# Pilots, why didn't Air Asia QZ8501 just change altitude? **URL:** \ **Category:** Factual Questions\ **Created:** [January 1, 2015, 9:18pm UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711 "2015-01-01T21:18:54Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [January 3, 2015, 9:37am UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/21 "2015-01-03T09:37:27Z")
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. ---
**Author:** ![Sodalite](https://avatars.discourse-cdn.com/v4/letter/s/34f0e0/32.png) [@Sodalite](https://boards.straightdope.com/u/Sodalite)\ **Post date:** [January 4, 2015, 5:32am UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/22 "2015-01-04T05:32:53Z")
> [@Richard\_Pearse](#): > > It’s a reasonable question and is more akin to a driver steering across multiple lanes in order to avoid an accident. > > There are times when you ignore ATC and do whatever you need to avoid crashing or an unacceptably unsafe situation. Things we practice regularly that include this type of action are wind-shear escape manoeuvres, TCAS alert manoeuvres, and emergency descents. In each of those cases you fly the aeroplane out of the unsafe situation and advise ATC, and/or other traffic, of what you are doing. There are even specific phrases we use to let ATC know that we have taken full responsibility for our flight path. > > Lets be clear that it’s not something done as a convenience such as cutting across 4 lanes to make a highway exit, they are emergency procedures to keep your aircraft safe. There are also things you do to mitigate the risk of the manoeuvre. In the case of an emergency change of levels, you can turn off the airway. Any traffic would most likely be directly above or below you so a turn to get off the airway laterally will reduce the chance of a collision. In the case of a TCAS manoeuvre the altitude deviation is normally no more than 500 feet so you shouldn’t come into conflict with other traffic. 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. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [January 4, 2015, 6:13am UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/23 "2015-01-04T06:13:10Z")
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. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [January 4, 2015, 6:57am UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/24 "2015-01-04T06:57:43Z")
> [@Sodalite](#): > > 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. 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. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [January 4, 2015, 9:51pm UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/25 "2015-01-04T21:51:15Z")
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. ---
**Author:** ![chiroptera](https://avatars.discourse-cdn.com/v4/letter/c/df705f/32.png) [@chiroptera](https://boards.straightdope.com/u/chiroptera)\ **Post date:** [January 4, 2015, 9:54pm UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/26 "2015-01-04T21:54:46Z")
Right now they are speculating that [ice caused engine damage](http://news.yahoo.com/weather-triggering-factor-airasia-crash-govt-agency-020340130.html). ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [January 4, 2015, 10:19pm UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/27 "2015-01-04T22:19:06Z")
> [@chiroptera](#): > > Right now they are speculating that [ice caused engine damage](http://news.yahoo.com/weather-triggering-factor-airasia-crash-govt-agency-020340130.html). 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. ---
**Author:** ![CGav8r](https://avatars.discourse-cdn.com/v4/letter/c/34f0e0/32.png) [@CGav8r](https://boards.straightdope.com/u/CGav8r)\ **Post date:** [January 5, 2015, 2:15am UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/28 "2015-01-05T02:15:17Z")
> [@Richard\_Pearse](#): > > 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. 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. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [January 5, 2015, 7:18am UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/29 "2015-01-05T07:18:32Z")
> [@CGav8r](#): > > 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. 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.) > [@](#): > > 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. 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. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 5, 2015, 2:05pm UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/30 "2015-01-05T14:05:14Z")
> [@Shagnasty](#): > > If you are going slow enough in an airliner and encounter severe wind shear in a thunderstorm (abrupt change in air speed due to changing winds), that can be enough to put the aircraft in a very deep stall that makes the control surfaces ineffective, destroys lift from the wings and makes the aircraft do what gravity wanted it to do all along. [Wind shear is a serious concern on final approach](http://en.wikipedia.org/wiki/Wind_shear#Impact_on_passenger_aircraft), 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](http://en.wikipedia.org/wiki/Deep_stall#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. > [@Magiver](#): > > 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. 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](http://en.wikipedia.org/wiki/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.](http://en.wikipedia.org/wiki/BOAC_Flight_911) ---
**Author:** ![chargerrich](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chargerrich/32/5399_2.png) [@chargerrich](https://boards.straightdope.com/u/chargerrich)\ **Post date:** [January 5, 2015, 3:48pm UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/31 "2015-01-05T15:48:21Z")
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](http://www.webcitation.org/63mlsUX81) ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [January 6, 2015, 12:29am UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/32 "2015-01-06T00:29:28Z")
> [@Machine\_Elf](#): > > 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](http://en.wikipedia.org/wiki/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.](http://en.wikipedia.org/wiki/BOAC_Flight_911) 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. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [January 6, 2015, 12:38am UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/33 "2015-01-06T00:38:25Z")
> [@Magiver](#): > > 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. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 6, 2015, 12:56pm UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/34 "2015-01-06T12:56:48Z")
> [@Magiver](#): > > 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. 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. > [@Richard Pearse](#): > > Everyone I’ve flown with has called moderate turbulence “severe”. 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.](https://www.youtube.com/watch?v=rB71t0-xAFY) ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [January 6, 2015, 5:30pm UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/35 "2015-01-06T17:30:36Z")
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. ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [January 6, 2015, 5:45pm UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/36 "2015-01-06T17:45:59Z")
> [@Machine\_Elf](#): > > 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.](https://www.youtube.com/watch?v=rB71t0-xAFY) 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. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 6, 2015, 6:04pm UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/37 "2015-01-06T18:04:30Z")
> [@MikeS](#): > > 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.” 😉 ---
**Author:** ![wake\_turbulence](https://avatars.discourse-cdn.com/v4/letter/w/bc8723/32.png) [@wake\_turbulence](https://boards.straightdope.com/u/wake_turbulence)\ **Post date:** [January 13, 2015, 10:12am UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/38 "2015-01-13T10:12:39Z")
> [@CGav8r](#): > > 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. 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. ---
**Author:** ![wake\_turbulence](https://avatars.discourse-cdn.com/v4/letter/w/bc8723/32.png) [@wake\_turbulence](https://boards.straightdope.com/u/wake_turbulence)\ **Post date:** [January 13, 2015, 10:19am UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/39 "2015-01-13T10:19:58Z")
> [@Quartz](#): > > So what? The pilot is the one on the scene; ATC are not. If there’s heavy traffic at the required altitude then surely ATC need to get busy? 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. ---
**Author:** ![cmdrpiffle](https://avatars.discourse-cdn.com/v4/letter/c/b4bc9f/32.png) [@cmdrpiffle](https://boards.straightdope.com/u/cmdrpiffle)\ **Post date:** [January 13, 2015, 7:52pm UTC](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711/40 "2015-01-13T19:52:24Z")
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 [Previous page](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711.md?page=1) [Next page](https://boards.straightdope.com/t/pilots-why-didnt-air-asia-qz8501-just-change-altitude/708711.md?page=3)