Read Understanding Air France 447 for Free Online Page B
Authors: Bill Palmer
Tags: Air France 447 Accident, A330
PF about the ITCZ. He did not respond to his worry by making a firm, clear decision, by applying a strategy, or giving instructions or a recommendation for action to continue the flight. He favored waiting and responding to any turbulence noticed. He vaguely rejected the PF’s suggestion to climb, by mentioning that if “we don’t get out of it at three six (36,000 ft), it might be bad”.
An enhanced satellite image, courtesy of Tim Vasquez’s site, shows the track of AF447 in relation to the storm. The image was captured about 5 minutes after the airplane entered the storm. The flight path is noted as a yellow line. The small deviation from their course did little to avoid the worst part of the storm.
An animation is also available from the BEA which shows the deviation of other aircraft through that area, including AF459 which was on the same assigned track as AF447, but about 37 minutes in trail. 9
The graphic below is an annotated snapshot from the animation. The deviation paths of other aircraft can be seen in blue, purple, and orange. AF447’s track is in yellow.
In the minutes prior to the accident, the crew discussed the appearance of St. Elmo’s fire. St. Elmo’s fire appears as a glowing static discharge, often accompanied by small lightning like discharges on the radome and windscreen. On the A330, St Elmo’s fire is often seen as a hazy glowing ball on the ice probe that protrudes forward between the windshields. The ice probe is where pilots check for airframe ice accumulation because it is very difficult to see any other part of the airframe. A YouTube.com search for “St. Elmo’s fire cockpit A330” will yield numerous examples of this for you to see. In my experience whenever I have seen St. Elmo’s fire, turning on the exterior lights has revealed snow conditions, which can lead to the static charge build-up causing the phenomenon. At 01:37 the captain remarked, “it’s snowing.”
The following illustration, from weathergraphics.com, is the result of analysis of satellite and other data on the storm’s profile and the flight’s progress through it. Light shading is precipitation near the surface, medium shading is cloud material, and dark shading is suspected updraft areas. The green line (not part of the original image) is an approximate vertical path through the storm.
Air France 447 encountered conditions that clogged its heated pitot tubes with frozen material. The question is-“How could heated pitot tubes ice over?”
One early theory, and the subject of a NOVA television production, The Crash of Flight 447, was one of supercooled water - water cooled to below its normal freezing temperature, yet remaining as water. When disturbed, the water freezes almost instantly.
Supercooled water is not difficult to produce in your own freezer at home. Take a bottle of purified water and put it in the freezer. Hours later you may find the water still in liquid form, but if you agitate it, the ice crystals will grow and it will freeze solid within seconds. This can happen in the air too. If an airplane encounters supercooled water, significant ice accumulation will rapidly occur.
Many experts discounted the likelihood of supercooled water in this type of storm. Supercooled water in the atmosphere would not only have iced over the probes, but the entire airplane, and that did not happen. We know this because the A330 is equipped with two very sensitive ice detectors, and the flight data recorder revealed that at no time during the flight did they detect any ice accumulation.
One commenter on the Weather Graphics website’s AF447 article provided this interesting observation: “ I'm an aircraft icing specialist and wanted to point out a factor that hasn't been discussed much...high ice crystal concentrations. I've seen flight test data from power rollbacks due to flight in high ice crystal environments … In our case, the crystals collected within heated, aspirated Ram Air
An enhanced satellite image, courtesy of Tim Vasquez’s site, shows the track of AF447 in relation to the storm. The image was captured about 5 minutes after the airplane entered the storm. The flight path is noted as a yellow line. The small deviation from their course did little to avoid the worst part of the storm.
An animation is also available from the BEA which shows the deviation of other aircraft through that area, including AF459 which was on the same assigned track as AF447, but about 37 minutes in trail. 9
The graphic below is an annotated snapshot from the animation. The deviation paths of other aircraft can be seen in blue, purple, and orange. AF447’s track is in yellow.
In the minutes prior to the accident, the crew discussed the appearance of St. Elmo’s fire. St. Elmo’s fire appears as a glowing static discharge, often accompanied by small lightning like discharges on the radome and windscreen. On the A330, St Elmo’s fire is often seen as a hazy glowing ball on the ice probe that protrudes forward between the windshields. The ice probe is where pilots check for airframe ice accumulation because it is very difficult to see any other part of the airframe. A YouTube.com search for “St. Elmo’s fire cockpit A330” will yield numerous examples of this for you to see. In my experience whenever I have seen St. Elmo’s fire, turning on the exterior lights has revealed snow conditions, which can lead to the static charge build-up causing the phenomenon. At 01:37 the captain remarked, “it’s snowing.”
The following illustration, from weathergraphics.com, is the result of analysis of satellite and other data on the storm’s profile and the flight’s progress through it. Light shading is precipitation near the surface, medium shading is cloud material, and dark shading is suspected updraft areas. The green line (not part of the original image) is an approximate vertical path through the storm.
Air France 447 encountered conditions that clogged its heated pitot tubes with frozen material. The question is-“How could heated pitot tubes ice over?”
One early theory, and the subject of a NOVA television production, The Crash of Flight 447, was one of supercooled water - water cooled to below its normal freezing temperature, yet remaining as water. When disturbed, the water freezes almost instantly.
Supercooled water is not difficult to produce in your own freezer at home. Take a bottle of purified water and put it in the freezer. Hours later you may find the water still in liquid form, but if you agitate it, the ice crystals will grow and it will freeze solid within seconds. This can happen in the air too. If an airplane encounters supercooled water, significant ice accumulation will rapidly occur.
Many experts discounted the likelihood of supercooled water in this type of storm. Supercooled water in the atmosphere would not only have iced over the probes, but the entire airplane, and that did not happen. We know this because the A330 is equipped with two very sensitive ice detectors, and the flight data recorder revealed that at no time during the flight did they detect any ice accumulation.
One commenter on the Weather Graphics website’s AF447 article provided this interesting observation: “ I'm an aircraft icing specialist and wanted to point out a factor that hasn't been discussed much...high ice crystal concentrations. I've seen flight test data from power rollbacks due to flight in high ice crystal environments … In our case, the crystals collected within heated, aspirated Ram Air