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mat
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Sounds like a tragic accident.
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Sounds like a tragic accident.
bumbleblue
Well-Known Member
Shit ..awful.
oakiecokie
Well-Known Member
A passenger jet has crashed in the southern Russian city of Rostov-on-Don with at least 55 passengers and six crew on board, officials say.
The FlyDubai Boeing 738, coming from Dubai, overshot the runway as it attempted to land and burst into flames, according to reports.
It is not clear what caused the crash but poor visibility and high winds are being considered as a factor.
Unconfirmed reports say everyone on board was killed.
Other flights have been diverted away from the airport.
About 100 rescue workers are at the site of the crash and the fire has been extinguished, media reports say.
The FlyDubai Boeing 738, coming from Dubai, overshot the runway as it attempted to land and burst into flames, according to reports.
It is not clear what caused the crash but poor visibility and high winds are being considered as a factor.
Unconfirmed reports say everyone on board was killed.
Other flights have been diverted away from the airport.
About 100 rescue workers are at the site of the crash and the fire has been extinguished, media reports say.
foetus
Well-Known Member
Faaaark. These things always happen right before I have an international flight. Doesn't help with the nerves. Poor people..
Really sad to hear. I fly more than the average American and whenever this sort of thing happens I can only imagine what I would do/feel. I've been in rough take offs/landings; I only hope they had no idea what was happening. Really horrendous way to die if you're aware of it.
ChicagoBlue
Well-Known Member
- Joined
- 10 Jan 2009
- Messages
- 16,514
As someone who flies that aircraft, the winds at the time of the accident (~60mph) were beyond the speeds deemed acceptable for landing, which may be why they attempted to land realized they could not (crosswinds of this magnitude are beyond the maximum demonstrated ability of the aircraft, but if they were closer to being more aligned with the runway, the crew may have felt it was possible.
Clearly, they executed a successful missed approach/aborted landing and went into a holding pattern waiting for the winds and weather to improve. This is the usual procedure, IF you have enough fuel to do it and the current weather is suitable for that decision. Here is where conjecture starts to become a much bigger factor and the CVR and DDR (voice and data "black boxes") will become extremely useful, if not vital.
One thought I had was that they held for so long that they were running out of fuel and needed to get the aircraft on the ground. Two hours is the international norm for extra fuel if there are no suitable landing sites near the airport, (for instance, flying to an island) so they may have had few options but to land.
A second thought is that they may have been holding so long in the weather that there was an ice build up on the aircraft, which made the landing virtually impossible, if not impossible. Let me explain. This aircraft does, of course, have icing protection, but this is limited to the leading edge of the wings, the engines, windshields and the numerous probes that stick out into the airflow to provide data to the Air Data Computers that determine speed, etc... One surface that is not anti-iced, and cannot be de-iced in the air by the hot air tapped off the engines, is the tail. Boeing allows for penalties for landing for this by utilizing higher airspeeds or restricting the aircraft weight for landing. However, in extreme conditions, the ambient weather conditions, especially during their two hours of low altitude holding, may have been such that the level of ice accretion was too severe for them to handle at low approach speeds coming into try to land, and they lost control of the aircraft.
In effect, as the aircraft flies, the forces on it are similar to a teeter totter (see saw), such that the "weight" of the nose and tail of the aircraft have to balance on the see-saws fulcrum, which is the lift provided by the wings. The tail is, in effect, a wing that flies down when you need it to, or up when you need it to, and this is accomplished by moving the yoke in the aircraft. However, if the downward force on the tail from the weight of ice build up increases too much, the see-saw gets too heavy on one side. This can be fixed, upto a point, by moving the yoke to compensate. This is all usually done automatically by the autopilot in autoflight, so the pilots actually have no "feel" for moving the yoke at all. This also makes the aircraft slow down, which means the engines spool up to compensate, increase speed, and burn more fuel. So, the scenario becomes this cascading series of factors that pilots are trained to recognize and extricate themselves from, either by flying faster to compensate (especially on landing where you are reconfiguring the aircraft to slow down, and land on the useable runway) or going somewhere where these icing conditions do not exist, which may not have been an option (see my comments above about two hours extra fuel and an island).
So, as they attempted a second approach, after holding for two hours, it appears (AT LEAST TO ME GIVEN WHAT I'VE SEEN IN THE VIDEO AND KNOW ABOUT THE AIRCRAFT) that they made the decision to land in such sub-optimal conditions because they were running out of fuel. This would make the aircraft relatively light, especially given how few passengers were onboard. A light aircraft would make for a slower approach speed NORMALLY. However, if the above is correct, and they had some severe ice accretion on the tail, they would have needed a faster approach speed to compensate. Such a slow approach speed, given the extra weight (I believe the penalty is some thing like 10-15,000lbs added to landing weight to increase approach speed), may have been too slow for the aircraft.
However...and it is a big one...approach speeds are increased for winds. So, they should have increased their approach speeds for the approach accordingly. Given the very high wind speeds, this could have made the speeds very fast. Much faster than usual, and possibly even faster the flap speeds designed into the aircraft. This may have led to the pilot flying that high speed ON APPROACH TO LANDING, but as he came in FOR THE LANDING to reduce this speed so he could land at a more normal speed, with a more normal landing distance, on what may have been a relatively short runway (I don't know how long the runway was, but anything less than about 8,000 feet is starting to get quite short for the aircraft and prevailing conditions).
So, coupled with the heavy tail from ice accretion, the higher approach speeds "masking" the effects of the added weight, and the autopilot being on, it MAY have seemed relatively normal....until they started changing it all!
To land, the wind speeds are too high for the autopilot to handle (Max headwind is 25kts, max crosswind is 15kts, max tailwind is 10kts), so it would have to be hand flown. When the pilot clicks off the autopilot, he suddenly starts to feel the aircraft loading...as in he starts to feel the weight and forces on the aircraft. These are all trimmed up by the autopilot for the most efficient flying conditions based on the aircraft at the time. However, they were probably much faster on the approach than the pilots wanted to be for landing, so the pilot would want to start slowing down. He does this by reducing the power on the engines, which reduces the thrust, thus reducing the speed in a steady state aircraft. This then changes all the forces on the aircraft, which the pilot had to compensate for, as the autopilot is no longer turned on.
I believe that somewhere in here, the weight of ice accretion on the tail, coupled with the decreasing speed, and increasing control forces on the yoke, may have caused the pilot to lose control of the aircraft, possibly in an ice-induced stall.
The video shows an aircraft that has fuel, because it explodes. However, they may not have had enough fuel to hold for any longer and needed to try to land. This would lead a smart pilot (I'm not sure holding in this weather for two hours is smart, but I don't know his options) to make sure he has enough fuel for a few landing attempts, so he may have still had about 6,000lbs (just under 1,000 gallons of jet fuel) or so, which is enough for a couple of landings. That extra fuel makes it look like there was a lot of fuel, because it caused a big fireball in the crash, but it is not a lot of fuel for landing the aircraft, it is a comfortable amount to be able to do a few attempts....but gravity says sooner or later the aircraft has to hit the ground!!!
So, as they flew the approach in bad weather, after holding for two hours, they may have had a significant amount of ice on the tail, possibly 1,000s of pounds of it. The aircraft compensates by flying faster on approach, winds also increase this speed, but too much speed means you can't put all the landing flaps down. So, as you come in to land, you break out of the clouds, see lights on the ground and a runway ahead, you click off the autopilot, suddenly you are now no,ding the control forces in your hands. You have to slow down, so these control forces start changing and thrust changes take place to try to maintain the speed you want. But, to slow down, you have to raise the nose, lower the flaps, pull back the power, etc...It is the proverbial ballet of a good drummer, where each hand and foot is doing something different while you cajole 150,000lbs of aluminium, jet fuel, and people to the ground, all while doing 150mph as you attempt to put it all on a strip of concrete in weather that is trying hard to stop you. If you are not at your sharpest, it is very, very easy to let ONE SINGLE THING get ahead of you, when it is YOU that needs to be well ahead of it, and trying to catch back up to it can be fatal if not done in a timely manner. Given enough time, every pilot recognizes an airplane is stalled, even in the weather when you have no visual cues. However, a pilot who has watched his aircraft go around in circles for two hours, who is worried about the weather, but might not have thought of every eventuality (such as the ice accretion on the tail, for instance, or the amount of speed (energy) he wants to lose for touchdown), and might be operating at lest than peak efficiency, might not have been as ahead of the aircraft as he thought. Indeed, this could have been a very long duty day (we can be on duty upto about 16-17 hrs, believe it or not!) and the crew was faced with this after an already long, tiring day...fatigue has the exact same effect on flying/driving as alcohol...but I don't know the length of their duty day before this flight.
The video makes me believe the aircraft either stalled close to the ground or the pilots, in their zeal to try to "make the runway" made a severe miscalculation of their energy state and "pushed" the aircraft down to try to land. From the video, and from the discussion above, I believe it supports the former outcome...a coming together of numerous hazardous conditions that ended up being beyond the capabilities of the aircraft and pilots in this, very specific, instance.
I'm sorry if my hypothesizing angers some people, because I also understand we need to wait for the official findings in about a year or so. However, after 25 years of flying, seeing crashes like this before, and my knowledge of the aircraft (I'm a Captain on it), I thought I might be able to provide some insights TO THIS FORUM ONLY as to what was going on in that little room in the sky and just outside it, as Mother Nature was trying to corner them and not let them out of her grasp.
Clearly, they executed a successful missed approach/aborted landing and went into a holding pattern waiting for the winds and weather to improve. This is the usual procedure, IF you have enough fuel to do it and the current weather is suitable for that decision. Here is where conjecture starts to become a much bigger factor and the CVR and DDR (voice and data "black boxes") will become extremely useful, if not vital.
One thought I had was that they held for so long that they were running out of fuel and needed to get the aircraft on the ground. Two hours is the international norm for extra fuel if there are no suitable landing sites near the airport, (for instance, flying to an island) so they may have had few options but to land.
A second thought is that they may have been holding so long in the weather that there was an ice build up on the aircraft, which made the landing virtually impossible, if not impossible. Let me explain. This aircraft does, of course, have icing protection, but this is limited to the leading edge of the wings, the engines, windshields and the numerous probes that stick out into the airflow to provide data to the Air Data Computers that determine speed, etc... One surface that is not anti-iced, and cannot be de-iced in the air by the hot air tapped off the engines, is the tail. Boeing allows for penalties for landing for this by utilizing higher airspeeds or restricting the aircraft weight for landing. However, in extreme conditions, the ambient weather conditions, especially during their two hours of low altitude holding, may have been such that the level of ice accretion was too severe for them to handle at low approach speeds coming into try to land, and they lost control of the aircraft.
In effect, as the aircraft flies, the forces on it are similar to a teeter totter (see saw), such that the "weight" of the nose and tail of the aircraft have to balance on the see-saws fulcrum, which is the lift provided by the wings. The tail is, in effect, a wing that flies down when you need it to, or up when you need it to, and this is accomplished by moving the yoke in the aircraft. However, if the downward force on the tail from the weight of ice build up increases too much, the see-saw gets too heavy on one side. This can be fixed, upto a point, by moving the yoke to compensate. This is all usually done automatically by the autopilot in autoflight, so the pilots actually have no "feel" for moving the yoke at all. This also makes the aircraft slow down, which means the engines spool up to compensate, increase speed, and burn more fuel. So, the scenario becomes this cascading series of factors that pilots are trained to recognize and extricate themselves from, either by flying faster to compensate (especially on landing where you are reconfiguring the aircraft to slow down, and land on the useable runway) or going somewhere where these icing conditions do not exist, which may not have been an option (see my comments above about two hours extra fuel and an island).
So, as they attempted a second approach, after holding for two hours, it appears (AT LEAST TO ME GIVEN WHAT I'VE SEEN IN THE VIDEO AND KNOW ABOUT THE AIRCRAFT) that they made the decision to land in such sub-optimal conditions because they were running out of fuel. This would make the aircraft relatively light, especially given how few passengers were onboard. A light aircraft would make for a slower approach speed NORMALLY. However, if the above is correct, and they had some severe ice accretion on the tail, they would have needed a faster approach speed to compensate. Such a slow approach speed, given the extra weight (I believe the penalty is some thing like 10-15,000lbs added to landing weight to increase approach speed), may have been too slow for the aircraft.
However...and it is a big one...approach speeds are increased for winds. So, they should have increased their approach speeds for the approach accordingly. Given the very high wind speeds, this could have made the speeds very fast. Much faster than usual, and possibly even faster the flap speeds designed into the aircraft. This may have led to the pilot flying that high speed ON APPROACH TO LANDING, but as he came in FOR THE LANDING to reduce this speed so he could land at a more normal speed, with a more normal landing distance, on what may have been a relatively short runway (I don't know how long the runway was, but anything less than about 8,000 feet is starting to get quite short for the aircraft and prevailing conditions).
So, coupled with the heavy tail from ice accretion, the higher approach speeds "masking" the effects of the added weight, and the autopilot being on, it MAY have seemed relatively normal....until they started changing it all!
To land, the wind speeds are too high for the autopilot to handle (Max headwind is 25kts, max crosswind is 15kts, max tailwind is 10kts), so it would have to be hand flown. When the pilot clicks off the autopilot, he suddenly starts to feel the aircraft loading...as in he starts to feel the weight and forces on the aircraft. These are all trimmed up by the autopilot for the most efficient flying conditions based on the aircraft at the time. However, they were probably much faster on the approach than the pilots wanted to be for landing, so the pilot would want to start slowing down. He does this by reducing the power on the engines, which reduces the thrust, thus reducing the speed in a steady state aircraft. This then changes all the forces on the aircraft, which the pilot had to compensate for, as the autopilot is no longer turned on.
I believe that somewhere in here, the weight of ice accretion on the tail, coupled with the decreasing speed, and increasing control forces on the yoke, may have caused the pilot to lose control of the aircraft, possibly in an ice-induced stall.
The video shows an aircraft that has fuel, because it explodes. However, they may not have had enough fuel to hold for any longer and needed to try to land. This would lead a smart pilot (I'm not sure holding in this weather for two hours is smart, but I don't know his options) to make sure he has enough fuel for a few landing attempts, so he may have still had about 6,000lbs (just under 1,000 gallons of jet fuel) or so, which is enough for a couple of landings. That extra fuel makes it look like there was a lot of fuel, because it caused a big fireball in the crash, but it is not a lot of fuel for landing the aircraft, it is a comfortable amount to be able to do a few attempts....but gravity says sooner or later the aircraft has to hit the ground!!!
So, as they flew the approach in bad weather, after holding for two hours, they may have had a significant amount of ice on the tail, possibly 1,000s of pounds of it. The aircraft compensates by flying faster on approach, winds also increase this speed, but too much speed means you can't put all the landing flaps down. So, as you come in to land, you break out of the clouds, see lights on the ground and a runway ahead, you click off the autopilot, suddenly you are now no,ding the control forces in your hands. You have to slow down, so these control forces start changing and thrust changes take place to try to maintain the speed you want. But, to slow down, you have to raise the nose, lower the flaps, pull back the power, etc...It is the proverbial ballet of a good drummer, where each hand and foot is doing something different while you cajole 150,000lbs of aluminium, jet fuel, and people to the ground, all while doing 150mph as you attempt to put it all on a strip of concrete in weather that is trying hard to stop you. If you are not at your sharpest, it is very, very easy to let ONE SINGLE THING get ahead of you, when it is YOU that needs to be well ahead of it, and trying to catch back up to it can be fatal if not done in a timely manner. Given enough time, every pilot recognizes an airplane is stalled, even in the weather when you have no visual cues. However, a pilot who has watched his aircraft go around in circles for two hours, who is worried about the weather, but might not have thought of every eventuality (such as the ice accretion on the tail, for instance, or the amount of speed (energy) he wants to lose for touchdown), and might be operating at lest than peak efficiency, might not have been as ahead of the aircraft as he thought. Indeed, this could have been a very long duty day (we can be on duty upto about 16-17 hrs, believe it or not!) and the crew was faced with this after an already long, tiring day...fatigue has the exact same effect on flying/driving as alcohol...but I don't know the length of their duty day before this flight.
The video makes me believe the aircraft either stalled close to the ground or the pilots, in their zeal to try to "make the runway" made a severe miscalculation of their energy state and "pushed" the aircraft down to try to land. From the video, and from the discussion above, I believe it supports the former outcome...a coming together of numerous hazardous conditions that ended up being beyond the capabilities of the aircraft and pilots in this, very specific, instance.
I'm sorry if my hypothesizing angers some people, because I also understand we need to wait for the official findings in about a year or so. However, after 25 years of flying, seeing crashes like this before, and my knowledge of the aircraft (I'm a Captain on it), I thought I might be able to provide some insights TO THIS FORUM ONLY as to what was going on in that little room in the sky and just outside it, as Mother Nature was trying to corner them and not let them out of her grasp.
aguero93:20
Well-Known Member
- Joined
- 21 Oct 2013
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- 90,262
- Location
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As someone who flies that aircraft, the winds at the time of the accident (~60mph) were beyond the speeds deemed acceptable for landing, which may be why they attempted to land realized they could not (crosswinds of this magnitude are beyond the maximum demonstrated ability of the aircraft, but if they were closer to being more aligned with the runway, the crew may have felt it was possible.
Clearly, they executed a successful missed approach/aborted landing and went into a holding pattern waiting for the winds and weather to improve. This is the usual procedure, IF you have enough fuel to do it and the current weather is suitable for that decision. Here is where conjecture starts to become a much bigger factor and the CVR and DDR (voice and data "black boxes") will become extremely useful, if not vital.
One thought I had was that they held for so long that they were running out of fuel and needed to get the aircraft on the ground. Two hours is the international norm for extra fuel if there are no suitable landing sites near the airport, (for instance, flying to an island) so they may have had few options but to land.
A second thought is that they may have been holding so long in the weather that there was an ice build up on the aircraft, which made the landing virtually impossible, if not impossible. Let me explain. This aircraft does, of course, have icing protection, but this is limited to the leading edge of the wings, the engines, windshields and the numerous probes that stick out into the airflow to provide data to the Air Data Computers that determine speed, etc... One surface that is not anti-iced, and cannot be de-iced in the air by the hot air tapped off the engines, is the tail. Boeing allows for penalties for landing for this by utilizing higher airspeeds or restricting the aircraft weight for landing. However, in extreme conditions, the ambient weather conditions, especially during their two hours of low altitude holding, may have been such that the level of ice accretion was too severe for them to handle at low approach speeds coming into try to land, and they lost control of the aircraft.
In effect, as the aircraft flies, the forces on it are similar to a teeter totter (see saw), such that the "weight" of the nose and tail of the aircraft have to balance on the see-saws fulcrum, which is the lift provided by the wings. The tail is, in effect, a wing that flies down when you need it to, or up when you need it to, and this is accomplished by moving the yoke in the aircraft. However, if the downward force on the tail from the weight of ice build up increases too much, the see-saw gets too heavy on one side. This can be fixed, upto a point, by moving the yoke to compensate. This is all usually done automatically by the autopilot in autoflight, so the pilots actually have no "feel" for moving the yoke at all. This also makes the aircraft slow down, which means the engines spool up to compensate, increase speed, and burn more fuel. So, the scenario becomes this cascading series of factors that pilots are trained to recognize and extricate themselves from, either by flying faster to compensate (especially on landing where you are reconfiguring the aircraft to slow down, and land on the useable runway) or going somewhere where these icing conditions do not exist, which may not have been an option (see my comments above about two hours extra fuel and an island).
So, as they attempted a second approach, after holding for two hours, it appears (AT LEAST TO ME GIVEN WHAT I'VE SEEN IN THE VIDEO AND KNOW ABOUT THE AIRCRAFT) that they made the decision to land in such sub-optimal conditions because they were running out of fuel. This would make the aircraft relatively light, especially given how few passengers were onboard. A light aircraft would make for a slower approach speed NORMALLY. However, if the above is correct, and they had some severe ice accretion on the tail, they would have needed a faster approach speed to compensate. Such a slow approach speed, given the extra weight (I believe the penalty is some thing like 10-15,000lbs added to landing weight to increase approach speed), may have been too slow for the aircraft.
However...and it is a big one...approach speeds are increased for winds. So, they should have increased their approach speeds for the approach accordingly. Given the very high wind speeds, this could have made the speeds very fast. Much faster than usual, and possibly even faster the flap speeds designed into the aircraft. This may have led to the pilot flying that high speed ON APPROACH TO LANDING, but as he came in FOR THE LANDING to reduce this speed so he could land at a more normal speed, with a more normal landing distance, on what may have been a relatively short runway (I don't know how long the runway was, but anything less than about 8,000 feet is starting to get quite short for the aircraft and prevailing conditions).
So, coupled with the heavy tail from ice accretion, the higher approach speeds "masking" the effects of the added weight, and the autopilot being on, it MAY have seemed relatively normal....until they started changing it all!
To land, the wind speeds are too high for the autopilot to handle (Max headwind is 25kts, max crosswind is 15kts, max tailwind is 10kts), so it would have to be hand flown. When the pilot clicks off the autopilot, he suddenly starts to feel the aircraft loading...as in he starts to feel the weight and forces on the aircraft. These are all trimmed up by the autopilot for the most efficient flying conditions based on the aircraft at the time. However, they were probably much faster on the approach than the pilots wanted to be for landing, so the pilot would want to start slowing down. He does this by reducing the power on the engines, which reduces the thrust, thus reducing the speed in a steady state aircraft. This then changes all the forces on the aircraft, which the pilot had to compensate for, as the autopilot is no longer turned on.
I believe that somewhere in here, the weight of ice accretion on the tail, coupled with the decreasing speed, and increasing control forces on the yoke, may have caused the pilot to lose control of the aircraft, possibly in an ice-induced stall.
The video shows an aircraft that has fuel, because it explodes. However, they may not have had enough fuel to hold for any longer and needed to try to land. This would lead a smart pilot (I'm not sure holding in this weather for two hours is smart, but I don't know his options) to make sure he has enough fuel for a few landing attempts, so he may have still had about 6,000lbs (just under 1,000 gallons of jet fuel) or so, which is enough for a couple of landings. That extra fuel makes it look like there was a lot of fuel, because it caused a big fireball in the crash, but it is not a lot of fuel for landing the aircraft, it is a comfortable amount to be able to do a few attempts....but gravity says sooner or later the aircraft has to hit the ground!!!
So, as they flew the approach in bad weather, after holding for two hours, they may have had a significant amount of ice on the tail, possibly 1,000s of pounds of it. The aircraft compensates by flying faster on approach, winds also increase this speed, but too much speed means you can't put all the landing flaps down. So, as you come in to land, you break out of the clouds, see lights on the ground and a runway ahead, you click off the autopilot, suddenly you are now no,ding the control forces in your hands. You have to slow down, so these control forces start changing and thrust changes take place to try to maintain the speed you want. But, to slow down, you have to raise the nose, lower the flaps, pull back the power, etc...It is the proverbial ballet of a good drummer, where each hand and foot is doing something different while you cajole 150,000lbs of aluminium, jet fuel, and people to the ground, all while doing 150mph as you attempt to put it all on a strip of concrete in weather that is trying hard to stop you. If you are not at your sharpest, it is very, very easy to let ONE SINGLE THING get ahead of you, when it is YOU that needs to be well ahead of it, and trying to catch back up to it can be fatal if not done in a timely manner. Given enough time, every pilot recognizes an airplane is stalled, even in the weather when you have no visual cues. However, a pilot who has watched his aircraft go around in circles for two hours, who is worried about the weather, but might not have thought of every eventuality (such as the ice accretion on the tail, for instance, or the amount of speed (energy) he wants to lose for touchdown), and might be operating at lest than peak efficiency, might not have been as ahead of the aircraft as he thought. Indeed, this could have been a very long duty day (we can be on duty upto about 16-17 hrs, believe it or not!) and the crew was faced with this after an already long, tiring day...fatigue has the exact same effect on flying/driving as alcohol...but I don't know the length of their duty day before this flight.
The video makes me believe the aircraft either stalled close to the ground or the pilots, in their zeal to try to "make the runway" made a severe miscalculation of their energy state and "pushed" the aircraft down to try to land. From the video, and from the discussion above, I believe it supports the former outcome...a coming together of numerous hazardous conditions that ended up being beyond the capabilities of the aircraft and pilots in this, very specific, instance.
I'm sorry if my hypothesizing angers some people, because I also understand we need to wait for the official findings in about a year or so. However, after 25 years of flying, seeing crashes like this before, and my knowledge of the aircraft (I'm a Captain on it), I thought I might be able to provide some insights TO THIS FORUM ONLY as to what was going on in that little room in the sky and just outside it, as Mother Nature was trying to corner them and not let them out of her grasp.
So, Aliens then?
BlueS
Well-Known Member
As someone who flies that aircraft, the winds at the time of the accident (~60mph) were beyond the speeds deemed acceptable for landing, which may be why they attempted to land realized they could not (crosswinds of this magnitude are beyond the maximum demonstrated ability of the aircraft, but if they were closer to being more aligned with the runway, the crew may have felt it was possible.
Clearly, they executed a successful missed approach/aborted landing and went into a holding pattern waiting for the winds and weather to improve. This is the usual procedure, IF you have enough fuel to do it and the current weather is suitable for that decision. Here is where conjecture starts to become a much bigger factor and the CVR and DDR (voice and data "black boxes") will become extremely useful, if not vital.
One thought I had was that they held for so long that they were running out of fuel and needed to get the aircraft on the ground. Two hours is the international norm for extra fuel if there are no suitable landing sites near the airport, (for instance, flying to an island) so they may have had few options but to land.
A second thought is that they may have been holding so long in the weather that there was an ice build up on the aircraft, which made the landing virtually impossible, if not impossible. Let me explain. This aircraft does, of course, have icing protection, but this is limited to the leading edge of the wings, the engines, windshields and the numerous probes that stick out into the airflow to provide data to the Air Data Computers that determine speed, etc... One surface that is not anti-iced, and cannot be de-iced in the air by the hot air tapped off the engines, is the tail. Boeing allows for penalties for landing for this by utilizing higher airspeeds or restricting the aircraft weight for landing. However, in extreme conditions, the ambient weather conditions, especially during their two hours of low altitude holding, may have been such that the level of ice accretion was too severe for them to handle at low approach speeds coming into try to land, and they lost control of the aircraft.
In effect, as the aircraft flies, the forces on it are similar to a teeter totter (see saw), such that the "weight" of the nose and tail of the aircraft have to balance on the see-saws fulcrum, which is the lift provided by the wings. The tail is, in effect, a wing that flies down when you need it to, or up when you need it to, and this is accomplished by moving the yoke in the aircraft. However, if the downward force on the tail from the weight of ice build up increases too much, the see-saw gets too heavy on one side. This can be fixed, upto a point, by moving the yoke to compensate. This is all usually done automatically by the autopilot in autoflight, so the pilots actually have no "feel" for moving the yoke at all. This also makes the aircraft slow down, which means the engines spool up to compensate, increase speed, and burn more fuel. So, the scenario becomes this cascading series of factors that pilots are trained to recognize and extricate themselves from, either by flying faster to compensate (especially on landing where you are reconfiguring the aircraft to slow down, and land on the useable runway) or going somewhere where these icing conditions do not exist, which may not have been an option (see my comments above about two hours extra fuel and an island).
So, as they attempted a second approach, after holding for two hours, it appears (AT LEAST TO ME GIVEN WHAT I'VE SEEN IN THE VIDEO AND KNOW ABOUT THE AIRCRAFT) that they made the decision to land in such sub-optimal conditions because they were running out of fuel. This would make the aircraft relatively light, especially given how few passengers were onboard. A light aircraft would make for a slower approach speed NORMALLY. However, if the above is correct, and they had some severe ice accretion on the tail, they would have needed a faster approach speed to compensate. Such a slow approach speed, given the extra weight (I believe the penalty is some thing like 10-15,000lbs added to landing weight to increase approach speed), may have been too slow for the aircraft.
However...and it is a big one...approach speeds are increased for winds. So, they should have increased their approach speeds for the approach accordingly. Given the very high wind speeds, this could have made the speeds very fast. Much faster than usual, and possibly even faster the flap speeds designed into the aircraft. This may have led to the pilot flying that high speed ON APPROACH TO LANDING, but as he came in FOR THE LANDING to reduce this speed so he could land at a more normal speed, with a more normal landing distance, on what may have been a relatively short runway (I don't know how long the runway was, but anything less than about 8,000 feet is starting to get quite short for the aircraft and prevailing conditions).
So, coupled with the heavy tail from ice accretion, the higher approach speeds "masking" the effects of the added weight, and the autopilot being on, it MAY have seemed relatively normal....until they started changing it all!
To land, the wind speeds are too high for the autopilot to handle (Max headwind is 25kts, max crosswind is 15kts, max tailwind is 10kts), so it would have to be hand flown. When the pilot clicks off the autopilot, he suddenly starts to feel the aircraft loading...as in he starts to feel the weight and forces on the aircraft. These are all trimmed up by the autopilot for the most efficient flying conditions based on the aircraft at the time. However, they were probably much faster on the approach than the pilots wanted to be for landing, so the pilot would want to start slowing down. He does this by reducing the power on the engines, which reduces the thrust, thus reducing the speed in a steady state aircraft. This then changes all the forces on the aircraft, which the pilot had to compensate for, as the autopilot is no longer turned on.
I believe that somewhere in here, the weight of ice accretion on the tail, coupled with the decreasing speed, and increasing control forces on the yoke, may have caused the pilot to lose control of the aircraft, possibly in an ice-induced stall.
The video shows an aircraft that has fuel, because it explodes. However, they may not have had enough fuel to hold for any longer and needed to try to land. This would lead a smart pilot (I'm not sure holding in this weather for two hours is smart, but I don't know his options) to make sure he has enough fuel for a few landing attempts, so he may have still had about 6,000lbs (just under 1,000 gallons of jet fuel) or so, which is enough for a couple of landings. That extra fuel makes it look like there was a lot of fuel, because it caused a big fireball in the crash, but it is not a lot of fuel for landing the aircraft, it is a comfortable amount to be able to do a few attempts....but gravity says sooner or later the aircraft has to hit the ground!!!
So, as they flew the approach in bad weather, after holding for two hours, they may have had a significant amount of ice on the tail, possibly 1,000s of pounds of it. The aircraft compensates by flying faster on approach, winds also increase this speed, but too much speed means you can't put all the landing flaps down. So, as you come in to land, you break out of the clouds, see lights on the ground and a runway ahead, you click off the autopilot, suddenly you are now no,ding the control forces in your hands. You have to slow down, so these control forces start changing and thrust changes take place to try to maintain the speed you want. But, to slow down, you have to raise the nose, lower the flaps, pull back the power, etc...It is the proverbial ballet of a good drummer, where each hand and foot is doing something different while you cajole 150,000lbs of aluminium, jet fuel, and people to the ground, all while doing 150mph as you attempt to put it all on a strip of concrete in weather that is trying hard to stop you. If you are not at your sharpest, it is very, very easy to let ONE SINGLE THING get ahead of you, when it is YOU that needs to be well ahead of it, and trying to catch back up to it can be fatal if not done in a timely manner. Given enough time, every pilot recognizes an airplane is stalled, even in the weather when you have no visual cues. However, a pilot who has watched his aircraft go around in circles for two hours, who is worried about the weather, but might not have thought of every eventuality (such as the ice accretion on the tail, for instance, or the amount of speed (energy) he wants to lose for touchdown), and might be operating at lest than peak efficiency, might not have been as ahead of the aircraft as he thought. Indeed, this could have been a very long duty day (we can be on duty upto about 16-17 hrs, believe it or not!) and the crew was faced with this after an already long, tiring day...fatigue has the exact same effect on flying/driving as alcohol...but I don't know the length of their duty day before this flight.
The video makes me believe the aircraft either stalled close to the ground or the pilots, in their zeal to try to "make the runway" made a severe miscalculation of their energy state and "pushed" the aircraft down to try to land. From the video, and from the discussion above, I believe it supports the former outcome...a coming together of numerous hazardous conditions that ended up being beyond the capabilities of the aircraft and pilots in this, very specific, instance.
I'm sorry if my hypothesizing angers some people, because I also understand we need to wait for the official findings in about a year or so. However, after 25 years of flying, seeing crashes like this before, and my knowledge of the aircraft (I'm a Captain on it), I thought I might be able to provide some insights TO THIS FORUM ONLY as to what was going on in that little room in the sky and just outside it, as Mother Nature was trying to corner them and not let them out of her grasp.
feck, my bacons under the grill.