Ask The Pilot

[rechoboam]

There was an Airbus remained pressurized when on ground after emergency descent. CC tried to open doors (unaware of alarm) and couldn't. One then succeeded, explosive outward movement of door took CC with it, he was killed and two other staff seriously injured. I assume the gradient is higher at altitude though. Boeing has had a venting system to prevent this, not sure if Airbus has since enabled one. I think it was bleed air into cabin and no specific training regarding the possibility.
edit: found the link
http://www.iasa.com.au/folders/Safety_Issues/Cabin_Safety/deadlydoors.html

 

[jb747]

Passenger tried to open door mid-flight

Could this turkey actually have opened a door mid-flight? Is it possible?

Basically the answer is no. The mechanism within the door would fail before enough pressure could be applied to cause the locks to open.

To take an extreme example, on QF30, the oxygen bottle hit the door handle, and moved it towards the open position with dramatically more force than could ever be applied by any person. The internal mechanism of the door failed, without the door locks moving at all.

The answer should be no, as the door is physically bigger than the hole it sits in. I think they are called plug doors, and if they do become open as such, it is pressure that holds them into place.

Plug doors are, in the main, a Boeing thing.

Not always, plug doors are in operation on some aircraft, given the type of aircraft is not known (from what I can tell) and Thomson operate A320/321 B733/738, 757 and 767, it might be difficult to say, for instance the A319 is not a plug door and has issues, and there is documented incidents involving the A330, both of course are not part of the fleet in question.

Whilst the action of the 757/767 door is quite different to the 747, they share the feature of moving inwards as the first step to opening. Any residual pressure will be released during that initial movement (on all of the Boeings).

Airbus persist with their main design feature...that of being different to Boeing at every opportunity. Whist that sometimes gives a good result, it also leads to complexity...reinventions of the wheel that don't give any improvements. Having a big red warning light on a door, to warn of pressurisation is all well and good, but in an evacuation it is likely to missed, no matter how well trained the crew. Airbus blaming people for not following the FCOM (their manuals) is a rather sick joke, as these manuals would have to be the worst written manuals that I have ever seen...and apparently the one I'm familiar with is their best effort. The US navy NATOPS that I used 30 years ago was clear, concise, and easily read, which is the exact opposite to FCOM.

There was an Airbus remained pressurized when on ground after emergency descent. CC tried to open doors (unaware of alarm) and couldn't. One then succeeded, explosive outward movement of door took CC with it, he was killed and two other staff seriously injured. I assume the gradient is higher at altitude though. Boeing has had a venting system to prevent this, not sure if Airbus has since enabled one. I think it was bleed air into cabin and no specific training regarding the possibility.
edit: found the link
http://www.iasa.com.au/folders/Safet...adlydoors.html

Using two hands in an attempt to open the door...shows a pretty vast lack of understanding of just what is happening. But, this does fit in with what could be described as the "eet weel not 'appen" design procedure. Red lights, and various other warnings may seem like good solutions to an engineer, sitting behind his workstation. But, in the heat of the moment, a design that is foolproof is superior to any warning system. The trouble with Airbus is that their version of foolproof isn't to simply design a vent into the system. It will be to place a computerised system into play, with a backup to that, and a backup to the backup. KISS is obviously an engineering principle that was missed in their universities.

 

[mannej]

With the plug v non plug door debate in mind, if the Oxygen bottle incident from QF30 occurred in an Airbus, would the door remain in place like it did on the 747?

 

[jb747]

With the plug v non plug door debate in mind, if the Oxygen bottle incident from QF30 occurred in an Airbus, would the door remain in place like it did on the 777?

I believe the door would have remained closed, although the design of the handle is totally different, so the bottle most likely would not have hit the handle (in such a way as to make it try to open).

The counterpoint is that hitting the handle removed most of the energy from the bottle, so had it not done so, then there possibly would have been an exit hole in the roof.

 

[Flying Fox]

Wingtips.

I understand that this may be more of an engineering question so you might not be the right person to ask but I thought that I would ask anyway.

As I understand it, planes fall into these basic categories -

1. No wingtips eg 737-400.

2. With wingtips eg 737-800/747-400

3. With wingtip fences (I think that's the correct term) eg A380

4. With raked wingtips (once again I think that's the correct term) eg 777-300/747-800

I understand the basic principle in that wingtips assist with fuel economy by stopping the air at the end of the wings creating more turbulence. So my questions are -

1. Is there much difference between the three wingtip types?

2. Why are Boeing's new aircraft now going with raked wingtips vs the normal wingtips?

Thanks

 

[jb747]

Wingtips.

I understand that this may be more of an engineering question so you might not be the right person to ask but I thought that I would ask anyway.

As I understand it, planes fall into these basic categories -

1. No wingtips eg 737-400.

2. With wingtips eg 737-800/747-400

3. With wingtip fences (I think that's the correct term) eg A380

4. With raked wingtips (once again I think that's the correct term) eg 777-300/747-800

I understand the basic principle in that wingtips assist with fuel economy by stopping the air at the end of the wings creating more turbulence. So my questions are -

1. Is there much difference between the three wingtip types?

2. Why are Boeing's new aircraft now going with raked wingtips vs the normal wingtips?

Thanks

Well, I'm sure you're right when you say that you'd be better off asking an engineer....

At the wingtip, the high pressure air from below the wing, mixes with the lower pressure air above, and forms a vortex. The vortex core can often be seen when aircraft land on humid days. It represents a loss of energy (in rotating the air) that gives no lift/drag benefit. Any form of reduction of the vortex makes the aircraft more economical. The various winglets, etc are simply the makers attempts at doing so, and, at times, a bit of marketing (passengers think that the ones with winglets must be 'better').

Those little A380 ones are, I'm told, about 3 metres high.

 

[Must...Fly!]

Those little A380 ones are, I'm told, about 3 metres high.

This image certainly supports that!



(Airbus A380 hits building at Bangkok Airport at Flightstory.net - Aviation Blog)

 

[markis10]

Wingtips.

I understand that this may be more of an engineering question so you might not be the right person to ask but I thought that I would ask anyway.



I understand the basic principle in that wingtips assist with fuel economy by stopping the air at the end of the wings creating more turbulence. So my questions are -

1. Is there much difference between the three wingtip types?

2. Why are Boeing's new aircraft now going with raked wingtips vs the normal wingtips?

Thanks

In terms of winglets they reduce the drag of a wing. The reduced drag can be as much as 6% at optimum cruise levels which equates to 3-4% reduction in block fuel consumption. Raked wingtips give similar benefits without the added weight penalty, and along with blunt raked wingtip are Boeing inventions. Airbus A330/A340 families use the 747-400 winglet. The A320 family of airplanes uses the BAE - UK developed delta winglet that has an opposite plan-form camber on the upper & lower half of the winglet. Winglets on bizjets are generally there because they look good!

The A380 Wingtip fences are a compromise between the need for a winglet and the 80m span rule for aircraft at airports.

 

[harvyk]

That photo kinda puts things into perspective... When sitting on the A380 and looking out the window those things look so small that you'd almost consider them an after thought.

 

[QF WP]

I am forever amazed at the depth of knowledge and willingness to share, in the AFF Community . I read something new every time I read this thread (notice I didn't say learn, because some of it is well over my head).

 

[Flying Fox]

Thanks all.

Raked wingtips give similar benefits without the added weight penalty, and along with blunt raked wingtip are Boeing inventions.

So I'm guessing that raked wingtips are made from a more flexible material that bends upwards when in flight vs the 747-400 winglets that are ridgid the whole time?

Given the weight savings (as stated above) why doesn't Boeing install raked wingtips on 737s and after market 767 vs the ridgid types currently being used?

 

[jb747]

So I'm guessing that raked wingtips are made from a more flexible material that bends upwards when in flight vs the 747-400 winglets that are rigid the whole time?

You mean bend up so that they look like normal winglets? No. The whole wing bends a bit, but control of the vortex doesn't necessarily need what amounts to a fence at the wingtip.

Given the weight savings (as stated above) why doesn't Boeing install raked wingtips on 737s and after market 767 vs the ridgid types currently being used?

Both the 737 and 767 can have large winglets installed. You see them every day. But note the comment that the winglet designs can give "up to" 3-4 burn improvement. They mostly give a lot less. I think the theory with regard to the -400 was that they basically saved enough fuel to pay for their own weight...but it certainly wasn't a substantial number. In the case of the 767, the cost of the retrofit wouldn't be paid for in their remaining life...though I suspect that was worked out before the 787 became vapourware. On a new aircraft they make sense, but rather less so on older machinery...unless you start selling the advertising space.

 

[markis10]

Thanks all.



So I'm guessing that raked wingtips are made from a more flexible material that bends upwards when in flight vs the 747-400 winglets that are ridgid the whole time?

Given the weight savings (as stated above) why doesn't Boeing install raked wingtips on 737s and after market 767 vs the ridgid types currently being used?

Gate space, where thats not going to be an issue they use it:

Boeing: Boeing Changes Wingtip Design on U.S. Navy's P-8A Multi-mission Maritime Aircraft

As does our own Wedgetails:

 

[harvyk]

How is it determined how much freight will be on any particular flight. For example once they finish selling seats do they then say "OK we can take an x amount of freight, lets find some stuff which need to go to xyz"
Or is it predetermined when an article for freight is first given to a courier company that it will be booked onto flight QF1 on this date for example.

A couple of years ago I did AKL-MEL on a B747. The plane was nearly empty. I was under the assumption that they would have loaded the plane up with as much freight as they could carry to make the flight profitable or would that flight have simply been marked off on the books as an unprofitable flight that morning and not loaded up with freight...
It was a good flight though as every Y pax had a row of seats to themselves... I believe J was fairly empty as well...

 

[jb747]

How is it determined how much freight will be on any particular flight. For example once they finish selling seats do they then say "OK we can take an x amount of freight, lets find some stuff which need to go to xyz"
Or is it predetermined when an article for freight is first given to a courier company that it will be booked onto flight QF1 on this date for example.

There's a lot of history to any given flight. Companies know pretty well how much capacity will be available, and cargo (if they have any) will be loaded to take as much advantage of it as possible. The one fly in the ointment then becomes the captain, who in some cases may well want to offload cargo to carry more fuel... That doesn't happen often, but it is an option that we may use.

A couple of years ago I did AKL-MEL on a B747. The plane was nearly empty. I was under the assumption that they would have loaded the plane up with as much freight as they could carry to make the flight profitable or would that flight have simply been marked off on the books as an unprofitable flight that morning and not loaded up with freight...

I've flown empty flights with full underfloor cargo, and others with absolutely nothing, above or below decks. They'll certainly try to use any capacity that they can, but there's no guarantee that they'll have the right cargo in the right place, at the right time. Some flights just make a loss....

Sometimes too, sticking that last kilo of cargo on board can be counterproductive. There was once a 767 flight, that was regularly presented with full passengers, and a solid cargo load. As it was operating to Singapore, and the weather there is notorious for what's called the 'creeping tempo' (poor weather on the forecast, for which they slowly move the time of the bad stuff). Crews were often offloading a pallet of freight to allow the carriage of some more fuel. An edict came out to the effect that they did not want us to do that, that the risk of a diversion was considered very low ('cos mostly the creeping tempo didn't convert into actual bad weather). So, in the next week, there were four out of seven flights that diverted, and three terminated at Jakarta. The problem was that the CASA rules that that particular flight operated under, gave an extension of allowed time for the planned tour of duty, whilst simultaneously removing any crew option to extend. So, the risk of a diversion actually turned out to be high, but worse than that, the risk was not of a diversion, but of a termination. And, it turned out that the cargo was 'standby', and most definitely not worth the problems. After that little experiment, that service was then planned with the tempo covered.

 

[Awesom Andy]

An edict came out to the effect that they did not want us to do that, that the risk of a diversion was considered very low ('cos mostly the creeping tempo didn't convert into actual bad weather). So, in the next week, there were four out of seven flights that diverted, and three terminated at Jakarta.

Sounds like the work of bean counters who do not have adequate knowledge and/or experiences of airlines operations?

 

[juddles]

... the cost of the retrofit wouldn't be paid for in their remaining life.....

Wingtips are a complex area. It isn't so much a competition between raked and winlets, as there are designs that incorporate both fundamental principles.

As has been posted by jb, the principle aerodynamic problem at the end of a wing is that there has to be some point where the different air pressures meet, thus creating that naughty turbulence. Both a winglet or a raked tip seek to smooth that mingling of differential air pressures. But it is not a simple matter of one being better than another - depends totally on the specific wing. That's why you don't see 777 with "winglets".

And also, as aviation is into miniscule improvements, different flight profiles for the same plane can make a difference. At the end of the day an airline has to balance drag reduction/weight/cost etc etc to come up with their best option.

But the fundamental principle is that reduction of the severity of differential airflows meeting.

 

[rechoboam]

Whats the restricted area just SE of the Mornington Peninsula FL 550?

 

[jb747]

Whats the restricted area just SE of the Mornington Peninsula FL 550?

On the chart it says Department of Defence - Navy. If I recall correctly, the RAN has gunnery school around there. Something that goes so high would have to be for weapons.

 

[markis10]

Whats the restricted area just SE of the Mornington Peninsula FL 550?

R323 Military firing (R323A to 9000 flying) (R323B FL550 Firing)
R332 Radar Flares to 2000
R339 Flying, gunnery and Naval Activity to FL550

Its active fairly often, think Kalkara activity or LR35 (VH-LRX)!


R339 ACT DUE FLYING SFC TO FL550 FROM 09 252200 TO 09 280600 1109252200 TO 1109260600 1109262200 TO 1109270600 1109272200 TO 1109280600