Air Asia Indonesia Lost Contact from Surabaya to Singapore
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From FAA site
To answer Jetjock
DATE: December 10, 2014
AD #:
2014-25-51
Emergency Airworthiness Directive (AD) 2014-25-51 is sent to owners and operators of Airbus Model A318, A319, A320, and A321 series airplanes.
Background
The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued Emergency Airworthiness Directive 2014-0266-E, dated December 9, 2014 (referred to after this as the Mandatory Continuing Airworthiness Information, or “the MCAI”), to correct an unsafe condition on all Model A318, A319, A320, and A321 series airplanes. The MCAI states:
An occurrence was reported where an Airbus A321 aeroplane encountered a blockage of two Angle of Attack (AoA) probes during climb, leading to activation of the Alpha Protection (Alpha Prot) while the Mach number increased. The flightcrew managed to regain full control and the flight landed uneventfully.
When Alpha Prot is activated due to blocked AoA probes, the flight control laws order a continuous nose down pitch rate that, in a worst case scenario, cannot be stopped with backward sidestick inputs, even in the full backward position. If the Mach number increases during a nose down order, the AoA value of the Alpha Prot will continue to decrease. As a result, the flight control laws will continue to order a nose down pitch rate, even if the speed is above minimum selectable speed, known as VLS.
This condition, if not corrected, could result in loss of control of the aeroplane.
To address this unsafe condition, Airbus *** [has] developed a specific Aircraft Flight Manual (AFM) procedure, which has been published in AFM Temporary Revision (TR) No. 502.
For the reasons described above, this AD requires amendment of the applicable AFM [to advise the flightcrew of emergency procedures for abnormal Alpha Prot].
DATE: December 10, 2014
AD #:
2014-25-51
Emergency Airworthiness Directive (AD) 2014-25-51 is sent to owners and operators of Airbus Model A318, A319, A320, and A321 series airplanes.
Background
The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued Emergency Airworthiness Directive 2014-0266-E, dated December 9, 2014 (referred to after this as the Mandatory Continuing Airworthiness Information, or “the MCAI”), to correct an unsafe condition on all Model A318, A319, A320, and A321 series airplanes. The MCAI states:
An occurrence was reported where an Airbus A321 aeroplane encountered a blockage of two Angle of Attack (AoA) probes during climb, leading to activation of the Alpha Protection (Alpha Prot) while the Mach number increased. The flightcrew managed to regain full control and the flight landed uneventfully.
When Alpha Prot is activated due to blocked AoA probes, the flight control laws order a continuous nose down pitch rate that, in a worst case scenario, cannot be stopped with backward sidestick inputs, even in the full backward position. If the Mach number increases during a nose down order, the AoA value of the Alpha Prot will continue to decrease. As a result, the flight control laws will continue to order a nose down pitch rate, even if the speed is above minimum selectable speed, known as VLS.
This condition, if not corrected, could result in loss of control of the aeroplane.
To address this unsafe condition, Airbus *** [has] developed a specific Aircraft Flight Manual (AFM) procedure, which has been published in AFM Temporary Revision (TR) No. 502.
For the reasons described above, this AD requires amendment of the applicable AFM [to advise the flightcrew of emergency procedures for abnormal Alpha Prot].
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Really? Care to back that up? As others have stated here, if you suffer loss of IAS the first rule is DONT PANIC! It's just an indication you've lost.
I think you'll find that being close to stall margin at altitude is not unique to the A320 - it's basic physics/aerodynamics.
Combine it with the company and crew where profit is above safety and you will have this situations sooner or later.
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This FAA recognition only means that the FO had an American licence, nothing more. ALL commercial pilots have this licence, it is the most basic of Commercial licences, and are not recognized in Europe by the way.
This however does not mean that the FO does not have an EASA licence.
This however does not mean that the FO does not have an EASA licence.
Possibly similar to this ?
Incident: Jetstar A320 enroute on Mar 12th 2014, alpha floor activation
Incident: Jetstar A320 enroute on Mar 12th 2014, alpha floor activation
Incident: Jetstar A320 enroute on Mar 12th 2014, alpha floor activation
By Simon Hradecky, created Tuesday, Mar 18th 2014 18:27Z, last updated Tuesday, Jun 17th 2014 14:50Z
A Jetstar Airways Airbus A320-200, registration VH-VQY performing positioning flight JQ-7991 from Melbourne,VI to Darwin,NT (Australia) with 2 crew, had just cleared from FL360 to FL380 and had just reached FL380 abeam Mildura,VI (Australia) when the crew noticed the airspeed was increasing. The crew reduced thrust to idle, extended the speedbrakes and disengaged the autopilot in order to reduce the airspeed, which resulted in speed warnings and a brief activation of flight envelope protection function. The aircraft continued to Darwin for a safe landing without further incident.
Australia's TSB reported an investigation has been opened into the flight envelope protection event (later adding more detail about the sequence of events).
On Mar 18th 2014 the French BEA reported in their weekly bulletin that the aircraft was climbing from FL360 to FL380, after the climb was completed the airspeed increased and the crew disconnected the autopilot in order to control the speed. The speed then decayed resulting in Alpha Floor Activation. Australia's TSB is investigating the occurrence rated an incident.
On Jun 17th 2014 the ATSB released their final bulletin releasing the safety message:
This incident provides a reminder to pilots of all aircraft types regarding the potential for an aerodynamic stall. The stall occurs at a critical angle of attack. The airspeed associated with the stall angle of attack varies depending on the aircraft weight and load factor (such as angle of bank), and the configuration of flaps, slats and spoilers.
The Golden Rules for Pilots article in Safety First - The Airbus Safety Magazine, Issue 15, January 2013, states that on highly automated and integrated aircraft, several levels of automation are available to perform a given task; and the ‘appropriate’ level of automation depends on the situation and task. It advises flight crew to understand the implication of the intended level of automation. Being able to anticipate the reaction of the automated response is important in deciding whether to proceed to rule 4 and change the level of automation.
In this incident, understanding the automated response to a potential overspeed situation may have given the first officer more time to analyse and resolve the situation. Disconnecting the autopilot and autothrust led to a rapid increase in workload and the aircraft changing from a potential overspeed to a slow speed state.
The ATSB reported that the captain briefed the first officer of the next suitable aerodrome in case of an emergency, then left the cockpit temporarily. The aircraft was enroute at FL360 on autopilot in managed speed mode at 0.78 mach. Abeam of Mildura the first officer received clearance to climb to FL380, the first officer selected the new altitude into the autopilot maintaining managed speed mode. The aircraft climbed through FL373 when the first officer noticed the speed had increased to 0.81 mach and had engaged in a 3000 fpm climb, the speed trend indicator suggesting the aircraft would accelerate beyond the maximum mach number operating (MMO) of 0.82 mach. The first officer attempted to arrest the speed by selecting the speed back to 0.76, however the speed continued to increase and the speed trend continued to indicate acceleration. Taken the Airbus golden rule "take action if things do not go as expected" the first officer reduced the thrust levers to idle, which effectively disconnected autothrust, in order to reduce speed, extended the speed brakes and disengaged the autopilot in order to level off and maintain the assigned flight level 380. The aircraft however climbed above FL380. At FL383 ATC queried to confirm altitude, the first officer radioed they were descending back to FL380. The first officer subsequently engaged autothrust and returned the levers to the climb detent and momentarily engaged the autopilot but disconnected again and pushed the nose down in order to re-acquire the assigned flight level.
The aircraft began to descend and the airspeed dropped to below the lowest speed that autothrust would permit to select. The first officer applied nose up commands in order to level at FL380 and moved the thrust levers back close to but not to idle position, which reduced the maximum thrust available from the engines. The nose up inputs increased the angle of attack beyond the alpha floor, the alpha floor protection activated, the speed brakes were automatically retracted and the TOGA lock was activated.
At that time the captain returned to the cockpit, scanned the primary instruments, noticed the aircraft pitch at 0 degrees, the speed in the yellow band about half way between stall and lowest selectable speed, the speed trend accelerating and the aircraft at FL365. There were no indications of any other aircraft in the vicinity that could have been affected by the altitude busts, the captain spotted the Thrust Lock indication. The captain took control of the aircraft, double clicked the autothrust disconnect button to disengage the thrust lock and moved the thrust levers to the climb detent, noticed the speed brake lever was extended and moved it to the retracted position, set a pitch attitude of about +5 to +7 degrees corresponding to a climb of 700-1000 fpm.
ATC noticed the aircraft was now below FL380 and queried to confirm the altitude again, the first officer radioed they were now climbing to FL380, operations were normal.
The captain, cognisant of a gentle recovery to avoid a secondary flight envelope event, levelled the aircraft at FL380 and re-engaged automation.
The ATSB reported that the flight data recorder revealed that during the climb a tail wind component of about 20 knots turned into a head wind component of about 15 knots beginning at FL365, an effective windshear of 35 knots which resulted in 3005 fpm climb rate and a CAS increase from 256 to 262 knots. The Alpha Floor activated when the aircraft descended through FL370 at a CAS of 226 knots with a rate of descend of 4500 fpm.
The ATSB rehearsed the flight crew operating manual procedures, renewed by Airbus mid 2013, stating that the autopilot should be kept on in case of a climbing/descending overspeed event.
The operator revised their standard operating procedures. Their SOPs did not require both crew members to be on the flight deck during cruise. The operator introduced that during altitude changes both flight crew should be present on the flight deck.
By Simon Hradecky, created Tuesday, Mar 18th 2014 18:27Z, last updated Tuesday, Jun 17th 2014 14:50Z
A Jetstar Airways Airbus A320-200, registration VH-VQY performing positioning flight JQ-7991 from Melbourne,VI to Darwin,NT (Australia) with 2 crew, had just cleared from FL360 to FL380 and had just reached FL380 abeam Mildura,VI (Australia) when the crew noticed the airspeed was increasing. The crew reduced thrust to idle, extended the speedbrakes and disengaged the autopilot in order to reduce the airspeed, which resulted in speed warnings and a brief activation of flight envelope protection function. The aircraft continued to Darwin for a safe landing without further incident.
Australia's TSB reported an investigation has been opened into the flight envelope protection event (later adding more detail about the sequence of events).
On Mar 18th 2014 the French BEA reported in their weekly bulletin that the aircraft was climbing from FL360 to FL380, after the climb was completed the airspeed increased and the crew disconnected the autopilot in order to control the speed. The speed then decayed resulting in Alpha Floor Activation. Australia's TSB is investigating the occurrence rated an incident.
On Jun 17th 2014 the ATSB released their final bulletin releasing the safety message:
This incident provides a reminder to pilots of all aircraft types regarding the potential for an aerodynamic stall. The stall occurs at a critical angle of attack. The airspeed associated with the stall angle of attack varies depending on the aircraft weight and load factor (such as angle of bank), and the configuration of flaps, slats and spoilers.
The Golden Rules for Pilots article in Safety First - The Airbus Safety Magazine, Issue 15, January 2013, states that on highly automated and integrated aircraft, several levels of automation are available to perform a given task; and the ‘appropriate’ level of automation depends on the situation and task. It advises flight crew to understand the implication of the intended level of automation. Being able to anticipate the reaction of the automated response is important in deciding whether to proceed to rule 4 and change the level of automation.
In this incident, understanding the automated response to a potential overspeed situation may have given the first officer more time to analyse and resolve the situation. Disconnecting the autopilot and autothrust led to a rapid increase in workload and the aircraft changing from a potential overspeed to a slow speed state.
The ATSB reported that the captain briefed the first officer of the next suitable aerodrome in case of an emergency, then left the cockpit temporarily. The aircraft was enroute at FL360 on autopilot in managed speed mode at 0.78 mach. Abeam of Mildura the first officer received clearance to climb to FL380, the first officer selected the new altitude into the autopilot maintaining managed speed mode. The aircraft climbed through FL373 when the first officer noticed the speed had increased to 0.81 mach and had engaged in a 3000 fpm climb, the speed trend indicator suggesting the aircraft would accelerate beyond the maximum mach number operating (MMO) of 0.82 mach. The first officer attempted to arrest the speed by selecting the speed back to 0.76, however the speed continued to increase and the speed trend continued to indicate acceleration. Taken the Airbus golden rule "take action if things do not go as expected" the first officer reduced the thrust levers to idle, which effectively disconnected autothrust, in order to reduce speed, extended the speed brakes and disengaged the autopilot in order to level off and maintain the assigned flight level 380. The aircraft however climbed above FL380. At FL383 ATC queried to confirm altitude, the first officer radioed they were descending back to FL380. The first officer subsequently engaged autothrust and returned the levers to the climb detent and momentarily engaged the autopilot but disconnected again and pushed the nose down in order to re-acquire the assigned flight level.
The aircraft began to descend and the airspeed dropped to below the lowest speed that autothrust would permit to select. The first officer applied nose up commands in order to level at FL380 and moved the thrust levers back close to but not to idle position, which reduced the maximum thrust available from the engines. The nose up inputs increased the angle of attack beyond the alpha floor, the alpha floor protection activated, the speed brakes were automatically retracted and the TOGA lock was activated.
At that time the captain returned to the cockpit, scanned the primary instruments, noticed the aircraft pitch at 0 degrees, the speed in the yellow band about half way between stall and lowest selectable speed, the speed trend accelerating and the aircraft at FL365. There were no indications of any other aircraft in the vicinity that could have been affected by the altitude busts, the captain spotted the Thrust Lock indication. The captain took control of the aircraft, double clicked the autothrust disconnect button to disengage the thrust lock and moved the thrust levers to the climb detent, noticed the speed brake lever was extended and moved it to the retracted position, set a pitch attitude of about +5 to +7 degrees corresponding to a climb of 700-1000 fpm.
ATC noticed the aircraft was now below FL380 and queried to confirm the altitude again, the first officer radioed they were now climbing to FL380, operations were normal.
The captain, cognisant of a gentle recovery to avoid a secondary flight envelope event, levelled the aircraft at FL380 and re-engaged automation.
The ATSB reported that the flight data recorder revealed that during the climb a tail wind component of about 20 knots turned into a head wind component of about 15 knots beginning at FL365, an effective windshear of 35 knots which resulted in 3005 fpm climb rate and a CAS increase from 256 to 262 knots. The Alpha Floor activated when the aircraft descended through FL370 at a CAS of 226 knots with a rate of descend of 4500 fpm.
The ATSB rehearsed the flight crew operating manual procedures, renewed by Airbus mid 2013, stating that the autopilot should be kept on in case of a climbing/descending overspeed event.
The operator revised their standard operating procedures. Their SOPs did not require both crew members to be on the flight deck during cruise. The operator introduced that during altitude changes both flight crew should be present on the flight deck.
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Hi,
Search Underway for AirAsia Jet Carrying 162 People; Reported Missing on Way from Indonesia to Singapore | Video | TheBlaze.com
Search Underway for AirAsia Jet Carrying 162 People; Reported Missing on Way from Indonesia to Singapore | Video | TheBlaze.com
UPDATE 3:15 a.m.: Fishermen reportedly heard a loud bang over Belitung Island between 7 and 8 a.m., the International Business Times reported, citing Indonesian website Bangka Tribun News.
Belitung is an island on the east coast of Sumatra, Indonesia, in the Java Sea, IBT noted.
The fishermen who were at sea engaged in their regular fishing activities near Coconut Island also claimed that the explosion was quite powerful, the outlet added.
Belitung is an island on the east coast of Sumatra, Indonesia, in the Java Sea, IBT noted.
The fishermen who were at sea engaged in their regular fishing activities near Coconut Island also claimed that the explosion was quite powerful, the outlet added.
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Winds
Quote:
Originally Posted by PJM
last aircraft ADSB reported airspeed was 469 kts. If the ground speed reported by primary radar of 353 is correct, then headwinds are 116 knots.
You're the second Aussie that's come up with this. Call up NAIPS and check out the jet streams in the area!
I realise the desire by armchair pilots to start speculating on the cause(s) but please bear in mind this aircraft was flying in an area of the Inter Tropical Conversion zone (big red blob on weather radar) and rapid Cu development is a distinct probability to envelope an aircraft and, we should all know, the air currents in these clouds can reach exceptionally high velocities ! Please wait for the facts.
Originally Posted by PJM
last aircraft ADSB reported airspeed was 469 kts. If the ground speed reported by primary radar of 353 is correct, then headwinds are 116 knots.
You're the second Aussie that's come up with this. Call up NAIPS and check out the jet streams in the area!
I realise the desire by armchair pilots to start speculating on the cause(s) but please bear in mind this aircraft was flying in an area of the Inter Tropical Conversion zone (big red blob on weather radar) and rapid Cu development is a distinct probability to envelope an aircraft and, we should all know, the air currents in these clouds can reach exceptionally high velocities ! Please wait for the facts.
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After 15 years in this profession, and avidly studying plane crashes, it's truly painful to read these threads early on.
First off all eyewitness accounts shouldn't be posted, or posted with a massive disclaimer that they are almost certainly and wildly inaccurate
Professional note: The ground speed on the radar is an estimate calculated by the radar position server, used often with Mosaic radar, but can be less accurately ascertained by a single sourced radar
Unless they have encoding ground speed display, not likely, the ground speed is not directly indicative of the ground speed of the airplane....
First off all eyewitness accounts shouldn't be posted, or posted with a massive disclaimer that they are almost certainly and wildly inaccurate
Professional note: The ground speed on the radar is an estimate calculated by the radar position server, used often with Mosaic radar, but can be less accurately ascertained by a single sourced radar
Unless they have encoding ground speed display, not likely, the ground speed is not directly indicative of the ground speed of the airplane....
If the ground speed in the ATC screenshot is correct, that would put them at an estimated IAS of 190kts. If we take the nearby UAE ground speed to indicate they had a ~20kt tailwind while heading to same direction roughly, that further drops their IAS to about 170kts, well within stall range of the A320 at MTOM in clean config.
Does anyone know what the transponder's source is for the reported altitude? This very much is looking like a pitot/static induced problem at this stage. Alpha protection wouldn't let the crew go near the ground speed shown on the ATC screenshot. If it's true...
Does anyone know what the transponder's source is for the reported altitude? This very much is looking like a pitot/static induced problem at this stage. Alpha protection wouldn't let the crew go near the ground speed shown on the ATC screenshot. If it's true...
if it exploded at cruise altitude fishermen could hardly hear it (provided their story is genuine), if it crashed debris should be all around so it will be found quickly
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Yes
The altitude on the radar display, the encoded mode c can be different than what the pilots see, however it is far more likely the radar display is more accurate than the pilots report
The altitude on the radar display, the encoded mode c can be different than what the pilots see, however it is far more likely the radar display is more accurate than the pilots report
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It's been 12 hours in constant day light on a busy route both shipping and air, I immediately refute an explosion theory based solely on those facts, until proven otherwise.
The fact wreckage is not found yet, is immensely troubling after this much time.
I'm not insinuating it's MH370 again, simply puzzling, perplexing and disappointing because any survivors may be running out of time should they exist
The fact wreckage is not found yet, is immensely troubling after this much time.
I'm not insinuating it's MH370 again, simply puzzling, perplexing and disappointing because any survivors may be running out of time should they exist
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One thing to also keep in mind is that aircraft performance data is based on density altitude, but we fly flight levels based on pressure altitude.
This difference can be important when operating near service limits (see for example, the infamous Pinnacle Airlines crash). But it's all just speculation at this point.
This difference can be important when operating near service limits (see for example, the infamous Pinnacle Airlines crash). But it's all just speculation at this point.
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Someone asked about if air asia do p2f? They may do in malaysia, but here in indo you cannot (as a non-indo) work in a cockpit unless you have 250hrs already on type. This rule only applies to foreigners, dont know if they do p2f for locals, I would suggest not.
As an aside, on my last air asia flight, there was an article in the inflight mag, about how their crews were superior, and do not be alarmed if you see a young captain as it is because their training is so much more advanced than the west, which is why there are so many older fo's in the west..it was quite staggering to read this arrogrance in their in flight mag, but this mind set is not surprising in this part of the world...
I witnessed one of our company pilots renew his IR with a DGCA inspector, by performing one visual approach...i kid you not. The level of oversight of the DGCA is unbelievable...you dont even require a me-ir to get a job on an airline in indo....
As an aside, on my last air asia flight, there was an article in the inflight mag, about how their crews were superior, and do not be alarmed if you see a young captain as it is because their training is so much more advanced than the west, which is why there are so many older fo's in the west..it was quite staggering to read this arrogrance in their in flight mag, but this mind set is not surprising in this part of the world...
I witnessed one of our company pilots renew his IR with a DGCA inspector, by performing one visual approach...i kid you not. The level of oversight of the DGCA is unbelievable...you dont even require a me-ir to get a job on an airline in indo....
"It's been 12 hours in constant day light on a busy route both shipping and air, I immediately refute an explosion theory based solely on those facts, until proven otherwise.
The fact wreckage is not found yet, is immensely troubling after this much time."
I don't think anyone would try something similar as authorities there are much more aware now than before.
But I agree it's strange nothing has been found yet in a very shallow sea full of traffic.
The fact wreckage is not found yet, is immensely troubling after this much time."
I don't think anyone would try something similar as authorities there are much more aware now than before.
But I agree it's strange nothing has been found yet in a very shallow sea full of traffic.
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john smifff (3 f's I assume ? )
you seem to be intent on confrontation on this thread.
What cozmo has suggested, is in essence correct, his conclusions may not be, certainly a 6000ft climb & 120 degree heading change would suggest that a lack of forward planning was present here (or maybe simply that the higher level was previously unavailable. )
As Despegue has pointed out to you, my comment Re P2F is (as I said ) not thread hijack (but is interesting given the content of the Jetstar incident, wouldn't you say ? )
What I think Ccozmo hasn't grasped, is that the A320 stall margin is (aerodynamically speaking) no less than (say) a B737, merely that Airbus (in their usual cocksure fashion) have (possibly to exaggerate the efficiency/economy of the machine) chosen to leave a smaller margin when flying at Optimum/Maximum than Boeing have with the 737. This has nothing to do with aerodynamics & is a choice by the manufacturer , not corrected by the certifying authority I would suggest.
As a serial Airbus basher, I find deeply disquieting the reports about Alpha Prot etc above, I have never been a great believer in having to reach up to the overhead panel & fumble for switches to regain manual pitch control (I assume that is the Airbus drill for that ? ) , god knows how they get that one past the certifiers .
you seem to be intent on confrontation on this thread.
What cozmo has suggested, is in essence correct, his conclusions may not be, certainly a 6000ft climb & 120 degree heading change would suggest that a lack of forward planning was present here (or maybe simply that the higher level was previously unavailable. )
As Despegue has pointed out to you, my comment Re P2F is (as I said ) not thread hijack (but is interesting given the content of the Jetstar incident, wouldn't you say ? )
What I think Ccozmo hasn't grasped, is that the A320 stall margin is (aerodynamically speaking) no less than (say) a B737, merely that Airbus (in their usual cocksure fashion) have (possibly to exaggerate the efficiency/economy of the machine) chosen to leave a smaller margin when flying at Optimum/Maximum than Boeing have with the 737. This has nothing to do with aerodynamics & is a choice by the manufacturer , not corrected by the certifying authority I would suggest.
As a serial Airbus basher, I find deeply disquieting the reports about Alpha Prot etc above, I have never been a great believer in having to reach up to the overhead panel & fumble for switches to regain manual pitch control (I assume that is the Airbus drill for that ? ) , god knows how they get that one past the certifiers .
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GS, not TAS
"ADS picks up the TAS, but if speed is unreliable, surely this read out could be unreliable to"
If I am not mistaken, it is GPS speed or GS that gets reported, and not TAS "velocity" word that is used, not airspeed. (there is a capability to transmit airspeed too, but that's another story)
http://adsb.tc.faa.gov/WG3_Meetings/...x_A%20Mods.pdf
upd. In this particular case - I don't know what is the source of ground speed value that gets received by the ADS-B Out equipment. I mean - it could be GPS receiver or IRS + sufficient data processing.
If I am not mistaken, it is GPS speed or GS that gets reported, and not TAS "velocity" word that is used, not airspeed. (there is a capability to transmit airspeed too, but that's another story)
http://adsb.tc.faa.gov/WG3_Meetings/...x_A%20Mods.pdf
upd. In this particular case - I don't know what is the source of ground speed value that gets received by the ADS-B Out equipment. I mean - it could be GPS receiver or IRS + sufficient data processing.
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Originally Posted by Old King Coal
it's a very foolish thing to try and out-climb a thunderstorm.
Even if there is no cloud above a Cb, that should not be taken to infer that the air above the Cb is free from severe turbulence, and all that climbing would do is put one even closer into coffin-corner, at a time when (if sever turbulence occurs) one needs as much airspeed margin as possible.
Even if there is no cloud above a Cb, that should not be taken to infer that the air above the Cb is free from severe turbulence, and all that climbing would do is put one even closer into coffin-corner, at a time when (if sever turbulence occurs) one needs as much airspeed margin as possible.
While different from Cb activity, a 1966 CAT accident illustrates all a/c (regardless of type) can encounter structural and control limits in flight. BOAC flt. 911 (a 707-436) flew into a mountain rotor near Mt. Fuji and broke up in flight. A U.S. Navy A-4 was sent to search for wreckage and flew into the same turbulence. The A-4 went out of control and nearly crashed. Its peak-reading g-meter was pegged at +9 and -4 g, and the plane was grounded for repairs.
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1) turbulence at lower levels
2) more fuel efficient altitude
3) better visual reference to maneuver around the weather
Maybe it was a combination of all three.
It would be interesting to know the maximum possible range from the last known potion. Probably only 3 or so hours - they had perhaps 90 minutes scheduled flying to reach Singapore plus various reserves. An earlier post suggested they had slightly more fuel than the minimum required.
No wreckage after a full day in a fairly crowded area close to shore. Agree that is concerning. I guess Inmarsat are checking for handshakes.
No wreckage after a full day in a fairly crowded area close to shore. Agree that is concerning. I guess Inmarsat are checking for handshakes.
