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Very Light Jets with no TCAS in commercial airspace

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Very Light Jets with no TCAS in commercial airspace

Old 2nd Mar 2008, 08:47
  #81 (permalink)  
PBL
 
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greywings,

you will already find plenty of discussion on TCAS in the thread TCAS Philosophies

Participants in that thread included people such as myself who have published analyses of TCAS, and people who are on the TCAS committees. It was also followed by some TCAS experts whose positions preclude them from contributing. Unfortunately, it became moribund due to the inability of one contributor to adhere to appropriate standards of discussion. This issue might not arise again; I suggest that anyone wishing to discuss TCAS consider starting that thread up.

Originally Posted by greywings
As someone who has had his bacon saved more than once by TCAS, yes, I do have a lot of confidence in it.
The number of people who claim to have had their bacon saved by TCAS is surprisingly large; indeed, it is far larger than the number of midair collisions one might have expected in the same time frame. So it cannot be the case that all TCAS "saves" would have been collisions. And on the other hand, one must also consider the near-accidents caused by the operation of TCAS, including one mid-air collision in which the use of TCAS was demonstrably a causal factor.

There are many aspects of TCAS which are not understood. For example, the algorithms (the pilot procedures) have been shown to be adequate for two-aircraft conflicts. However, it is not known whether they will suffice for three-aircraft conflicts or higher. And there have been, say, four-aircraft incidents caused by responses to RAs, which resulted in an airmiss filing.

The safety analysis of the system is to my mind (as I have published) also inadequate. The hazards in the system have not been adequately addressed; in particular the hazard of erroneous information coming from a source "outside" the immediate TCAS environment affecting the behavior of one participant (as happened in the midair to which I referred above), and the decision problems faced by RA participants, which can present them with quandaries which no one to date has been able to resolve.

None of this is to say whether TCAS is a "good thing" or a "bad thing". It is to say that it seems to be the case that because the introduction of TCAS was a political and not a technical decision, various necessary safety analyses that would ordinarily have been performed before a system such as this could be mandated seem to have fallen by the wayside over the last 18 years, and the associated problems reoccur without anybody necessarily being able to do much about them (TCAS is regarded as a "done thing").

Originally Posted by greywings
I think we should all remember what led to the push to have TCAS developed - an awful accident involving a public transport aircraft and a light trainer, in, I think, the Los Angeles TCA (or at least very close to it).
That is incorrect. TCAS had been under development for a very long time before the Cerritos accident. Furthermore, it would not have helped avoid the collision as the Warrior was not squawking Mode C. However, Congress reacted to the Cerritos accident by mandating TCAS introduction for commercial airplanes. One can wonder about the wisdom involved in mandating a measure that would not even have avoided the accident which triggered the political process.

PBL
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Old 2nd Mar 2008, 16:27
  #82 (permalink)  
 
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TCAS philosophies

PBL, I have now read through the 'TCAS Philiosophies' that you referred to and have found nothing in any of the posts to even remotely change my mind. Without a doubt, there are flaws in the system (TCAS), but, to the average pilot, it makes no difference if the kit is 6.04 or any other version. What he / she needs is a piece of equipment that enhances situational awareness and provides an escape route if things get really messy.

I found nothing enlightening in your 'statistics' regarding the number of pilots who implied that TCAS had saved their bacon. We all know that if an event were allowed to run it's course, maybe an actual collision would not have happened, but may instead have resulted in a near miss. Frankly, that is immaterial when one is trawling 400+ pax around the sky. A near-miss should be investigated diligently, and any lessons learned circulated as widely as possible, in the same way that we study incidents that may have become accidents..

There are certainly inadequacies that need to be addressed, amongst them the standard of training given to pilots. Some are fortunate enough to have excellent training in the classroom and simulator and feel well-prepared for use of the equipment - under any circumstances. Others are not, and we are all familiar with the consequences of incorrect actions at critical times.

Rather than engage in technical one-upmanship, I would like to see us leave the design of equipment to the engineers while we, the pilot body, make sure that we understand the euipment - flaws and all - and use it correctly.

GW
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Old 2nd Mar 2008, 22:27
  #83 (permalink)  
 
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Here are some price indications ( from a year 2001 spec sheet ) for mid size corporate aircraft:

a) TCAS I Bendix/King US$ 83.200

b) TCAS II Bendix King US$ 149.700

c) TCAS II Honeywell US$ 149.700

Assume that TCAS II is now closer to 100.000 US$, which is more than affordable for a 2.5 Mio $ fly away price VLJ. ( Especially if you convert it to Euros nowadays ).

Frank
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Old 11th Mar 2008, 13:03
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There seems to be one item of understanding that is missing. All these aircraft have a possibility of having a traffic system easily installed. Infact, most of the Cessna 182s, Piper Senecas, etc HAVE this when they leave the factories! But these are not TCAS, in that they give you no command. They simply display the traffic on the screen and give you the relative position, changing colour if a danger, and then an aural warning as the final step. That final step of ordering me about, I can frankly do without. So if the box is telling me where the traffic is, showing it to me and yelling at me, if I donīt react to the visuals.....cannot the pilots take some reasonable responsibilty to avoid? This takes care of 2,3,4 aircraft, whereas the commands are uncertain in a true TCAS II installation...

Sometimes technology is a tool, sometimes it is allowed to become a crutch.
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Old 11th Mar 2008, 21:00
  #85 (permalink)  
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Very Light Jets with no TCAS in commercial airspace
Excuse me? Commercial airspace? Did you mean Class A airspace, frequently used by commercial traffic?
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Old 11th Mar 2008, 22:23
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TCAS required

It's a no-brainer, get TCAS fitted, these are not cheap old spam cans, these are high cost a/c $$$$$$$$$$$$
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Old 23rd Mar 2008, 13:15
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Why not focus the effort on reducing cost of TCAS?

It's amusing to me that the cost of these systems are more than a whole german luxury sedan!

Given the number of existing & potential customers, the justification for these prices is getting thinner. Could it be that manufacture is limited to ICAO just 3 suppliers?

For a reasonable price, operators & owners wouldn't think twice about it.
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Old 23rd Mar 2008, 18:18
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The number of potential manufacturers of VLJ's is melting like snow in spring sun. Adams closed doors some weeks ago, the survival of Eclipse is in jeopardy in the current lending climate. They need urgently another cash injection to stay afloat. This leaves the Cessna Mustang and the Embraer Phenom as the most likely survivors offering VLJ's. Both are pricing their products in the +/- 3 Mio US$ range, so making a TCAS mandatory should not really be an issue for the operators.

The current real backlog for VLJ's is estimated to be only 1500 planes and not the 10.000 to 15.000 reported (and believed ) by some whacky Wall Street guys or dubious private equity houses. Gone are also the Eclipse fairy tales of selling an eclipse for 1 Mio US$. I think that the "VLJ's darkening the sky" is no longer an issue.

Frank
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