Good points jezzaOZ, though I would note that the airspace they were flying through was not unregulated at all and the aircraft would all be flying on designated routes and recognised altitudes.
OK. What you say here makes good sense but only if they knew they were in real trouble. We’ll have to wait until more details become available.
The way it’s being presented in the news here, they weren’t asking to change course in a way that indicated an emergency. More like they wanted to avoid a difficult but manageable flight with a lot of turbulence. They may not have known how bad things were until it was too late. The fact that they made no other (received) communication with ATC seems to support that.
If ATC had seen something in the storm that looked dangerous they would have given warnings and diverted all flights around it. If the pilots had seen an immediate threat they would never have gone in. My best guess is that the pilot had a gut feeling about it but not enough evidence to justify declaring an emergency.
Pilots have a great deal of latitude regarding control of the aircraft. If they flew into a thunderstorm they can deviate in whatever manner secures the safety of the aircraft.
With that said it’s been reported that the pilot did not respond to ATC’s directive and the plane was lost on radar soon after. It’s safe to assume something really bad happened at that point.
they could have hit severe turbulence or stalled it due to shifting high speed winds. Severe turbulence is not what you see on TV. That’s moderate turbulence. Severe turbulence would rip the plane apart. As a general rule if there’s lightning then there’s hail. Imagine flying into hail and 70 mph windshear at 450 mph.
In my small plane I would never fly near a storm cell. But I have flown on the edge of what I would call a freshet and I’ve been hammered for the effort.
ATC don’t divert aircraft around storms. Pilots decide whether they’re happy with the route they’re on and decide whether they want to get diversions.
To clarify something, the pilots asked for and received clearance to divert around the weather, they were already off track when the accident happened. What they had not received was clearance to climb. So they had dealt with the weather problem in the normal way by diverting, and this is a regular occurrence (daily).
It is not clear whether they actually felt that they needed to climb, it is normal to climb during the flight anyway as it is more efficient. I haven’t read any ATC transcripts but the normal thing to say is “QZ8501 request deviations 50NM left of track due weather” or “QZ8501 moderate turbulence at FL320 request climb to FL360”, or something along those lines. This is when you are planning how to tackle whatever weather you can see ahead and when it is not necessary yet to divert or climb, it is still a request and ATC will grant or deny depending on the traffic situation. ATC now know what you want to do and why and they will let you do it as soon as they can. If you get to the point that you must take action then you can use the magic word “require” and hope they get the hint or to make things absolutely clear you can call a “mayday” or “pan pan”* and just do what you need to do.
It is also not known that they were actually in a storm. We know there were storms around and that they were diverting around one or more storms but we don’t know they actually flew into one.
QZ8501 had requested deviations, received clearance, and were some distance off track when the accident happened. They had also requested climb, but we don’t know why (at least I don’t know). Was it a routine climb in accordance with their flight plan so they could save a bit of fuel? Was it a comfort climb to try and find a smoother level for the passengers? Was it a convenience climb so they could get a look at the cloud tops and get more information about the weather around them? Or was it some kind of emergency climb?
I don’t know why they wanted to climb. I do know that I am not aware of any reason you would need to do an emergency climb, an emergency descent maybe, but a climb?
Back to the OP’s question. It is reasonable to ask “why didn’t they just climb?” because doing what you want is a valid response to an emergency, the broad answer is that they presumably didn’t have any emergency that required climbing.
- A Pan call is an ICAO recognised declaration of “urgency”, it means you require priority but it is a step below a mayday and does not indicate an immediate danger to life. It is not used much in the USA AFAIK.
While we don’t know why they requested a climb we do know 4 things: they were maneuvering around weather, There were no transmissions after being denied a request to climb, The plane disappeared from radar soon after the last transmission, and the plane is at the bottom of the ocean.
It sounds like a weather related event at this point.
Right now they are speculating that ice caused engine damage.
Call me skeptical for that being the whole explanation. It doesn’t really match what is known. Icing or hail could certainly take out one or more engines in the right circumstances but it doesn’t explain why the plane came almost straight down. It also doesn’t explain why the pilots did not make any emergency calls. Losing the engines is certainly a bad situation but an airliner has a glide capability of well over 50 miles at that altitude and closer to 100 miles give or take under favorable conditions.
If engine loss was all that was going on, they would have tried to divert to the nearest airport and may even have made it because land wasn’t that far away from the most likely crash site. In any event, they would have had plenty of time to make Mayday calls and attempt some type of emergency landing if multiple engine failures were the main issue.
Small disagreement: I’ve been diverted around storms many times by ATC; either through a “There’s convective activity ahead-how’s it looking for you?”, followed by them asking me if I want to deviate or them putting me on another airway, and I’ve had Approach take me around t-storms dozens & dozens of times when I was stationed in Central Florida. I agree with everything else in your post, though.
I’d be interested to read the CVR transcript. I’ve flown through heavy weather a few times for work (picked thru outer and middle bands of hurricanes and same with thunderstorms) and had my altitude “changed” by nature a few times, as well, where I lost or gained 1000+ feet in a few seconds and had to let ATC know what happened. I’ve also diverted quickly due to an embedded storm and called ATC afterward, with no repercussions. Not much they really could have done to me anyway, though.
Yeah fair enough. Most of the times there’s been TS activity on the approach frequency it’s been a bit of a mutual decision: “Can you accept a heading of 120 for base?” “yes we can”, “do it” (paraphrased ;)), or more often it’s simply been holding somewhere. Enroute has always been dictated by the pilots though, in this part of the world at least (keeping in mind that Australia is largely unpopulated and a lot of enroute airspace has no ground based weather radar coverage so ATC have no idea what you are flying around other than what you tell them.)
Same. As usual the information coming from the media has been filtered several times and a lot of important information is lost in the filtering. I’d be interested to know the exact phraseology used when asking for climb as well as the CVR for that period.
Wind shear is a serious concern on final approach, when the plane is close to the ground and close to stall speed, leaving little time for recovery; I’m not aware of it being an issue for aircraft at high altitude and high speed, like QZ8501.
Deep stall was not an issue for AF447. It was certainly a high-alpha stall, but not “deep” in the sense that it was unrecoverable; it was held there by a constant control stick input, applied by the dim-witted copilot and unnoticed by the other cockpit crew members.
Passengers and crew have been severely injured and even killed by being tossed around inside the cabin during severe turbulence. However, apart from the wake turbulence that brought down AA587 (which had at least as much to do with the unusually aggressive sequence of rudder control inputs), the last time a commercial aircraft at altitude was brought down by severe turbulence was 1966.
I hope this is not hijacking the thread but popular mechanics did what I found to be an amazing write up on AF447 based on the translated CVR transcript.
You can find it at http://www.webcitation.org/63mlsUX81
you missed my point. what is billed as extreme turbulence on TV is not. It’s possible to fly into a storm that exceeds the structural limits of the plane.
If you slow down to your Va speed, then the wings will stall before the G load limits are exceeded, but you don’t want to stall either.
Pilots are also guilty of overstating the severity of turbulence. Everyone I’ve flown with has called moderate turbulence “severe”. It’s a bit like having the flu, if you think you have the flu then it’s probably just a cold, if you think you’re going to die, then yes, you have the flu. I’ve been in severe turbulence just once in my career. We entered a cloud bank containing thunderstorms (but weren’t flying into the thunderstorms themselves) and got a severe thumping that removed my headset and glasses and shook us so much we couldn’t see what instrument was what let alone read them. We turned around and got out of there. I’ve also been in a severe downdraught from inadvertently entering the top of a thunderstorm, but it wasn’t particularly rough, just gave us a very high rate of descent. I braced myself for the inevitable corresponding up-draught but the transition was quite smooth.
I suppose anything’s possible, but again, the last time this (in-flight breakup of a commercial airliner caused by turbulence) was believed to have happened was 1966 - and they’re not even certain about that one.
As a general rule, I propose the turbulence not be regarded as “severe” until such time as all the passenger’s meals are in the aisle.
When flying an instrument approach following a big iron that reports mild turbulence on the glide slop, be sure you are buckled up tight and all lose items are behind the cargo net.
That would cut down on the number of reports of severe turbulence, to be sure. I can’t recall the last time I’ve been served a meal on an airplane.
For the purposes of this rule, peanuts, pretzels, and soft drinks shall also be regarded as “meals.” 
The radar used by Center controllers is extremely lousy for weather returns. It can tell us that there is something there, but the exact position, altitude, intensity, etc is for the most part a mystery. There’s something like a 12-minute lag on it to boot. Actually issuing a vector “around” a displayed area of convective activity would, for all the controller knows, put the aircraft right into it. Many times when I’ve approved deviations around convective activity, when the pilot reports back on course and direct to their next fix they’ll fly right through the heaviest displayed area of convective activity and eschew the part that is showing nothing at all.
Perhaps they already were busy and all the spaces at the requested altitude were already full. I’m not sure about other countries, but when I’ve worked non-radar here in the US (such as over the ocean), the required separation for planes at the same altitude was ten minutes. You can’t just put someone up there at a whim; you have to ensure that he is ten minutes behind the plane in front of him, ten minutes ahead of the plane behind him, and ten minutes away from any plane in the altitudes he’ll go through on the way to the altitude he’s trying to get to. The pilot can ask for whatever he wants, and it’s the controller’s job to make sure that the plane will have the required separation. Sometimes the answer is going to be no.
Ex air traffic controller here, Oakland ARTCC, as well as a licensed ATP (air transport pilot)
Lot’s of blah blah blah in this thread.
My opinion is that the aircraft went into an extreme attitude, (probably weather induced) from which the 2 pilots were unable to recover.
The “ice in the engines” may or may not be anything. If the aircraft did ‘lose’ both engines, the plane is still capable of flying normally at its best engine(s) out glide speed. Engines don’t make aircraft point straight down.
Hopefully they’ll recover the data recorders and be able to find out more. The crew would have had available thunderstorm cell activity and intensity on their wx radar.
There won’t be anything definitive until the recovery of the recorders