Ask The Pilot

[Captain Halliday]

Yesterday, Sydney airport closed to arrivals and departures due to a fire alarm that went off in the old tower. Aircraft holding were advised of “we have no idea on how long this will last. Please advise your latest diversion time and destination”.


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We’d started taxiing to RWY34R and were just past Shep’s Mound when the ground stop happened.

From that position we could see the fire crews at the radar room.

Our delay was approx. 20 mins but on approach into Brisbane the captain reported there was still long holding and/or diversions to clear the backlog.

 

[jb747]

Our delay was approx. 20 mins but on approach into Brisbane the captain reported there was still long holding and/or diversions to clear the backlog.

Unless I had a vast amount of fuel, I'd bug out as soon as I heard something like that. And worth considering the situation of aircraft that actually have no alternate (as they aren't always required). In some cases you simply have to press on, and if they don't open the airspace, there's a word that will make it happen.

 

[Captain Halliday]

Unless I had a vast amount of fuel, I'd bug out as soon as I heard something like that. And worth considering the situation of aircraft that actually have no alternate (as they aren't always required). In some cases you simply have to press on, and if they don't open the airspace, there's a word that will make it happen.

I was wondering about fuel while we waited, especially because of efforts to cool the cabin.

From row 2 I heard the CSM call up front about the temp.

That was followed by the engines spooling up slightly and a PA from the captain to say this was to increase the air con effectiveness.

Does an increase to N1 actually improve the air con effectiveness?

If so, by how much would you need to increase it?

And what would the likely corresponding fuel burn be over 20 mins?

 

[jb747]

Does an increase to N1 actually improve the air con effectiveness?

It may increase the duct pressure, and that should increase the air flow through the packs. I don't know whether the amount would be worthwhile.

If so, by how much would you need to increase it?

Not something I ever even thought of doing in the 767/747/380, so I can' say for sure. You might actually be better off restarting the APU and feeding the cabin air from there.

And what would the likely corresponding fuel burn be over 20 mins?

You're not going to increase the power by much, simply because of the jet blast. Perhaps a couple of hundred kilos an hour of fuel flow.

 

[Saab34]

Do you factor any potentially contingency fuel into flight planning for these unexpected events? Or is that the alternate fuel.

 

[jb747]

Do you factor any potentially contingency fuel into flight planning for these unexpected events? Or is that the alternate fuel.

Contingency fuel is sometimes planned, but any 'contingencies' are generally carried within the variable fuel. Basically that's 10% of the flight fuel, but to a maximum number preflight. For the 380, that was 5,000 kgs. In flight it's 10% of what you'll need to get somewhere. Anywhere.

Calculations for fuel are quite different on the ground, and in the air.
In flight:
You must have 30 minutes of fuel (to dry tanks) at the end of the landing roll. That's about 5(and a bit) tonnes in the 380. Called fixed fuel reserve.
You need approach fuel, which is 1,000 kgs, and gets you from 1,500 on the approach to the ground.
At this point you add in any ATC or weather holding fuel requirements.
Then you need fuel to get from where you are, to that 1,500' point on the approach, plus 10% of that amount.

Note that there is NO alternate fuel, unless required by the weather forecast. On most occasions that aircraft divert, it's from a spot enroute, not from the destination. A destination from alternate is a different animal entirely, and it means you've flown to the minima, and then gone around, and now it's fuel to fly somewhere else, plus 10%, plus that fixed fuel, and approach fuel again. Unless it was required on the forecast, you are unlikely to have it.

And example from a somewhat squeezy flight from LAX to Melbourne. Taken after shutdown

 

[Carrots]

I know that it's only part of the job....but I wonder if the energy efficiency of the lights would ever offset the energy wasted by this one service.

Not sure it would even offset the lighting it's replacing

 

[flyer89]

Just something on destination alternate fuel elsewhere in the world. In late 2022 EASA changed the rules so that you are required to carry alternate fuel as a matter of default unless you meet certain requirements. See below.

BASIC FUEL SCHEME — DESTINATION ALTERNATE AERODROME

1. For each IFR flight, the operator should select and specify in the operational and ATS flight plans at least one destination alternate aerodrome.
2. For each IFR flight, the operator should select and specify in the operational and ATS flight plans two destination alternate aerodromes when for the selected destination aerodrome, the safety margins for meteorological conditions of AMCS CAT.OP.MPA.182, and the planning minima of AMC6 CAT.OP.MPA.182 cannot be met, or when no meteorological information is available.
3. The operator may operate with no destination alternate aerodrome when the destination aerodrome is an isolated aerodrome or when the following two conditions are met:

1. the duration of the planned flight from take-off to landing does not exceed 6 hours or, in the event of in-flight re-planning, in accordance with point CAT.OP.MPA.181d), the remaining flying time to destination does not exceed 4 hours; and
2. two separate runways are usable at the destination aerodrome and the appropriate weather reports and/or weather forecasts indicate that for the period from 1 hour before to 1 hour after the expected time of arrival, the ceiling is at least 2 000 ft (600 m) or the circling height 500 ft (150 m), whichever is greater, and ground visibility is at least 5 km.

 

[jb747]

Just something on destination alternate fuel elsewhere in the world. In late 2022 EASA changed the rules so that you are required to carry alternate fuel as a matter of default unless you meet certain requirements.

And the workaround to that is to simply use an alternate that is close. For instance Stansted or Gatwick for London. They're so close that they are more or less sharing the same approach procedures. Rather like using Tulla and Avalon, or Changi and Paya Lebar. Legal, but just as likely to have exactly the same issues.

Australia is problematic, because alternates are so far away that the fuel requirements are always onerous, and often impossible. Of course, if we had a much smaller country, much closer to the rest of the world, it would be easy.

 

[RSD]

Planes taking off with pitot tube covers left on or pins still in the landing gear happens occasionally - but has anyone ever heard of this happening before?

 

[flyer89]

Australia is problematic, because alternates are so far away that the fuel requirements are always onerous, and often impossible. Of course, if we had a much smaller country, much closer to the rest of the world, it would be easy.

Yes, well the infamous A330 landing in Perth that has been riddled with fan fiction about what did and didn’t take place is an example. Although I must say I do like the visual of an A330 scud running….

 

[jb747]

Planes taking off with pitot tube covers left on or pins still in the landing gear happens occasionally - but has anyone ever heard of this happening before?

I doubt that there's really anything new in aviation, so I'm sure that it's been done before, and probably will be again. Pins are always an issue, because the tags can be pulled off, leaving just the pin. I always taught people to look at the hole the pins go into, and not to use the presence or otherwise of a tag as an indication.

Yes, well the infamous A330 landing in Perth that has been riddled with fan fiction about what did and didn’t take place is an example. Although I must say I do like the visual of an A330 scud running….

I don't think I recall that one.

 

[Quickstatus]

And example from a somewhat squeezy flight from LAX to Melbourne. Taken after shutdown

What would 7500- go around - fixed reserve = ?

I always taught people to look at the hole the pins go into

Why not sonething that goes over the tubes?

 

[flyer89]

I don't think I recall that one.

Below minima landing - Perth Airport, WA, 16 September 2006, VH-QPJ, Airbus A330 | ATSB

www.atsb.gov.au

The narratives that people have added onto it over the years are probably far more interesting than the actual event. This is what I get for going down PPrune rabbit holes in the middle of the night. More fool me.

 

[oz_mark]

Below minima landing - Perth Airport, WA, 16 September 2006, VH-QPJ, Airbus A330 | ATSB

www.atsb.gov.au

The narratives that people have added onto it over the years are probably far more interesting than the actual event. This is what I get for going down PPrune rabbit holes in the middle of the night. More fool me.

For a time, it seemed the Jetstar flight Singapore to Perth wouldn't even leave Singapore if there was even a mention of fog in Perth.

 

[jb747]

What would 7500- go around - fixed reserve = ?

It means you'd probably eat into the fixed reserve. There comes a time when you may not be able to go around. If you just flew a quick circuit, and not an instrument approach, then you could keep the burn down to about 2,000 kgs.

Why not sonething that goes over the tubes?

The point is that you don't look for the tags. They break, get pulled off, blow away. You look for the actual pin, or cover...the bit that will cause issues.

 

[jb747]

The narratives that people have added onto it over the years are probably far more interesting than the actual event. This is what I get for going down PPrune rabbit holes in the middle of the night. More fool me.

I'm not sure I would have even gone around off the first approach. It's only going to get worse at that time of day. Realistically no real danger in landing. I suspect the only difference between the approach as it was then and later would have been changes to the lights, and if you're going to autoland, I'd just about prefer it to be unlit. Can't get scared then.

Remember when reading pprune that a huge percentage of the commentary comes from people who are not pilots at all. They've devalued themselves enormously by not insisting on professional qualifications to join or comment.

 

[Major]

Would this be reasonably accurate for the A380 ?

 

[AviatorInsight]

I’d say that’s accurate. This helped me with my type rating.

 

[Captain Halliday]

I’d say that’s accurate. This helped me with my type rating.
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At least they spelt “brakes” correctly in your version.