Ask The Pilot

[jb747]

The APU provides both electricity and air for the packs. We will turn the APU off if we have access to power and air, but it will need to be back on around the time passenger boarding starts, as it's rare for the external air to be up to the task of cooling the aircraft when it's hot and lots of people are on board.

The quality of the power/air varies dramatically around the world. At the new Dubai terminal both are excellent. In most of Oz, the bloke should pedal a lot faster. Provide poor electricity to a 380, and the aircraft won't like it, and will almost certainly end up with length system reboots being required (these take much longer than the average turnaround).

Arriving in Dubai last night, we transferred to external power/air, and shut the APU down. It would have been started again about 45 minutes later. There is some doubt as to whether these short running cycles are cost effective at all, as APU maintenance is an extremely expensive proposition, and their reliability seems to go down as we take the supposedly more green option of using ground sources.

 

[jb747]

Flights this week.

Last minute change had me doing yesterdays' QF9

So for the rest of the week....
12/6 DXB-LHR QF9
14/6 LHR-DXB QF2
16/6 DXB-SYD QF2

 

[oz74]

Nice to see you got a few flights jb.

 

[jb747]

Nice to see you got a few flights jb.

I got them for a sad reason, so I wouldn't have minded if the original guy got to keep them.

I was planned to ferry another aircraft to Manila.

 

[markis10]

The last conversion??

 

[jb747]

The last conversion??

Don't know, I haven't kept track of them. Must be close though. Could just be a check at Lufthansa Technic too....

 

[oz74]

I got them for a sad reason, so I wouldn't have minded if the original guy got to keep them.

I was planned to ferry another aircraft to Manila.

That's never good

 

[oz74]

Just watching sbs, there going to crash a 727

 

[markis10]

Don't know, I haven't kept track of them. Must be close though. Could just be a check at Lufthansa Technic too....

Charlie is the last to be done and on her way back from LHR as the 2 shortly, I suspect its her. Be interested to hear of crews experiences of DXB during Ramadan, quite a big change from what I hear to the normal DXB scene.

 

[jb747]

Charlie is the last to be done and on her way back from LHR as the 2 shortly, I suspect its her. Be interested to hear of crews experiences of DXB during Ramadan, quite a big change from what I hear to the normal DXB scene.

See, you know more about what they are doing than I do... I guess C was the one I was supposed to take to Manila then. They all look the same to me.

We all survived in Bahrain when we went there...mostly without noticing. I suspect the effects within the hotels will be muted. I'm sure I'll be here at some point to find out anyway.

 

[doctork]

I was on a Qantas 737 (new one with BSI) the other day, and on landing, noticed that a hatch retracted on the engine side facing me.
It may have happened on other aircraft as well, but I'm not normally in the window seat near the leading edge of the wing.
Is this an engine braking mechanism?

 

[jb747]

I was on a Qantas 737 (new one with BSI) the other day, and on landing, noticed that a hatch retracted on the engine side facing me.
It may have happened on other aircraft as well, but I'm not normally in the window seat near the leading edge of the wing.
Is this an engine braking mechanism?

I'd have to admit that I've never taken any notice of 737 engines during landing. I don't fly on them all that often.

You may have seen part of the cowl move whilst reverse was selected. There are a few different ways of engineering 'reverse' thrust, one of which has the cowl translate aft, opening up a gas path around the outside of the engine. Was this what you saw? https://www.youtube.com/watch?v=oZtmSkGNH54

 

[doctork]

You may have seen part of the cowl move whilst reverse was selected. There are a few different ways of engineering 'reverse' thrust, one of which has the cowl translate aft, opening up a gas path around the outside of the engine. Was this what you saw? https://www.youtube.com/watch?v=oZtmSkGNH54

Yes, that's it - at 1.01 on the video. "Reverse thrust" - will remember the correct term, now. Thanks.

 

[jb747]

Yes, that's it - at 1.01 on the video. "Reverse thrust" - will remember the correct term, now. Thanks.

In this sort of engine, about 20% of the intake air goes through the 'core', and that is the only air that is mixed with fuel and burnt in the combustion chambers. The rest simply passes through the large fan and then down the sides of the engine. Effectively, the fan is behaving like a propellor, which is driven by the core.

At the exhaust end, you have two flows. Hot air that passed through the core, and cool air, that bypassed the core. Most modern reversers (but not all) work by blocking and deflecting the cool air sideways and slightly forward, whilst leaving the core flow untouched. Given that the core is producing a large amount of forward thrust, and the sideways blocking of flow is inefficient (perhaps having only a 10% or so reverse effect), the net effect of reverse thrust is virtually zero actual reverse thrust. But, it is very effective at blasting water off runways, and it also tends to destroy lift, which makes the aircraft put more weight onto the wheels and so makes the brakes more effective. The disturbed airflows also produce a fair bit of drag.

Core reversers do exist, and can be seen on aircraft like MD-80s and older 737s. They're the ones that allow aircraft to actually 'reverse'. Very uncommon these days though.

The Harrier used a fairly extreme example of these split air flows, with the front nozzles only having cool fan air, and the rear the hot core exhaust.

 

[Hvr]

Something different in London the other day....I was interviewed by the BBC (in a 380's coughpit) for an upcoming show called "Airport Live". Hopefully I didn't make a prat of myself.

The gave me a couple of GoPro 3 Blacks to get some coughpit shots with. The quality of the 3, especially in low light, is dramatically better than the 2 that I've been using, so I guess I'll have to buy my own soon. If I can arrange another flight back into London in the next couple of weeks, the aim is to simultaneously get the GP shots, plus footage from ATC and by the runway, as we land. That's been passed to the QF hierarchy to work out if they want to do it, and if so just how. It's not quite as easy as it sounds, as all of the trips within the BBC's time limit are already allocated to other pilots. I guess it amounts to free advertising though....

The first episode is due to air in the UK on 17 June. "Dallas finds out more about the A380, the world’s largest passenger jet."
Airport Live TV Show BBC TWO | Airport Live Online Series Summary

I'm sure we'll get some early reports on the quality of the actual program.

I have just watched the first episode of another UK program 'Terror in the Skies' and at the 16 minute mark there is an interview with RdC about QF32 along with footage from the flight and afterwards.

 

[Must...Fly!]

Coming back from Sydney last night, we hit fog in Perth that came in earlier than forecast (alternate was MEL). Landed without trouble happily however sitting on the tarmac waiting to disembark it was obvious that the fog was getting progressively worse and worse...several aircraft deviated.

It did raise a few questions though as I was listening to ATC on the net when I got home.

They kept reporting the RVR to the aircraft as you'd expect, I am sure PER is Cat II, what are the RVR minima for that? Is it something that you go for until that minima, or is it a guideline and you just take a look if you wish, taking that RVR in to consideration?

Also, does fog tend to vary in intensity quite rapidly for you (keeping in mind this was around 1-2am local)? I ask because there was a point at which Emirates (from DXB) was attempting a landing, while Jetstar and Garuda held to see how they went. EK bailed out at 2000ft and almost immediately elected to go to ADL. JQ (from BNE) flew over for a look then decided to go to KGI, while Garuda decided to have a go themselves and got on the ground. Soon after that, another QF bird which had stopped in KGI for a top-up came by, got RVR and did a fly-over before electing to head to ADL.

 

[jb747]

Coming back from Sydney last night, we hit fog in Perth that came in earlier than forecast (alternate was MEL). Landed without trouble happily however sitting on the tarmac waiting to disembark it was obvious that the fog was getting progressively worse and worse...several aircraft deviated.

Perth can be very problematic. Basically it is a long way from anywhere, so any alternate will have some pretty hefty fuel requirements. Kalgoorlie is of marginal use, as it has a small apron, which is full with only a couple of diversions, especially if 767 sized. Learmonth is a decent runway, but not much in the way of aids, a long way off, and nothing on the ground when you get there. So Adelaide becomes the closest reasonable choice.

They kept reporting the RVR to the aircraft as you'd expect, I am sure PER is Cat II, what are the RVR minima for that? Is it something that you go for until that minima, or is it a guideline and you just take a look if you wish, taking that RVR in to consideration?

Perth is not CAT II. It's only CAT I, and the minima are 250'/.8km vis. That's 207' AGL.

Low vis procedures (CAT II and III) include approach bans. Basically you can fly the approach to 1000', but if any element of the reported cloudbase or RVR is less than required, you have to give it away at that point. If you're already below 1000', you can continue. These bans don't apply to CAT I, so you can 'have a look', though RVR reports of less than required are pretty definite, so it's (continuing the approach) of limited value unless the values fluctuating a fair bit.

Also, does fog tend to vary in intensity quite rapidly for you (keeping in mind this was around 1-2am local)? I ask because there was a point at which Emirates (from DXB) was attempting a landing, while Jetstar and Garuda held to see how they went. EK bailed out at 2000ft and almost immediately elected to go to ADL. JQ (from BNE) flew over for a look then decided to go to KGI, while Garuda decided to have a go themselves and got on the ground. Soon after that, another QF bird which had stopped in KGI for a top-up came by, got RVR and did a fly-over before electing to head to ADL.

Fog tends to be quite homogenous. You get variation in and out of limits with wind and rain, but fog doesn't change quickly ('cos if there's wind to make it change, it tends to disappear).

My guess is that it didn't change for Garuda, but they were going to land anyway. Be interesting to know their final fuel figure.

 

[Must...Fly!]

Thanks for the clarification and information as always jb

I guess when you're flying a narrowbody in from Denpasar on a flight that is the better part of 4 hours, the choices you have on what to do in these situations are somewhat limited. I can't imagine you'd get to Adelaide (well, not if you didn't take the forecast seriously and plan accordingly with fuel) and Kalgoorlie is surely not a nice option for an international arrival...although I have just noticed that JQ115 from Jakarta actually diverted to KGI and spent the night there, arriving in to Perth a couple of hours ago - there must be immigration facilities of some kind to facilitate this?

I saw you posted the Sydney TAF for tomorrow morning in another thread (PROB40 1013/1023 0500 FG) what do the bolded numbers represent? Expected visibility?

 

[mjt57]

JB, have you killed your YT channel? Just went there to check something out, but get message saying that it's "currently unavailable"...

If so, will you be making your vids available elsewhere?

 

[jb747]

Thanks for the clarification and information as always jb

I guess when you're flying a narrowbody in from Denpasar on a flight that is the better part of 4 hours, the choices you have on what to do in these situations are somewhat limited. I can't imagine you'd get to Adelaide (well, not if you didn't take the forecast seriously and plan accordingly with fuel) and Kalgoorlie is surely not a nice option for an international arrival...although I have just noticed that JQ115 from Jakarta actually diverted to KGI and spent the night there, arriving in to Perth a couple of hours ago - there must be immigration facilities of some kind to facilitate this?

I saw you posted the Sydney TAF for tomorrow morning in another thread (PROB40 1013/1023 0500 FG) what do the bolded numbers represent? Expected visibility?

40% probability, between 1300 and 2300Z (2300 to 0900 local) of fog, with a visibility of 500 metres.