1. For many commercial aircraft, there is an emergency procedure for when pitot static based flight instruments become inoperable.
Pitot static based flight instruments include airspeed indications, altimeters and rate of climb instruments.
2. The scenarios encountered that might render these systems inoperative include a blocked pitot tube or a blocked static port.
A. In the past safety investigations found the following factors involved in pitot tube blockage:
1. loss of pitot tube heater allowing ice to build up or precipitation to clog the tube and/ or the associated plumbing.
2. a protective maintenance cover left on the pitot tube
3. insect, bird or other debris or object entering the pitot tube.
B. In the past, safety investigators have found the following factor most commonly involved in static port blockage:
1. Masking tape place over the static port by crews washing, waxing or painting the plane, where the tape was not removed prior to flight.
3. Since from what has been reported in the media that the flight was proceeding normally, it can be deduced that the problem with the pitot and static system was most likely due to the pitot tube icing over due to lack of heat.
A. Since most pitot heat systems are electrically powered, it is possible that there was some interruption in that electrical system.
B. When the loss of pitot static powered instrumentation occurs, the flight crew is directed by emergency procedures to use instruments which indicate flight attitude, that is pitch, roll and yaw.
C. The attitude instrument most often found in jet powered tranport aircraft is the attitude indicator. It will simultaneously indicate pitch, roll and yaw.
D. Attitude instruments are most often powered on commercial jet transport aircraft electrically and therefore will provide valid data in the event the pitot static system is inoperative. Their source is either laser ringed gyros, mechanical gyros or other similar systems.
E. Laws of aerodynamic performance state that pitch-attitude controls airspeed and engine power controls altitude. So as long as the flight crew maintains the cruise pitch attitude and the cruise power settings on the engine, the aircraft should stay relatively level in flight and the airspeed should remain at the speed required for cruise flight. The crew is often directed to seek an area of clear sky outside of icing conditions or precipitation in an attempt to regain use of the pitot-static system in the event icing caused the problem.
4. This is an emergency procedure which is successful and will allow the flight crew to maintain control of the aircraft through all flight regimes. I can speak from experience that this procedure works just fine. I can also state that this procedure is practiced in training simulators at many US airlines and I would suspect at many European airlines as well.
5. If the investigators state that the aircraft stalled, there are many scenarios by which this could have taken place. One common scenario is that the pitot tube ices up decreasing the dynamic pressure input to the airspeed indicator and rate of climb indicator. The static pressure port may not be blocked so it continues to show static pressure. If the crew does not cross check the pitch-attitude indicator, and only looks at pitot-static instruments, they may see an increasing airspeed and react by increasing pitch and reducing power. This could lead to as stall within a short time at altitude with an aircraft heavily laden with fuel, passengers and cargo.
6. To prevent this type of mishap, many airlines employ training in emergency procedures for the loss of pitot static instruments. The procedure includes disconnecting the auto pilot from control of the aircraft and hand flying the aircraft, again using pitch attitude and engine power settings from a chart. The charts carried on the aircraft include variables such as flight altitude and aircraft weight.
7. If the loss of pitot static system occurred while in a severe thunderstorm, the crew would have had to deal with both the severe turbulence, icing, possible lightning as well as the disconnecting of the autopilot. That would have been a handful for any crew to handle, but that is why most major airlines have strong training programs.
Monday, May 23, 2011
AF447
1. Air France Flight Control Dispatcher in Paris should have been monitoring AF 447. Flight Control should have been monitoring all hazards impacting the flight such as severe convective weather and rerouted AF 447 around the hazard.
A. Scheduled passenger airlines that operate under both US and European regulations control all flight operations from a central office known as "Flight Control" or "Dispatch." Despite the name "dispatch," (meaning to send out or send off) the office uses the radio and data call sign of "Flight Control." By US and European aviation regulations Flight Control must be in continuous communications and control of all dispatched flights. By US and European aviation regulations Flight Control is legally in control of the flight from before engine start and taxi out until the flight parks in its final parking spot at the completion of the flight. This is known as "block to block."
B. Flight Control plans the flight route prior to flight and files this flight plan with international aeronautical agencies that control the airspace through which the flight is planned to proceed. The agency determines the actual flight route and provides this authorization to Flight Control and the flight crew just prior to the flight departing its origin. During the flight, when entering oceanic airspace, this agency is coordinated through agreements between international civil aviation organization member states (ICAO) and is handled through radio calls in a non-radar environment.
C. Flight crew members, especially the captain, must be authorized to move the flight by Flight Control and must remain in constant communications with Flight Control during the flight, by regulation. This regulation is in place so that Flight Control is able to pass along information materially and directly affecting the flight, such as weather enroute and at destination and remain in control of the flight for all sorts of reasons affecting international authorizations for airspace entrance and transit.
2. No modern jet passenger transport aircraft in service then or today are certified to penetrate and fly into severe thunderstorms with tops above 50,000 feet, such as those in the tropical convergence zone near the equator.
A. Modern jet passenger transport aircraft are capable of flying high enough to be above much if not all of severe convective weather in the US, in Europe and over much of the non-tropical oceanic routes between Europe, the US and Asia. As a result, most of the time pilots can handle enroute weather with the information available on on-board weather radar and by looking out visually during day light and at night if in the clear. But at night, especially if the flight is operating in the clouds or at lower altitudes and in the vicinity of heavy, severe convective weather, weather radar might not be powerful enough to display the full extent of severe convective weather ahead on the flight path.
B. In the areas near the equator, severe convective weather very often occurs with heights much greater than modern jet passenger transport aircraft are capable of flying. This is a known meteorological phenomenon and these storms occurs routinely day and night. (Repeat these two statements in your mind.) They are observable by satellite with both optical, infrared and other technologies. In many cases they are exceed the ability of onboard radar to determine their size, severity, and height. On board radar in these cases is only useful for defining the edges of the storms for circumnavigation if the aircraft is outside of precipitation.
C. Oceanic navigation areas where modern jet passenger transport aircraft operate and are authorized to operate routes, such as from Brazil to Europe and to North America lie outside ground based weather radar coverage and therefore are not observable by ground based radar.
D. Weather information in these areas are obtained by weather imaging from a wide range of both photographic, infra red and other technology satellites. This information is made available from government agencies to airline Flight Control offices and other subscribers through commercial services by way of the internet. This internet facilitated information is not now accessible in the cockpit (although current technology would allow it and it is accessible in some cases onboard passenger aircraft in the cabin where on board internet is provided). Therefore the only way that flight crew can be advised of this critically important weather data is by Flight Control advising them by radio and data communications from the Dispatch or Flight Control Office.
E. It does not appear that the lack of action on the part of the Air France Flight Control Office in Paris is being investigated as a relevant factor in the loss of AF 447. Rather the attention of investigators and journalists is being redirected towards equipment manufacturers such as Air Bus and the flight crew.
3. Sophisticated weather data is accessible at Flight Control. Managing this information is the direct legal responsibility of Flight Control. US and European aviation regulations thereby give Flight Control the direct responsibility and authority to keep dispatched flights informed of weather hazards along the route of flight and at destination. (Repeat that to your self.)
A. Flight Control is fully equipped with all internet facilitated current satellite based meteorological information. Flight Control has the current and up to the minute information about severe weather phenomenon and the ability and the responsibility to communicate that information to the flight crew.
B. Flight crew graphic information, such as satellite images of photographic or infrared data are provided only at the time of preflight briefing, which can be as much as 1 ½ hours prior to departure. Very often the briefing itself is prepared an hour before the flight crew arrives to receive their briefing, because Flight Control may be dispatching multiple flights at or about the same time. A flight crew that is three hours into a flight for example, could possibly have therefore weather data that is five and a half hours old, in other words, not current.
4. Since severe weather, such as tropical convergence zone thunderstorms can routinely develop at a build-up rate of 4000-6000 feet per minute, new severe convective weather with heights of 60,000 feet, and higher, can develop in a very short period of time. Areas and lines of these thunderstorms can and do develop in the space of less than two hours and can build to heights well above the flight capability of modern jet passenger transport aircraft and pose severe hazards to flight such as hail, severe turbulence, lightning, icing and heavy precipitation.
5. No modern jet passenger transport aircraft are or have been certified to operate in severe thunderstorms, although many have been strengthened, equipped with electrical bond wiring and some level of engine, wing and windscreen deicing in the event that they encounter these severe convective weather conditions of a thunderstorm inadvertently.
6. Actual US and European aviation regulations require flights to be dispatched and while airborne to remain miles away from severe convective weather activity.
A. Yet in this case, the Air France Flight Control did not reroute AF447 around a known area of severe convective weather, that had heights above the possible service ceiling of the Airbus 330.
Why not? Why has the investigation not asked this question?
A. Scheduled passenger airlines that operate under both US and European regulations control all flight operations from a central office known as "Flight Control" or "Dispatch." Despite the name "dispatch," (meaning to send out or send off) the office uses the radio and data call sign of "Flight Control." By US and European aviation regulations Flight Control must be in continuous communications and control of all dispatched flights. By US and European aviation regulations Flight Control is legally in control of the flight from before engine start and taxi out until the flight parks in its final parking spot at the completion of the flight. This is known as "block to block."
B. Flight Control plans the flight route prior to flight and files this flight plan with international aeronautical agencies that control the airspace through which the flight is planned to proceed. The agency determines the actual flight route and provides this authorization to Flight Control and the flight crew just prior to the flight departing its origin. During the flight, when entering oceanic airspace, this agency is coordinated through agreements between international civil aviation organization member states (ICAO) and is handled through radio calls in a non-radar environment.
C. Flight crew members, especially the captain, must be authorized to move the flight by Flight Control and must remain in constant communications with Flight Control during the flight, by regulation. This regulation is in place so that Flight Control is able to pass along information materially and directly affecting the flight, such as weather enroute and at destination and remain in control of the flight for all sorts of reasons affecting international authorizations for airspace entrance and transit.
2. No modern jet passenger transport aircraft in service then or today are certified to penetrate and fly into severe thunderstorms with tops above 50,000 feet, such as those in the tropical convergence zone near the equator.
A. Modern jet passenger transport aircraft are capable of flying high enough to be above much if not all of severe convective weather in the US, in Europe and over much of the non-tropical oceanic routes between Europe, the US and Asia. As a result, most of the time pilots can handle enroute weather with the information available on on-board weather radar and by looking out visually during day light and at night if in the clear. But at night, especially if the flight is operating in the clouds or at lower altitudes and in the vicinity of heavy, severe convective weather, weather radar might not be powerful enough to display the full extent of severe convective weather ahead on the flight path.
B. In the areas near the equator, severe convective weather very often occurs with heights much greater than modern jet passenger transport aircraft are capable of flying. This is a known meteorological phenomenon and these storms occurs routinely day and night. (Repeat these two statements in your mind.) They are observable by satellite with both optical, infrared and other technologies. In many cases they are exceed the ability of onboard radar to determine their size, severity, and height. On board radar in these cases is only useful for defining the edges of the storms for circumnavigation if the aircraft is outside of precipitation.
C. Oceanic navigation areas where modern jet passenger transport aircraft operate and are authorized to operate routes, such as from Brazil to Europe and to North America lie outside ground based weather radar coverage and therefore are not observable by ground based radar.
D. Weather information in these areas are obtained by weather imaging from a wide range of both photographic, infra red and other technology satellites. This information is made available from government agencies to airline Flight Control offices and other subscribers through commercial services by way of the internet. This internet facilitated information is not now accessible in the cockpit (although current technology would allow it and it is accessible in some cases onboard passenger aircraft in the cabin where on board internet is provided). Therefore the only way that flight crew can be advised of this critically important weather data is by Flight Control advising them by radio and data communications from the Dispatch or Flight Control Office.
E. It does not appear that the lack of action on the part of the Air France Flight Control Office in Paris is being investigated as a relevant factor in the loss of AF 447. Rather the attention of investigators and journalists is being redirected towards equipment manufacturers such as Air Bus and the flight crew.
3. Sophisticated weather data is accessible at Flight Control. Managing this information is the direct legal responsibility of Flight Control. US and European aviation regulations thereby give Flight Control the direct responsibility and authority to keep dispatched flights informed of weather hazards along the route of flight and at destination. (Repeat that to your self.)
A. Flight Control is fully equipped with all internet facilitated current satellite based meteorological information. Flight Control has the current and up to the minute information about severe weather phenomenon and the ability and the responsibility to communicate that information to the flight crew.
B. Flight crew graphic information, such as satellite images of photographic or infrared data are provided only at the time of preflight briefing, which can be as much as 1 ½ hours prior to departure. Very often the briefing itself is prepared an hour before the flight crew arrives to receive their briefing, because Flight Control may be dispatching multiple flights at or about the same time. A flight crew that is three hours into a flight for example, could possibly have therefore weather data that is five and a half hours old, in other words, not current.
4. Since severe weather, such as tropical convergence zone thunderstorms can routinely develop at a build-up rate of 4000-6000 feet per minute, new severe convective weather with heights of 60,000 feet, and higher, can develop in a very short period of time. Areas and lines of these thunderstorms can and do develop in the space of less than two hours and can build to heights well above the flight capability of modern jet passenger transport aircraft and pose severe hazards to flight such as hail, severe turbulence, lightning, icing and heavy precipitation.
5. No modern jet passenger transport aircraft are or have been certified to operate in severe thunderstorms, although many have been strengthened, equipped with electrical bond wiring and some level of engine, wing and windscreen deicing in the event that they encounter these severe convective weather conditions of a thunderstorm inadvertently.
6. Actual US and European aviation regulations require flights to be dispatched and while airborne to remain miles away from severe convective weather activity.
A. Yet in this case, the Air France Flight Control did not reroute AF447 around a known area of severe convective weather, that had heights above the possible service ceiling of the Airbus 330.
Why not? Why has the investigation not asked this question?
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