Take off with snow on wing
Join Date: Feb 2008
Location: New York
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
[/QUOTE]highly irresponsible from a gentleman point of view to make a lady worrying bout the snow on the wing. Jeez spray it clean and make them smile and I'm sure they'll be more approachable during next layover. Besides, as far as I know, pretty much all airlines pay for block time. Go figure, what's the rush line up in a queue for deice, have a coffee and a friendly chat with a lady and off you go with few extra bucks. It's safe, relaxed and maybe even far-reaching deicing catching up with the future Mrs. Brilliant opportunity to engage in social intercourse with the ladies. Can't wait for the next winter ops.[QUOTE]
More Approachable? No question.
More Approachable? No question.
Join Date: Jun 2007
Location: NC, USA
Age: 80
Posts: 92
Likes: 0
Received 0 Likes
on
0 Posts
The point is that the accident was actually caused by something other than a low power setting. However, because this is a 30-year old accident, there may be little interest in learning more about it - so I'll refrain until I know that there might be some interest. If you are interested in knowing what this additional information would be, I’d be glad to provide you with some facts that, while they were available at the time, were not given the attention they deserved....
Join Date: Aug 2002
Location: Up north
Posts: 1,657
Likes: 0
Received 0 Likes
on
0 Posts
From the NTSB report of the Air Florida crash states: (still relevant, 30 years later!!)
So...
....and then....
The de-icing at the gate was completed 15:10, the aircraft finally took off at 15:59:46 after taxi out and waiting in turn for T/O in snow reported as alternating between "moderate" and "heavy".
@ 15:47, about 12 min before take off the First Officer made the following comment in reference to his (right) wing:
The report then goes on stating:
Nothing much to say really.....
I read the report years ago but went back and read it again. I can really recommend to all of you to read it as it highlights a lot of potential issues with operating in winter conditions.
The National Transportation Safety Board determines that the probable cause of this accident was the flight crew’s failure to use engine anti-ice during ground operation and takeoff, their decision to take off with snow/ice on the airfoil surfaces of the aircraft, and the captain’s failure to reject the takeoff during the early stage when his attention was called to anomalous engine instrument readings. Contributing to the accident were the prolonged ground delay between deicing and the receipt of ATC takeoff clearance during which the airplane was exposed to continual precipitation, the known inherent pitchup characteristics of the B-737 aircraft when the leading edge is contaminated with even small amounts of snow or ice, and the limited experience of the flightcrew in winter operations./
their decision to take off with snow/ice on the airfoil surfaces of the aircraft
the prolonged ground delay between deicing and the receipt of ATC takeoff clearance during which the airplane was exposed to continual precipitation
@ 15:47, about 12 min before take off the First Officer made the following comment in reference to his (right) wing:
this one’s got about a quarter to half an inch on it all the way
...the V2 callout occurred at 1600:37 and the sound of the stall warning (stickshaker) began 2 seconds later and continued until impact.
I read the report years ago but went back and read it again. I can really recommend to all of you to read it as it highlights a lot of potential issues with operating in winter conditions.
Last edited by CaptainProp; 17th Apr 2012 at 08:10.
Join Date: Jun 2007
Location: I bucked one and Tim bucked two
Posts: 68
Likes: 0
Received 0 Likes
on
0 Posts
Wimps......looks like a little bit of hoar frost.....
Big Balls Airlines Funny Video Clip - Airplanes
Big Balls Airlines Funny Video Clip - Airplanes
Join Date: Jun 2007
Location: NC, USA
Age: 80
Posts: 92
Likes: 0
Received 0 Likes
on
0 Posts
Join Date: Aug 2002
Location: Up north
Posts: 1,657
Likes: 0
Received 0 Likes
on
0 Posts
Ok, yea could be that he was implying that he had more to add.
I thought he meant the snow / ice contamination of the aircraft airfoils in addition to the more know EPR issue they had due to ice and that's why I posted.
I thought he meant the snow / ice contamination of the aircraft airfoils in addition to the more know EPR issue they had due to ice and that's why I posted.
De-icing could easily wipe the profit (or increase the loss!) from a short-haul flight and perhaps a long haul as well but you need to look at a route over the course of a year. Any sensible operator will factor in the total costs over a year which if its a route that requires a lot of de-icing in winter will be considerably higher than one that doesn't.
Join Date: Oct 2006
Location: British Airspace
Age: 53
Posts: 39
Likes: 0
Received 0 Likes
on
0 Posts
OK - deice fluid currently in the order of £2 per litre in the UK and takes around 1500lts to deice a mini-'Bus. But it's still cheaper than crashing (and my lot are quite happy to budget for this in their accounts - the fluid, not the crashing)
Join Date: Apr 2005
Location: Southeast USA
Posts: 801
Likes: 0
Received 0 Likes
on
0 Posts
Air Florida Accident First of Two in Sequence
Please understand that my motive in saying what I’m saying (and what I’ve said previously), is in no way intending to impugn the fine reputation or the integrity of the NTSB or of the dedicated and professional employees at the Safety Board. My only motive has been a continuing effort to describe the actions of the flight crew from a slightly different perspective while providing what I believe to be clarifying information regarding the cause of the accident and, to the best I am able, set the record straight– as much as one can this long after the fact.
I should also say, up front, that I, too, continue to have questions for which I still do not have answers. There is not a winter flying season that comes and goes that I do not wish that the flight crew of that Air Florida flight had been more inquisitive about the condition of the wings. Perhaps if one of them had taken a few moments to observe the wing surfaces on a walk back through the cabin at some point prior to the takeoff, he would have noticed something … anything … that would have triggered a different course of action. But that didn’t happen. So, what I’m left with is what happened … the results of the investigation … and a long-time consideration of what that investigation revealed to me. For simplicity, I would like to address some issues I believe are important, and I’ll do that in chronological order, beginning with the airplane de-icing.
The De-icing. The NTSB Aircraft Accident Report described an “analysis of the deicer vehicle found that a nonstandard nozzle had been used” and was dispensing deicer fluid with a mixture different from what was expected. The accident report states “the mixture dispensed differed substantially from the mixture selected…” such that the “deicing fluid in solution was about 18 percent rather than 30 percent.” The report further states that the right side of the aircraft was “deiced with 100 percent water and a final overspray applied with a 20 to 30 percent deicer to water solution selected.” The “20 to 30 percent” mixture for the overspray was the selected value, not the mixture that was actually applied. Standard deicing procedures called for deicing and overspray to be conducted with 30 to 40 percent solution of glycol in heated water. What the report does not contain is that the nonstandard nozzle dispensing fluid at 18 percent glycol mixture was a reasonably accurate measurement for the minimal flow of fluid from the deicing wand at a nominal, or minimal, flow rate. However, when the operator increased the flow rate, all of the additional volume flow came from the heated water tank, and none from the glycol tank – effectively lowering the solution percentage by an unknown but substantial proportion. From my perspective, deicing over half of the airplane and the wing surfaces with 100 percent hot water and over-spraying the entire aircraft with a maximum concentration of 18 percent glycol (and very probably significantly less depending on the volume flow at any given point in the overspray process) cannot simply be catalogued and filed away. I believe this to be the pivotally significant action in the series of actions leading up to the accident and was, singularly, the accident cause.
The Takeoff Clearance and the Absence of an Aborted Takeoff. The accident report goes into some detail about the lack of assertiveness on the part of the F/O and the lack of receptiveness on the part of the Captain during the initial stages of the takeoff roll when the F/O apparently noted some engine indication anomalies. Many have quoted from the CVR transcript indicating that during the takeoff roll there were a number of times the F/O questioned the accuracy of the engine instruments. My question is how do the readers of the transcript know that the F/O was referencing the engine instruments? If it was an “anomaly” with the engine instrument readings, the logical question that the casual observer would make is “why didn’t they simply abort the takeoff?” In fact, the accident report cites 3 factors as the probable cause of the accident, with the third one being “the captain’s failure to reject the takeoff during the early stages when his attention was called to anomalous engine instrument readings.” The report also states that the investigation “considered the possibility that the captain was aware of and concerned about the decreasing separation between his aircraft and the aircraft landing behind him.” However, the report concludes that this decreasing separation “would likely have become a factor only after the landing aircraft reported ‘over the lights.’” I’d like to look at that conclusion for just a moment.
Pilots sit at the arrival ends of runways multiple times each day – day in and day out. They watch arrival after arrival – big airplanes, little airplanes, fast airplanes, and airplanes not so fast. What they do is get a “feel” for the timing involved. I know of no pilot who has ever taxied into position on an active runway, knowing there is an airplane on final, who has not had at least a slight “tingle” down the back of his or her neck. That tingle grows until takeoff clearance is received, the throttles are pushed forward, the airplane accelerates, and the crew rotates into the air. Then, and only then, does the tingle subside. The investigators concluded that the Captain would not have considered the approaching airplane to be worrisome until that crew reported “over the lights.” I respectfully disagree with that conclusion; and I know of few, if any pilots who would accept that conclusion. Would you?
The traffic that was referred to was Eastern flight 1451, a B-727. I know that the final approach speed is dependent on several factors (weight, flap setting, etc.), but because the tower operator asked the Eastern crew to fly “reduced speed,” I’ll use a speed of 130 knots. With a head wind of approximately 10 knots, the ground speed would have been approximately 120 knots, or 138 miles per hour. At that speed it would take the airplane approximately 64 seconds to cover the “two and a half miles,” or the 13,200 feet, reported by the tower operator. From that time of that report (59:28) until the F/O took control of the throttles (59:46), 18 seconds had passed. It was 16 seconds later (00:02) when the F/O first indicated that there was something that he questioned. This was now 34 seconds after the tower’s notification that landing traffic was “…two and a half out for the runway.” When the Captain called “80-knots” (00:09), the airplane had probably reached a position 1000 to 1500 feet down the runway. The investigators believed that the F/O was concerned about engine “anomalies,” but I believe he was confused about physical throttle position being different from what he had become used to recognizing. He was used to having his arm and his hand at a position that “felt familiar” (i.e., muscle memory), but when the instruments told him that the proper position had been reached, he recognized “something” different but didn’t recognize that his arm and hand were in a slightly different position – and this is what was confusing for him. I believe that it is quite likely that both crewmembers were attempting to identify anything out of the ordinary – but I contend that the engine instruments were reading what the crew expected them to read – and it is only after-the-fact that we’ve learned that the PT2 probes being blocked would have allowed the EPR gauges to indicate the desired setting for takeoff with the engine thrust actually set to a lower value. The other engine instruments were likely close to what should have been “normal” but, and I think significantly, those indications were steady and symmetrical. The flaps were properly set. The speed brakes were stowed. Everything that either crew member could see seemed normal.
The investigators believe that once the F/O voiced those concerns the Captain should have aborted the takeoff. Before agreeing or disagreeing with that belief, I think the significant question should be … where was the B-727 at this time? Assuming the airspeed of the B-727 was 120 knots and that this speed remained constant, and that its position was accurately relayed by the controller to the departing flight crew, at this 34 second mark, mathematics tells us that the B-727 would have been approximately 6300 feet from the threshold. That’s well over a mile out … but, that is ONLY if the assumptions are correct. To some – perhaps to many – that distance may seem to be adequate spacing for the departing airplane to abort with little or no problem. However, the fact is that a scant 2 seconds after the B-737 reached 80 knots (which happened at 00:09) the B-727 crew reported “cleared to land, over the lights” (which happened at 00:11) The approach lighting system extends 2,400 feet from the threshold. If the B-727 was indeed “over the lights” as they, themselves reported, they were something less than 2,400 feet from the threshold – still maintaining that constant 120 knots. Either they were flying a lot faster than my assumption or the tower operator provided inaccurate information to the departing crew. At that point, the B-737 was probably less than 2000 feet down the runway. Again, estimates vary, but there are some who believe that the B-727 actually landed prior to the B-737 lifting off … meaning that both aircraft were on the runway at the same time! Had the B-737 crew aborted, I believe there is at least a reasonable possibility that two aircraft would have been involved in an accident on the runway, and the probability of that accident occurring goes up dramatically, second by second.
I probably should point out that the both the aircraft immediately preceding the accident B-737, “Apple 58” (a New York Air DC-9) and the aircraft immediately following the accident B-737, “Six Eight Golf” were both in the takeoff que for approximately the same amount of time and both aircraft took off from the same runway and departed without incident.
The Airplane Performance During the Takeoff. It would come as no surprise to anyone that a lower engine power setting would result in a longer than normal takeoff roll given that all other parameters were the same. In this case, as I’ve said previously, I have little doubt that the accident airplane PT2 probes were blocked – most likely blocked with ice. I also believe that this resulted in erroneous EPR readings in the cockpit. I believe that the flight crew set the takeoff EPR at 2.04 and that, because of the blocked PT2 probes, the actual engine thrust was set to approximately 75% of maximum. Undoubtedly, this increased the ground roll. But the point that goes unmentioned in this discussion is that the airplane was certificated to be able to accelerate to decision speed, or V1, (and I recognize that airplane certification is based on all engines operating at full power up to that V1 speed), experience the complete failure of one engine, and be able to continue the takeoff safely. What happened in this case was that the airplane accelerated down the runway with both engines producing approximately 75% power. Again, I acknowledge that the takeoff roll would be longer to get to this point. However, once the computed V1 speed was reached, regardless of how long it took to get there (downhill roll, rubber-band, whatever…), from that, “V1” point forward, the airplane should have been able to fly on one engine at 100% power. From the CVR transcripts we know that the V1, Vr, and V2 speeds were noted to be “thirty eight, forty, forty four” – meaning 138, 140, and 144 knots, respectively. In fact, after reaching “V1” (and we know this speed was reached, as the Captain’s “Vee One” call-out is noted on the transcript) this airplane had 2 engines operating at 75% power, which is clearly 50 percent more power than should have been required – and as an added benefit the power that was being produced was produced symmetrically. We also see on the CVR transcript that in addition to the “V1” speed being reached, we know that “V2” speed was also reached, and was also confirmed by the Captain’s callouts. We should also recall that V2 is generally 20% above the stall speed for that aircraft weight and configuration. Yet after having reached a speed of more than V2 (actually 150 knots), as confirmed by the Flight Data Recorder (FDR) tracings, with symmetrical power of two engines, each producing 75 of maximum power, the airplane failed to fly. Why?
Many people instantly respond with the assumption that the airplane had added weight due to the accretion of ice. Today we know that if an airplane the size of a B-727 is completely covered in ice, the total weight of that ice is something on the order 180 to 350 pounds – somewhere between 1 and 2 additional passengers. So, if there was additional weight of ice, that small increase should not have had such significant detriment to the performance of the airplane. However, it would be interesting to note where it was that this ice came from. Recall that the aircraft that was immediately in front, and the aircraft that was immediately behind, the Air Florida B737 in the takeoff line, took off with no problems. All three airplanes were deiced at approximately the same time. All three airplanes were exposed to the elements for approximately the same time. Yet two of the three flew successfully, and one did not. If it wasn’t weight, what prevented the airplane from flying? In my opinion, it aerodynamically stalled.
Pilots fly airplanes according to airspeeds, not power settings. Airplanes fly or fail to fly because of the wing moving through the air at sufficient or insufficient speed. Did this accident airplane have insufficient airspeed? No. The airplane reached a speed slightly higher than V2, computed to be 144 knots. At 20 percent above the stalling speed, this meant that the airplane would have stalled at 120 knots. In that any additional weight due to ice accretion seems not to be the answer, why did the airplane stall at 24 – 30 knots above stalling speed? In my opinion it was because of the pitch attitude of the airplane.
I should also say, up front, that I, too, continue to have questions for which I still do not have answers. There is not a winter flying season that comes and goes that I do not wish that the flight crew of that Air Florida flight had been more inquisitive about the condition of the wings. Perhaps if one of them had taken a few moments to observe the wing surfaces on a walk back through the cabin at some point prior to the takeoff, he would have noticed something … anything … that would have triggered a different course of action. But that didn’t happen. So, what I’m left with is what happened … the results of the investigation … and a long-time consideration of what that investigation revealed to me. For simplicity, I would like to address some issues I believe are important, and I’ll do that in chronological order, beginning with the airplane de-icing.
The De-icing. The NTSB Aircraft Accident Report described an “analysis of the deicer vehicle found that a nonstandard nozzle had been used” and was dispensing deicer fluid with a mixture different from what was expected. The accident report states “the mixture dispensed differed substantially from the mixture selected…” such that the “deicing fluid in solution was about 18 percent rather than 30 percent.” The report further states that the right side of the aircraft was “deiced with 100 percent water and a final overspray applied with a 20 to 30 percent deicer to water solution selected.” The “20 to 30 percent” mixture for the overspray was the selected value, not the mixture that was actually applied. Standard deicing procedures called for deicing and overspray to be conducted with 30 to 40 percent solution of glycol in heated water. What the report does not contain is that the nonstandard nozzle dispensing fluid at 18 percent glycol mixture was a reasonably accurate measurement for the minimal flow of fluid from the deicing wand at a nominal, or minimal, flow rate. However, when the operator increased the flow rate, all of the additional volume flow came from the heated water tank, and none from the glycol tank – effectively lowering the solution percentage by an unknown but substantial proportion. From my perspective, deicing over half of the airplane and the wing surfaces with 100 percent hot water and over-spraying the entire aircraft with a maximum concentration of 18 percent glycol (and very probably significantly less depending on the volume flow at any given point in the overspray process) cannot simply be catalogued and filed away. I believe this to be the pivotally significant action in the series of actions leading up to the accident and was, singularly, the accident cause.
The Takeoff Clearance and the Absence of an Aborted Takeoff. The accident report goes into some detail about the lack of assertiveness on the part of the F/O and the lack of receptiveness on the part of the Captain during the initial stages of the takeoff roll when the F/O apparently noted some engine indication anomalies. Many have quoted from the CVR transcript indicating that during the takeoff roll there were a number of times the F/O questioned the accuracy of the engine instruments. My question is how do the readers of the transcript know that the F/O was referencing the engine instruments? If it was an “anomaly” with the engine instrument readings, the logical question that the casual observer would make is “why didn’t they simply abort the takeoff?” In fact, the accident report cites 3 factors as the probable cause of the accident, with the third one being “the captain’s failure to reject the takeoff during the early stages when his attention was called to anomalous engine instrument readings.” The report also states that the investigation “considered the possibility that the captain was aware of and concerned about the decreasing separation between his aircraft and the aircraft landing behind him.” However, the report concludes that this decreasing separation “would likely have become a factor only after the landing aircraft reported ‘over the lights.’” I’d like to look at that conclusion for just a moment.
Pilots sit at the arrival ends of runways multiple times each day – day in and day out. They watch arrival after arrival – big airplanes, little airplanes, fast airplanes, and airplanes not so fast. What they do is get a “feel” for the timing involved. I know of no pilot who has ever taxied into position on an active runway, knowing there is an airplane on final, who has not had at least a slight “tingle” down the back of his or her neck. That tingle grows until takeoff clearance is received, the throttles are pushed forward, the airplane accelerates, and the crew rotates into the air. Then, and only then, does the tingle subside. The investigators concluded that the Captain would not have considered the approaching airplane to be worrisome until that crew reported “over the lights.” I respectfully disagree with that conclusion; and I know of few, if any pilots who would accept that conclusion. Would you?
The traffic that was referred to was Eastern flight 1451, a B-727. I know that the final approach speed is dependent on several factors (weight, flap setting, etc.), but because the tower operator asked the Eastern crew to fly “reduced speed,” I’ll use a speed of 130 knots. With a head wind of approximately 10 knots, the ground speed would have been approximately 120 knots, or 138 miles per hour. At that speed it would take the airplane approximately 64 seconds to cover the “two and a half miles,” or the 13,200 feet, reported by the tower operator. From that time of that report (59:28) until the F/O took control of the throttles (59:46), 18 seconds had passed. It was 16 seconds later (00:02) when the F/O first indicated that there was something that he questioned. This was now 34 seconds after the tower’s notification that landing traffic was “…two and a half out for the runway.” When the Captain called “80-knots” (00:09), the airplane had probably reached a position 1000 to 1500 feet down the runway. The investigators believed that the F/O was concerned about engine “anomalies,” but I believe he was confused about physical throttle position being different from what he had become used to recognizing. He was used to having his arm and his hand at a position that “felt familiar” (i.e., muscle memory), but when the instruments told him that the proper position had been reached, he recognized “something” different but didn’t recognize that his arm and hand were in a slightly different position – and this is what was confusing for him. I believe that it is quite likely that both crewmembers were attempting to identify anything out of the ordinary – but I contend that the engine instruments were reading what the crew expected them to read – and it is only after-the-fact that we’ve learned that the PT2 probes being blocked would have allowed the EPR gauges to indicate the desired setting for takeoff with the engine thrust actually set to a lower value. The other engine instruments were likely close to what should have been “normal” but, and I think significantly, those indications were steady and symmetrical. The flaps were properly set. The speed brakes were stowed. Everything that either crew member could see seemed normal.
The investigators believe that once the F/O voiced those concerns the Captain should have aborted the takeoff. Before agreeing or disagreeing with that belief, I think the significant question should be … where was the B-727 at this time? Assuming the airspeed of the B-727 was 120 knots and that this speed remained constant, and that its position was accurately relayed by the controller to the departing flight crew, at this 34 second mark, mathematics tells us that the B-727 would have been approximately 6300 feet from the threshold. That’s well over a mile out … but, that is ONLY if the assumptions are correct. To some – perhaps to many – that distance may seem to be adequate spacing for the departing airplane to abort with little or no problem. However, the fact is that a scant 2 seconds after the B-737 reached 80 knots (which happened at 00:09) the B-727 crew reported “cleared to land, over the lights” (which happened at 00:11) The approach lighting system extends 2,400 feet from the threshold. If the B-727 was indeed “over the lights” as they, themselves reported, they were something less than 2,400 feet from the threshold – still maintaining that constant 120 knots. Either they were flying a lot faster than my assumption or the tower operator provided inaccurate information to the departing crew. At that point, the B-737 was probably less than 2000 feet down the runway. Again, estimates vary, but there are some who believe that the B-727 actually landed prior to the B-737 lifting off … meaning that both aircraft were on the runway at the same time! Had the B-737 crew aborted, I believe there is at least a reasonable possibility that two aircraft would have been involved in an accident on the runway, and the probability of that accident occurring goes up dramatically, second by second.
I probably should point out that the both the aircraft immediately preceding the accident B-737, “Apple 58” (a New York Air DC-9) and the aircraft immediately following the accident B-737, “Six Eight Golf” were both in the takeoff que for approximately the same amount of time and both aircraft took off from the same runway and departed without incident.
The Airplane Performance During the Takeoff. It would come as no surprise to anyone that a lower engine power setting would result in a longer than normal takeoff roll given that all other parameters were the same. In this case, as I’ve said previously, I have little doubt that the accident airplane PT2 probes were blocked – most likely blocked with ice. I also believe that this resulted in erroneous EPR readings in the cockpit. I believe that the flight crew set the takeoff EPR at 2.04 and that, because of the blocked PT2 probes, the actual engine thrust was set to approximately 75% of maximum. Undoubtedly, this increased the ground roll. But the point that goes unmentioned in this discussion is that the airplane was certificated to be able to accelerate to decision speed, or V1, (and I recognize that airplane certification is based on all engines operating at full power up to that V1 speed), experience the complete failure of one engine, and be able to continue the takeoff safely. What happened in this case was that the airplane accelerated down the runway with both engines producing approximately 75% power. Again, I acknowledge that the takeoff roll would be longer to get to this point. However, once the computed V1 speed was reached, regardless of how long it took to get there (downhill roll, rubber-band, whatever…), from that, “V1” point forward, the airplane should have been able to fly on one engine at 100% power. From the CVR transcripts we know that the V1, Vr, and V2 speeds were noted to be “thirty eight, forty, forty four” – meaning 138, 140, and 144 knots, respectively. In fact, after reaching “V1” (and we know this speed was reached, as the Captain’s “Vee One” call-out is noted on the transcript) this airplane had 2 engines operating at 75% power, which is clearly 50 percent more power than should have been required – and as an added benefit the power that was being produced was produced symmetrically. We also see on the CVR transcript that in addition to the “V1” speed being reached, we know that “V2” speed was also reached, and was also confirmed by the Captain’s callouts. We should also recall that V2 is generally 20% above the stall speed for that aircraft weight and configuration. Yet after having reached a speed of more than V2 (actually 150 knots), as confirmed by the Flight Data Recorder (FDR) tracings, with symmetrical power of two engines, each producing 75 of maximum power, the airplane failed to fly. Why?
Many people instantly respond with the assumption that the airplane had added weight due to the accretion of ice. Today we know that if an airplane the size of a B-727 is completely covered in ice, the total weight of that ice is something on the order 180 to 350 pounds – somewhere between 1 and 2 additional passengers. So, if there was additional weight of ice, that small increase should not have had such significant detriment to the performance of the airplane. However, it would be interesting to note where it was that this ice came from. Recall that the aircraft that was immediately in front, and the aircraft that was immediately behind, the Air Florida B737 in the takeoff line, took off with no problems. All three airplanes were deiced at approximately the same time. All three airplanes were exposed to the elements for approximately the same time. Yet two of the three flew successfully, and one did not. If it wasn’t weight, what prevented the airplane from flying? In my opinion, it aerodynamically stalled.
Pilots fly airplanes according to airspeeds, not power settings. Airplanes fly or fail to fly because of the wing moving through the air at sufficient or insufficient speed. Did this accident airplane have insufficient airspeed? No. The airplane reached a speed slightly higher than V2, computed to be 144 knots. At 20 percent above the stalling speed, this meant that the airplane would have stalled at 120 knots. In that any additional weight due to ice accretion seems not to be the answer, why did the airplane stall at 24 – 30 knots above stalling speed? In my opinion it was because of the pitch attitude of the airplane.
Join Date: Apr 2005
Location: Southeast USA
Posts: 801
Likes: 0
Received 0 Likes
on
0 Posts
Air Florida Accident Second of Two in Sequence
The accident report describes “the Boeing 737’s tendency to significant(ly) pitch up in conditions where the wing was presumably contaminated by snow, sleet, or rain in near-freezing conditions prior to takeoff.” This phenomenon directly relates to asymmetrical lift. Asymmetrical or differential lift is not new, and is, in fact, used every day by every airplane that uses roll control spoilers. Asymmetrical or differential lift is used to assist not only in rolling the airplane, but in assisting in maintaining coordinated flight by compensating for adverse yaw. Here, however, in the B-737’s tendency to pitch up, the asymmetry comes not laterally but longitudinally. With the outboard portion of the wings sufficiently deformed by leading edge ice accretion, they provide less, or no lift, leaving the inboard portions of the wings (also farther forward) producing an asymmetrically large lift differential. As the airplane accelerated during the takeoff roll, the pilot, to ensure nose gear contact with the runway surface, normally would hold the controls in a forward, or nose-down, position. However, as the rotation speed is approached, the pilot is instructed to move the control column to a neutral or slightly aft of neutral position in preparation to initiate the rotation to the takeoff attitude. My opinion is that when this action occurred, or immediately when beginning the rotation, as the wing was rotated from an essentially negative angle of attack to a positive angle of attack, the inboard portion of the wing, producing virtually all of the lift being generated and that forward of the center of gravity, rotated the airplane, without the assistance of the pilot, and continued that rotation to a point where the wing was aerodynamically stalled.
An “aside” here, I think, may be appropriate. I know for a fact that the Air Force KC-135, Strato-Tanker airplane (essentially a hybrid of the original B-707 and the B-720)was equipped with roll control spoilers. However, additionally, the KC-135 had spoiler control valve switches (both of which were guarded switches) located just under the center of the glare shield. The left switch activated the inboard spoiler control valve and the right switch activated the outboard spoiler control valve. These valves were checked prior to each and every flight. What was their use? Well, that’s a questionable call about which many would not be willing to offer an opinion. Personally, I believe it was a safety feature that was made available in case loading of fuel in the massive fuel tanks located both forward and aft of the center of gravity created a longitudinal shift in that center of gravity that might needed to be managed. In fact, all instructors were trained on their use, as during takeoff, a pilot could reach up under the glare shield, open the left guard, depress the switch (thereby cutting off hydraulic fluid to the inboard spoilers) and without doing anything with the control column, reach down an raise the speed brakes (now, because of deactivating the inboard spoilers, only the outboard spoilers would respond – raising only the outboard spoilers) to create a differential lift on the swept wings of the KC-135, where the inboard portion of the wing is farther forward than the outboard portion of the wing – resulting in the outboard portion of both winds having the lift “spoiled” and the lift on the inboard portion remaining unchanged, the airplane would rotate smartly – so smartly, in fact, the speed brake extension had to be moderated to avoid driving the tail of the airplane onto the runway prior to becoming airborne. Asymmetrical lift is quite powerful.
In the accident B-737, if this condition existed, it is very likely that continued forward control column movement and continued forward pressure on the control column would be insufficient to bring the nose down. We see on the CVR transcript that the Captain is urging “Forward, forward.” “Easy.” “We only want Five Hundred.” “Come on forward.” “Forward.” “Just barely climb.” What do you think was going on in that cockpit? I think that the flight crew had the control column fully forward and the airplane was not responding the way they had expected it to respond. Speculation has been raised that trimming the stabilizer to its maximum nose down position may have been able to provide some additional nose down elevator authority. However, this action would have been completely non-intuitive to a pilot never having experienced this phenomenon previously, and being airborne for only 22 seconds would probably not have allowed sufficient time to allow the trim to achieve sufficient movement to make enough of a difference.
Interestingly, the accident report also states “there were other incidents similar to this one reported, in which the crew was able to overcome the contamination, but they needed the proper thrust level of 2.04 EPR.” I believe this statement inaccurately and unfairly characterizes the recoverability of any B-737 that has aerodynamically stalled due to a significant pitch up resulting from contamination of the wing by freezing precipitation. In support of this belief I call your attention to an occurrence on the same day as the Air Florida accident, with another B-737 operator’s experience out of Oslo, Norway. While perhaps one may be able to conclude that flight and ground personnel in Washington may misunderstand snow and ice conditions, there is no way that anyone is going to believe that pilots or ground crew in Oslo, Norway, are going to misunderstand the necessities or the procedures for deicing an airplane. However, on this day, the B-737 departing from Oslo was exposed to a snowstorm during taxi out and takeoff, and the problems experienced immediately after takeoff were chillingly identical to the Air Florida accident.
Because of the storm in Oslo that day, ice was built up on the wing leading edge. But, because of the nature of the storm, the build-up was asymmetrical. As in the Air Florida airplane, at takeoff there was a resulting pitch-up, but in Oslo, it was a rolling pitch (due to the asymmetry of the deformation). Even though the crew slammed the throttles to the firewall immediately, used full opposite aileron and full opposite rudder, they were unable to control the pitch/roll of the aircraft. Fortunately, because of the radical bank angle (approaching 90 degrees), the nose dropped back down to the horizon, and with the throttles fully forward, the airplane began to accelerate. As the airplane accelerated, lift was produced over the outboard portions of the wing, including the ailerons, and that allowed the crew to roll back to level flight. The crew did recover the airplane; but the recovery was below 100 feet above the ground. Had they not had this bit of inconsistency from Mother Nature, resulting in the asymmetrical lift on the wings, providing the roll, and allowing the nose to fall, the world would have seen B-737s on opposite ends of the world crash on the same day from the same problem.
I contend that this problem is a very slight accumulation of ice on the leading edge of the wing causes asymmetrical lift, longitudinally, resulting in a nose up pitching moment. The relationship is that the greater the accumulation of ice, the more asymmetrical lift, and the greater the pitch tendency. Perhaps there were some incidents where the crew was able to recover the airplane by, among other things, advancing the power. But in Washington and in Oslo, the ice build-up was sufficient to result in uncontrollable pitch. Even with both throttles full forward throughout the event, the Oslo aircraft was not recovered by assuring the engines were producing at least 2.04 EPR. In fact, had the differential lift been symmetrical, and the aircraft not rolled over on its own, full thrust on the under-slung engines on the B737 may have exacerbated the pitch tendency.
Is this what happened to the Air Florida airplane? I believe it is. Look at the CVR and the Flight Data Recorder (FDR) readouts. The CVR has the Captain calling “V2,” and scarcely 2 seconds later the transcript describes “sound of stickshaker starts.” When listening to the actual recording of the CVR there is little doubt that there are sounds of severe buffeting as well as the stick shaker operating. The airplane had gone well past the stall warning (the stick shaker) and had gone well into the stall buffet. Opinions differ as to what pitch angle would have been required to get into the stall buffet – but they range from 22 to 24 degrees of pitch. Think about that for a minute. In just over 2 seconds the airplane goes from level attitude to at least somewhere between 22 and 24 degrees of pitch. That is a rate of rotation in the neighborhood of 12 degrees per second. Recall that the normal rotation rate is 3 degrees per second; and the F/O, who was at the controls, had indicated he was going to “takeoff the nose gear and then just let the airplane fly off by itself.” The F/O wanted to deliberately limit the rotation to just getting the nose gear into the air, and the airplane was rotated at 12 degrees per second or more. Does that indicate anything inconsistent to you?
The bottom line is this. I have no explanation as to why one of the crew did not look more closely at the wings prior to departure. I don’t know why the crew was lead into accepting a clearance that would have been “challenging” on a clear day with unlimited visibility. I regret that we all didn’t know more about deicing effects and “hold-over” times. I don’t know why we were not made aware of the tendency of the B737 to have pitch-up and roll-off problems in winter weather conditions. What I do know is that I am grateful that the errors made that day, by all who made them, have been talked about and hopefully will be used to educate others and save lives. I also know that two competent aviators, former colleagues of mine, and extremely nice young men, lost their lives, as did most of the rest of those on board the airplane along with four motorists who died on the bridge that fateful afternoon.
My only goal in providing this information is to provide at least an alternative to the understanding that many have had for a number of years. I believe that the real cause of this tragic accident wasn’t because these young men forgot to use, or chose not to use, engine anti-ice. The acceleration rate was immaterial. It was not because they attempted to power-back out of the gate. They did not do that. It was not because they chose to “deice” their airplane by deliberately taxiing too close behind other aircraft “jet wash.” I don’t believe they did that. It was not because they disregarded the snow that accumulated on their aircraft while waiting to takeoff. I believe they placed their confidence in the deicing / anti-icing process. It was not because these professional pilots lacked critical knowledge of cold weather and de-icing operations. (I probably should point out that prior to being hired at the airline, the F/O who was at the controls of the accident airplane, had been an F-15 pilot stationed at Minot, North Dakota – where, as everyone probably knows, the residents do have something more than a nodding acquaintance with ice and snow.) I am firmly convinced that the accident was caused by the fact that the airplane was highly susceptible to very minor amounts of ice deformation of the leading edge of the wing; that it was caused by the fact that they were deiced with an inadequate system that coated their aircraft and engine intakes with water – and only a small token of the glycol solution on which they depended.
I believe that once this crew pushed the throttles forward with the intent to takeoff, they were doomed. The only way that an accident could have been avoided at that point, was to have kept the airplane on the ground until a sufficiently higher airspeed was reached prior to initiating the rotation. Unfortunately, not only did the crew not know that this would be necessary, they wouldn’t have known the “magic” airspeed number. Even if they had pushed both throttles all the way to the firewall from brake release, and then rotated at the computed rotation airspeed (as they did) the airplane would have performed in exactly the same way. It would have uncontrollably pitched up to at least the 22 – 24 degree attitude; likely more given witness statements … where some said they saw “the aircraft was flying at an unusually low altitude with the wings level at a nose-high attitude of 30 degrees to 40 degrees before it hit the bridge.” It would have entered the same deep aerodynamic stall. The flight crew would have been unable to bring the nose down aerodynamically. Unfortunately, in that condition, full thrust on both engines would have been insufficient to maintain flight. All who were affected by this tragedy were victims of longitudinal differential lift. The flight crew did not have the luxury of time to analyze, consider, and choose accordingly.
An “aside” here, I think, may be appropriate. I know for a fact that the Air Force KC-135, Strato-Tanker airplane (essentially a hybrid of the original B-707 and the B-720)was equipped with roll control spoilers. However, additionally, the KC-135 had spoiler control valve switches (both of which were guarded switches) located just under the center of the glare shield. The left switch activated the inboard spoiler control valve and the right switch activated the outboard spoiler control valve. These valves were checked prior to each and every flight. What was their use? Well, that’s a questionable call about which many would not be willing to offer an opinion. Personally, I believe it was a safety feature that was made available in case loading of fuel in the massive fuel tanks located both forward and aft of the center of gravity created a longitudinal shift in that center of gravity that might needed to be managed. In fact, all instructors were trained on their use, as during takeoff, a pilot could reach up under the glare shield, open the left guard, depress the switch (thereby cutting off hydraulic fluid to the inboard spoilers) and without doing anything with the control column, reach down an raise the speed brakes (now, because of deactivating the inboard spoilers, only the outboard spoilers would respond – raising only the outboard spoilers) to create a differential lift on the swept wings of the KC-135, where the inboard portion of the wing is farther forward than the outboard portion of the wing – resulting in the outboard portion of both winds having the lift “spoiled” and the lift on the inboard portion remaining unchanged, the airplane would rotate smartly – so smartly, in fact, the speed brake extension had to be moderated to avoid driving the tail of the airplane onto the runway prior to becoming airborne. Asymmetrical lift is quite powerful.
In the accident B-737, if this condition existed, it is very likely that continued forward control column movement and continued forward pressure on the control column would be insufficient to bring the nose down. We see on the CVR transcript that the Captain is urging “Forward, forward.” “Easy.” “We only want Five Hundred.” “Come on forward.” “Forward.” “Just barely climb.” What do you think was going on in that cockpit? I think that the flight crew had the control column fully forward and the airplane was not responding the way they had expected it to respond. Speculation has been raised that trimming the stabilizer to its maximum nose down position may have been able to provide some additional nose down elevator authority. However, this action would have been completely non-intuitive to a pilot never having experienced this phenomenon previously, and being airborne for only 22 seconds would probably not have allowed sufficient time to allow the trim to achieve sufficient movement to make enough of a difference.
Interestingly, the accident report also states “there were other incidents similar to this one reported, in which the crew was able to overcome the contamination, but they needed the proper thrust level of 2.04 EPR.” I believe this statement inaccurately and unfairly characterizes the recoverability of any B-737 that has aerodynamically stalled due to a significant pitch up resulting from contamination of the wing by freezing precipitation. In support of this belief I call your attention to an occurrence on the same day as the Air Florida accident, with another B-737 operator’s experience out of Oslo, Norway. While perhaps one may be able to conclude that flight and ground personnel in Washington may misunderstand snow and ice conditions, there is no way that anyone is going to believe that pilots or ground crew in Oslo, Norway, are going to misunderstand the necessities or the procedures for deicing an airplane. However, on this day, the B-737 departing from Oslo was exposed to a snowstorm during taxi out and takeoff, and the problems experienced immediately after takeoff were chillingly identical to the Air Florida accident.
Because of the storm in Oslo that day, ice was built up on the wing leading edge. But, because of the nature of the storm, the build-up was asymmetrical. As in the Air Florida airplane, at takeoff there was a resulting pitch-up, but in Oslo, it was a rolling pitch (due to the asymmetry of the deformation). Even though the crew slammed the throttles to the firewall immediately, used full opposite aileron and full opposite rudder, they were unable to control the pitch/roll of the aircraft. Fortunately, because of the radical bank angle (approaching 90 degrees), the nose dropped back down to the horizon, and with the throttles fully forward, the airplane began to accelerate. As the airplane accelerated, lift was produced over the outboard portions of the wing, including the ailerons, and that allowed the crew to roll back to level flight. The crew did recover the airplane; but the recovery was below 100 feet above the ground. Had they not had this bit of inconsistency from Mother Nature, resulting in the asymmetrical lift on the wings, providing the roll, and allowing the nose to fall, the world would have seen B-737s on opposite ends of the world crash on the same day from the same problem.
I contend that this problem is a very slight accumulation of ice on the leading edge of the wing causes asymmetrical lift, longitudinally, resulting in a nose up pitching moment. The relationship is that the greater the accumulation of ice, the more asymmetrical lift, and the greater the pitch tendency. Perhaps there were some incidents where the crew was able to recover the airplane by, among other things, advancing the power. But in Washington and in Oslo, the ice build-up was sufficient to result in uncontrollable pitch. Even with both throttles full forward throughout the event, the Oslo aircraft was not recovered by assuring the engines were producing at least 2.04 EPR. In fact, had the differential lift been symmetrical, and the aircraft not rolled over on its own, full thrust on the under-slung engines on the B737 may have exacerbated the pitch tendency.
Is this what happened to the Air Florida airplane? I believe it is. Look at the CVR and the Flight Data Recorder (FDR) readouts. The CVR has the Captain calling “V2,” and scarcely 2 seconds later the transcript describes “sound of stickshaker starts.” When listening to the actual recording of the CVR there is little doubt that there are sounds of severe buffeting as well as the stick shaker operating. The airplane had gone well past the stall warning (the stick shaker) and had gone well into the stall buffet. Opinions differ as to what pitch angle would have been required to get into the stall buffet – but they range from 22 to 24 degrees of pitch. Think about that for a minute. In just over 2 seconds the airplane goes from level attitude to at least somewhere between 22 and 24 degrees of pitch. That is a rate of rotation in the neighborhood of 12 degrees per second. Recall that the normal rotation rate is 3 degrees per second; and the F/O, who was at the controls, had indicated he was going to “takeoff the nose gear and then just let the airplane fly off by itself.” The F/O wanted to deliberately limit the rotation to just getting the nose gear into the air, and the airplane was rotated at 12 degrees per second or more. Does that indicate anything inconsistent to you?
The bottom line is this. I have no explanation as to why one of the crew did not look more closely at the wings prior to departure. I don’t know why the crew was lead into accepting a clearance that would have been “challenging” on a clear day with unlimited visibility. I regret that we all didn’t know more about deicing effects and “hold-over” times. I don’t know why we were not made aware of the tendency of the B737 to have pitch-up and roll-off problems in winter weather conditions. What I do know is that I am grateful that the errors made that day, by all who made them, have been talked about and hopefully will be used to educate others and save lives. I also know that two competent aviators, former colleagues of mine, and extremely nice young men, lost their lives, as did most of the rest of those on board the airplane along with four motorists who died on the bridge that fateful afternoon.
My only goal in providing this information is to provide at least an alternative to the understanding that many have had for a number of years. I believe that the real cause of this tragic accident wasn’t because these young men forgot to use, or chose not to use, engine anti-ice. The acceleration rate was immaterial. It was not because they attempted to power-back out of the gate. They did not do that. It was not because they chose to “deice” their airplane by deliberately taxiing too close behind other aircraft “jet wash.” I don’t believe they did that. It was not because they disregarded the snow that accumulated on their aircraft while waiting to takeoff. I believe they placed their confidence in the deicing / anti-icing process. It was not because these professional pilots lacked critical knowledge of cold weather and de-icing operations. (I probably should point out that prior to being hired at the airline, the F/O who was at the controls of the accident airplane, had been an F-15 pilot stationed at Minot, North Dakota – where, as everyone probably knows, the residents do have something more than a nodding acquaintance with ice and snow.) I am firmly convinced that the accident was caused by the fact that the airplane was highly susceptible to very minor amounts of ice deformation of the leading edge of the wing; that it was caused by the fact that they were deiced with an inadequate system that coated their aircraft and engine intakes with water – and only a small token of the glycol solution on which they depended.
I believe that once this crew pushed the throttles forward with the intent to takeoff, they were doomed. The only way that an accident could have been avoided at that point, was to have kept the airplane on the ground until a sufficiently higher airspeed was reached prior to initiating the rotation. Unfortunately, not only did the crew not know that this would be necessary, they wouldn’t have known the “magic” airspeed number. Even if they had pushed both throttles all the way to the firewall from brake release, and then rotated at the computed rotation airspeed (as they did) the airplane would have performed in exactly the same way. It would have uncontrollably pitched up to at least the 22 – 24 degree attitude; likely more given witness statements … where some said they saw “the aircraft was flying at an unusually low altitude with the wings level at a nose-high attitude of 30 degrees to 40 degrees before it hit the bridge.” It would have entered the same deep aerodynamic stall. The flight crew would have been unable to bring the nose down aerodynamically. Unfortunately, in that condition, full thrust on both engines would have been insufficient to maintain flight. All who were affected by this tragedy were victims of longitudinal differential lift. The flight crew did not have the luxury of time to analyze, consider, and choose accordingly.
Join Date: Apr 2012
Location: planet earth
Age: 59
Posts: 48
Likes: 0
Received 0 Likes
on
0 Posts
OK AirRabbit, I'll bite. What did cause AF to go for a swim?
From the NTSB report of the Air Florida crash states: (still relevant, 30 years later!!)
You certainly have my attention there. I'll reread the full NTSB report and your posts over the coming days. You certainly do seem to know the case very well!
Join Date: Nov 2006
Location: N/A
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
I was under the impression that the crew never firewalled the throttles, even AFTER airborne.
The aircraft pitches up to 22 degrees, with both hands on the yoke pushing down with all their might, how many of us would take a hand off the yoke and push the throttles forward?
I believe the crew is wrongly criticized for pilot error "at this point" in the error chain. We are all human and without prior experience or knowledge, it would have happened to every single one of us.
Its human factors, in our brain we set T/O EPR, uncommanded pitch to 22degrees, stick shaker, we push down with all our might with both hands...
the end
The aircraft pitches up to 22 degrees, with both hands on the yoke pushing down with all their might, how many of us would take a hand off the yoke and push the throttles forward?
I believe the crew is wrongly criticized for pilot error "at this point" in the error chain. We are all human and without prior experience or knowledge, it would have happened to every single one of us.
Its human factors, in our brain we set T/O EPR, uncommanded pitch to 22degrees, stick shaker, we push down with all our might with both hands...
the end
Join Date: Jan 2008
Location: Bracknell, Berks, UK
Age: 52
Posts: 1,133
Likes: 0
Received 0 Likes
on
0 Posts
no being anything but an aircraft enthusiast
i saw earlier that i costs $4000 to de-ice a 747,not much less for 777's and the like i expect
how do airlines make a profit on that particular flight ?
from what i've read over the years on flying seems to me some flights won't break even ?
i saw earlier that i costs $4000 to de-ice a 747,not much less for 777's and the like i expect
how do airlines make a profit on that particular flight ?
from what i've read over the years on flying seems to me some flights won't break even ?
Join Date: Apr 2005
Location: Southeast USA
Posts: 801
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by 8sugarsugar
I was under the impression that the crew never firewalled the throttles, even AFTER airborne.
The aircraft pitches up to 22 degrees, with both hands on the yoke pushing down with all their might, how many of us would take a hand off the yoke and push the throttles forward?
I believe the crew is wrongly criticized for pilot error "at this point" in the error chain. We are all human and without prior experience or knowledge, it would have happened to every single one of us.
Its human factors, in our brain we set T/O EPR, uncommanded pitch to 22degrees, stick shaker, we push down with all our might with both hands...
the end
The aircraft pitches up to 22 degrees, with both hands on the yoke pushing down with all their might, how many of us would take a hand off the yoke and push the throttles forward?
I believe the crew is wrongly criticized for pilot error "at this point" in the error chain. We are all human and without prior experience or knowledge, it would have happened to every single one of us.
Its human factors, in our brain we set T/O EPR, uncommanded pitch to 22degrees, stick shaker, we push down with all our might with both hands...
the end
I know that I indicated that most people believed that it would take a minimum of 22 – 24 degrees of pitch to actually enter an aerodynamic stall – where buffeting of the airplane could not be overlooked. If you consider any of the eye-witness accounts to be even close to accurate, the airplane achieved substantially more than 22 – 24 degrees of pitch. Several eye-witnesses estimated the pitch to be higher than 30 degrees and a couple estimated the pitch attitude to be 40 degrees. These estimates were not given as numerical values - each witness formed an angle with his/her hands and the investigator selected the numerical value he thought was appropriate. And, as I’ve pointed out on more than one occasion, the F/O clearly said that what he was going to do was “…take the nose wheel off and then we'll let it fly off.” How much pitch attitude do you think would have been just enough to raise the nose gear off the surface? The other question would be … just how surprised would you be if, when planning to rotate to something like 10 or 12 degrees of pitch, as you begin to move the control column aft, the airplane rotates up to 12 degrees and immediately goes up to 20 … then 25 … then 30 … then 35 degrees! You have your flying partner yelling in your ear “…come on forward. Forward. Just barely climb. Forward. Forward.” What do you think you’d be doing?
Join Date: Jun 2007
Location: NC, USA
Age: 80
Posts: 92
Likes: 0
Received 0 Likes
on
0 Posts
Many thanks for that very well thought out analysis AirRabbit. Makes more sense than the NTSB report which I never considered a complete enough explanation. I assume the difference in lift degradation between wing outer & inner sections is due to Krueger flaps inboard & slats outboard. I could see how ice would affect slats more, especially if the flaps were left up during the ground delay.
Join Date: Nov 2006
Location: N/A
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
the pitch up tendency of underslung engines is negligible when you're <50 feet off the ground. You want that thrust vector regardless of increased pitch moment.
Jets can power out of stalls and still climb when buffetting.
Jets can power out of stalls and still climb when buffetting.
Join Date: Aug 2002
Location: south england
Posts: 393
Likes: 0
Received 0 Likes
on
0 Posts
Depends on stab trim.
BOH TUI 737 had slowed down on finals with A/P engaged and manual thrust (either at idle, or too little thrust). Aircraft trimmed to maintain glide as IAS reduced, on commencing the missed approach the pitch couple caused by advancing the thrust levers caused a nose up moment for which they did not have enough elevator authority to overcome unless they trimmed forward.
BOH TUI 737 had slowed down on finals with A/P engaged and manual thrust (either at idle, or too little thrust). Aircraft trimmed to maintain glide as IAS reduced, on commencing the missed approach the pitch couple caused by advancing the thrust levers caused a nose up moment for which they did not have enough elevator authority to overcome unless they trimmed forward.