Posted on 06/06/2009 5:29:56 PM PDT by george76
Why would it be necessary for the sensor pitot tubes to ice over? The navigation computer apparently uses three sets of tubes to monitor velocity components in three dimensional space. Lets assume horizontal flight during which the plane flies into a "micro burst" of several hundred mph downward. Would not that appear to the "Z" axis sensor as a rapid climb which would cause the autopilot to go hard over into a dive, just exactly the wrong thing to do in a severe downdraft? I can not figure out how the system can differentiate between a speed signal generated by motion of the plane and one generated by the wind alone. Nor can I understand why they are not using inertial guidance which has no external sensors to confuse the issue.
Maybe I'm not seeing something obvious here, but it seems to me that a three axis system based on pitot tubes is almost certain to get bogus signals from external wind forces and icing can only make matters worse.
Regards,
GtG
The airlines refuse to make all their aircraft bright orange.
Retrofit costs or technology costs? Or bot
Prayers for the families.
Then they'd have to search for the entire plane. (Yes, I know it's a joke.)
They normally make sounds underwater so they can be found.
I do wonder though if they can take the likely water pressures involved. Anything with voids or that is compressible will be utterly crushed at that depth.
“What about the French subs? Why do we have to do it? “
You know the answer. Because no one else can get it done.
One theory holds that in this very tall 50k' storm, there may have been a hail "nursery" that they flew into. In theory, all the pitot tubes from one side could have been damaged or blocked but not the other side.
Airspeed is critical for control at that altitude and on that Airbus, cannot exceed .8 mach. If auto pilot erroneously increased air speed, the plane would quicky stall and then spiral dive.
Late at night, one pilot asleep, computer dampening any needed correction, a layering of faults. That is the key in accident investigation, unforseen layering of problems.
Pilots are warned not to believe disagreeing speed indicators but switch over to their backup GPS speed indicators. If that wasn't done, and pilots increased speed manually by mistake, a nose up stall.
When to believe and not believe instruments is the critical judgement of pilots and the cause of most accidents. Flying at night, autopilot, no visual references, sleepy tired.....pilot error.
One issue I have with fly-by-wire is that there is no "push-back" from the throttle levers, no tactile sense of turbulence or engine strain.
You are correct about the inertial guidance and GPS back up systems, they are available....if the pilots use and believe them.
If it is as deep as they say, the batteries and electronics may have been crushed by the extreme pressures at that depth.
Retrofit costs. The airframe has to have a hole cut in it for an ejection port, very spendy.
The idea is that the “black boxes” are supposed to stay attached to the aircraft; not go drifting off into the sunset.
But as we all learned in school, correlation does not imply causation.
Our hydrophones are much more sensitive. At 500 foot depth, we can tell how hard it is raining on the surface by the "loudness" of the raindrops hitting the water, that we can distinguish from the sound of the waves and wind. Very crispy.
A sonic beacon transponder transmitting at a known frequency, no problem from at least 50 miles. Two or three subs and you are triangulated very quickly. If the black boxes are pinging we're on them already.
Also, the speed indicators on the instrument panel of this aircraft were ordered to be replaced on April 27 because of this same problem and the work was to be done upon landing, oops.
Don't tempt them to surrender to the waves, traveling on the surface is challenging enough.
The pitot-based system cannot. It measures speed relative to the air, not ground speed. Again, the pitot A/S sensors are used for fly-by-wire FLIGHT-CONTROL, not nav.
Inertial-guidance has been used for a long time for navigation. However, the gyros drift and the 'fix' needs to be corrected frequently. GPS is preferred for navigation.
A stall occurs when the airspeed is too LOW, not when it is increased. If the airspeed exceeds Vne, the plane will start to break apart, due to the air-flow induced forces on tail and/or wings.
Obama emasculated the United States and undermined Israel beyond anything the terrorist could have wished for. If Obama had not gushed, then they’d claim credit.
We’re back to the Clinton era. They’ll get four-five attacks without any notable response. Biden warned us of as much. This is how it will go, so long as the MSM keeps its absolute allegiance to Obama.
Else Obama needs to wag the dog => Obama doesn’t take criticism well, but then what Marxist does.
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