21st century instrumentation
Barking Mad, re, "Why are so many on this forum obsessed with new shiny hardware solutions which will not be fitted to ALL airframes til long after the next few high-altitude LOC accidents?"
Not only will they not be fitted for years, but the instrumentation is already available and installed. The key is in knowing one's aircraft and systems and using them correctly, bearing in mind that no installation is perfect in preventing accidents.
Let us look at some of the examples which may be driving this desire for "new" instrumentation, and why I think that such a drive is focussed in the wrong direction.
AF447
The key to AF447 as we know was to "do nothing", except maintain thrust and pitch attitude. The airplane was already stable; a loss of airspeed indication does not affect airflow over the wings or engine thrust.
Some systems will be lost of course. In such a case, one must slow down, respond with measured actions, then first of all aviate which means stabilized the airplane, (even if here, that meant "doing nothing"), then deal with the ECAM or EICAS and the loss of airspeed indication(s), for which there is the UAS drill including Airbus directions as to when to apply the "flight not at risk" section of the UAS drill, (which states that pitch and power must be maintained and not changed, while values for those two metrics are looked up in the QRH).
A loss of airspeed indication at cruise altitude, in and of itself, does NOT put flight at risk and it is NOT an emergency - it is an abnormal. Thirty-one other A330 crews faced this problem successfully. I would not say the "cause" was the loss of speed information but the absence of SOPs and cockpit discipline. No set of new technical gear or software is going to fix what was/is a training and checking matter.
UPS1354
If "new, improved" instrumentation is desired we might include something that may have prevented for example, the UPS A300 accident at Birmingham - a "side-view" of the approach showing the aircraft's actual height above ground, with a display of actual terrain, (from the EGPWS database).
Certainly there was crew fatigue involved and FAA regulations which do not consider cargo aircraft crews as susceptible to fatigue like passengers crews are. But the fact remains that non-precision approaches such as the one which resulted in this accident (because the crew was late in getting the GNSS approach in and the airplane didn't capture it), are higher-risk approaches, and a "side-view" horizontal situation would have made a difference, particularly if predictive arcs were present much as they are in the NAV displays of the B767/B777/Airbus series, etc. when descending to a set altitude.
Airbus BUSS
The Airbus "BUSS", (Backup Speed System) only works at/below FL250 due to Mach Number effects on stall AoA, (which are much lower at cruise Mach Numbers). One must still know the drills and know one's airplane.
As an aside, it will be well worth establishing why the QZ8501 crew was not able to recover a very-likely-stalled aircraft. What was unavailable to this crew and what did they do to try to recover? AF447 was recoverable with sustained, (about 50"), full-ND stick, even moreso in lower, thicker air. (I'm not re-arguing anything here, just trying to understand why the notion of "new" technology has legs.
Not only will they not be fitted for years, but the instrumentation is already available and installed. The key is in knowing one's aircraft and systems and using them correctly, bearing in mind that no installation is perfect in preventing accidents.
Let us look at some of the examples which may be driving this desire for "new" instrumentation, and why I think that such a drive is focussed in the wrong direction.
AF447
The key to AF447 as we know was to "do nothing", except maintain thrust and pitch attitude. The airplane was already stable; a loss of airspeed indication does not affect airflow over the wings or engine thrust.
Some systems will be lost of course. In such a case, one must slow down, respond with measured actions, then first of all aviate which means stabilized the airplane, (even if here, that meant "doing nothing"), then deal with the ECAM or EICAS and the loss of airspeed indication(s), for which there is the UAS drill including Airbus directions as to when to apply the "flight not at risk" section of the UAS drill, (which states that pitch and power must be maintained and not changed, while values for those two metrics are looked up in the QRH).
A loss of airspeed indication at cruise altitude, in and of itself, does NOT put flight at risk and it is NOT an emergency - it is an abnormal. Thirty-one other A330 crews faced this problem successfully. I would not say the "cause" was the loss of speed information but the absence of SOPs and cockpit discipline. No set of new technical gear or software is going to fix what was/is a training and checking matter.
UPS1354
If "new, improved" instrumentation is desired we might include something that may have prevented for example, the UPS A300 accident at Birmingham - a "side-view" of the approach showing the aircraft's actual height above ground, with a display of actual terrain, (from the EGPWS database).
Certainly there was crew fatigue involved and FAA regulations which do not consider cargo aircraft crews as susceptible to fatigue like passengers crews are. But the fact remains that non-precision approaches such as the one which resulted in this accident (because the crew was late in getting the GNSS approach in and the airplane didn't capture it), are higher-risk approaches, and a "side-view" horizontal situation would have made a difference, particularly if predictive arcs were present much as they are in the NAV displays of the B767/B777/Airbus series, etc. when descending to a set altitude.
Airbus BUSS
The Airbus "BUSS", (Backup Speed System) only works at/below FL250 due to Mach Number effects on stall AoA, (which are much lower at cruise Mach Numbers). One must still know the drills and know one's airplane.
As an aside, it will be well worth establishing why the QZ8501 crew was not able to recover a very-likely-stalled aircraft. What was unavailable to this crew and what did they do to try to recover? AF447 was recoverable with sustained, (about 50"), full-ND stick, even moreso in lower, thicker air. (I'm not re-arguing anything here, just trying to understand why the notion of "new" technology has legs.
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UPS1354
If "new, improved" instrumentation is desired we might include something that may have prevented for example, the UPS A300 accident at Birmingham - a "side-view" of the approach showing the aircraft's actual height above ground, with a display of actual terrain, (from the EGPWS database).
If "new, improved" instrumentation is desired we might include something that may have prevented for example, the UPS A300 accident at Birmingham - a "side-view" of the approach showing the aircraft's actual height above ground, with a display of actual terrain, (from the EGPWS database).
Denti - certainly the changes I mention are not necessary for safe flight. The original argument was "new-stuff = safer flight" and I don't agree with that premise - what we have is doing the job. Appreciate the feedback on the "side-view" tho'...I hadn't spoken to anyone who'd used the display.
Under the heading of "knowing one's airplane" and the fact that you say both are sufficient to fly safely, with which I agree, (I flew the A320/A330/A340 and they didn't have the "side-display" but it was never an issue), the argument for "new instrumentation" is to me, moot.
Out of interest, are you flying the classic or NG?
Under the heading of "knowing one's airplane" and the fact that you say both are sufficient to fly safely, with which I agree, (I flew the A320/A330/A340 and they didn't have the "side-display" but it was never an issue), the argument for "new instrumentation" is to me, moot.
Out of interest, are you flying the classic or NG?
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I started out on the classic (500/300) and then transitioned to a mix of classic and NG (700/800) until the classic was phased out. No we're phasing out the 737 altogether for the A320 which was our second fleet for the last 10 years or so anyway.
Most colleagues don't use the VSD (vertical situation display) much, but i grew accustomed to it and used it during approach and departure. It doesn't only provide a side view of the terrain, waypoints and restrictions, but an energy state view as well. And the added bonus is of course that one can have both a terrain and weather radar display at the same time, which is impossible with the usual depiction. Only downside is that the sideview of the terrain follows the current track, not the "magenta" line like it does on the 787.
I believe airbus copied that thing and it is available on the A380 and A350, but won't be retrofitted to the older planes. Then again, they all have very tiny screens to begin with and probably taking some away for a VSD wouldn't improve the overall display.
Most colleagues don't use the VSD (vertical situation display) much, but i grew accustomed to it and used it during approach and departure. It doesn't only provide a side view of the terrain, waypoints and restrictions, but an energy state view as well. And the added bonus is of course that one can have both a terrain and weather radar display at the same time, which is impossible with the usual depiction. Only downside is that the sideview of the terrain follows the current track, not the "magenta" line like it does on the 787.
I believe airbus copied that thing and it is available on the A380 and A350, but won't be retrofitted to the older planes. Then again, they all have very tiny screens to begin with and probably taking some away for a VSD wouldn't improve the overall display.
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IIRC, Embry-Riddle demonstrated use of GPS to determine attitude. I think they outfitted a single-engine Piper with GPS on nose/tail/wingtips. I don't remember results of study. The story I read was in AOPA magazine or AWST. It works well enough IIRC.
I think they outfitted a single-engine Piper with GPS on nose/tail/wingtips
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jtt, thank you for a very interesting reply and for helping me straight on that.
I'm not sure I understand your last about the speed not depending on the medium, or the source. If you could elaborate a little on that please? In the case of pings, say nose to tail, if the temp and density of the medium, air, is known, would comparing the time difference between the expected static speed of sound in air at that density vs the measured speed of the ping give us the speed of the medium? Which is the airspeed?
Thanks for your input
I'm not sure I understand your last about the speed not depending on the medium, or the source. If you could elaborate a little on that please? In the case of pings, say nose to tail, if the temp and density of the medium, air, is known, would comparing the time difference between the expected static speed of sound in air at that density vs the measured speed of the ping give us the speed of the medium? Which is the airspeed?
Thanks for your input
The radome of an airliner is attached to the fuselage with a number of fixings, (four?). If each of these incorporated a strain gauge, then the dynamic pressure of the air on the radome as a consequence of the forward motion of the aircraft could be measured and converted to an airspeed. In theory, this system would be immune to icing and insects etc., since there would be no holes or pipes which are prone to blockage.
And/or you might be able to make a similar measurement on the slats, or the fin mountings.
I wonder if this would be accurate, sensitive and stable enough to give a useable IAS readout?
And/or you might be able to make a similar measurement on the slats, or the fin mountings.
I wonder if this would be accurate, sensitive and stable enough to give a useable IAS readout?
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I'm not sure I understand your last about the speed not depending on the medium, or the source.
The problem I see is that the speed of sound depends on (at least) three things: the temperature of the medium, the pressure and the its composition. Temperature and pressure already get measured (but I don't know if the precision would be sufficient). But you also need to know the amount of moisture in the air (or even if there are water droplets). And that might be harder to measure, especially if flying into and out of clouds at rather high speeds. Where such a device might come handy would be in situations where there are conditions leading to the pitot tubes clogging up with ice, i.e. conditions where there's quite a bit of moisture (perhaps super-cooled water?). And measuring reliably and with sufficient speed the exact composition of the air you're moving through to arrive at a good enough estimate of the local value of the speed of sound might pose a bit of a problem.
One possible solution might be to measure the speed of sound directly and independently by having another "pinging" device perpendicular to the direction of flight (assuming that cross winds aren't too large to mess up everything). I.e., measure, for example, the time it takes a ping from the tip to the root of the wing to arrive at an estimate for the speed of sound at that moment and use this for calculating the speed of air in the direction of flight. Unfortunately, that could make the device twice as expensive (and double the likelyhood of failures;-)
