Ask The Pilot

[Fergo747]

Thanks JB - I would like to think I could perform that replacement given I'm quite adept at following Ikea instructions!

For that reason, the QF 767s had their maximum reduced by about 20 tonnes when they ceased international operations

Interesting. I wonder whether QF got a refund from Boeing for this mod....

 

[docjames]

And even before that, there was a pair of weights that could be used (differing by about 13 tonnes), and the only difference was the plaque that engineering installed in the coughpit.

Must have been an impressive plaque.....

 

[lastrow]

How often did you get to fly the axact same aircraft or were you allocated the next in line for your flight SYD-LAX.? From one aircraft to another (assuming A380 in both cases) can you detect differences between each aircraft ?

 

[Quickstatus]

Max take off weight is defined at the start of the take off roll. So, even though the fuel flow during the take off roll may be high enough to get below the MTW figure...you need it before you go.

How many tons do you burn in the A380 from start of takeoff roll to rotate?

Can” burnoff” occur if there is another aircraft queuing up behind in the taxiway?

 

[AviatorInsight]

While JB is on holiday, I may as well throw my 2c in...

How often did you get to fly the axact same aircraft or were you allocated the next in line for your flight SYD-LAX.? From one aircraft to another (assuming A380 in both cases) can you detect differences between each aircraft ?

With only 5 B777s, it was very common to fly the same aircraft. VPD was the easiest to tell apart because of the amount of rudder trim needed. It was also the most time I had spent in that aircraft at just over 800hrs compared to the others.

 

[jb747]

How many tons do you burn in the A380 from start of takeoff roll to rotate?

I tended to be a bit busy at the time, so it wasn't something I took particular note of....but, I expect it would have been in the order of a tonne. Not as much as you'd expect perhaps, but the take off roll only lasts for about 1 minute.

Can” burnoff” occur if there is another aircraft queuing up behind in the taxiway?

Burnoff is happening all the time. The engines are burning about 700 kgs/hour/engine whilst at ground idle, so even if you do nothing, your weight is going down by 40 kgs every minute. If you need to help that along, you can't push the power up too much, as you'll cause issues with blast...even to the point of eroding a tarmac surface if you pushed it up enough. So, you might push the power up to about 2,000 kgs per hour (per engine), which will increase the weight loss to about 135 kgs/minute.

It wasn't an issue you ran into all that often. Mostly it would happen on 24L out of LAX, and it was generally a result, not of being overfuelled, but of having too efficient a taxi out. Taxi allowances were mostly in the order of 1,000 to 1,500 kgs, but I used to reduce it if I expected 24L, down to 600 kgs. Even if you did have to reduce the weight, it was normally in the order of 1-200 kgs, so it could sometimes be accommodated on the runway, after line up.

If you needed to select more than idle power, you'd to run it past ATC. They'd help with any spacing. Selecting higher than normal power is also required in icing conditions, but those ATC units that see icing also regularly see aircraft that need to go through that procedure, and are aware of the needs.

 

[AviatorInsight]

How many tons do you burn in the A380 from start of takeoff roll to rotate?

Can” burnoff” occur if there is another aircraft queuing up behind in the taxiway?

The B777 used about 1t in 35sec for the take off roll. That was for GE powered. The RRs/PWs may be different.

We used to get put onto the freight apron a bit to burn off fuel. The flight plan calculated 0.7t for a 20min taxi (24L was rarely used), we’d always have to opt for 25R.

 

[Quickstatus]

Presumably there is a vent in the fuel tank system to allow for expansion/overfill and as fuel is consumed it is replaced by air. Potentially water is introduced by this. Is there a way to drain this?

 

[docjames]

While JB is on holiday, I may as well throw my 2c in...



With only 5 B777s, it was very common to fly the same aircraft. VPD was the easiest to tell apart because of the amount of rudder trim needed. It was also the most time I had spent in that aircraft at just over 800hrs compared to the others.

Why does VPD require more rudder trim? Is it just a quirk or does it have some other reason? Does that have an effect on the (cruise) fuel consumption?

 

[AviatorInsight]

Why does VPD require more rudder trim? Is it just a quirk or does it have some other reason? Does that have an effect on the (cruise) fuel consumption?

That aircraft is the one that unfortunately has had the most prangs (things running into it etc). So it requires more trim to keep it wings level, so it definitely does have a higher fuel consumption compared to the others.

 

[jb747]

Presumably there is a vent in the fuel tank system to allow for expansion/overfill and as fuel is consumed it is replaced by air. Potentially water is introduced by this. Is there a way to drain this?

The fuel tanks have ‘surge/overflow’ tanks. These never have any fuel in them from normal ops, but can pick some up for various reasons on the ground. It drains back into the mains when it can, so there should be none lost.

There is a certain degree of water in all fuel. Checking the amount of water (and doing something about it) is an engineering task, that we have no involvement in.

 

[jb747]

Why does VPD require more rudder trim? Is it just a quirk or does it have some other reason? Does that have an effect on the (cruise) fuel consumption?

All aircraft are slightly different, and just through use pick up bends and bumps. It normally isn’t all that noticeable, and FBW masks it, but it will show up through slightly different performance from rest of the fleet. When loading the FMC, each aircraft has it’s own percentage variation that you load for the difference from the standard. Even new aircraft aren’t necessarily all that straight. Curiously, OJH, which was famous for its golfing excursion, was probably the straightest of the RR 400s.

 

[flyer89]

There is a certain degree of water in all fuel. Checking the amount of water (and doing something about it) is an engineering task, that we have no involvement in.

Not particularly relevant to your question but in light aircraft that use avgas, which is more comparable to petrol than Jet A1 part of the preflight is to check the fuel tanks to see if they have water in them with a fuel drain. This must be done to all of the drain points that the particular aircraft has. If water is detected you simply keep draining it until water is no longer visibly present. Perhaps JB remembers having to do this in the good old days, pre Skygod.

 

[straitman]

Not particularly relevant to your question but in light aircraft that use avgas, which is more comparable to petrol than Jet A1 part of the preflight is to check the fuel tanks to see if they have water in them with a fuel drain. This must be done to all of the drain points that the particular aircraft has. If water is detected you simply keep draining it until water is no longer visibly present. Perhaps JB remembers having to do this in the good old days, pre Skygod.

Similar tests are used for drain testing with Jet A1 using a chemical in the bottle. It is normally done by the engineers rather than the pilots.

 

[Quickstatus]

AVgas still contain lead?

 

[flyer89]

AVgas still contain lead?

Yes. The two types in Oz are 100LL blue and 100/130 avgas. Both contain lead with the LL referring to ‘Low Lead’.

 

[AviatorInsight]

Similar tests are used for drain testing with Jet A1 using a chemical in the bottle. It is normally done by the engineers rather than the pilots.

Not particularly relevant to your question but in light aircraft that use avgas, which is more comparable to petrol than Jet A1 part of the preflight is to check the fuel tanks to see if they have water in them with a fuel drain. This must be done to all of the drain points that the particular aircraft has. If water is detected you simply keep draining it until water is no longer visibly present. Perhaps JB remembers having to do this in the good old days, pre Skygod.

And is also checked again by the refuelling truck before being uplifted.

Talking about the good old days, first flight of the day on the Saab even though it was still JetA1, a fuel drain was required. You can imagine my excitement once I got onto the jet that fuel drains are a little harder to do ourselves and so are left to the engineers during their “daily” routine check.

 

[Quickstatus]

Is refuelling done in volume or weight from the refueller’s perspective?

 

[AviatorInsight]

Is refuelling done in volume or weight from the refueller’s perspective?

All done in weight. On the fuel docket however, will be a volume amount only, we then enter this into the flight log and then this will convert it to a weight. It’s a way of doing a gross error check of the fuel.

 

[Quickstatus]

What was the root cause of the 41Tonne overfuelling of the SQ 777-200ER in 2014?

No one believed the 121T uplift...

https://skybrary.aero/bookshelf/books/4368.pdf