Ask The Pilot

[juddles]

I have learnt through this thread the relative unimportance of reverse thrust in braking - essentially I understand that more than braking in itself, it destroys lift and aids the wheel brakes.

What my question is, is there some sort of numerical valuation of wheel braking? IE can you apply "20%" or "70%" braking via the wheels? Or is it all "feel"?

My most memorable flying event was an aborted takeoff, a Lufthansa 747 from FRA, where the pilot decided just before rotation to STOP. It was incredible to me the braking power that was applied - the cabin was literally alive with any loose object bouncing forward through the cabin. (I felt this acutely being in the nose). On that occasion I think the wheels caught fire - it was hard to see from inside, but a stack of firefighting machines surrounded us and moved in, and we sat on the runway for four hours before we got towed off to one side. I believe they were changing tyres. My amateur assessment is that the pilot "hit" the brakes completely.

I also get the concept of heating of brakes. But as i say, is there an organised protocol re wheel brakes?

 

[jb747]

I have learnt through this thread the relative unimportance of reverse thrust in braking - essentially I understand that more than braking in itself, it destroys lift and aids the wheel brakes.

Which is important in itself, but mostly on a wet runway.

What my question is, is there some sort of numerical valuation of wheel braking? IE can you apply "20%" or "70%" braking via the wheels? Or is it all "feel"?

Manual braking is by feel, and as there is virtually no feedback, it’s something you have to learn the feel of. When we had the early 767s, there were a couple of different braking systems in use (carbon brakes or steel), and their feel and use was quite different. If you remember travelling in them, you might recall some quite jerky applications, especially at very low speeds.

99% of landings will have the auto brake system armed at touchdown. We may disconnect it shortly thereafter. On the 380, the possible settings are LO, 2, 3, HI, and RTO. In all cases except RTO, you are selecting a deceleration rate (4, 5, 6 & 7 knots/second). The braking system will use as much braking as it needs to achieve that, right up to anti skid activation if it’s a particularly slippery runway.

RTO simply applies maximum hydraulic pressure to the brakes, and lets the anti skid control everything. RTO is the maximum possible, and is the same as flooring the pedals manually.

There are some other braking modes that activate in failures, but basically they limit the pressure available.

After an RTO, the brakes and tyres will be extremely hot. 7-900ºC. The tyres have fusible plugs fitted, which will melt and deflate the tyres. You’ll feel that happen in the cabin. That exists to stop the tyres from exploding. The area around the brakes and tyres would be dangerous, so it will be some time before maintenance personnel would be able to change tyres. On the other hand, as long as it’s not on fire, the passengers are safe within the aircraft.

RTO does not activate automatically in low speed (<72 knot) rejected take offs.

 

[Quickstatus]

Is there anti skid availability in manual braking - and can you feel it’s activation?

I had always thought that the jerky braking in the 767 was a subtle reminder for recalcitrant passengers to wear their seatbelt..
Some (road) bus drivers do it too but I think they are having a bad day.

Any movement in the industry for seatbelt indicators similar to the ones in cars now that beep when seatbelt not worn (activated when seatbelt sign comes on)??

 

[ChrisGibbs]

I've been fortunate enough to fly QF into JFK on the Canarsie RWY13 approach a number of times. Compared to most other approaches in the world (apart from KaiTak) this one still has a wow factor to it. For the first time I got to sit downstairs upfront on the right hand side of the aircraft (Row 1 window gives you a slight view of what's in front of you) and got to see the lead in strobe lighting to line up onto RWY13L. I would imagine this approach is one you wouldn't want to get behind the aircraft on. A couple of questions:

- Is this conducted as a VOR approach or has it been updated to be a GPS approach
- Would this approach be hand flown or on the automatics
- At what height would the final right hand turn be and how does this line up with the company requirement to have a stabilised approach prior to touchdown

For those who regularly fly into JFK you will know by now that QF has moved from Terminal 7 to the AA Terminal 8. The AA Flagship lounge gives you a good view of aircraft on the Canarsie approach turning onto short finals for RWY13L.

 

[Captain Halliday]

- At what height would the final right hand turn be and how does this line up with the company requirement to have a stabilised approach prior to touchdown

Might depend if you're flying EK or another carrier.

 

[ChrisGibbs]

I've flown a couple of AA domestic sectors over the last couple of days and was getting bored between SFO-LAX, JFK-CLT-MIA and there are many things different in the way the cabin is secured on AA compared to QF. A couple of differences I've seen are:

- no one (passenger or crew) appears to take any notice of the seatbelt sign. It gets turned off when the aircraft is at the top of cruise and gets turned on at top of descent. It also gets turned on again when the cabin crew are doing a meal service
- window shades can be down for take off and landing
- with two pilot operations a member of the cabin crew doesn't enter the coughpit to replace the one who has stepped out
- the jump seat appears to get used to a greater extent for uniformed cabin crew

When things go to plan none of these items would be an issue however if things went pear shaped I would imagine there would be an issue. For example window shades being down would prevent passengers from seeing outside and emergency personnel from seeing in...

 

[ChrisGibbs]

Might depend if you're flying EK or another carrier.

I think the kids in Canarsie Park would have had an up close view of an EK A380 on that occasion.

 

[Flashback]

I've flown a couple of AA domestic sectors over the last couple of days and was getting bored between SFO-LAX, JFK-CLT-MIA and there are many things different in the way the cabin is secured on AA compared to QF. A couple of differences I've seen are:

- no one (passenger or crew) appears to take any notice of the seatbelt sign. It gets turned off when the aircraft is at the top of cruise and gets turned on at top of descent. It also gets turned on again when the cabin crew are doing a meal service
- window shades can be down for take off and landing
- with two pilot operations a member of the cabin crew doesn't enter the coughpit to replace the one who has stepped out
- the jump seat appears to get used to a greater extent for uniformed cabin crew

When things go to plan none of these items would be an issue however if things went pear shaped I would imagine there would be an issue. For example window shades being down would prevent passengers from seeing outside and emergency personnel from seeing in...

.. and eyes being better adjusted to the outside light.

 

[AviatorInsight]

Is there anti skid availability in manual braking - and can you feel it’s activation?

Absolutely! Antiskid is definitely available during manual braking. It controls each wheel during the deceleration. If a wheel slows down too quickly, the skid control releases brake pressure (on that wheel) until the wheel speed increases. Touching down at 140kts and pulling up in 1800m or so, means I generally have no idea what is going on with the antiskid. I'm more worried with making the rapid taxiway and transitioning from the autobrake to manual braking smoothly.

 

[jb747]

- Is this conducted as a VOR approach or has it been updated to be a GPS approach

The approach can be conducted using VOR or GPS. But, it makes no difference to the path flown, or the altitudes.

- Would this approach be hand flown or on the automatics

You could use either down to the position DMYHL, which is the missed approach point, and basically the point at which the turns have to start. From that point manual would be far easier.

My understanding is that EK had some form of home grown procedure that allowed further use of automatics...which obviously worked well.

- At what height would the final right hand turn be and how does this line up with the company requirement to have a stabilised approach prior to touchdown.

It's a long time since I've looked at these in the sims, but I expect the line up point for both would be about 400'

Stabilised approach does not necessarily mean you have to be wings level. On what should be a straight in approach, yep, you should be in the slot with no manoeuvring to do at 500', but if a procedure calls for otherwise, then as long as you are within that procedure's profile, then you would be considered stable. At the old Hong Kong for instance, the turn onto finals didn't even start until about 450' and wasn't complete until about 200'.

 

[jb747]

Is there anti skid availability in manual braking - and can you feel it’s activation?

Without anti skid, there would be aircraft blowing tyres all over the place on wet days. You have virtually no feel of the brakes. You learn that a certain amount of application has a given result, but there is no feedback through the pedals. You can sometimes feel a change in the braking, but generally through the whole aircraft, not the pedals. The bigger the aircraft, the less the feedback.

Any movement in the industry for seatbelt indicators similar to the ones in cars now that beep when seatbelt not worn (activated when seatbelt sign comes on)??

Oh more electronics...just what we don't need. A quick push to -.5g will show who isn't strapped in.

 

[jb747]

- no one (passenger or crew) appears to take any notice of the seatbelt sign. It gets turned off when the aircraft is at the top of cruise and gets turned on at top of descent. It also gets turned on again when the cabin crew are doing a meal service

When you use it that way, you've taught people to take no notice. That's why we turn it on, only as needed, and off as soon as we assess it safe.

- window shades can be down for take off and landing

I'm on the fence about this one. I've heard the reasons, but don't particularly believe them.

- with two pilot operations a member of the cabin crew doesn't enter the coughpit to replace the one who has stepped out

Pointless rule that should be done away with. It introduces more issues than it solves. It's being progressively removed around the world.

- the jump seat appears to get used to a greater extent for uniformed cabin crew

I think it's free for them. Not so here. They are more likely to be helpful than otherwise.

 

[RooFlyer]

For any of our pilots who fly into HBA.

Last year, Air Services Australia changed from individual flight vectoring for approach (and, I guess, departures) to a standard approach path. Its been a bit controversial locally as ASA got caught out not doing the 'community consultation' it was supposed to do - they just announced it as a fait accompi. Now its 'under review'.

As all commercial flights arrive from the north, if they have to land towards the north, previously most would come down the Coal River Valley a bit to the north-east of a southerly landing approach, then do a sporty, tight right hand turn over Tiger Head Bay and then land. This was always a bit of a thrill when the winds were up.

Now, the standard southern approach takes the aircraft more to the east, over populated areas (mainly small towns - such as Carlton River, Dunally, I think), then much further to the south (down to Slopen Island, I think) before turning and approach.

Question for pilots, if they do this run - was there any pressure or wish from them to have this change? I understand that it was mainly driven from ?Melbourne? control, as they previously had to deal with each individual craft, but now its more 'set and forget' (not really, I know, but hopefully that's the gist).

 

[Melburnian1]

In the last day the media slightly sensationalised the diversion of QF568 (the 2355 hours Friday 13 April PER - SYD redeye) to MEL due, apparently, to airconditioning system problems.

Flyerqf asked this in the QF delays thread but it wasn't answered: from the flight path, it looks as if there may have been problems prior to the flight being anywhere near ADL. Was the decision to divert to MEL not ADL driven by the lack of staff in ADL early in the morning (say at 0500) due to the curfew, or some other reason?

When aircon fails, does it tend to be a complex job for the mechanics? Fiddly?

As at 1100 hours on Sunday 15, the affected aircraft, A333 VH-QPF looks still to be inoperable in MEL, presumably under repair.

 

[jb747]

In the last day the media slightly sensationalised the diversion of QF568 (the 2355 hours Friday 13 April PER - SYD redeye) to MEL due, apparently, to airconditioning system problems.

Flyerqf asked this in the QF delays thread but it wasn't answered: from the flight path, it looks as if there may have been problems prior to the flight being anywhere near ADL. Was the decision to divert to MEL not ADL driven by the lack of staff in ADL early in the morning (say at 0500) due to the curfew, or some other reason?

When aircon fails, does it tend to be a complex job for the mechanics? Fiddly?

As at 1100 hours on Sunday 15, the affected aircraft, A333 VH-QPF looks still to be inoperable in MEL, presumably under repair.

So, I gather that the gist of your question, is why the aircraft went to Melbourne and not Adelaide.

If you had an emergency, then the curfew at Adelaide does not apply. But, nothing actually forces you to land at any particular location, especially if all engines are operating.

There are a number of reasons that the packs might decide to shut themselves down. If they do, the cabin pressure bleeds down, but not at anything like the rate of a rapid depressurisation. It is possible in some cases to get the aircraft below 14,000' before the cabin rises above it, which means that you won't have to deploy the oxygen masks.

It may also be possible to restart/reset a pack or system that has shut itself down. If you could then you'd be able to climb again, although the fuel burn could well still force a diversion.

In this case the aircraft is at 17,000', which is an unusual level. The depressurisation model is for 14,000' until depletion of oxygen, and then 10,000. FL170 isn't part of that profile.

My guess (and that's all it is), would be that during the descent, the oxygen was tripped. It is generated oxygen, which means that it cannot be shut off, and has a life of around 20 minutes. At some point, the initial problem was resolved. But, the aircraft no longer has supplementary oxygen available, so it would be altitude limited, and I suspect that's where the FL170 came in.

There is no longer an emergency, and Melbourne is within reach, so there is no real reason to land at Adelaide.

A guess, but it makes some sense.

 

[Quickstatus]

Todays Aurora predictions over the Northern hemisphere:
Any of your SYD colleagues to LHR see any of this?

 

[jb747]

I doubt it. I used to do a lot of the 29/30s which were a long way north, and never saw it.

Some of the guys doing the South America/Africa runs have seen the southern version.

 

[flyer89]

Manual braking is by feel, and as there is virtually no feedback, it’s something you have to learn the feel of. When we had the early 767s, there were a couple of different braking systems in use (carbon brakes or steel), and their feel and use was quite different. If you remember travelling in them, you might recall some quite jerky applications, especially at very low speeds.

I had a jerky experience of a different kind in South Africa last year. It was my first flight flight on an A319 and I was amazed at the difference in flight dynamics compared to say the 320. Just seemed to be all over the place.

 

[Captain Halliday]

Todays Aurora predictions over the Northern hemisphere:
Any of your SYD colleagues to LHR see any of this?View attachment 123105

OT, but what site are you getting that from? I’m considering a trip to northern Finland in Dec.

 

[Quickstatus]

OT, but what site are you getting that from? I’m considering a trip to northern Finland in Dec.

Google Space Weather Prediction Centre
Northern lights are most intense at the equinoxes - March and Sept
However you need the sky to be very dark - so mid winter is the best compromise
Solar Storms like the one the Earth is experiencing at the moment can bring the Northern lights further South.