PowerFlarm and ADS-B solution, can we find one?

On Saturday, January 9, 2016 at 7:30:48 PM UTC-5, jfitch wrote:
On Saturday, January 9, 2016 at 12:08:39 PM UTC-8, XC wrote:
SNIPLet's make sure these numbers are based on some evidence.

Based on evidence presented so far, we don't even have a need for a stealth, so that is an odd statement.

The 5 second TCAS has got to be a minimum, panic mode number. Also do not just consider the case of one glider meeting one glider. Consider 5 gliders meeting 5 gliders. No longer can you just turn right or pull up, doing so may well cause an accident rather than prevent one.

More details about TCAS for comparison:

5 sec. is the maximum expected reaction time for a warning or RA. That is with the autopilot engaged and the pilot not actively engaged on the flight controls. The anticipated reaction time to reverse, increase or decrease vertical speed once the pilot is flying the machine is 2.5 sec.

"Initial vertical speed reaction to a RA is expected within 5 seconds; maneuvering G forces should be similar to those felt when responding to an ATC clearance to climb or defend "immediately" (+/- 0.25 G change in load factor)." That doesn't sound too panicked.

The TCAS display is selectable Above/Norm/Below. My company recommends normal in all phases of flight which gives +/- 2700 ft on the display. This is for aircraft capable of climbing or descending 6000 ft/min. "Above" can be selected in the climb which would give a view of aircraft 7000 ft above and 2700 ft below.

Now this is a different system, I understand, but my point is that it is not cross referenced continuously as a source of SA. Rather, it is an alert system that provides traffic advisories (TA) as aircraft are getting to be a factor ("Traffic") and resolution advisories (RA) ("Traffic, Climb/Descend)"when action is required by the pilot. The audio alerts and warnings have priority and have been determined to be more effective than the instrument panel display for collision avoidance.

Similarly, displaying all traffic on FLARM at these greater distances and relative altitudes is not required for SA or collision avoidance. In fact, spending too much time looking down at the display may be contrary to safety.. Again, this discussion goes beyond collision avoidance and gets into pilots wanting to track other gliders for tactical reasons.

XC

XC,

Again, you assume the flawless function of the Flarm system. 25 seconds, if the Flarm "network" is not perfectly functional due to say structural interference, may be reduced to 5 seconds. Or zero. Arbitrary discussions about were "safety ends" and "philosophical Flarm fairness?" (whatever the hell this should be) begins has proven quite frightening to observe.

The longer the time period the Flarm has to make a potential warning (beep as "bogey" appears), the better. This is a fact (from a safety viewpoint). Artificial reductions in Flarms engineered performance potential will by definition also increase the odds of a dangerous situation occurring. While being far better than nothing, the Flarm network is still prone to regular coverage challenges and clearly does not have, perfect, 100%, 360 degree coverage at all times. Far, FAR from it.

We need to kill this whole idea for at least one year. It's out of control.. It is irresponsible (at best) to screw around with Flarms potential range at this point. The unintended consequences are potentially huge. The philosophical competitive "fairness" argument is simply no peer to safety. It's not even on the same planet as safety. Stop treating this discussion like this as a debate between equals. Start respecting the fact that Flarm, while valuable for safety, is far, far from perfect or infallible. So when you say a supposed time value that you find acceptable for your little crusade, imagine that the gliders 25 seconds away from a potential collision are not seeing each others antenna at 25 seconds for whatever reason. Or maybe you get a proximity "beep" and then lose coverage for 15 seconds.

Bottom line, some here care far more about philosophical fairness arguments than the significant safety value Flarm provides via its ability to create situational awareness for us. This crusade become an literal obsession for some.

I won't debate or compromise Flarm at this point until some sort of impartial, objective study (and extensive testing) has been completed. This was the requirement of my initial support for a limitation. Since then, the almost reckless abandon that many supporters (almost certainly coordinated in a pseudo RAS Flarm "mode" campaign) have demonstrated here is a real problem. The USRC opinion poll does not support this desperate position.

Perhaps the FAA should be involved. Has anyone discussed this topic with the FAA? I wonder what their take would be.

Sean

On Saturday, January 9, 2016 at 5:47:04 PM UTC-8, XC wrote:
On Saturday, January 9, 2016 at 7:30:48 PM UTC-5, jfitch wrote:
On Saturday, January 9, 2016 at 12:08:39 PM UTC-8, XC wrote:
SNIPLet's make sure these numbers are based on some evidence.

Based on evidence presented so far, we don't even have a need for a stealth, so that is an odd statement.

The 5 second TCAS has got to be a minimum, panic mode number. Also do not just consider the case of one glider meeting one glider. Consider 5 gliders meeting 5 gliders. No longer can you just turn right or pull up, doing so may well cause an accident rather than prevent one.

More details about TCAS for comparison:

5 sec. is the maximum expected reaction time for a warning or RA. That is with the autopilot engaged and the pilot not actively engaged on the flight controls. The anticipated reaction time to reverse, increase or decrease vertical speed once the pilot is flying the machine is 2.5 sec.

"Initial vertical speed reaction to a RA is expected within 5 seconds; maneuvering G forces should be similar to those felt when responding to an ATC clearance to climb or defend "immediately" (+/- 0.25 G change in load factor)." That doesn't sound too panicked.

The TCAS display is selectable Above/Norm/Below. My company recommends normal in all phases of flight which gives +/- 2700 ft on the display. This is for aircraft capable of climbing or descending 6000 ft/min. "Above" can be selected in the climb which would give a view of aircraft 7000 ft above and 2700 ft below.

Now this is a different system, I understand, but my point is that it is not cross referenced continuously as a source of SA. Rather, it is an alert system that provides traffic advisories (TA) as aircraft are getting to be a factor ("Traffic") and resolution advisories (RA) ("Traffic, Climb/Descend)"when action is required by the pilot. The audio alerts and warnings have priority and have been determined to be more effective than the instrument panel display for collision avoidance.

Similarly, displaying all traffic on FLARM at these greater distances and relative altitudes is not required for SA or collision avoidance. In fact, spending too much time looking down at the display may be contrary to safety. Again, this discussion goes beyond collision avoidance and gets into pilots wanting to track other gliders for tactical reasons.

XC

In searching for the best anti collision system, few people hold out TCAS as the ideal. I have heard much more criticism of it than praise, the latter usually confined to "it's better than nothing". This is why the regulators and industry worldwide are moving as fast as they possibly can towards ADS-B, a system much more like Flarm. Before we decide that the metrics of TCAS are ideal or even adequate, we should ask why that system is being discarded in favor of one that shows all aircraft within 15 miles, all the time: position, altitude, and tail number. Going by that metric, the FAA has already decided that 15 miles range is the right answer. Even at 1000 mph closing speed, 15 miles gives over 50 seconds warning. I propose 50 seconds is the best supported number.

On Saturday, January 9, 2016 at 11:07:04 PM UTC-8, jfitch wrote:
On Saturday, January 9, 2016 at 5:47:04 PM UTC-8, XC wrote:
On Saturday, January 9, 2016 at 7:30:48 PM UTC-5, jfitch wrote:
On Saturday, January 9, 2016 at 12:08:39 PM UTC-8, XC wrote:
SNIPLet's make sure these numbers are based on some evidence.

Based on evidence presented so far, we don't even have a need for a stealth, so that is an odd statement.

The 5 second TCAS has got to be a minimum, panic mode number. Also do not just consider the case of one glider meeting one glider. Consider 5 gliders meeting 5 gliders. No longer can you just turn right or pull up, doing so may well cause an accident rather than prevent one.

More details about TCAS for comparison:

5 sec. is the maximum expected reaction time for a warning or RA. That is with the autopilot engaged and the pilot not actively engaged on the flight controls. The anticipated reaction time to reverse, increase or decrease vertical speed once the pilot is flying the machine is 2.5 sec.

"Initial vertical speed reaction to a RA is expected within 5 seconds; maneuvering G forces should be similar to those felt when responding to an ATC clearance to climb or defend "immediately" (+/- 0.25 G change in load factor)." That doesn't sound too panicked.

The TCAS display is selectable Above/Norm/Below. My company recommends normal in all phases of flight which gives +/- 2700 ft on the display. This is for aircraft capable of climbing or descending 6000 ft/min. "Above" can be selected in the climb which would give a view of aircraft 7000 ft above and 2700 ft below.

Now this is a different system, I understand, but my point is that it is not cross referenced continuously as a source of SA. Rather, it is an alert system that provides traffic advisories (TA) as aircraft are getting to be a factor ("Traffic") and resolution advisories (RA) ("Traffic, Climb/Descend)"when action is required by the pilot. The audio alerts and warnings have priority and have been determined to be more effective than the instrument panel display for collision avoidance.

Similarly, displaying all traffic on FLARM at these greater distances and relative altitudes is not required for SA or collision avoidance. In fact, spending too much time looking down at the display may be contrary to safety. Again, this discussion goes beyond collision avoidance and gets into pilots wanting to track other gliders for tactical reasons.

XC

In searching for the best anti collision system, few people hold out TCAS as the ideal. I have heard much more criticism of it than praise, the latter usually confined to "it's better than nothing". This is why the regulators and industry worldwide are moving as fast as they possibly can towards ADS-B, a system much more like Flarm. Before we decide that the metrics of TCAS are ideal or even adequate, we should ask why that system is being discarded in favor of one that shows all aircraft within 15 miles, all the time: position, altitude, and tail number. Going by that metric, the FAA has already decided that 15 miles range is the right answer. Even at 1000 mph closing speed, 15 miles gives over 50 seconds warning. I propose 50 seconds is the best supported number.

Oh what a pile of utter nonsense. TCAS II *is* the gold standard in collision avoidance. ADS-B does not replace TCAS II in *any* way. Not a single FAA regulation currently or proposed allows for replacement of TCAS II mandatory carriage with any ADS-B product.

TCAS II is not being discarded/abandoned for anything, including ADS-B anything. There is no technology that uses ADS-B for active collision avoidance similar to TCAS available as any RTCA standard and so nothing that can be build and no research projects that could be turned into such a standards any time soon. So at best anything based on ADS-B would likely be decades away. I have now idea where you are getting this 15 miles from. The ADS-B ground services hockey-puck diameter? That really has no direct relevance to TCAS. It is a stopgap layered on a complex dual-link mess.

TCAS II version 7.1 (the current standard) makes use of ADS-B In data to reduce the activeTCAS II transponder interrogation rates and provide better long range tracking of targets (esp. without excessive RF congestion). These systems do not use ADS-B data to issue an RA, that is all determined by active TCAS II to transponder interrogation. One of the specific advantages of Change 7.1 ADS-B integration is improved long range (much longer than 15nm you mention) traffic display... which in USA Class A airspace they will be able to rely on every aircraft being quipped with after 2020.

So not a single thing you stated is correct.

On Sunday, January 10, 2016 at 12:57:03 AM UTC-5, smfidler wrote:
XC,

Again, you assume the flawless function of the Flarm system. 25 seconds, if the Flarm "network" is not perfectly functional due to say structural interference, may be reduced to 5 seconds. Or zero. Arbitrary discussions about were "safety ends" and "philosophical Flarm fairness?" (whatever the hell this should be) begins has proven quite frightening to observe.

The longer the time period the Flarm has to make a potential warning (beep as "bogey" appears), the better. This is a fact (from a safety viewpoint). Artificial reductions in Flarms engineered performance potential will by definition also increase the odds of a dangerous situation occurring. While being far better than nothing, the Flarm network is still prone to regular coverage challenges and clearly does not have, perfect, 100%, 360 degree coverage at all times. Far, FAR from it.

We need to kill this whole idea for at least one year. It's out of control. It is irresponsible (at best) to screw around with Flarms potential range at this point. The unintended consequences are potentially huge. The philosophical competitive "fairness" argument is simply no peer to safety. It's not even on the same planet as safety. Stop treating this discussion like this as a debate between equals. Start respecting the fact that Flarm, while valuable for safety, is far, far from perfect or infallible. So when you say a supposed time value that you find acceptable for your little crusade, imagine that the gliders 25 seconds away from a potential collision are not seeing each others antenna at 25 seconds for whatever reason. Or maybe you get a proximity "beep" and then lose coverage for 15 seconds.

Bottom line, some here care far more about philosophical fairness arguments than the significant safety value Flarm provides via its ability to create situational awareness for us. This crusade become an literal obsession for some.

I won't debate or compromise Flarm at this point until some sort of impartial, objective study (and extensive testing) has been completed. This was the requirement of my initial support for a limitation. Since then, the almost reckless abandon that many supporters (almost certainly coordinated in a pseudo RAS Flarm "mode" campaign) have demonstrated here is a real problem. The USRC opinion poll does not support this desperate position.

Perhaps the FAA should be involved. Has anyone discussed this topic with the FAA? I wonder what their take would be.


I was just pointing out some of the time values involved in operating with TCAS. I suspect that research was more extensive and the technology is more proven. Many TCAS resolution advisories occur before they are displayed as targets on the screen. The pilot's eyes are directed to the display (on the VSI in our case) to make a correction because it is a system used during IFR.

With FLARM the eyes are directed outside as they should be. The best way to do this is through the audio warning system. More could be done with this to improve safety. For example, there could be a warning "Multiple traffic, One o'clock high." This is another real suggestion that would enhance the FLARM system. The TCAS time values are real numbers to add perspective to the discussion.

XC

On Sunday, January 10, 2016 at 5:42:30 AM UTC-5, XC wrote:
On Sunday, January 10, 2016 at 12:57:03 AM UTC-5, smfidler wrote:
XC,

Again, you assume the flawless function of the Flarm system. 25 seconds, if the Flarm "network" is not perfectly functional due to say structural interference, may be reduced to 5 seconds. Or zero. Arbitrary discussions about were "safety ends" and "philosophical Flarm fairness?" (whatever the hell this should be) begins has proven quite frightening to observe.

The longer the time period the Flarm has to make a potential warning (beep as "bogey" appears), the better. This is a fact (from a safety viewpoint). Artificial reductions in Flarms engineered performance potential will by definition also increase the odds of a dangerous situation occurring. While being far better than nothing, the Flarm network is still prone to regular coverage challenges and clearly does not have, perfect, 100%, 360 degree coverage at all times. Far, FAR from it.

We need to kill this whole idea for at least one year. It's out of control. It is irresponsible (at best) to screw around with Flarms potential range at this point. The unintended consequences are potentially huge. The philosophical competitive "fairness" argument is simply no peer to safety.. It's not even on the same planet as safety. Stop treating this discussion like this as a debate between equals. Start respecting the fact that Flarm, while valuable for safety, is far, far from perfect or infallible. So when you say a supposed time value that you find acceptable for your little crusade, imagine that the gliders 25 seconds away from a potential collision are not seeing each others antenna at 25 seconds for whatever reason. Or maybe you get a proximity "beep" and then lose coverage for 15 seconds.

Bottom line, some here care far more about philosophical fairness arguments than the significant safety value Flarm provides via its ability to create situational awareness for us. This crusade become an literal obsession for some.

I won't debate or compromise Flarm at this point until some sort of impartial, objective study (and extensive testing) has been completed. This was the requirement of my initial support for a limitation. Since then, the almost reckless abandon that many supporters (almost certainly coordinated in a pseudo RAS Flarm "mode" campaign) have demonstrated here is a real problem. The USRC opinion poll does not support this desperate position.

Perhaps the FAA should be involved. Has anyone discussed this topic with the FAA? I wonder what their take would be.


I was just pointing out some of the time values involved in operating with TCAS. I suspect that research was more extensive and the technology is more proven. Many TCAS resolution advisories occur before they are displayed as targets on the screen. The pilot's eyes are directed to the display (on the VSI in our case) to make a correction because it is a system used during IFR.

With FLARM the eyes are directed outside as they should be. The best way to do this is through the audio warning system. More could be done with this to improve safety. For example, there could be a warning "Multiple traffic, One o'clock high." This is another real suggestion that would enhance the FLARM system. The TCAS time values are real numbers to add perspective to the discussion.

XC

Then point out all the time values not just the ones that seem to support your stance on stealth. TCAS Non threat traffic more than 6 miles away can be displayed to well over 40 miles away. Proximity intruder traffic less than 6 miles away fill in the diamond display(visual no audio) to get your attention and provide situation awareness to prevent surprise TA and RA alerts. Traffic Alerts (TA) for potential collisions will happen from 20-48 seconds to closest point of approach(collision) with a visual change to yellow diamond and audio "Traffic Traffic" Under normal conditions a TA will proceed an RA by 15 seconds which prepares the pilots for any required RA avoidance maneuver while giving time to acquire the target visually if possible.. Resolution Advisories (RA) which TCAS deems an imminent collision threat with a time of closest approach of 15-35 seconds warns with a red diamond visual cue and audio avoidance commands (Climb Climb Climb, Monitor Vertical speed etc...) as well as the required vertical speed required for the 5 second maneuver you posted.


TCAS uses these multiple steps of awareness from well over 40 miles away to try and prevent surprise RAs as well as to give crews the time required to scan visually for the traffic. I also find it very hard to believe there have been many instant RAs without the targets going through the normal threat scales of non threat, proximity, TA, RA, Clear of Conflict or at least some of them. Does it happen yes but it is not the norm.

To suggest that your eyes are inside looking at the TCAS only because you are IFR is misleading. It gives you the fastest way of locating the direction and altitude of the potential collision traffic so you can then start looking visually for the traffic if your not in clouds. No one using TCAS gets a pop up TA and starts randomly visually scanning the sky hoping to see the traffic. It takes much longer than looking at the TCAS visual display for a split second to find out where the traffic is then back outside to find it visually.

This is exactly the same method that FLARM uses with a scaled response to traffic threats as they get closer and are deemed a threat. Both TCAS and FLARM allow much better situational awareness of traffic. I would argue that FLARM stealth mode is exactly like the pop up surprise TCAS RA example you used. It should never happen as there is only 5 seconds to respond. TCAS users get the advantage of a computer giving an immediately calculated escape maneuver. FLARM users only have seconds to find the traffic visually to find out what to do.

On Sunday, January 10, 2016 at 6:45:59 AM UTC-8, Greg Delp wrote:
On Sunday, January 10, 2016 at 5:42:30 AM UTC-5, XC wrote:
On Sunday, January 10, 2016 at 12:57:03 AM UTC-5, smfidler wrote:
XC,

Again, you assume the flawless function of the Flarm system. 25 seconds, if the Flarm "network" is not perfectly functional due to say structural interference, may be reduced to 5 seconds. Or zero. Arbitrary discussions about were "safety ends" and "philosophical Flarm fairness?" (whatever the hell this should be) begins has proven quite frightening to observe.

The longer the time period the Flarm has to make a potential warning (beep as "bogey" appears), the better. This is a fact (from a safety viewpoint). Artificial reductions in Flarms engineered performance potential will by definition also increase the odds of a dangerous situation occurring. While being far better than nothing, the Flarm network is still prone to regular coverage challenges and clearly does not have, perfect, 100%, 360 degree coverage at all times. Far, FAR from it.

We need to kill this whole idea for at least one year. It's out of control. It is irresponsible (at best) to screw around with Flarms potential range at this point. The unintended consequences are potentially huge. The philosophical competitive "fairness" argument is simply no peer to safety. It's not even on the same planet as safety. Stop treating this discussion like this as a debate between equals. Start respecting the fact that Flarm, while valuable for safety, is far, far from perfect or infallible. So when you say a supposed time value that you find acceptable for your little crusade, imagine that the gliders 25 seconds away from a potential collision are not seeing each others antenna at 25 seconds for whatever reason. Or maybe you get a proximity "beep" and then lose coverage for 15 seconds..

Bottom line, some here care far more about philosophical fairness arguments than the significant safety value Flarm provides via its ability to create situational awareness for us. This crusade become an literal obsession for some.

I won't debate or compromise Flarm at this point until some sort of impartial, objective study (and extensive testing) has been completed. This was the requirement of my initial support for a limitation. Since then, the almost reckless abandon that many supporters (almost certainly coordinated in a pseudo RAS Flarm "mode" campaign) have demonstrated here is a real problem. The USRC opinion poll does not support this desperate position.

Perhaps the FAA should be involved. Has anyone discussed this topic with the FAA? I wonder what their take would be.


I was just pointing out some of the time values involved in operating with TCAS. I suspect that research was more extensive and the technology is more proven. Many TCAS resolution advisories occur before they are displayed as targets on the screen. The pilot's eyes are directed to the display (on the VSI in our case) to make a correction because it is a system used during IFR.

With FLARM the eyes are directed outside as they should be. The best way to do this is through the audio warning system. More could be done with this to improve safety. For example, there could be a warning "Multiple traffic, One o'clock high." This is another real suggestion that would enhance the FLARM system. The TCAS time values are real numbers to add perspective to the discussion.

XC

Then point out all the time values not just the ones that seem to support your stance on stealth. TCAS Non threat traffic more than 6 miles away can be displayed to well over 40 miles away. Proximity intruder traffic less than 6 miles away fill in the diamond display(visual no audio) to get your attention and provide situation awareness to prevent surprise TA and RA alerts. Traffic Alerts (TA) for potential collisions will happen from 20-48 seconds to closest point of approach(collision) with a visual change to yellow diamond and audio "Traffic Traffic" Under normal conditions a TA will proceed an RA by 15 seconds which prepares the pilots for any required RA avoidance maneuver while giving time to acquire the target visually if possible. Resolution Advisories (RA) which TCAS deems an imminent collision threat with a time of closest approach of 15-35 seconds warns with a red diamond visual cue and audio avoidance commands (Climb Climb Climb, Monitor Vertical speed etc...) as well as the required vertical speed required for the 5 second maneuver you posted.


TCAS uses these multiple steps of awareness from well over 40 miles away to try and prevent surprise RAs as well as to give crews the time required to scan visually for the traffic. I also find it very hard to believe there have been many instant RAs without the targets going through the normal threat scales of non threat, proximity, TA, RA, Clear of Conflict or at least some of them. Does it happen yes but it is not the norm.

To suggest that your eyes are inside looking at the TCAS only because you are IFR is misleading. It gives you the fastest way of locating the direction and altitude of the potential collision traffic so you can then start looking visually for the traffic if your not in clouds. No one using TCAS gets a pop up TA and starts randomly visually scanning the sky hoping to see the traffic. It takes much longer than looking at the TCAS visual display for a split second to find out where the traffic is then back outside to find it visually.

This is exactly the same method that FLARM uses with a scaled response to traffic threats as they get closer and are deemed a threat. Both TCAS and FLARM allow much better situational awareness of traffic. I would argue that FLARM stealth mode is exactly like the pop up surprise TCAS RA example you used. It should never happen as there is only 5 seconds to respond. TCAS users get the advantage of a computer giving an immediately calculated escape maneuver. FLARM users only have seconds to find the traffic visually to find out what to do.


There has been lots of good work on human reaction times (much of it as relates to OODA-loop types of cognitive processing). If you also look at the research studies done on visual scan and collision avoidance, you realize that there are some profound differences between how Flarm and TCAS operate with the pilot(s) in the loop. An RA climb/decend command is pretty unambiguous and the context is pretty clear - push or pull on the stick as commanded or you will hit someone. You can act with confidence that the systems is giving complementary commands if both aircraft are TCAS II equipped. The "Orient" phase of this "Observe-Orient-Decide-Act" loop in collision avoidance has the biggest potential variance in time because it is not always 100% clear what is happening based on limited inputs. An RA cuts this time down dramatically, just Act on what the system tells you. Flarm doesn't do this so the pilot needs to go through an entire OODA-loop cycle to figure out what to do.

I'd also call into question the wisdom and effectiveness of trying to implement any strategy that is 100% eyes out the window with audio cues only. Audio cues take a long time (multiple seconds) to generate precise information on distance, relative altitude, track, speed, orientation, yet much of this information can be important in the "Orient-Decide" part of the loop. Picking up a collision target visually is hard (as opposed to one that is not a threat and therefore has angular movement in the pilot's visual field). The pilot has to orient his gaze to the right location +/- about 2 degrees to pick up a target - peripheral vision isn't much help. With enough scanning around you may pick up the target, but getting into the right ballpark more precisely with the aid of a look at the display may in fact be a faster and more effective way to acquire a threat target visually.

I don't think TCAS is intended for RAs to be the first line of defense, rather, they are the last line. Being able to have most of the "Observe-Orient" part of collision avoidance mostly taken care of with traffic 5+ miles away is preferred, especially since most of the preemptive maneuvering will be with an Air Traffic Controller in the loop for TCAS-equipped traffic. Flarm and gliders instead of SSR/TCAS and jets present very different scenarios so direct comparisons are challenging, especially if you are talking about timing.

9B

On Saturday, January 9, 2016 at 11:54:33 PM UTC-8, Darryl Ramm wrote:
On Saturday, January 9, 2016 at 11:07:04 PM UTC-8, jfitch wrote:
On Saturday, January 9, 2016 at 5:47:04 PM UTC-8, XC wrote:
On Saturday, January 9, 2016 at 7:30:48 PM UTC-5, jfitch wrote:
On Saturday, January 9, 2016 at 12:08:39 PM UTC-8, XC wrote:
SNIPLet's make sure these numbers are based on some evidence.

Based on evidence presented so far, we don't even have a need for a stealth, so that is an odd statement.

The 5 second TCAS has got to be a minimum, panic mode number. Also do not just consider the case of one glider meeting one glider. Consider 5 gliders meeting 5 gliders. No longer can you just turn right or pull up, doing so may well cause an accident rather than prevent one.

More details about TCAS for comparison:

5 sec. is the maximum expected reaction time for a warning or RA. That is with the autopilot engaged and the pilot not actively engaged on the flight controls. The anticipated reaction time to reverse, increase or decrease vertical speed once the pilot is flying the machine is 2.5 sec.

"Initial vertical speed reaction to a RA is expected within 5 seconds; maneuvering G forces should be similar to those felt when responding to an ATC clearance to climb or defend "immediately" (+/- 0.25 G change in load factor)." That doesn't sound too panicked.

The TCAS display is selectable Above/Norm/Below. My company recommends normal in all phases of flight which gives +/- 2700 ft on the display. This is for aircraft capable of climbing or descending 6000 ft/min. "Above" can be selected in the climb which would give a view of aircraft 7000 ft above and 2700 ft below.

Now this is a different system, I understand, but my point is that it is not cross referenced continuously as a source of SA. Rather, it is an alert system that provides traffic advisories (TA) as aircraft are getting to be a factor ("Traffic") and resolution advisories (RA) ("Traffic, Climb/Descend)"when action is required by the pilot. The audio alerts and warnings have priority and have been determined to be more effective than the instrument panel display for collision avoidance.

Similarly, displaying all traffic on FLARM at these greater distances and relative altitudes is not required for SA or collision avoidance. In fact, spending too much time looking down at the display may be contrary to safety. Again, this discussion goes beyond collision avoidance and gets into pilots wanting to track other gliders for tactical reasons.

XC

In searching for the best anti collision system, few people hold out TCAS as the ideal. I have heard much more criticism of it than praise, the latter usually confined to "it's better than nothing". This is why the regulators and industry worldwide are moving as fast as they possibly can towards ADS-B, a system much more like Flarm. Before we decide that the metrics of TCAS are ideal or even adequate, we should ask why that system is being discarded in favor of one that shows all aircraft within 15 miles, all the time: position, altitude, and tail number. Going by that metric, the FAA has already decided that 15 miles range is the right answer. Even at 1000 mph closing speed, 15 miles gives over 50 seconds warning. I propose 50 seconds is the best supported number.

Oh what a pile of utter nonsense. TCAS II *is* the gold standard in collision avoidance. ADS-B does not replace TCAS II in *any* way. Not a single FAA regulation currently or proposed allows for replacement of TCAS II mandatory carriage with any ADS-B product.

TCAS II is not being discarded/abandoned for anything, including ADS-B anything. There is no technology that uses ADS-B for active collision avoidance similar to TCAS available as any RTCA standard and so nothing that can be build and no research projects that could be turned into such a standards any time soon. So at best anything based on ADS-B would likely be decades away. I have now idea where you are getting this 15 miles from. The ADS-B ground services hockey-puck diameter? That really has no direct relevance to TCAS. It is a stopgap layered on a complex dual-link mess.

TCAS II version 7.1 (the current standard) makes use of ADS-B In data to reduce the activeTCAS II transponder interrogation rates and provide better long range tracking of targets (esp. without excessive RF congestion). These systems do not use ADS-B data to issue an RA, that is all determined by active TCAS II to transponder interrogation. One of the specific advantages of Change 7.1 ADS-B integration is improved long range (much longer than 15nm you mention) traffic display... which in USA Class A airspace they will be able to rely on every aircraft being quipped with after 2020.

So not a single thing you stated is correct.

I should have said, "ADS-B is being incorporated into TCAS to make up for its shortcomings". According to reports, TCAS IV was abandon in favor of ADS-B enhancements. A couple of the main enhancements in question being accurate position, vector and ID information, precisely the things stealth advocates want to suppress. Whether we are talking about TCAS or ADS-B or ADS-B enhanced TCAS, there is not even a suggestion that the FAA thinks 5 seconds is adequate for anything but a last ditch panic maneuver.

There is a parallel in shipping collision avoidance, which depended on automated radar tracking aids for many years. This has been replaced in less than a decade by a GPS based digital network operated on VHF. No one I know wants to go back as it is far superior to radar tracking. In all of these systems, situational awareness is considered the first line of defense against collision, and automated warnings intended as a stop gap to cover cases where situational awareness was lost.

On Sunday, January 10, 2016 at 1:00:09 PM UTC-5, jfitch wrote:
On Saturday, January 9, 2016 at 11:54:33 PM UTC-8, Darryl Ramm wrote:
On Saturday, January 9, 2016 at 11:07:04 PM UTC-8, jfitch wrote:
On Saturday, January 9, 2016 at 5:47:04 PM UTC-8, XC wrote:
On Saturday, January 9, 2016 at 7:30:48 PM UTC-5, jfitch wrote:
On Saturday, January 9, 2016 at 12:08:39 PM UTC-8, XC wrote:
SNIPLet's make sure these numbers are based on some evidence.

Based on evidence presented so far, we don't even have a need for a stealth, so that is an odd statement.

The 5 second TCAS has got to be a minimum, panic mode number. Also do not just consider the case of one glider meeting one glider. Consider 5 gliders meeting 5 gliders. No longer can you just turn right or pull up, doing so may well cause an accident rather than prevent one.

More details about TCAS for comparison:

5 sec. is the maximum expected reaction time for a warning or RA. That is with the autopilot engaged and the pilot not actively engaged on the flight controls. The anticipated reaction time to reverse, increase or decrease vertical speed once the pilot is flying the machine is 2.5 sec.

"Initial vertical speed reaction to a RA is expected within 5 seconds; maneuvering G forces should be similar to those felt when responding to an ATC clearance to climb or defend "immediately" (+/- 0.25 G change in load factor)." That doesn't sound too panicked.

The TCAS display is selectable Above/Norm/Below. My company recommends normal in all phases of flight which gives +/- 2700 ft on the display. This is for aircraft capable of climbing or descending 6000 ft/min. "Above" can be selected in the climb which would give a view of aircraft 7000 ft above and 2700 ft below.

Now this is a different system, I understand, but my point is that it is not cross referenced continuously as a source of SA. Rather, it is an alert system that provides traffic advisories (TA) as aircraft are getting to be a factor ("Traffic") and resolution advisories (RA) ("Traffic, Climb/Descend)"when action is required by the pilot. The audio alerts and warnings have priority and have been determined to be more effective than the instrument panel display for collision avoidance.

Similarly, displaying all traffic on FLARM at these greater distances and relative altitudes is not required for SA or collision avoidance. In fact, spending too much time looking down at the display may be contrary to safety. Again, this discussion goes beyond collision avoidance and gets into pilots wanting to track other gliders for tactical reasons.

XC

In searching for the best anti collision system, few people hold out TCAS as the ideal. I have heard much more criticism of it than praise, the latter usually confined to "it's better than nothing". This is why the regulators and industry worldwide are moving as fast as they possibly can towards ADS-B, a system much more like Flarm. Before we decide that the metrics of TCAS are ideal or even adequate, we should ask why that system is being discarded in favor of one that shows all aircraft within 15 miles, all the time: position, altitude, and tail number. Going by that metric, the FAA has already decided that 15 miles range is the right answer. Even at 1000 mph closing speed, 15 miles gives over 50 seconds warning. I propose 50 seconds is the best supported number.

Oh what a pile of utter nonsense. TCAS II *is* the gold standard in collision avoidance. ADS-B does not replace TCAS II in *any* way. Not a single FAA regulation currently or proposed allows for replacement of TCAS II mandatory carriage with any ADS-B product.

TCAS II is not being discarded/abandoned for anything, including ADS-B anything. There is no technology that uses ADS-B for active collision avoidance similar to TCAS available as any RTCA standard and so nothing that can be build and no research projects that could be turned into such a standards any time soon. So at best anything based on ADS-B would likely be decades away. I have now idea where you are getting this 15 miles from. The ADS-B ground services hockey-puck diameter? That really has no direct relevance to TCAS. It is a stopgap layered on a complex dual-link mess.

TCAS II version 7.1 (the current standard) makes use of ADS-B In data to reduce the activeTCAS II transponder interrogation rates and provide better long range tracking of targets (esp. without excessive RF congestion). These systems do not use ADS-B data to issue an RA, that is all determined by active TCAS II to transponder interrogation. One of the specific advantages of Change 7.1 ADS-B integration is improved long range (much longer than 15nm you mention) traffic display... which in USA Class A airspace they will be able to rely on every aircraft being quipped with after 2020.

So not a single thing you stated is correct.

I should have said, "ADS-B is being incorporated into TCAS to make up for its shortcomings". According to reports, TCAS IV was abandon in favor of ADS-B enhancements. A couple of the main enhancements in question being accurate position, vector and ID information, precisely the things stealth advocates want to suppress. Whether we are talking about TCAS or ADS-B or ADS-B enhanced TCAS, there is not even a suggestion that the FAA thinks 5 seconds is adequate for anything but a last ditch panic maneuver.

There is a parallel in shipping collision avoidance, which depended on automated radar tracking aids for many years. This has been replaced in less than a decade by a GPS based digital network operated on VHF. No one I know wants to go back as it is far superior to radar tracking. In all of these systems, situational awareness is considered the first line of defense against collision, and automated warnings intended as a stop gap to cover cases where situational awareness was lost.

While I "mostly read" these discussions, I would like to say that the FAA is looking at mostly commercial traffic (when writing rules for distance & timing of TCAS/etc.) where you have 250KTS for each aircraft (500KTS closure, below 10K') and more speed higher.
Rarely do you have sailplanes doing 250KTS closure, let alone airspeed (maybe opposing ridge runs, western US big cloud streets), thus what the FAA is looking for in collision avoidance is just, "a wee bit different" than what sailplanes are looking for.

Granted, more time is better, more heads up time is better, basically we seem to have a "****ing contest" going on but since I'm not a current US contest pilot, I sorta just sit back and watch what is going on (so I have an idea on what to expect down the road).

If I could vote on a rule for "what to do with Flarm in a US contest", I would likely vote to:
-Reduce our range to 5KM (likely proposed US RC idea)
-Squash contest ID & "rate of climb" outside of 5KM
-Keep full info within 5KM to aid in collision avoidance per whatever Flarm can provide (yes, there will be cases that even the best algorithm gets befuddled....)

I'm speaking for myself, I'm NOT speaking for anyone else, nor do I have outside input to the US RC.

PS, I also understand that potential upcoming US FAA rules may make some of this moot, even current US contest pilots (with certified installed equipment) may make this whole discussion rather moot.
I also ask myself, "Why do some push their Flarm agenda so hard, do they want to change the sport today rather than wait until the FAA does it for them?!?!".

I don't know although I have my own ideas I won't really share.

Then point out all the time values not just the ones that seem to support your stance on stealth. TCAS Non threat traffic more than 6 miles away can be displayed to well over 40 miles away. Proximity intruder traffic less than 6 miles away fill in the diamond display(visual no audio) to get your attention and provide situation awareness to prevent surprise TA and RA alerts. Traffic Alerts (TA) for potential collisions will happen from 20-48 seconds to closest point of approach(collision) with a visual change to yellow diamond and audio "Traffic Traffic" Under normal conditions a TA will proceed an RA by 15 seconds which prepares the pilots for any required RA avoidance maneuver while giving time to acquire the target visually if possible. Resolution Advisories (RA) which TCAS deems an imminent collision threat with a time of closest approach of 15-35 seconds warns with a red diamond visual cue and audio avoidance commands (Climb Climb Climb, Monitor Vertical speed etc...) as well as the required vertical speed required for the 5 second maneuver you posted.


TCAS uses these multiple steps of awareness from well over 40 miles away to try and prevent surprise RAs as well as to give crews the time required to scan visually for the traffic. I also find it very hard to believe there have been many instant RAs without the targets going through the normal threat scales of non threat, proximity, TA, RA, Clear of Conflict or at least some of them. Does it happen yes but it is not the norm.

To suggest that your eyes are inside looking at the TCAS only because you are IFR is misleading. It gives you the fastest way of locating the direction and altitude of the potential collision traffic so you can then start looking visually for the traffic if your not in clouds. No one using TCAS gets a pop up TA and starts randomly visually scanning the sky hoping to see the traffic. It takes much longer than looking at the TCAS visual display for a split second to find out where the traffic is then back outside to find it visually.

This is exactly the same method that FLARM uses with a scaled response to traffic threats as they get closer and are deemed a threat. Both TCAS and FLARM allow much better situational awareness of traffic. I would argue that FLARM stealth mode is exactly like the pop up surprise TCAS RA example you used. It should never happen as there is only 5 seconds to respond. TCAS users get the advantage of a computer giving an immediately calculated escape maneuver. FLARM users only have seconds to find the traffic visually to find out what to do.

Sorry to not have done my homework better. The 5 seconds reaction time from holding a cup of coffee to change in vertical speed is the one give in our book at work. It is 2.5 sec with a little bit more G (+/- 0.35 G) to increase, decrease or reverse vertical speed. I didn't have any of those other numbers ready when I posted last night. The reaction times can be inferred as the "get moving" time. Add seconds as necessary to make the extra decisions needed for FLARM. How many more do you need? 10 sec?

TCAS II is a different system with a different criteria for what is "close".. To find this you have to get beyond the seconds and look at the protected distances which are also part of the equation. They apply when aircraft are closing slowly.

5000-10000 ft MSL TA= 0.75 nm or 850 ft vertical, RA = 0.55 nm or 600 ft vertical
10000-20000 ft MSL TA= 1.00 nm or 850 ft vertical, RA = 0.80 nm or 600 ft vertical

So you have to read between the lines a little, granted, but the above distances can be used to explain what TCAS thinks is a close call. The warnings are designed so the aircraft never gets any closer than this.

I think (I hope) we can agree that gliders routinely fly together inside of these distances without creating a bad situation. The times involved would logically be different.

A couple of other points to make about TCAS. Our display range is 6 or 12 nm. It routinely is set to show aircraft +/- 2700 ft. So all the tracking stuff is going on behind the scene and yes, TA's and RA's outside of those distances are show. But proximate traffic is not show beyond 12 nm on our installation.

XC