The best solution I can think up (following Occam's Razor) is that there was an electrical fire in the plane, which originated in the radio and somehow spread to the radar. The pilots lose the radio first, try to make an emergency landing at the closest airport they can, but then lose the radar, which puts them completely blind, and they aim wantonly for land, not realising that they are slowly turning south, and further and further away from land.
-kizzap
The best solution I can think up (following Occam's Razor) is that there was an electrical fire in the plane, which originated in the radio and somehow spread to the radar. The pilots lose the radio first, try to make an emergency landing at the closest airport they can, but then lose the radar, which puts them completely blind, and they aim wantonly for land, not realising that they are slowly turning south, and further and further away from land.
-kizzapEven very hi-tech aircraft such as a B777 have a completely old school 'wet compass' that has no integration with any avionics. Apart from the lighting, it requires no electricity and it cannot fail.
All pilots know how to read a compass.
It is that little box at the very top of this image:
http://farm3.static.flickr.com/2031/2264742995_e10991959b.jpg
The best solution I can think up (following Occam's Razor) is that there was an electrical fire in the plane, which originated in the radio and somehow spread to the radar. The pilots lose the radio first, try to make an emergency landing at the closest airport they can, but then lose the radar, which puts them completely blind, and they aim wantonly for land, not realising that they are slowly turning south, and further and further away from land.
-kizzapEven very hi-tech aircraft such as a B777 have a completely old school 'wet compass' that has no integration with any avionics. Apart from the lighting, it requires no electricity and it cannot fail.
All pilots know how to read a compass.
It is that little box at the very top of this image:
http://farm3.static.flickr.com/2031/2264742995_e10991959b.jpg
Even very hi-tech aircraft such as a B777 have a completely old school 'wet compass' that has no integration with any avionics. Apart from the lighting, it requires no electricity and it cannot fail.
All pilots know how to read a compass.
It is that little box at the very top of this image:
http://farm3.static.flickr.com/2031/2264742995_e10991959b.jpg
I think it also has backup insturments independent of the computers like an altimeter, a heading indicator, attitude indicator and an airspeed indicator. But I don't know if the 777 has all of these. It should, I guess.
The best solution I can think up (following Occam's Razor) is that there was an electrical fire in the plane, which originated in the radio and somehow spread to the radar.
Indeed the B777 does have backup primary flight instruments (airspeed, altitude, attitude). These do have independant sensor inputs and dedicated displays. However, in the B777 they still require electricity to function and although they do operate off the standby bus (which is powered by the battery and ram air turbine), if the worst case does happen with the power supply (bus short or open circuit, eg; fire in equipment bay), then these displays will cease to function, unlike the wet compass.
Damn, Australia... AC/DC *and* the CVR. Next, you're going to be telling me that Australia gave the world the SCRAM jet or box wine.
....Although if that was the case, then I'm surprised it apparently flew so far? As I presume if there was no computer left to drive the hydraulics to the control surfaces to keep it level, then a plane would crash pretty quickly?
So, as long as the aircraft remained clear of thunderstorms/convective turbulence and jetstream related clear air turbulence, I can conceive it remaining in the air for many hours with no active control, although it will wander up and down and left and right. Essentially the natural aerodynamic forces of a well designed aircraft provide a negative feedback loop.
Roll stability is provided by the dihedral of the wings (upward bending). Many aircraft are fairly neutral in roll stability and a large gust upset can lead to a roll angle that won't naturally restore (typically > 5 or 10 degrees), leading to what is known as 'the graveyard spiral'. But since a B777 has a very flexible wing and a lot of dihedral in cruise, I suspect that a B777 has quite a strong dihedral effect/roll stability.
Roll stability is provided by the dihedral of the wings (upward bending). Many aircraft are fairly neutral in roll stability and a large gust upset can lead to a roll angle that won't naturally restore (typically > 5 or 10 degrees), leading to what is known as 'the graveyard spiral'. But since a B777 has a very flexible wing and a lot of dihedral in cruise, I suspect that a B777 has quite a strong dihedral effect/roll stability.
Airplanes have no natural roll stability with respect to the ground. Dihedral only functions in what is called 'uncoordinated flight' which deals with the orientation of the aircraft with respect to the relative air stream. Dihedral is added to make airplanes 'easier' to fly, not to give them self-righting ability.
Aerodynamics for Navy Aviators (PDF)
http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/00-80T-80.pdf
pg 300: "If the airplane is unrestrained and sideslip is allowed, the affect of the directional stability and dihedral effect can be appreciated."
Also "graveyard spirals" are a pilot induced phenomena. They have nothing to do with the stability analysis of an aircraft. Ironically, they occur precisely because pilots are not trained to understand and respond to the inherent lack of roll stability found in all airplanes.
Anyway, the point I was trying to make is that any aircraft's intrinsic natural positive stability (unstable fighters excepted) makes the immediate "stall, spin, crash, burn, die" event unlikely - especially for an airliner where maneuverability is not a high priority and even more so in smooth air.
Perhaps the stupidest questions of the day.
- If a pilot turns on the autopilot, is that a single button affair? Could it be invoked by anyone to maintain level flight?
- Is the Autopilot the same as the Flight Management System (I'm thinking no)?
You're correct with respect to an aircraft's pitch attitude. Most airplanes (including most fighters) exhibit a natural pitch stability which extends to all modes of flight -- normal, stalled, and spinning. Some modern designs (namely UVA's) are unstable in pitch which makes them more maneuverable and more efficient to operate but more difficult to control. You either need special training (e.g. the Wright Flyer) or a sophisticated computer aid to fly a pitch-unstable airplane.
But, again, airplanes have no stability in roll. Some can be highly damped, which is what you are talking about. But no airplane is self-righting in roll. A control loop must be added to keep the plane's wings level -- the pilot looking at the horizon, the pilot looking at the gyroscopic instruments, or an autopilot.
But back to the point about MH370 zombie'ing across the Indian Ocean -- no pilots and a broken control system. 1) The engines would probably keep turning. I'm not familiar with the engines on MH370, but in general turbines are designed to fail in the 'on' direction under the notion that more thrust is better than no thrust. 2) The plane probably wouldn't stall. As we've both noted, most airplanes have a natural pitch stability. So baring some extreme event -- like a thunderstorm -- I don't think it would stall. But... 3) Airplanes have no natural roll stability. How far a plane could get without functional feedback (e.g. autopilot or roll control surfaces) is a matter of statistics. But for light aircraft flying in convective conditions accident studies have shown it to be 178 seconds (oddly specific huh?).
How far could MH370 in such a condition? Its anybody's guess, but its not on the order of 'hours'. Personally, I'd put the mark at ones to tens of minutes. If it flew for any longer than this, something on board the plane was keeping the wings level.
Perhaps the stupidest questions of the day.
- If a pilot turns on the autopilot, is that a single button affair? Could it be invoked by anyone to maintain level flight?
- Is the Autopilot the same as the Flight Management System (I'm thinking no)?
Ok, so you'd use the autopilot to give yourself time to evaluate the problem (if possible).
So how would you evacuate smoke from the aircraft? Switch off potential causes, lower the altitude so the air is breathable when the masks run out. Then what? Not like you can open a window.
I was in a training situation years ago with full face protection and an air tank, the room was so full of smoke I couldn't see my hand 2 inches from the mask. Even so I was barely able to see for the next 10 minutes (and I had full face coverage), I could imagine without eye protection you'd be in real trouble.
Today (in the US), NPR aired an interview with Richard Branson and the CEO of Delta:
http://www.npr.org/2014/04/03/298779764/transatlantic-duo-looks-into-the-future-of-flight?ft=1&f=1006
They were asked about transponders and ELT's -- specifically why after 9/11 nothing was done to improve the technology of either. They didn't mention ADS-B, but I think the intent of the questions was more about how we can loose a plane with our current state of technology.
Does anyone know if MH370's ELT was set up to broadcast on 121.5Mhz or did they dump that completely in favor of 406?