I guess DV has made up his mind, based on a PQ and whether he wants headlights in his car or satnav. The drivers (OK, I understand the source of the metaphor now) will not be heard because they can't tell whether their aircraft is safe or not. :mad: me, we're doomed.

Sorry, I was addressing collision risk assessment, which involves an understanding of Hazard logs, Risk registers and Risk clasifications (Frequency and Severity) etc.

I am sure that you appreciate it is not just a case of understanding the functioning of TCAS but what protection it provides when the risk of collision is realised (Loss of safe seperation with another aircraft in class G airspace). At that point TCAS is the only "recovery control" that can prevent a collision/near miss from occurring. I am please to note, from the lastest MAA "bow tie" diagram of Nov 2014 (After the event of 2012), that this has now been recognised by the MAA.

DV

Minnie Burner, I did not say that, nor did I imply it. I simply pointed out that aircrew do not always have the full picture when it comes to safety.

I should add that SAFE means ALARP and tolerable, and the collision risk for Typhoon is not ALARP. Even the DG believes it is "questionable"; not a firm endorsement.

DV

Distant Voice

That ranks as one of the most ridiculous posts I've read in a long long time.

TCAS is far from being the last line of defence from collision. It operates at huge distances, usually pre visual.

If TCAS fails there is still the old fashioned version called "eyes"
It has worked surprisingly well for a really long time.

"Sorry, I was addressing collision risk assessment, which involves an understanding of Hazard logs, Risk registers and Risk clasifications (Frequency and Severity) etc."

I am absolutely staggered by that statement.

No.

Collision risk assessment is what pilots do when flying continuously.

What you are doing is called "bigging your part up"

And just occasionally (but sadly and fatally) f@ck it up.

The prime, and flawed, thrust of your argument seems to be leave it to the pilot because they won't make the fatal error.

TCAS is not the ultimate solution, but surely it adds to SA which probably is the solution.

Wow! Tourist, clearly you have a limited understanding of hazard/risk assessment and management, so let me explain in a little more detail what I am talking about.

Hazards become risks when the "Prevention Controls" fail. In our case flying in Class G airspace is the hazard, and loss of safe separation with another aircraft is the risk. Prevention Controls take the form of ATC facilities, onboard radar and passive detectors, deconfliction planning and TCAS (if fitted). In this role one is using the Traffic Advisory (TA) function of TCAS.

However, if the Prevention Contols fail and the risk is realised then we have to rely on "Recovery Controls" in order to prevent a collision/near miss. The Resolution Advisory (RA) fuction of TCAS (if fitted) is the only meaningful Recovery Control. And that is what I am talking about. And that is why two Tornado aicraft collided over the Moray Firth in 2012; NO RECOVERY CONTROL. The Mk 1 eye ball was useless, as many near miss AIRPROX reports will testify

The Risk assessment and management that I am talking about is at Duty Holder level.

DV

DV

This is a perfect example of desk sitters believing that paperwork has a positive effect on flight safety.

It reminds me of the time I had to cancel my final display practise because the paperwork was not correct. How could I possibly be safe without the correct paperwork?

TCAS is not and has never been the only recovery control.
The pilot is the primary and final recovery control. He is highly trained and has far more sensors and options to maneuver than TCAS will ever have and he can to it in very fine tolerances to the last second before collision. He has options until very close proximity and he is specifically trained to operate in a military aircraft unlike TCAS which has 2 dimensional options optimised for civil airliner profiles.

Pointing out a time where TCAS may have helped is obtuse. Aircraft fitted with TCAS collide/have airprox all the time.
The fact that it is possible for an aircraft to collide despite all the clever air to air sensors and eyesight carried on a fighter does not mean that TCAS would be an improvement.

TCAS is designed for a particular application. Some of the reasons that make it useful for an airliner are invalid.
An airliner has exceptionally poor viz compared to a fighter.
An airline pilot very rarely looks out of the cockpit. I'm estimating less than 1% of the time an airliner cockpit has a pilot actively looking out rather than reading the paper, programming the FMS, chatting up hosties etc.
An airliner can't agressively maneuver like a fighter

A 1hz refresh rate is fine for an airliner, but at the accelerations of a fighter this can cause the system to fail and not give an RA.

For TCAS to work the pilot has to be trained to trust it and do as it says. There are various instances where TCAS has led aircraft into close proximity where eyes might not have. Usually this is in the case of one aircraft being TCAS fitted and one not and RA reversals have come too late.

I think this push for TCAS is post holder ass covering and nothing more.
Nobody wants to be asked the asinine question at a board of inquiry "I've heard of TCAS. How come you have not given our boys this kit?"
The fact that it is inappropriate to the application is by the by.
Next will come "we must all have EGPWS!"
It's a fantastic bit of kit for an airliner and has saved countless lives. Why not fit the civvy version to all military kit? Surely it will work fine?.......

Tourist, I suggest that you read Appendix C to AAIB report into the collision of a Tornado aircraft and Jetranger in June 1993. I think you will be surprised at the amount of time that is needed in order scan, recognise an approaching aircraft, recognise a collision course, decide on action, exicute the control movement and allow the aircraft to resond. According to the report, see and avoid has been described as a maritime concept originally developed for slow moving ships which is now out of place in an era of high speed aviating.

DV

DV

I don't think anyone has ever successfully won a debate with any argument beginning with "I suggest you read Appendix C"

Eyeballs are by no means perfect, but that is not the point. TCAS is a good early stage system for preventing collisions in suitable aircraft profiles. It is certainly not the last line of defence even in an airliner.

You will note, that despite the vast amounts of cash always available in military contracts, they never advertised it as suitable for military jets........

[QUOTE]
It reminds me of the time I had to cancel my final display practise because the paperwork was not correct. How could I possibly be safe without the correct paperwork?
/QUOTE ]

'nuff said.

Typhoons Need Midair Collision Avoidance System, Safety Officials Say
 

DV and Tourist.
Your discussion reminds me a little of the 'whale is heavier, but the dinosaur was longer argument'. You're never going to reach a resolution.
Neither of you is really looking at it from the others viewpoint. Tourist you clearly have a lot of airborne experience which I respect. DV your crusade is both admirable and well intentioned.
Please allow me to be the man that bridges the gap. I've never flown the Typhoon or Tornado, but I have operated the Hawk T1, T2, 115 and Jaguar (similar to the Tornado for the sake of this argument). I also served as the UFSO for the Hawk T2 so I know a thing or two about risk matrices and ALARP etc.
Trying to justify TCAS to a pilot by citing paperwork is never going to get you very far. Likewise citing unsubstantiated testimony without evidence to support it won't cut the mustard.
However based on what I have experienced I would rather we fitted TCAS to all FJs now.
As I have said previously TCAS II is not perfect for FJ use. I just fail to see a good reason not to fit it in this day and age. Some people will grumble and we'll never really know if it prevented any accidents but we can't keep prevaricating whilst we wait for the gold plated solution. If it is not fitted then I hope the SoS has the balls to own the risk. After all money will be the reason why and you can't really blame the military for that.
Honestly I think many Typhoon guys would laugh at the limitations of the current system but they'd soon get over it. It's not always 9G and vertical climbs.
I don't expect this to be the final word, just my two penn'orth as they say.
BV

For my two penn'orth, some TCAS facts:

It doesn't provide a response with closure rates >10,000fpm and/or >1200kts - software limit. i.e. it won't 'see' traffic doing that.

Different kinds of RA's are inhibited at 'low level', of the order of 1400ft and below (rad alt), e.g. RA 'Descend' inhibited below 1100ft

TCAS broadly uses time to 'collision' (tau) as the measure of when to alert (TA or RA). The tau limits change with altitude - gets bigger - to compensate for the IAS/TAS relationship I think. A head to head RA is the same time to collision with a Typhoon at 800kts as it is with another airliner at 250kts. I recommend using your favourite search engine to find the FAA document 'Introduction to TCAS II, Version 7.1'. Especially if you're having trouble sleeping - actually has a few useful nuggets of info.

There may be some conflation with TCAS (the only current implementation of the Airborne Collision Avoidance System (ACAS) standard) and a Traffic Advisory System (TAS). TCAS tells you how to get out of the way (in pitch only) whereas a TAS just tells you where the other traffic is (+/- angle of arrival errors). Studies have indicated that cued lookout is much more effective than a '360' scan - no surprises there.

The point I'm trying to make is that the blanket use of the term 'TCAS' indicates a system that provides an RA that (in the civvy world) the pilot is obliged to follow. That may well not be the case in the military environment, where the system could easily be used in the TAS sense to cue lookout. It's not really important what it's called, just how it's used, but it is important not to get wrapped around the axle due to misconceptions caused by calling something TCAS when it may not be used in the same way or indeed be the same thing.

Also, pilots may be reluctant to use it but while MAC remains the number one risk the relevant AOC will no doubt be keen to explain why such reluctance may be misplaced ... :ooh:

Bob

I'm interested how the information is displayed to you in a Hawk?

Certainly in the various aircraft I have flown fitted with TCAS the contacts sometimes have a habit of roaming around the screen a little. (Sometimes 30 degrees and a few miles in position)

In the TA phase of any encounter, in an airliner there are two of you to look out as you try to discern where the screen contact is in the real world.
Are you head down in the hawk, or is there a clever HUD integration?

I'm surprised that you find it generally positive in the Hawk, as in the military aircraft I have flown fitted with it, while it had it's undeniable uses, it was a pure irritation in RA mode.
There is the problem that RA is all or nothing. What I mean by that is that unless I'm mistaken, the system expects both of you to follow the RA and plans accordingly. If you choose to ignore it the plan is compromised. This means that military aircraft cannot opt in but give ourselves options to ignore if visual etc.

Tourist
 

Google will show you an image of how the cockpit looks. TCAS can be displayed on any of the three MFDs but in the event of an RA or TA it will 'steal' your left hand screen. It gives a colour coded display on a black background with each tag presented with height information. From what I can tell it is pretty similar to other comercially available displays. You can also select various range options.

It currently doesn't (or at least didn't in 2012) have a HUD function but it wouldn't be impossible to incorporate into software upgrades.

It has similar angle of arrival issues to which you mention (it was recognised as a risk in fact in the risk register), hence it cannot completely replace visual lookout.

As a Jaguar and Hawk T1 man I was clearly sceptical about the need for it initially. It has it's drawbacks but can be useful at times. Puddle jumpers flying through Wales whilst you're engaged in a spot of low level evasion can be tricky to spot and it's nice to have an advanced warning of their presence. Yes I know, provided they're squawking.

Some people swear by it and will even keep it on in the visual circuit to see people joining etc but I preferred to turn it to standby once inside the MATZ.

The way that it would trip off when you exceeded the AoB or climb angle limitations was annoying but at least in the latest software update it would self reset every time (it didn't stop the repetitive AVBIT warnings though).

As for the RA thing it never really affected me. You would clearly be presented with one in the sim from time to time to test your knowledge of the system but we used it very infrequently in the air. If I were to fly in airways or busy airspace and it were to issue an RA then I would follow it but it is not something that will affect the FJ guys very often. That is not to say there aren't airliners being forced to follow an RA on an aggressively manoeuvring FJ outside of CAS however. Put simply it didn't annoy me sufficiently that I would rather operate without it.

On that note how often would your average civilian pilot expect to be hearing RAs? It can't be that often surely?

Anyway, as I have said I am aware of it's limitations but, despite these, it is not a bad comfort blanket to have. It is hardly going to max out a Typhoon pilot to have a TCAS working in the background and even they, with a RADAR, can still miss things.

It's bad enough that Tornado didn't have it fitted in 2012 but can we really still be debating the issue three years later?

BV:confused:

Sounds a reasonably balanced and considered opinion/assessment BV.

Sold.

Out of interest, what is the false alarm rate like on fast jet GPWS? (TERPROM based). Low enough to ensure trust in the system and react without hesitation to a warning? Or do the tolerances make it a distraction in low level flight?

JFZ90
 

Mostly pretty good. I had total confidence in the Jaguar system (but maybe I was too inexperienced and trusting to know any better!).

The Hawk T2 GPWS is also good. Occasionally you will get erroneous warnings mostly on entrance to valley systems (the ski toe looking out the front will react to valley walls and such). Many of those photos from the mach loop you see are accompanied by in-cockpit "pull up" warnings!

BV:cool:

BV.......:D


A Well reasoned and structured argument, to which I fully agree. TCAS has limitations, but in 'helping' to mitigate the main risks of MAC GA & MAC CAT (From a societal perspective) It could play a big part.


In the future, I would be very surprised if TCAS or similar systems were not mandated for all commercial and military types above certain weights.


I wonder what the Lightning II team feel about this........


Advo

BV, Big Mil TCAS. I never had an RA in civilian ATC environment, quite a few TA, usually conflicting and climbing/descending traffic breaking the ROC/ROD closure thresholds. Military environment, had a couple of RA from other traffic not accurately flying their assigned altitude. Also, many thousand TA during AAR, which was expected (TA only selected) and easily worked into the routine. However, several occasions saw (on TCAS) joining/departing traffic at incorrect levels and kit allowed safe resolution of the situation.:ok:
Cheers

OAP