I was 'lucky!' enough to fly out of Sydney in the middle of the severe storms yesterday. My flight was JQ1 to MEL, and whilst we pushed back at 1310, we weren't airborne until 1423.
My question comes from what the captain told us just prior to takeoff - he said that ATC switched runways '5 times' in 40 minutes. What I'd like insight into is how the pilots handle rapidly changing weather (and runway) conditions. Are you constantly updating the wind speeds and directions into the flight management system as they are provided by ATC?
On some aircraft, you can get the laptop (or ipad) to calculate multiple runways' performance data simultaneously. So, you might, for instance, select 16R full length and F, as well as 07, and the single run would produce all three data sets. Having said that, you generally just work it out for the one you expect, but as the ATIS or tower advises changes, you enter them into the app and recalculate the data. That then has to be manually entered into the FMC. A change every few minutes is a pain, and has the potential to set people up for using the wrong data set, but when the weather is the way it's been in Sydney over the last few days that's unavoidable.
Yesterday, departing Sydney, we were planning on using the full length of 16R. We don't normally look at the other options, because even if the aircraft can use them, there is no point in using up the engines any more than needed. As we asked for push back, we were told that we'd be unable to go direct to the runway end from our parking bay due to an inspection, and were offered either F, or to be 'processed to access the runway from the other side'. That means mixing the 380 in with the domestics, and would slow everyone down. We looked at F, and found we could accept it, and still get a derate, so we departed from there (at 569 tonnes...the max).
Also, once we lifted off we experienced some moderate to heavy turbulence. I saw from our track and the weather overlay on Flightaware that we essentially flew a narrow path between 2 storm cells. In situations like this, especially on departure or arrival in congested airspace, what options are open to the flight crew to avoid or circumnavigate the storm cells?
You simply tell ATC what you want to do. They can't (and won't try anyway) force you to fly through a cell. The crew would have looked at the radar on taxi out, and also lining up, so you can get a heading requirement in, even before you take off. ATC also work out where the weather is, and will modify there procedures to suit. An example of that was arriving in Dubai this morning, where there was substantial storm activity through the whole area. They'd moved their normal airborne holding point to a spot that was less weather affected.
