Cyprus-Forum.com

[Paphitis]

Hiya Kiks,

I will reply to your post with greater detail, but first do a search on Coffins Corner, and let me know what you think. This is the reason why it is assumed that the Pitot Tubes played their part.

Also, try and relate this with the severe turbulence AF447 encountered, and a requirement to maintain a speed below Turbulence Penetration Speed.

Terrorism can not be ruled out, but it is unlikely. But having said this, an aircraft accident can even be caused as a result of passengers carrying dangerous goods within their check in baggage, such as various batteries, and highly flammable substances or pressurized aerosol cans which can explode when placed in an environment where the temperature and cabin pressure is changing. Aircraft have crashed as a result of Dangerous Goods.

Get back to me about Coffins Corner. I will try and find a graph you can analyse.

[Paphitis]

Kikapu wrote:

"The French are leading the crash investigation, while the Brazilians are leading the rescue operation."


It had got me thinking why Brazil was taking the lead into the performing the autopsies as well as the rescue operation, which means basically, that they are gathering all the pieces of the aircraft and the remains of the passengers for examination and not France. Is it possible that Brazil wanted to "contain" all the information for a purpose I did not understand why at the time, until I read this piece couple of days ago, which helped me understand the reasons just a little bit better.

You are placing a little too much emphasis on this.

France would be leading the investigation because the incident occurred on a French Registered Aircraft in International Airspace. Since the aircraft is registered under the French Aviation Authorities and operates under their Aviation Act, then it is French Aviation Authorities that are charged with the responsibilities of investigating the accident. If the crash occurred in Brazilian Airspace, then it would be the Brazilian Aviation Authorities that would investigate the accident.

Also, nations are allocated Search and Rescue (SAR) zones and Flight Information Regions (FIR) by ICAO. Some countries, like Brazil, are allocated a rather extensive SAR zone or FIR. Brazil is in charge of the resue operation because the aircraft crashed in a zone in which Brazil is obligated to provide a SAR and an Area Control function as it was within their FIR.

France can however request assistance with the investigation from other countries, which I doubt they will do. If you want to explore conspiracy theories, then carefully spare a thought about French interests within the Airbus Industries Consortium and also bear in mind the significant influence of Airbus within France and the French Aviation Authorities...

Likewise, Brazil could have also requested assistance with the rescue operation for AF447. I don't believe Brazil is trying to cover anything up.

http://www.icao.int/anb/icaoimojwg/meet ... g9/9-2.pdf

[Kikapu]

I just read some articles on "Coffins Corner" with interest. Miles O'Brian who covers the Space program for CNN also had an article and a blog on Flt 447 and "coffins corner"..

I understand the critical margins at high altitudes and speed, which is why I was concern with if there was a partially blocked Pitot tube which would have given false low speed indication on the speed indicators, then the AP would have powered up the engines to maintain cruising speed at that set altitude, at 35,000 ft. The danger of course, would be that the aircraft would have gotten close to the sound barrier, or may have even broke it, which would have had grave consequences on an aircraft that is not design for. They were doing 500 mph and to break the sound barrier at that altitude, would have been around 650+ mph. Therefore, if the crew did not have any instrument to read and any possible lightning that may have fried all electronics in the cockpit, and it is pitch black inside and outside the aircraft, the aircraft could have pitched nose down and picked up speed in no time which would have broken off the tail first, which would have had way to much pressure at that speed. If on the other hand the plane slowed down if the AP thought they were going too fast once the pitot tubes iced up, then the plane would have stalled, but at that altitude, they might have been able to recover and gain control, assuming of course, that all the electronics were not fried in a potential lightning. Just way too many variables at the moment I'm afraid.

By the way, I tend to use MPH rather than KNOTS for speed since most people do not comprehend what the speed of a knot is. It's just like talking to Americans about Kilometers, they have no idea what you are talking about or worse in Celsius for temperature.!

One of my favourite movies is the adventure/love/comedy story is the "Six Days and Seven Nights" with Anne Heche and Harrison Ford where towards the end of the movie they are flying back in his crippled DeHavilland DHC-2 Beaver and Ford passes out from his injuries but not before giving her instructions how to land the plane close to the beach, to lower the flaps at 65 Knots first, and when the time comes to do it, she says, "65 knots, what the hell is a knot.! :lol:

[Paphitis]

There is a good graph of "Coffins Corner"- Stall Buffet/High Speed Buffet in the below link:

http://www.iasa-intl.com/folders/belfast/AF447.htm

At high altitude, the Stall Speed (Vs) increases and the high Speed buffet Stall (Mmo) decreases.

Now bear in mind that AF447 would also be manoeuvring to avoid Cumulonimbus Formations.

And let's say the Pitot Tubes iced over. Then we can suggest that the Total Air Temperature (TAT) Probe also iced over along with the Static Air Probe.

Therefore, we are now faced with the following:
1) Inaccurate Indicated Air Speed (IAS),
2) Inaccurate Outside Air Temperature (OAT), and
3)Inaccurate Pressure Altitude (QFE)

Now, in order for the to work out True Air Speed TAS, the in flight computer requires an IAS, OAT, and QFE. The computer is then able to calculate a Mach Number and a True Air Speed (TAS).

AF447 was flying at FL350. Therefore, it will be operating close to Vs and the High Speed Buffet (Mmo). It is flying in what we pilots call "Coffins Corner".

Now throw in the freak weather conditions such as Cumulonimbus (CB) formations, with wind shear, icing, and severe turbulence.

Due to severe turbulence, the pilots would be required to reduce to Turbulence Penetration Speed in order to reduce stress on the airframe, which could increase the chance of Structural Failure.

However, if their IAS, and Mach Number is indicating low, they might have increased power to avoid Vs. They may have exceeded Turbulence Penetration causing a High Speed Buffet Stall. The airframe was exposed to increased stress, possibly leading to Structural Failure (VS stabiliser falling off, and maybe the HS stabiliser also falling off).

When encountering severe weather, all pilots will broadcast to Area Control and if things are bad, you would broadcast a Distress Message. When things are critical, all pilots will give a Mayday Call, on all frequencies if possible. No such calls were given. As you say, this could mean that there was a terrorist event on board or the aircraft was struck by lightning. Since the aircraft was flying around CB formations, the probability for lightning strike was high. Therefore, the latter is more likely IMO.

This is another very interesting link to read:

http://trueslant.com/milesobrien/2009/0 ... scale-maw/

The above link gives a good appreciation of the severity of the thunderstorms that AF447 flew through. There is an interesting Flight Profile Diagram, as well as Infrared image of the storm.

I am not saying that my above analysis is the cause of the AF447 crash. It could be something entirely different. The Cockpit Voice and Data recorders need to be salvaged in order to get a clearer picture.

[Paphitis]

I just read some articles on "Coffins Corner" with interest. Miles O'Brian who covers the Space program for CNN also had an article and a blog on Flt 447 and "coffins corner"..

I understand the critical margins at high altitudes and speed, which is why I was concern with if there was a partially blocked Pitot tube which would have given false low speed indication on the speed indicators, then the AP would have powered up the engines to maintain cruising speed at that set altitude, at 35,000 ft. The danger of course, would be that the aircraft would have gotten close to the sound barrier, or may have even broke it, which would have had grave consequences on an aircraft that is not design for. They were doing 500 mph and to break the sound barrier at that altitude, would have been around 650+ mph. Therefore, if the crew did not have any instrument to read and any possible lightning that may have fried all electronics in the cockpit, and it is pitch black inside and outside the aircraft, the aircraft could have pitched nose down and picked up speed in no time which would have broken off the tail first, which would have had way to much pressure at that speed. If on the other hand the plane slowed down if the AP thought they were going too fast once the pitot tubes iced up, then the plane would have stalled, but at that altitude, they might have been able to recover and gain control, assuming of course, that all the electronics were not fried in a potential lightning. Just way too many variables at the moment I'm afraid.

Lightning strike should only fry all HF/VHF/UHF comms and GPS.

Nothing else would be effected, in theory. Aircraft disperse electricity on the outer skin like a Faraday's Tube. The only way this static electricity can enter the aircraft is through external HF/VHF/HF antennas (radio antennas) and the GPS antenna. This of course will overload them causing loss of all radio comms and perhaps GPS as well.

This could explain why there were no broadcasts from AF447.

If the Mach Number was low, then the Auto throttle will power up. since ACARS mentions that the AT failed, the pilots would have manually advanced the throttles themselves causing AF447 to over speed passed Turbulence Penetration and then to Thee High Speed Buffet Stall and possibly breaking up in mid air.

By the way, I tend to use MPH rather than KNOTS for speed since most people do not comprehend what the speed of a knot is. It's just like talking to Americans about Kilometers, they have no idea what you are talking about or worse in Celsius for temperature.!

When you say MPH, do you mean Nautical Miles Per Hour?

I KNOT = 1.852 km/hr
1000 KNOTS = 1852 km/hr (in one hour you will travel 1000 nautical miles).

One of my favourite movies is the adventure/love/comedy story is the "Six Days and Seven Nights" with Anne Heche and Harrison Ford where towards the end of the movie they are flying back in his crippled DeHavilland DHC-2 Beaver and Ford passes out from his injuries but not before giving her instructions how to land the plane close to the beach, to lower the flaps at 65 Knots first, and when the time comes to do it, she says, "65 knots, what the hell is a knot.! :lol:

I also liked this movie.

Kiks, aviation is all about flying the numbers. It is a numbers game, and what we do is just ensure the aircraft is flying within its profile and that all the numbers in the box are correct. Whether you fly a light single engine aircraft, or a light twin engine aircraft or an advance Airbus A330, we still just fly the numbers or the Auto pilot flies them for us and we just go through our procedures and checks.

BTW, you are more than welcome to come flying with me.

[Kikapu]

When you say MPH, do you mean Nautical Miles Per Hour?

I KNOT = 1.852 km/hr
1000 KNOTS = 1852 km/hr (in one hour you will travel 1000 nautical miles).

As below!

1 nautical miles = 1.15077945 miles

1 knots = 1.15077945 mph

1 mph = 0.868976242 knots

1 miles = 0.868976242 nautical miles

Kiks, aviation is all about flying the numbers. It is a numbers game, and what we do is just ensure the aircraft is flying within its profile and that all the numbers in the box are correct. Whether you fly a light single engine aircraft, or a light twin engine aircraft or an advance Airbus A330, we still just fly the numbers or the Auto pilot flies them for us and we just go through our procedures and checks.

You got that right. This is one of the reasons why I stop flying (no, not because I can't count ) is because flying is a serious business and cannot be taken very casually. Casual flyers (only fly once in a while) are very dangerous to themselves and others who fly with them.. Then there are those who are way over confident, that they become too complacent. When things go wrong while flying, they can go very wrong, very fast, and if you are not up to the task of solving the problem in a very short time, you are in dead trouble. That's why I stick to sailing, since things happen much slower, unless a tanker is about to run you over, just because you did not do a 360° look-out every 15-20 minutes while on the ocean or in the San Francisco Bay, but lets not go there right now.

BTW, you are more than welcome to come flying with me.

Thanks for the invite. I'll bring a bottle along.! Oops, sorry, I was thinking sailing again.!

[Paphitis]

When you say MPH, do you mean Nautical Miles Per Hour?

I KNOT = 1.852 km/hr
1000 KNOTS = 1852 km/hr (in one hour you will travel 1000 nautical miles).

As below!

1 nautical miles = 1.15077945 miles

1 knots = 1.15077945 mph

1 mph = 0.868976242 knots

1 miles = 0.868976242 nautical miles

Kiks, aviation is all about flying the numbers. It is a numbers game, and what we do is just ensure the aircraft is flying within its profile and that all the numbers in the box are correct. Whether you fly a light single engine aircraft, or a light twin engine aircraft or an advance Airbus A330, we still just fly the numbers or the Auto pilot flies them for us and we just go through our procedures and checks.

You got that right. This is one of the reasons why I stop flying (no, not because I can't count ) is because flying is a serious business and cannot be taken very casually. Casual flyers (only fly once in a while) are very dangerous to themselves and others who fly with them.. Then there are those who are way over confident, that they become too complacent. When things go wrong while flying, they can go very wrong, very fast, and if you are not up to the task of solving the problem in a very short time, you are in dead trouble. That's why I stick to sailing, since things happen much slower, unless a tanker is about to run you over, just because you did not do a 360° look-out every 15-20 minutes while on the ocean or in the San Francisco Bay, but lets not go there right now.

BTW, you are more than welcome to come flying with me.

Thanks for the invite. I'll bring a bottle along.! Oops, sorry, I was thinking sailing again.!

I will have to buy you dinner as well as I don't think I can manage to get you in the right seat. The jump seat is a definite possibility though..

Oh and one more thing. I don't fly passengers and so there is no in flight trolley Dolley service and you must wear a life jacket throughout because if things go wrong we will be going for a swim within seconds...

[Kikapu]

To get back to AF flt 447, 4 hours into the flight to what was to be an 8 hour flight I believe, and having an extra flight crew on board to relive the Captain and the First Officer for limited breaks, for a short nap perhaps on these long overnight flights, it would be just about the right time when either the Captain or the F/O was replaced. If the Captain was relieved for an hour to get a short nap, I'm just wondering if the other 2 pilots did everything correctly. Did they have enough or any experience with this kind of bad weather flying before. We will never know who were the two pilots sitting in the front and who was taking a short nap until the CVR is recovered.!

I don't fly passengers and so there is no in flight trolley Dolley service

Oh well, will have to "brown bag" lunch in that case.!

[cyprusgrump]

There is a good graph of "Coffins Corner"- Stall Buffet/High Speed Buffet in the below link:

http://www.iasa-intl.com/folders/belfast/AF447.htm

At high altitude, the Stall Speed (Vs) increases and the high Speed buffet Stall (Mmo) decreases.

Now bear in mind that AF447 would also be manoeuvring to avoid Cumulonimbus Formations.

And let's say the Pitot Tubes iced over. Then we can suggest that the Total Air Temperature (TAT) Probe also iced over along with the Static Air Probe.

Therefore, we are now faced with the following:
1) Inaccurate Indicated Air Speed (IAS),
2) Inaccurate Outside Air Temperature (OAT), and
3)Inaccurate Pressure Altitude (QFE)

Now, in order for the to work out True Air Speed TAS, the in flight computer requires an IAS, OAT, and QFE. The computer is then able to calculate a Mach Number and a True Air Speed (TAS).

AF447 was flying at FL350. Therefore, it will be operating close to Vs and the High Speed Buffet (Mmo). It is flying in what we pilots call "Coffins Corner".

Now throw in the freak weather conditions such as Cumulonimbus (CB) formations, with wind shear, icing, and severe turbulence.

Due to severe turbulence, the pilots would be required to reduce to Turbulence Penetration Speed in order to reduce stress on the airframe, which could increase the chance of Structural Failure.

However, if their IAS, and Mach Number is indicating low, they might have increased power to avoid Vs. They may have exceeded Turbulence Penetration causing a High Speed Buffet Stall. The airframe was exposed to increased stress, possibly leading to Structural Failure (VS stabiliser falling off, and maybe the HS stabiliser also falling off).

When encountering severe weather, all pilots will broadcast to Area Control and if things are bad, you would broadcast a Distress Message. When things are critical, all pilots will give a Mayday Call, on all frequencies if possible. No such calls were given. As you say, this could mean that there was a terrorist event on board or the aircraft was struck by lightning. Since the aircraft was flying around CB formations, the probability for lightning strike was high. Therefore, the latter is more likely IMO.

This is another very interesting link to read:

http://trueslant.com/milesobrien/2009/0 ... scale-maw/

The above link gives a good appreciation of the severity of the thunderstorms that AF447 flew through. There is an interesting Flight Profile Diagram, as well as Infrared image of the storm.

I am not saying that my above analysis is the cause of the AF447 crash. It could be something entirely different. The Cockpit Voice and Data recorders need to be salvaged in order to get a clearer picture.

Surely you mean QNH, not QFE?

[Paphitis]

There is a good graph of "Coffins Corner"- Stall Buffet/High Speed Buffet in the below link:

http://www.iasa-intl.com/folders/belfast/AF447.htm

At high altitude, the Stall Speed (Vs) increases and the high Speed buffet Stall (Mmo) decreases.

Now bear in mind that AF447 would also be manoeuvring to avoid Cumulonimbus Formations.

And let's say the Pitot Tubes iced over. Then we can suggest that the Total Air Temperature (TAT) Probe also iced over along with the Static Air Probe.

Therefore, we are now faced with the following:
1) Inaccurate Indicated Air Speed (IAS),
2) Inaccurate Outside Air Temperature (OAT), and
3)Inaccurate Pressure Altitude (QFE)

Now, in order for the to work out True Air Speed TAS, the in flight computer requires an IAS, OAT, and QFE. The computer is then able to calculate a Mach Number and a True Air Speed (TAS).

AF447 was flying at FL350. Therefore, it will be operating close to Vs and the High Speed Buffet (Mmo). It is flying in what we pilots call "Coffins Corner".

Now throw in the freak weather conditions such as Cumulonimbus (CB) formations, with wind shear, icing, and severe turbulence.

Due to severe turbulence, the pilots would be required to reduce to Turbulence Penetration Speed in order to reduce stress on the airframe, which could increase the chance of Structural Failure.

However, if their IAS, and Mach Number is indicating low, they might have increased power to avoid Vs. They may have exceeded Turbulence Penetration causing a High Speed Buffet Stall. The airframe was exposed to increased stress, possibly leading to Structural Failure (VS stabiliser falling off, and maybe the HS stabiliser also falling off).

When encountering severe weather, all pilots will broadcast to Area Control and if things are bad, you would broadcast a Distress Message. When things are critical, all pilots will give a Mayday Call, on all frequencies if possible. No such calls were given. As you say, this could mean that there was a terrorist event on board or the aircraft was struck by lightning. Since the aircraft was flying around CB formations, the probability for lightning strike was high. Therefore, the latter is more likely IMO.

This is another very interesting link to read:

http://trueslant.com/milesobrien/2009/0 ... scale-maw/

The above link gives a good appreciation of the severity of the thunderstorms that AF447 flew through. There is an interesting Flight Profile Diagram, as well as Infrared image of the storm.

I am not saying that my above analysis is the cause of the AF447 crash. It could be something entirely different. The Cockpit Voice and Data recorders need to be salvaged in order to get a clearer picture.

Surely you mean QNH, not QFE?

No QFE.

QFE is Pressure altitude above 1013 Hpa. This is what aircraft fly above 10,000FT. It is not altitude above Mean Sea Level.

QNH is Altitude above Mean Sea Level, as the altimeters are set to the actual QHH or surface pressure.

http://en.wikipedia.org/wiki/Atmospheric_pressure