I am not an aerospace engineer, never claimed to be an engineer, so I can't speak to the design of the system.
From a pilot's perspective I think persuading/begging folks in industry to come up with a solution is a worthy pursuit.
You can't tell me there's nothing that can be done. Much greater difficulties have been overcome. The Colgan flight's wing stall system worked and they were accreting ice. How about a tail AOA indicator? I don't buy the idea we resign so easily.
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Having an AOA indicator or something like it on the tail wouldn't help, heated or not, because the real threat of the tail stall comes from an iced up tail that will stall at an unknown angle of attack. You would have to have some kind of system to detect the disrupted airflow below the horizontal stabilizer due to an impending stall.
At any rate, though, I'm not really convinced that it's a necessary indicator. It would make more sense to me to have better indictations of how much and what kind of ice is building on the surfaces of the aircraft, that way you would get an early warning of a dangerous situation before you were chin deep in it.
That might give us a way to quantify how much ice is acceptable, also. Right now we have no quantitative measure for how much ice we can consider safe, and when we need to start looking for other options.
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The Colgan flight's wing stall system worked and they were accreting ice. How about a tail AOA indicator?
It appears you do not understand how stall warning systems work.
The Colgan flight's stall warning worked (only to be overridden) because there actually wasn't enough ice that night to change the stall AOA of the wing by any measurable amount.
Stall warning systems are triggered to go off at a pre-determined AOA, based on the design stall AOA of the wing.
Once the wing becomes contaminated, it no longer stalls at its design AOA. A badly iced up airplane can stall well before any shaker/pusher action.
What you are suggesting is the invention of a totally new system that can determine the stalling AOA of an airfoil on the fly, and generate a warning prior to reaching this AOA. It would be great if you can manage that, but its a lot more complicated than sticking a AOA vane on the tail and wiring a buzzer in the cockpit.
It appears you do not understand how stall warning systems work.
It appears you don't understand how stall warning systems work. Depending on your equipment, with ice protection selected the stall warning system will automatically trigger at lower AOA. Thus corresponding to the fact that an airfoil stalls at a lower AOA when contaminated.
In theory, sharper objects accrete ice more quickly, thus the tail could be particularly vulnerable (type of aircraft dependent). I'd honestly hate to be put in the situation where I'm not 100 percent confident in which type of stall may be imminent.
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They INCORRECTLY reacted to a WING STALL AURAL WARNING, STICK SHAKER, and STICK PUSHER.
Now please tell me, how in the heck would a tail ice warning / tail stall warning device would have prevented this accident? IT WOULDN'T because in the same situation, they would have the same indications that they received.
In NASA's video on tail plane icing, do they ever mention traditional stall warning devices going off? No.
Even after the crew abruptly pulled up and applied power, they didn't exactly perform a tail plane icing recovery correctly. Why didn't they notice they were too slow? We will never know.
To the best of my knowledge, we haven't lost one airliner (ok, maybe there is one somewhere) to tailplane icing. On my list of threats, it is relatively low. However, I've seen the NASA video and as such, if my yoke starts doing something funky associated with a pitch over tendency, I will revert to what I saw in the NASA video. However, if the stall warnings go off and my airspeed is slow, I certainly hope that I react accordingly.
The evidence does point to a plain old wing stall versus tail stall, but what did the crew think was happening? Most importantly can we prevent other crews from thinking the wrong thing?
I just read an article that said the captain had watched NASAs icing video a few months previously. And for anyone who has watched that video, a large segment is dedicated to tail stalls.
I know particularly the video discusses a sign of tail stall is buffet in the controls versus an airframe buffet. Did the pilot confuse the shaker with a control wheel buffet? I don't know. I think he is being written off as an idiot waaaay too easily from our spot here on terra firma.
God bless.
I think if you look into the warning systems, a regular stall has an aural warning, and a tail stall doesn't, which itself is a warning. If the plane buffets and stalls with no noise, it is likely a tail stall. It takes more thought to decipher, but if you think about it before you get into ice, you have a better chance of telling one from the other. This is not 100%, as another poster said, the AOA vane or whatever system may be less accurate in icing conditions.
KC10 DO YOU NEED TO WRITE IN ALL CAPS? THAT'S LIKE SHOUTING.
What am I saying that is so damn offensive that folks are taking this personally? When have I been uncivil?
-Break-
I also find this curious- beaten into my head is that sharper objects acrete ice faster. The research backs this up. But yet tail stalls really haven't been much of an issue, while the wing has been. This seems to contradict that the tail will be collecting ice at a higher rate. Why is this?
Also, Left Handed, thank you for your input.
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Depending on your equipment, with ice protection selected the stall warning system will automatically trigger at lower AOA.
Well in this case then wouldn't you be already aware that your surfaces are iced up? And this lower AOA trigger is simply another pre-determined value based on a pre-determined amount of ice left over from the ice protection. What additional information are you gaining exactly?
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This is not only unrealistic, but it's like saying we need a anti-float warning so when we land we know when the planes going to float/balloon/etc..
Ironically, there is such a system out there. It's called the Pilot, and the Pilot must be properly trained, with the useful knowledge required to complete the job safely with good judgement. Lacking in any of these subject areas' can cause problems with 1/2 the cockpit working, if you are 0/2 in this case, the resulting events are catastrophic.
Nothing replaces actual real-life in the cockpit experience. Secondly, I know you can't always get all the experience in real life, so reading, learning, talking, and just generally educating yourself in the ways of our trade will make you a better pilot. There's people that just do the paces to get where they are going, and then there are those of us that dive in head-first. What type of pilot/person are you?
Finally, the whole "You are shouting because you type in CAPS" is juvenile. I feel it was appropriate in KC10's post because he's trying to get you to focus on the point at hand, that such a system, in your example, wouldn't do anything that the currently developed systems would accomplish. You are refusing to actually take in account his opinion because it disagree's with your vantage point.
*OFF SOAPBOX*
Everyone fly safe out there, the fun time of year is upon us.
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