Ask The Pilot

[jb747]

JB, have you done any interesting flight sims as of late?

No, I've been on long service leave. I'm back in the sim next Tuesday morning, though that is all about practising basic stuff after a long break.

 

[mjt57]

JB, with respect to descent and approach speeds, which is better; slower or faster? That is, do you aim for a faster descent or rather, fastest possible descent or the slowest possible descent?

 

[jb747]

JB, with respect to descent and approach speeds, which is better; slower or faster? That is, do you aim for a faster descent or rather, fastest possible descent or the slowest possible descent?

Neither actually. Descending from altitude, you want a descent that gives you the best glide range (and that will be close to the speed you were cruising at) as that will, in theory at least, give a marginally lower fuel burn. Faster IAS gives a much shorter overall descent, and more time in the cruise, so burns more fuel. The FMC generates that number for us. Slower makes the descent take more time, but may burn more fuel. ATC considerations tend to lock in specific speeds, so in Oz, it's generally your cruise mach initially, then 280 knots, then 250 k.

We may manipulate the descent speeds for traffic management or to help us with curfew or arrival timing.

 

[Bjet]

Do you have to sit for the exams every year?

 

[Julesmac]

BJ, can you tell me, how do you know the weight load of an aircraft? Obviously the luggage is weighed, but not the passengers. Does it make much difference to you if the plane is fully or lightly loaded, in fuel economy for instance. I understand in a little plane they have to distribute passengers in order to trim the plane, is that applicable in a jet at all?
Second question - if you are going into a very busy airport say Heathrow, where the planes land every - is it under a minute? - I notice you said a few posts previously that you sometimes manipulate descent speeds for traffic management. Is that hairy? I guess a busy airport would want you to be pretty nimble coming in, but how much would you ahve to speed up compared say to Melbourne?

 

[jb747]

BJ, can you tell me, how do you know the weight load of an aircraft? Obviously the luggage is weighed, but not the passengers. Does it make much difference to you if the plane is fully or lightly loaded, in fuel economy for instance. I understand in a little plane they have to distribute passengers in order to trim the plane, is that applicable in a jet at all?

Trim is handled exactly the same in a large aircraft as a small one. Average weights are used for passengers, but the result will be accurate within a tolerance that has been allowed for by the aircraft makers. Load sheets are generally calculated for us, though if given all the information, we can calculate it ourselves. In flight the aircraft trim is kept quite aft as long as possible, by keeping fuel in the tail. That reduces overall drag, and so helps reduce fuel burn.

Second question - if you are going into a very busy airport say Heathrow, where the planes land every - is it under a minute? - I notice you said a few posts previously that you sometimes manipulate descent speeds for traffic management. Is that hairy? I guess a busy airport would want you to be pretty nimble coming in, but how much would you ahve to speed up compared say to Melbourne?

London has some standardised speeds, basically wanting you at 220 knots at about 12 miles to run, 180 joining finals, and then 160 to 4 miles. The 160 speed is not an issue in the 747 as that will put it about 15 knots above the planned approach speed, and it's easy enough to lose that in a mile or two. The 380 will want to be at about 135 knots, and it's more difficult to lose that and still fulfil the 'stable approach' requirements. Knowing what they want in advance does make is easier to deliver though. LAX has a habit of wanting a relatively high speed, but additionally of delaying your descent in close. The combination results in the occasional go around. Australian ATC tends to give speed reductions a little further out, and they generally don't hang you out up high. It's a dynamic place, and you're expected to fly the aircraft to fit in. It's not hairy in the slightest, and like everything, is a lot easier if you've thought about how you'll handle it before you get there.

 

[mjt57]

The 380 will want to be at about 135 knots, and it's more difficult to lose that and still fulfil the 'stable approach' requirements.

When I was observing traffic around SYD via that FlightRadar site and listening to ATC via atc.net (watching for my wife's flight back from the US), I was watching a SIA 380 approaching SYD from the NW. Anyway, they contacted the tower to advise of a go around due to "stability problems".

Obviously I wasn't on the flight deck so I don't know what the problem was, except that my wife's B744 was intercepting on the localiser for its approach and was behind it, seemingly at the same speeds, etc (you don't know how accurate the data from that Flight Radar site is).

What could cause this stability issue that the guys needed to go around?

 

[jb747]

When I was observing traffic around SYD via that FlightRadar site and listening to ATC via atc.net (watching for my wife's flight back from the US), I was watching a SIA 380 approaching SYD from the NW. Anyway, they contacted the tower to advise of a go around due to "stability problems".

Obviously I wasn't on the flight deck so I don't know what the problem was, except that my wife's B744 was intercepting on the localiser for its approach and was behind it, seemingly at the same speeds, etc (you don't know how accurate the data from that Flight Radar site is).

What could cause this stability issue that the guys needed to go around?

Well an unstable approach is one in which they aren't back within the speed or sink rate tolerances, or perhaps glideslope or localiser, by 1,000 feet in IMC or 500 VMC. Basically it's way better to admit defeat and do it again, than it is to try to fix a dud approach.

 

[oz74]

Well an unstable approach is one in which they aren't back within the speed or sink rate tolerances, or perhaps glideslope or localiser, by 1,000 feet in IMC or 500 VMC. Basically it's way better to admit defeat and do it again, than it is to try to fix a dud approach.

Might be a silly question jb but would too many 'go a rounds' result in any consequences for a pilot?

Extra training maybe?

 

[jb747]

Might be a silly question jb but would too many 'go a rounds' result in any consequences for a pilot?

Rather hard to say really. They happen occasionally, but more than that would certainly be unusual. But, there could certainly be circumstances that make it more likely. Just fly to HK too often in the typhoon season, and you're exposed to the risk more than people who don't go there. I expect that all go arounds are looked at, and 99% are dismissed immediately.

The other way to look at it is that continuing a dud approach is dramatically worse than giving it away.

 

[kiwi1972]

G'day JB,
Thanks for such an in depth reply to my other question!!!
i am a train driver for a large mining company and fly in fly out with a well known western australian airline.
We recently took off from Perth on a Fokker 100 and we leveled out really early then headed off towards the ocean which was unusual for this departure. After about 15 minutes the pilot came on and said we would be returning to Perth with a technical problem. We circled around rotnest island for an hour to burn off fuel so we could land back in Perth. As we headed back towards the airport the pilot came on and said we may notice a few things approaching the airport, we would be going a lot faster than normal and we may see emergency services on the side of the runway. At this point I thought we were in real trouble! I was sitting quite close to where the main gear extended from. He wasn't wrong we were going way faster than normal and we hit with a massive thud, thought the gear was going to come through the floor! And yes the fire brigade were on the side of the runway and followed us down the runway. I found out later that the flaps weren't working, well I think they got stuck in the takeoff configuration.
Was a little nerve racking, just wondering if this sort of thing happens regularly? I wouldn't have thought so but maybe as passengers we are blissfully unaware of problems like this and never know.
Also I thought the pilots nailed the landing with awesome skill, It was hard but we were going really quickly.
you had situations like this?
thanks mate and hope you had a great long service leave.

 

[jb747]

We recently took off from Perth on a Fokker 100 and we leveled out really early then headed off towards the ocean which was unusual for this departure. After about 15 minutes the pilot came on and said we would be returning to Perth with a technical problem. We circled around rotnest island for an hour to burn off fuel so we could land back in Perth. As we headed back towards the airport the pilot came on and said we may notice a few things approaching the airport, we would be going a lot faster than normal and we may see emergency services on the side of the runway. At this point I thought we were in real trouble! I was sitting quite close to where the main gear extended from. He wasn't wrong we were going way faster than normal and we hit with a massive thud, thought the gear was going to come through the floor! And yes the fire brigade were on the side of the runway and followed us down the runway. I found out later that the flaps weren't working, well I think they got stuck in the takeoff configuration.
Was a little nerve racking, just wondering if this sort of thing happens regularly? I wouldn't have thought so but maybe as passengers we are blissfully unaware of problems like this and never know.
Also I thought the pilots nailed the landing with awesome skill, It was hard but we were going really quickly.
you had situations like this?

Flap issues aren't common, but like everything, they happen every now and then. They are rare because the flaps/slats are generally powered and controlled by multiple systems, so, for instance, the loss of an hydraulic system should have no effect other than perhaps making extension/retraction take longer than usual. The only flap problems that I've ever had related to 'asymmetry' trips, in which the protection system disables the flaps after deciding that it was seeing slightly asymmetric movement. And even then, it was actually false, although the flaps remain locked.

The only thing that sounds a bit wrong is the extremely solid landing. The sink rate will be higher than usual on approach (to go with the faster approach speed), so you need to sort out the flare a bit earlier than usual...and perhaps they didn't get that quite right.

As problems go, it's fairly straightforward, and no need for any nerves to be wracked.

 

[Skyhigh777]

In this event, will the flaps remain locked for the remainder of the flight? Is there any way to reset the protection system?

Thanks for answering all these questions JB, you must get inundated with notification emails.

 

[jb747]

In this event, will the flaps remain locked for the remainder of the flight? Is there any way to reset the protection system?

Not in flight...it's a maintenance step. A reset like that would be an extremely dangerous thing for the manufacturer to enable. You couldn't guarantee that the trip was false until engineering looked at it.

 

[WheelieBagWanderer]

Hi JB,

Are the QF 767 tech crews separated into DOM/INTL or Short/Long Haul?
ie. Could you be flying SYD-MEL doubles every day for a week and then the next week find yourself off to HNL?
(This probably had more relevance to previous times when the 767's were flying routes that the A330's are flying now).

How does QF work it's crews for the 767? I would imagine it would get a little mundane if they do "short haul" only - isn't there only so much "SYD-BNE/SYD-MEL" one can take? High intensity with many take-offs and landings!

How is landing in a 767 at NOU? Is the runway length there overly long? I know QF flies its 767's there, but it's not an overly frequent sector - did you fly there often?

Thanks in advance, and have a good "flight" in the simulator tomorrow!

 

[jb747]

Are the QF 767 tech crews separated into DOM/INTL or Short/Long Haul?
ie. Could you be flying SYD-MEL doubles every day for a week and then the next week find yourself off to HNL?
(This probably had more relevance to previous times when the 767's were flying routes that the A330's are flying now).

There's no separation. In days past, the 767 guys could fly to a good selection of destinations to offset the mundane monorail. Sadly, the east coast is about all they have left.

How is landing in a 767 at NOU? Is the runway length there overly long? I know QF flies its 767's there, but it's not an overly frequent sector - did you fly there often?

I don't recall anything particularly difficult about Noumea. Some surrounding high terrain, and only one ILS approach. Not much different to Cairns.

 

[mjt57]

JB, see you're up late. Don't you have the sim in the morning???

Anyway, I take it that you read about UA839 having a bit of a mishap at MEL yesterday. Any speculation as to how they could have impacted something on the inner left leading edge? The photo that I saw in the paper showed a substantial ding.

 

[jb747]

JB, see you're up late. Don't you have the sim in the morning???

More a case of up early. The sim started at 0215. A nice 'welcome back'.

Anyway, I take it that you read about UA839 having a bit of a mishap at MEL yesterday. Any speculation as to how they could have impacted something on the inner left leading edge? The photo that I saw in the paper showed a substantial ding.

It would almost certainly be a hit on the aerobridge. That can come about a number of ways. One is to go too far, but the type of guidance used at Tulla gives a very definite indication of when to stop. It could have been set for, or automatically recognised, the wrong aircraft type, but that's something you can check as you line up. A bridge may not have been correctly parked/retracted, but there should be a green light showing to indicate that. Or, perhaps the aircraft stopped prematurely, and the bridge operator started to move, and then the aircraft moved towards the correct spot.

They are very close when parking, so there are lots of ways for it to go wrong.

 

[oz74]

More a case of up early. The sim started at 0215. A nice 'welcome back'.


It would almost certainly be a hit on the aerobridge. That can come about a number of ways. One is to go too far, but the type of guidance used at Tulla gives a very definite indication of when to stop. It could have been set for, or automatically recognised, the wrong aircraft type, but that's something you can check as you line up. A bridge may not have been correctly parked/retracted, but there should be a green light showing to indicate that. Or, perhaps the aircraft stopped prematurely, and the bridge operator started to move, and then the aircraft moved towards the correct spot.

They are very close when parking, so there are lots of ways for it to go wrong.

Would the captain be in deep poo for this?

Hope the sim was good!

 

[jb747]

Would the captain be in deep poo for this?

Hope the sim was good!

Whilst it isn't a good idea to bend the metal, there are too many ways for it to go awry to start blaming any particular person. Anyway, I might be next.

The sim was very straightforward. Full pre and post flight checks (they are very time consuming).

A number of circuits...just like you'd do in a Cessna. Some low visibility ops. Engine failure with abort, and another where we took off, and then returned for a 3 engined manual approach. Nothing sneaky...just practice.