First TCAS II on helicopters
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First TCAS II on helicopters
I see that Bristow has finally received certification for its TCAS II installation on an AS332L - the first on a helicopter 
. It took a while but then we were fighting the establishment, who said that TCAS II was inappropriate for helicopters - though when you asked why they were not sure.
TCAS I is great for VMC flight but due to the inaccuracy of the displayed bearing, you have to get the threatening aircraft visual before taking evasive manoeuvres - kind of tricky in IMC. The team responsible for developing the idea summed it up by saying that TCAS I is VFR collision avoidance, TCAS II is for IFR collision avoidance, and here on the North Sea we fly mostly IFR.
I was not involved in the project but I hope we get it on the EC225 fleet soon!
HC
. It took a while but then we were fighting the establishment, who said that TCAS II was inappropriate for helicopters - though when you asked why they were not sure.TCAS I is great for VMC flight but due to the inaccuracy of the displayed bearing, you have to get the threatening aircraft visual before taking evasive manoeuvres - kind of tricky in IMC. The team responsible for developing the idea summed it up by saying that TCAS I is VFR collision avoidance, TCAS II is for IFR collision avoidance, and here on the North Sea we fly mostly IFR.
I was not involved in the project but I hope we get it on the EC225 fleet soon!
HC
Thread Starter
Hi Aser
Only that its a Rockwell-Collins system - but I think they only make 1 model. There is a press release on the R-C website about it. There is also of course a replacement electronic VSI which displays the traffic information and the Resolution Advisories - maybe that's R-C as well.
HC
Only that its a Rockwell-Collins system - but I think they only make 1 model. There is a press release on the R-C website about it. There is also of course a replacement electronic VSI which displays the traffic information and the Resolution Advisories - maybe that's R-C as well.
HC
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Announcement link here (via Vertical magazine):
http://www.verticalmag.com/control/n...es/?a=7310&z=5
http://www.verticalmag.com/control/n...es/?a=7310&z=5
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Well done!
The antenna is probably the tiny white pimple on top of the giant orange lump. The other is visible just below the baggage bay.
http://www.rockwellcollins.com/news/page10561.html
"It was commonly believed in aviation circles that the installation of a TCAS II for helicopters would not be possible because of their speed and flight profiles. Our team, together with Rockwell Collins and with the support of Shell Aircraft, successfully met that challenge and created an implementation of TCAS II for helicopters, which is a world first," said John Cloggie, director of European Operations for Bristow Helicopters. "We are committed to investment in systems such as this because of our ongoing commitment to enhancing the safety of the many thousands of passengers we transport offshore."
http://www.bristowgroup.com/about/ne...m.php?offset=0
"It is proposed that this system be installed across the Bristow fleet, starting with the Super Pumas, and we believe it will not be long before such systems are mandated by both our customers and the authorities for the industry as a whole. Mike Meyer"
http://www.rockwellcollins.com/news/page10561.html
"It was commonly believed in aviation circles that the installation of a TCAS II for helicopters would not be possible because of their speed and flight profiles. Our team, together with Rockwell Collins and with the support of Shell Aircraft, successfully met that challenge and created an implementation of TCAS II for helicopters, which is a world first," said John Cloggie, director of European Operations for Bristow Helicopters. "We are committed to investment in systems such as this because of our ongoing commitment to enhancing the safety of the many thousands of passengers we transport offshore."
http://www.bristowgroup.com/about/ne...m.php?offset=0
"It is proposed that this system be installed across the Bristow fleet, starting with the Super Pumas, and we believe it will not be long before such systems are mandated by both our customers and the authorities for the industry as a whole. Mike Meyer"
Why don't I be the first to say that I am not convinced it adds anything to helicopter operations except expense. First of all, you are applying it to old analog instrumentation in old helicopters that never even had TCAD. Some operators with both TCAD and TCAS have told me that they prefer the information from the TCAD presented on a map view for traffic information in helicopter situations. The fancy TCAS II system that Bristow would like all operators to splurge for has serious limitations on lateral presentation, and in fact relies on altitude differentiation for traffic avoidance. It will command (via the modified VSI) either a 1500fpm climb or descent. OK so let's forget that most helicopters have a limitation against this in IMC. Let's forget the questional benefits of a "bunt", pushing the nose over and the risk of negative "G". This system does nothing to present in the lateral, and is inferior to a TCAD presented in a map view. Even more inferior to a map view with routings and reporting points displayed on it, like you would have if you displayed on a SAGEM or Garmin or Honeywel MFD.
I don't know where you guys fly where you can change altitude a few thousand feet on a TCAS threat, but most of us bottom feeders jammed into a few hundred feet between MOCA and IFR airspace and icing and wrong way traffic above and below just simply cannot climb or descend very much at all.
Why don't I close by saying that the Bristow system was already obsolete 10 years ago on top of being irrelevant to helicopter operations. If you really want to see what operators are more likely to install, have a look at the ADS-B going into the Gulf of Mexico. Present that on a map display and you really have something. Probably the North Sea will be out of oil before it gets there.
I don't know where you guys fly where you can change altitude a few thousand feet on a TCAS threat, but most of us bottom feeders jammed into a few hundred feet between MOCA and IFR airspace and icing and wrong way traffic above and below just simply cannot climb or descend very much at all.
Why don't I close by saying that the Bristow system was already obsolete 10 years ago on top of being irrelevant to helicopter operations. If you really want to see what operators are more likely to install, have a look at the ADS-B going into the Gulf of Mexico. Present that on a map display and you really have something. Probably the North Sea will be out of oil before it gets there.
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Just started working offshore a few months ago. Its scary how accurate the GPS are today. If you are at the same altitude and on the same route in opposit directions, it seems that a mid air would most likely occur. The tcas we use is not accurate at all. It can see the traffic if its above OR below. But not when you are at same altitude. Collegue told me that Eurocopter have tryed to fix it but cant find a solution.
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voodoo2 - you mean TCAS I, presume problem is antenna postioning which Bristow seem to have mastered
Malabo - any issue on lateral presentation on TCAS II on whateever specific installation you have seen is insignificant compared to the advantage of Resolution Advisories which are not available from the current TCAS II.
Malabo - any issue on lateral presentation on TCAS II on whateever specific installation you have seen is insignificant compared to the advantage of Resolution Advisories which are not available from the current TCAS II.
Thread Starter
Malabo sorry but I don't think you understand the issues. Bristow is not completely stupid (well sometimes, maybe!) and they have only developed this system - at great expense- because of its advantages over TCAS I / TCAD. The fixed wing world long ago recognised the limitations of TCAS I and that is why TCAS II is mandatory on even the smaller commercial aircraft.
The bottom line is that all TCAS / TCAD systems rely on direction finding technology to assess the bearing of the intruding traffic. Because of the high frequencies involved in a transponder, diffraction is a big issue and bearing accuracies are only around +-20 deg, and that is not a fixed error so if you try to assess the track of the intruding traffic you could be in for a bad day. This is why we say its a VFR collision avoidance tool - ie it makes you look for the traffic, then when you see it, avoidance is carried using conventional eyeballs. That's why it doesn't work in IMC.
The lack of bearing accuracy (on TCAS I, II or TCAD) is why TCAS II has to rely on vertical displacments for collision avoidance (vertical position is reported by the intruder's Mode S or Mode C transponder and so should be accurate). But you are wrong to think that means 1000's of feet. A typical TCAS Resolution Advisory will make you climb or descend only 300' or so. Its designed for an IFR environment and will be aware of other traffic above and below you when giving its commands.
Its true that the commanded vertical speed is 1500'/min or so but this is configurable and any helis that can't manage that can be configured accordingly. None of the helicopters I have flown have been limited to below 1500'/min in IMC.
You are also exagerating the g required - flying an RA is not a violent manoeuvre, don't forget you are 30 seconds away from collision at that point and it calls for about 1.2 g up / 0.8g down I think (someone will correct me) which is a long way from negative g. The need to fly the RAs correctly is one of the reasons why TCAS II training is mandatory (in the UK anyway).
I agree that the display of traffic only on the vertical speed indicator is not very good - a cramped display with no other references on it. However this is just for the AS332L, which is a 25 year old aircraft with no fancy moving maps or displays for route waypoints etc. You have to remember that the purpose of this project was to myth-bust the establishment, and Bristow wanted to keep it as simple as possible so that if it didn't work, it would clearly be the fault of TCAS II and not of some other aircraft system.
The plan for all our newer aircraft (EC225, S92, S76C++, EC155 etc) will be to incorporate it on the nav displays.
Yes, I also agree that ADS-B is a good system, certainly much more accurate that TCAS but unfortunately it only works for participating aircraft, and neither does it tell you how to avoid the collision. At the moment the world is full of transponding aircraft that don't have the necessary extended squitter to make ADSB work. So at the moment TCAS detects 99.9% of all aircraft, TCAS II tells you how to avoid them, whereas ADSB would probably detect about 1% and leave you to work out how to avoid them. In the fullness of time that might change but there is a huge hurdle of acceptance to overcome first.
HC
The bottom line is that all TCAS / TCAD systems rely on direction finding technology to assess the bearing of the intruding traffic. Because of the high frequencies involved in a transponder, diffraction is a big issue and bearing accuracies are only around +-20 deg, and that is not a fixed error so if you try to assess the track of the intruding traffic you could be in for a bad day. This is why we say its a VFR collision avoidance tool - ie it makes you look for the traffic, then when you see it, avoidance is carried using conventional eyeballs. That's why it doesn't work in IMC.
The lack of bearing accuracy (on TCAS I, II or TCAD) is why TCAS II has to rely on vertical displacments for collision avoidance (vertical position is reported by the intruder's Mode S or Mode C transponder and so should be accurate). But you are wrong to think that means 1000's of feet. A typical TCAS Resolution Advisory will make you climb or descend only 300' or so. Its designed for an IFR environment and will be aware of other traffic above and below you when giving its commands.
Its true that the commanded vertical speed is 1500'/min or so but this is configurable and any helis that can't manage that can be configured accordingly. None of the helicopters I have flown have been limited to below 1500'/min in IMC.
You are also exagerating the g required - flying an RA is not a violent manoeuvre, don't forget you are 30 seconds away from collision at that point and it calls for about 1.2 g up / 0.8g down I think (someone will correct me) which is a long way from negative g. The need to fly the RAs correctly is one of the reasons why TCAS II training is mandatory (in the UK anyway).
I agree that the display of traffic only on the vertical speed indicator is not very good - a cramped display with no other references on it. However this is just for the AS332L, which is a 25 year old aircraft with no fancy moving maps or displays for route waypoints etc. You have to remember that the purpose of this project was to myth-bust the establishment, and Bristow wanted to keep it as simple as possible so that if it didn't work, it would clearly be the fault of TCAS II and not of some other aircraft system.
The plan for all our newer aircraft (EC225, S92, S76C++, EC155 etc) will be to incorporate it on the nav displays.
Yes, I also agree that ADS-B is a good system, certainly much more accurate that TCAS but unfortunately it only works for participating aircraft, and neither does it tell you how to avoid the collision. At the moment the world is full of transponding aircraft that don't have the necessary extended squitter to make ADSB work. So at the moment TCAS detects 99.9% of all aircraft, TCAS II tells you how to avoid them, whereas ADSB would probably detect about 1% and leave you to work out how to avoid them. In the fullness of time that might change but there is a huge hurdle of acceptance to overcome first.
HC
Thread Starter
Voodoo / Sox
Yes, the EC offering for TCAS I has only one directional aerial on a very small ground plane, and bearing accuracy / detection is poor as a result. The Bristow offering for TCAS II has directional aerials above and below the fuselage with massive groundplanes, so the bearing accuracy and detection is very good, however its big and heavy.
As Buddah says, the middle path is the best way, with a compromise between the two extremes above!
HC
Yes, the EC offering for TCAS I has only one directional aerial on a very small ground plane, and bearing accuracy / detection is poor as a result. The Bristow offering for TCAS II has directional aerials above and below the fuselage with massive groundplanes, so the bearing accuracy and detection is very good, however its big and heavy.
As Buddah says, the middle path is the best way, with a compromise between the two extremes above!
HC
Good news - well done Mark et al.
I look forward to hearing details of the S-92 retrofit (I gather possibly in AMS 6.0)
I look forward to hearing details of the S-92 retrofit (I gather possibly in AMS 6.0)
