx the same fuel from the arr Fix.

Capn Rex Havoc 26th Jan 2019 05:38

Here is a suggestion - perhaps they could plan a refuel stop somewhere like oh - I don't know - Dubai :}

Troo believer 26th Jan 2019 05:59

Constellation is the problem.

ruprecht 26th Jan 2019 06:34


Originally Posted by Troo believer (Post 10371139)
Constellation is the problem.


How can you blame Constellation? It calculates the fuel to 3 decimal places... :rolleyes:

Derfred 26th Jan 2019 11:36


Originally Posted by Troo believer (Post 10371139)
Constellation is the problem.

Capricorn is still there pumping out flight plans for other fleets... why canít they whip out a backup Capricorn plan?

catseye 26th Jan 2019 12:00


Originally Posted by Derfred (Post 10371353)


Capricorn is still there pumping out flight plans for other fleets... why canít they whip out a backup Capricorn plan?

About 4 mins for a LHR - SYD fpl when OJA was being planned in Capricorn.


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