AF447
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HarryMann:
Simple way to think about it:
Airplane is travelling down. It makes contact with the water which stops the fall. This causes upward acceleration (possibly to a zero vertical speed).
Strong vertical acceleration means a strong CHANGE in the vertical component of the velocity. It doesn't necessarily mean anything beyond that.
It has been pointed out earlier that engineers using this phrase in this way means 'deceleration' i.e. force (=ma)
Airplane is travelling down. It makes contact with the water which stops the fall. This causes upward acceleration (possibly to a zero vertical speed).
Strong vertical acceleration means a strong CHANGE in the vertical component of the velocity. It doesn't necessarily mean anything beyond that.
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VHF Radio
A careful read of the radio contacts section shows the last voice comms at 0153 was on HF radio with ATLANTICO. To include a SELCAL check. Normal procedure was to take (noisy) HF off of speaker/headset at that point. A voice only recall from ATLANTICO requesting TASIL update would not have been 'heard'. There has been no explanation as to why ATLANTICO did not use SELCAL again to get a response from AF447.
But all of this last comm was on HF, so any involvement with VHF was moot at that point.
Also, the 'usual' setup was that the F/O was doing all the comms, and the swapped 'control panel' was between station one (Capt) and station 3 (Overhead panel). Station 2 (F/O) was never involved with swap.
Hope this helps.
But all of this last comm was on HF, so any involvement with VHF was moot at that point.
Also, the 'usual' setup was that the F/O was doing all the comms, and the swapped 'control panel' was between station one (Capt) and station 3 (Overhead panel). Station 2 (F/O) was never involved with swap.
Hope this helps.
I had missed that switch from VHF to HF.
So that closes the VHF MEL issue.
The controller debate will continue until hopefully procedures are improved. Clearly there was a breakdown(s) in the controller handover and all the checks and balances failed. Hard to beleive post 9-11 that a passanger transport can go AWOL for several hours and not raise a red flag with someone somewhere.
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Hi ! I'm a newbie here so I read and don't write but...
"Strong vertical acceleration means a strong CHANGE in the vertical component of the velocity. It doesn't necessarily mean anything beyond that."
Absolutely! You've got it right It is a simple statement from a frenchman with a scientific background. We do not talk of "deceleration" that is a word barely used in sciences only in more standard french. May I add the BEA report is very careful. The sentence is noted twice:
p.40 under the header "synthesis of an eye -visual- examination". To a frenchman this too is very clear it means this is what we see (with all the limitations it implies to a frenchman at least) nothing else.
Then it says "the plane has probably (vraisemblablement)) hit the surface of water in flight line ("with" but the word is missing here) a strong vertical acceleration"
p.72 Where it has to be linked with the previous sentence ("the identified elements are coming from all parts -the whole?- of the plane") and it says "their eye examination (again!) show that the plane was not destroyed in flight -because pieces coming from the whole plane dislay the same pattern of mishapenness so they might have been still in the plane when it crashed- it looks like it hit the water surface in flight line -roughtly flat attitude- with a strong vertical acceleration.
..italics +underscore= my comments.
Hope this helps our non/ french speaking and not familiar with the french culture friends here.
"Strong vertical acceleration means a strong CHANGE in the vertical component of the velocity. It doesn't necessarily mean anything beyond that."
Absolutely! You've got it right It is a simple statement from a frenchman with a scientific background. We do not talk of "deceleration" that is a word barely used in sciences only in more standard french. May I add the BEA report is very careful. The sentence is noted twice:
p.40 under the header "synthesis of an eye -visual- examination". To a frenchman this too is very clear it means this is what we see (with all the limitations it implies to a frenchman at least) nothing else.
Then it says "the plane has probably (vraisemblablement)) hit the surface of water in flight line ("with" but the word is missing here) a strong vertical acceleration"
p.72 Where it has to be linked with the previous sentence ("the identified elements are coming from all parts -the whole?- of the plane") and it says "their eye examination (again!) show that the plane was not destroyed in flight -because pieces coming from the whole plane dislay the same pattern of mishapenness so they might have been still in the plane when it crashed- it looks like it hit the water surface in flight line -roughtly flat attitude- with a strong vertical acceleration.
..italics +underscore= my comments.
Hope this helps our non/ french speaking and not familiar with the french culture friends here.
FanAviation;
It helps me m'sieur, many thanks!
takata;
You're very welcome. Re "not suggesting ditching", ah okay - misunderstood. Re loss of control lower down, yes, possible but given the statements about a clear vertical acceleration component such a scenario would take a lot of altitude to develop - so any "mishandling resulting in a stall" would not occur below, say, 10,000ft as there would still be significant, not slight, forward component at collision with the sea precluding the vertical descent scenario. Obviously the further away from 02:14:59 we are, the more exponentially broader the scenarios become.
PJ2
Hope this helps our non/ french speaking and not familiar with the french culture friends here.
takata;
I was not suggesting that F-GZCP could have planned to ditch because it would be fairly suicidal by night and bad weather in the middle of the Atlantic, possibly without comms, and absolutely nothing is suggesting a single trace of preparation. So, I was wondering about a loss of control at low altitude during a desperate attempt to restart the engines, or a battery exhaustion...
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Hi FanAviation. I appreciate your help, and would reply that where you can characterize what has been written in the report as an analysis, description of circumstances, or conclusion, then back up and read WilyB's post, especially the red part, and see if you see any contradictions between stated purpose, and text in fact. I see many analyses, descriptions of circumstance, and conclusions; the apparent conflict vis a vis purpose versus product is clear to me. I have merely stated that the text involving a report of the condition of the bodies recovered by the French team is gratuitous, unscientific, and irrelevent. It is also a "description" (a vague one) something they warn is not appropriate.
Will
Will
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p51guy said...
But can you imagine if AF447 had pulled a 'Sully' and landed/ditched reasonably intact, and there were actually survivors in the water?
Every moment of delay at that point could have mattered. 6 hours to launch a SAR plane from Brest, France to backtrack the route (another 9-ish hour flight), and then arrive at TASIL at midnight the next day.....
Would it have mattered? After all of these days of searching, three hours is meaningless.
Every moment of delay at that point could have mattered. 6 hours to launch a SAR plane from Brest, France to backtrack the route (another 9-ish hour flight), and then arrive at TASIL at midnight the next day.....
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singpilot, annex 3 of the French version of the BEA report gives the last radio contact from AF 447 as occurring at 01:35:43, "-AIR FRANCE FOUR FOUR SEVEN, thank you"
AF447 was replying to Atlantico saying this at 01:35:38: "Acionamento do código SELCALL"
Is there another section of the BEA report that describes a subsequent radio communication from AF447 at 0153?
AF447 was replying to Atlantico saying this at 01:35:38: "Acionamento do código SELCALL"
Is there another section of the BEA report that describes a subsequent radio communication from AF447 at 0153?
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Aw come on, rgbrock1, where's the fire? You are requiring every piece of the plane that was subjected to fire failed to float. While that is maybe possible it seems to be more far fetched than most of the notions here. The rather sparse sampling of the plane and passengers that exists all, seemingly, belie any hint of fire.
JD-EE
JD-EE
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Flat spin / final ACARS message
Given that most people here seem to be accepting and/or claiming that a flat spin occurred shortly after 0210 and the plane hit the water shortly later, I think we may be able to determine the impact time a little closer.
The ACARS cabin rate warning message could be due to bad air data. But if it is, it is bad altitude data. We have no sure indication that there was bad altitude data, only bad airspeed data. On the fairly reasonable assumption that the altitude data was approximately correct, we can then conclude that the cabin rate warning came out about the time the plane was passing thru 8500-8000 feet. Since its a warning rather than a fault it was sent as soon as the condition was recognized, with the usual ACARS transmission delay.
The cabin probably starts descending while the craft is well above 8500 (at a guess, please correct me if I'm wrong), but is I believe limited to a fairly slow descent rate until the plane altitude caches the cabin. At that point the cabin descent rate can exceed the 1800fpm limit and generate the warning. So we might make a ballpark guess that the warning was generated at FL80. Given the descent rate in a flat spin and a time for FL80, one can compute/guess a time for FL0.
The ACARS cabin rate warning message could be due to bad air data. But if it is, it is bad altitude data. We have no sure indication that there was bad altitude data, only bad airspeed data. On the fairly reasonable assumption that the altitude data was approximately correct, we can then conclude that the cabin rate warning came out about the time the plane was passing thru 8500-8000 feet. Since its a warning rather than a fault it was sent as soon as the condition was recognized, with the usual ACARS transmission delay.
The cabin probably starts descending while the craft is well above 8500 (at a guess, please correct me if I'm wrong), but is I believe limited to a fairly slow descent rate until the plane altitude caches the cabin. At that point the cabin descent rate can exceed the 1800fpm limit and generate the warning. So we might make a ballpark guess that the warning was generated at FL80. Given the descent rate in a flat spin and a time for FL80, one can compute/guess a time for FL0.
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Clear Prop,
Nope, gliding implies loss of power to the ACARS equipment. So may be consistent with the plane reaching some point within a fairly well definable range of locations for some time afterwards. I'm simply sitting here trying to define what is within the realm of possibility and physics and what is not. I am tossing in some extra margin for the fact that what we think is possible may not be beyond a really desperate and creative pilot.
One thing that I am willing to give up myself is the flat spin scenario unless flat spin includes considerable motion in a constant direction after the spin is entered. The 02:10:34 point is one I have some faith in. I know rather more about GPS than I wish I did. (Nothing bad - just at this age it'd be fun to have those brain cells back.
) So I have faith in the GPS aided nav data. You can bet the plane was within a couple miles of that position at that time and walk away richer if you can find a sucker to bet to the contrary. I also know general RF communications, including SatCom. If the plane had power and had a more or less horizontal orientation there was no technical reason to claim ACARS data could not be transmitted. So either no new ACARS messages were generated (seems unlikely to me), there was a loss of power, or there was a loss of integrity for the plane before 02:15:30 give or take some. This all happened after the last ACARS message was sent and the message handshake completed.
These parameters do NOT rule out a glide in an attempt to restart the engines. Such a glide might not extend very far, though. I'm led to believe the engine restart dive is not properly called "gliding." And the accident description is compatible with such a dive and a last minute attempt to pull up and ditch, for an example.
JD-EE
Before completely ruling out the possibility that the aircraft may have glided or attempted a controlled descent/diversion and ultimately compromised ditching, is it worth considering again that the report mentions the swapped RMP1 at Rio?
One thing that I am willing to give up myself is the flat spin scenario unless flat spin includes considerable motion in a constant direction after the spin is entered. The 02:10:34 point is one I have some faith in. I know rather more about GPS than I wish I did. (Nothing bad - just at this age it'd be fun to have those brain cells back.
) So I have faith in the GPS aided nav data. You can bet the plane was within a couple miles of that position at that time and walk away richer if you can find a sucker to bet to the contrary. I also know general RF communications, including SatCom. If the plane had power and had a more or less horizontal orientation there was no technical reason to claim ACARS data could not be transmitted. So either no new ACARS messages were generated (seems unlikely to me), there was a loss of power, or there was a loss of integrity for the plane before 02:15:30 give or take some. This all happened after the last ACARS message was sent and the message handshake completed.These parameters do NOT rule out a glide in an attempt to restart the engines. Such a glide might not extend very far, though. I'm led to believe the engine restart dive is not properly called "gliding." And the accident description is compatible with such a dive and a last minute attempt to pull up and ditch, for an example.
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Saturn V
No, you are correct, a little dyslexia there on the numbers. 0135 it is.
singpilot, annex 3 of the French version of the BEA report gives the last radio contact from AF 447 as occurring at 01:35:43, "-AIR FRANCE FOUR FOUR SEVEN, thank you"
AF447 was replying to Atlantico saying this at 01:35:38: "Acionamento do código SELCALL"
Is there another section of the BEA report that describes a subsequent radio communication from AF447 at 0153?
AF447 was replying to Atlantico saying this at 01:35:38: "Acionamento do código SELCALL"
Is there another section of the BEA report that describes a subsequent radio communication from AF447 at 0153?
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xcitation, look no further than the performance of Dakar.
At 1 h 46, the DAKAR controller asked the ATLANTICO controller for further information regarding flight AF447 since he had no flight plan. The ATLANTICO controller provided the following elements: A332, from SBGL to LFPG, SELCAL: CPHQ.
The DAKAR OCEANIC Regional Control Centre created the flight plan and activated it. The result of this was to generate a virtual flight following the planned trajectory in the DAKAR FIR between TASIL and POMAT. There was no radio contact between AF447 and DAKAR, nor any ADS-C connection. [Bolding not in original. There is no indication that Dakar ever attempted to contact AF 447, or have another airplane contact AF 447 during the entire time (1 hour and 25 minutes) that AF447 was supposedly transiting the Dakar FIR.]. The flight remained virtual.....
At 2 h 47 min 00 s, the DAKAR controller coordinated flight AF447 by telephone (ATS/DS) with the SAL controller (Cape Verde) with the following information: passing the POMAT point (leaving the DAKAR FIR) estimated at 3 h 45, FL350, Mach 0.82.
At 2 h 48 min 07 s, the DAKAR controller told the SAL controller that flight AF447 had not yet established contact with him. [AF447 was to enter the Dakar FIR at Tasil at 0220.]
At 3 h 54 min 30 s, the SAL controller called the DAKAR controller by telephone (ATS/DS) to confirm the estimated time for passing the POMAT point. The latter confirmed that POMAT was estimated at 3 h 45. The DAKAR controller stated that the crew of flight AF447 had not contacted him to correct its estimate. The SAL controller replied that the estimate was
probably later. He asked the DAKAR controller if there was any change. The DAKAR controller then said that he was going to try to contact flight AF447. [The DAKAR controller apparently makes no effort to contact AF 447.]
At 4 h 07 min 4 s, the SAL controller requested confirmation of the flight AF447 estimate. The DAKAR controller confirmed again that POMAT was estimated at 3 h 45. The SAL controller pointed out that it was 4 h 8 and that the estimate was not correct. The DAKAR controller recalled that contact had not been established with flight AF447. The SAL controller stated that he had identified flight AF459 on his radar whereas its estimate was later than that of flight AF447. The SAL controller said that he thought that the POMAT estimate was later, at 4 h 29 or 4 h 30. The Dakar controller told the SAL controller that he would call him back.
At 4 h 11 min 53 s, the DAKAR controller asked flight AF459 to contact flight AF447. At 4 h 20 min 27 s, the crew of AF459 informed the DAKAR controller that they were passing point POMAT at FL370. They had not succeed in contacting flight AF447 and said that they had sent a message to Air France so that the airline should try to contact flight AF447. [This is 2 hours after AF447 should have entered Dakar FIR,]
At 4 h 21 min 52s, the DAKAR controller asked the ATLANTICO controller to confirm that flight AF447 had passed TASIL at 2 h 20 at FL350. The ATLANTICO controller confirmed that TASIL was estimated at 2 h 20 but that no contact had been made.
At 4 h 18, the crew of flight AF459 sent a message to Air France so that the airline should try to contact flight AF447. At 4 h 24, Air France asked flight AF447 by ACARS to contact DAKAR OCEANIC
At 4 h 37 min 7 s, the DAKAR controller asked the SAL controller if he had still not been able to contact flight AF447 and informed him that, according to the ATLANTICO controller, the flight should have left the FIR at 2 h 20 and consequently the POMAT estimate should be 3 h 45.
At 4 h 39 min 42 s, the DAKAR controller asked the ATLANTICO controller to confirm that he had not had contact with flight AF447. The latter replied that he had not had contact at TASIL but that the first contact was at INTOL at 1 h 33. The DAKAR controller told the ATLANTICO controller that SAL had not established contact either.
.......
At 5 h 01 min 34 s, the DAKAR controller asked the CANARIAS controller if he was in contact with AF447. The latter replied that he had no information.
At 5 h 09 min 15 s, the ATLANTICO controller asked the DAKAR controller if he had any news of flight AF447. The DAKAR controller replied that he hadn’t and then the ATLANTICO controller requested confirmation that the flight was already in the SAL FIR. The DAKAR controller replied: "yes, no worry". He also confirmed that SAL had not established contact with flight AF447.
At 5 h 50, after several unsuccessful attempts to obtain information on flight AF447, Air France contacted the SARSAT (Search and Rescue Satellite Aided Tracking) centre. The latter had not detected any beacon transmission. Acting upon the advice of SARSAT, Air France contacted the Cinq Mars La Pile Regional Control Centre.
The DAKAR OCEANIC Regional Control Centre created the flight plan and activated it. The result of this was to generate a virtual flight following the planned trajectory in the DAKAR FIR between TASIL and POMAT. There was no radio contact between AF447 and DAKAR, nor any ADS-C connection. [Bolding not in original. There is no indication that Dakar ever attempted to contact AF 447, or have another airplane contact AF 447 during the entire time (1 hour and 25 minutes) that AF447 was supposedly transiting the Dakar FIR.]. The flight remained virtual.....
At 2 h 47 min 00 s, the DAKAR controller coordinated flight AF447 by telephone (ATS/DS) with the SAL controller (Cape Verde) with the following information: passing the POMAT point (leaving the DAKAR FIR) estimated at 3 h 45, FL350, Mach 0.82.
At 2 h 48 min 07 s, the DAKAR controller told the SAL controller that flight AF447 had not yet established contact with him. [AF447 was to enter the Dakar FIR at Tasil at 0220.]
At 3 h 54 min 30 s, the SAL controller called the DAKAR controller by telephone (ATS/DS) to confirm the estimated time for passing the POMAT point. The latter confirmed that POMAT was estimated at 3 h 45. The DAKAR controller stated that the crew of flight AF447 had not contacted him to correct its estimate. The SAL controller replied that the estimate was
probably later. He asked the DAKAR controller if there was any change. The DAKAR controller then said that he was going to try to contact flight AF447. [The DAKAR controller apparently makes no effort to contact AF 447.]
At 4 h 07 min 4 s, the SAL controller requested confirmation of the flight AF447 estimate. The DAKAR controller confirmed again that POMAT was estimated at 3 h 45. The SAL controller pointed out that it was 4 h 8 and that the estimate was not correct. The DAKAR controller recalled that contact had not been established with flight AF447. The SAL controller stated that he had identified flight AF459 on his radar whereas its estimate was later than that of flight AF447. The SAL controller said that he thought that the POMAT estimate was later, at 4 h 29 or 4 h 30. The Dakar controller told the SAL controller that he would call him back.
At 4 h 11 min 53 s, the DAKAR controller asked flight AF459 to contact flight AF447. At 4 h 20 min 27 s, the crew of AF459 informed the DAKAR controller that they were passing point POMAT at FL370. They had not succeed in contacting flight AF447 and said that they had sent a message to Air France so that the airline should try to contact flight AF447. [This is 2 hours after AF447 should have entered Dakar FIR,]
At 4 h 21 min 52s, the DAKAR controller asked the ATLANTICO controller to confirm that flight AF447 had passed TASIL at 2 h 20 at FL350. The ATLANTICO controller confirmed that TASIL was estimated at 2 h 20 but that no contact had been made.
At 4 h 18, the crew of flight AF459 sent a message to Air France so that the airline should try to contact flight AF447. At 4 h 24, Air France asked flight AF447 by ACARS to contact DAKAR OCEANIC
At 4 h 37 min 7 s, the DAKAR controller asked the SAL controller if he had still not been able to contact flight AF447 and informed him that, according to the ATLANTICO controller, the flight should have left the FIR at 2 h 20 and consequently the POMAT estimate should be 3 h 45.
At 4 h 39 min 42 s, the DAKAR controller asked the ATLANTICO controller to confirm that he had not had contact with flight AF447. The latter replied that he had not had contact at TASIL but that the first contact was at INTOL at 1 h 33. The DAKAR controller told the ATLANTICO controller that SAL had not established contact either.
.......
At 5 h 01 min 34 s, the DAKAR controller asked the CANARIAS controller if he was in contact with AF447. The latter replied that he had no information.
At 5 h 09 min 15 s, the ATLANTICO controller asked the DAKAR controller if he had any news of flight AF447. The DAKAR controller replied that he hadn’t and then the ATLANTICO controller requested confirmation that the flight was already in the SAL FIR. The DAKAR controller replied: "yes, no worry". He also confirmed that SAL had not established contact with flight AF447.
At 5 h 50, after several unsuccessful attempts to obtain information on flight AF447, Air France contacted the SARSAT (Search and Rescue Satellite Aided Tracking) centre. The latter had not detected any beacon transmission. Acting upon the advice of SARSAT, Air France contacted the Cinq Mars La Pile Regional Control Centre.
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Will Fraser, I am not a wild eyed liability lawyer trying to drum up business. Why are you trying to sound like one rather than try to knock down the silly theories bouncing around here? I rather belatedly put on my engineering hat and started looking critical at the data being presented. It is WAY WAY premature to say that the data favors any given conclusion or conspiracy theory or other nonsense.
The ABSOLUTE furthest in that direction I am willing to go is that both the Brazilians and the French had some thought for the deceased and tried to avoid the circus that will happen after the autopsy reports are revealed to the public. And that's only within the realm of possible. It's not required to meet the facts as presented.
JD-EE
(I bet this gets pulled but I just had to vent.... Sorry folks.)
The ABSOLUTE furthest in that direction I am willing to go is that both the Brazilians and the French had some thought for the deceased and tried to avoid the circus that will happen after the autopsy reports are revealed to the public. And that's only within the realm of possible. It's not required to meet the facts as presented.
JD-EE
(I bet this gets pulled but I just had to vent.... Sorry folks.)
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> And how is the acars still transmitting in a flat spin?
Do you still have AC 1 bus? If so, it can still transmit. If not, then no, it can't transmit.
If we're absolutely sure that AC 1 is dead in a flat spin, then we know that a flat spin can't be entered until the end of 0214. If we aren't sure, then maybe it can be entered earlier.
If a flat spin is incompatable with ACARS transmission, and we still believe that Bad Things(tm) happened around 0210-0211, then the Bad Things must not have included a flat spin.
Do you still have AC 1 bus? If so, it can still transmit. If not, then no, it can't transmit.
If we're absolutely sure that AC 1 is dead in a flat spin, then we know that a flat spin can't be entered until the end of 0214. If we aren't sure, then maybe it can be entered earlier.
If a flat spin is incompatable with ACARS transmission, and we still believe that Bad Things(tm) happened around 0210-0211, then the Bad Things must not have included a flat spin.
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The concept of the descent of AF447 troubles me.
Anyone who has brought a 208 ton aircraft from altitude (normal, normal, normal) knows how 'difficult' it is to do when heavy. The aircraft will VERY happily accel to MMax with very slight pitchover. From FL350 to surface is 'normally' 25 minutes (powered), clean, and with unrestricted clearance. Gliding, under control as described, 15-ish minutes. Emergency dive, spoilers, (loss of pressurization) maybe 10 minutes (Regs) to 10000, then who knows to surface.
Throw in CB activity, mod to extreme turbulence, nightime, surprise, inattention, one or more failed engines, reversion to some unknown control law, and how long will that take?
Who knows. After a high altitude upset. Geez, maybe speed of a rock from 7 miles up.
My point is that a LOT of attention needs to normally be paid to keep the speed under control in a descent.
These modern designs are so clean, they accel going downhill at the drop of a hat.
Anyone who has brought a 208 ton aircraft from altitude (normal, normal, normal) knows how 'difficult' it is to do when heavy. The aircraft will VERY happily accel to MMax with very slight pitchover. From FL350 to surface is 'normally' 25 minutes (powered), clean, and with unrestricted clearance. Gliding, under control as described, 15-ish minutes. Emergency dive, spoilers, (loss of pressurization) maybe 10 minutes (Regs) to 10000, then who knows to surface.
Throw in CB activity, mod to extreme turbulence, nightime, surprise, inattention, one or more failed engines, reversion to some unknown control law, and how long will that take?
Who knows. After a high altitude upset. Geez, maybe speed of a rock from 7 miles up.
My point is that a LOT of attention needs to normally be paid to keep the speed under control in a descent.
These modern designs are so clean, they accel going downhill at the drop of a hat.
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Art-Deco,
I've remarked in the past that the Inmarsat satellites and protocols are designed to work well within a deluge. I dug into references (the ITT handbook) and looked at the charts. Rain attenuation at Inmarsat frequencies is a bit under 2dB per km in a 25mm/hour rain storm at sea level. So in the very middle of a storm at low altitude the Inmarsat communications probably can become lost, at sea level. At FL350 there is less rain and less distance through it. For rain attenuation to be a factor the plane would have had to have already descended well down into the storm.
That's another useful data point. I am guessing the point where a loss due to rain becomes feasible to consider is maybe 15,000 feet give or take some.
JD-EE
I've remarked in the past that the Inmarsat satellites and protocols are designed to work well within a deluge. I dug into references (the ITT handbook) and looked at the charts. Rain attenuation at Inmarsat frequencies is a bit under 2dB per km in a 25mm/hour rain storm at sea level. So in the very middle of a storm at low altitude the Inmarsat communications probably can become lost, at sea level. At FL350 there is less rain and less distance through it. For rain attenuation to be a factor the plane would have had to have already descended well down into the storm.
That's another useful data point. I am guessing the point where a loss due to rain becomes feasible to consider is maybe 15,000 feet give or take some.
JD-EE