LHRT don’t forget that if 90% fleet coverage is the go, then most aircraft will be seen (and Heard) by other aircraft (with IN+ aural) IRRESPECTIVE OF ATS COVERAGE!!
werbil
Great minds think alike cobba, read the extracts below from the study re radio non/mis-use O/S … bare in mind this study was completed on data up to 2003, with the report published in May 2004 i.e.
before MBZ’s were binned in favour of the garbage we have now! .. like I said earlier, how many mid-air’s since then??? … hmmm, and don’t they dove tail into what was known back then …. No wonder there is a mood for change-back!
Bing
Scurvy.D.Dog, in a GAAP, under IFR conditions, I expect then that we will be able to have nice tight VFR like circuits with ADS-B (IN) .........
.. what on earth are you smoking???
I will repeat that my experience of 'Traffic' systems in a GAAP or simular well used VFR circuit, is they are a dangerous distractor.
… might be so with a blunt instrument like TAS .. please do not compare the two as they are like chalk and cheese!!
Perhaps you care to tell us of your inflight experiences of these 'traffic' systems Scurvy.D.Dog.........
… have flown with basic TAS systems (famil flights with BaE CT4’s), have flown countless famil flights in TCAS equipped RPT’s … have seen for myself the limitations of see-and-lucky if you avoid through my own experiences traversing through the training area west of Sydney, and in the CTAF at Grafton … on both occasions I was lucky … I have at conservative estimate somewhere in the vacinity of 10,500hrs console time providing GAAP services at BK and CN, not to mention sh1tloads more hours providing most other types of ATS services .... for the record I also have better than 20/20 vision! ... so what!!
........oh, there is that little problem of terrorist miss-use of GPS - at least my eyes and TAS still works when the terrorist targeting system (GPS) gets turned off
… are you aware of the Euro/US agreement signed in 2004 regarding Galileo and GPS? .. no thought not …. Have a bex and a lie down mate!
.
Non-
Jet-man
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Thanks for the link, had it anyway! now that you have confirmed you actually know what the report says, others would do well to read the document to compare your attempted use of it
and reality.
.
For those who could not be shagged, here are some of the relevant bits for this discussion …. pollogies for the length of the post, but it is relevant
3.3 Location and type of operation
Table 2 presents basic data on the general location of the 37 collisions. Most (24) of the collisions occurred in the circuit area (that is, at least one of the aircraft was flying in the circuit pattern for landing or departure). These included 20 aeroplane-aeroplane collisions, one aeroplane-ultralight collision, and three aeroplane-glider collisions.
Eleven of the collisions occurred when both aircraft were on final approach, two occurred during the base-to-final turn, and one occurred on the turn to base. The collision at Moorabbin in 1968 occurred either on the base leg or the final approach. Six collisions occurred on the downwind leg (one with an aircraft departing) and two occurred on the crosswind leg (one with an aircraft departing). One collision involved two aircraft on initial climb. Figure 1 presents a diagrammatic representation of the location of collisions in the circuit area. The dots indicate in which leg of the circuit the collisions occurred rather than the specific location within each leg.
There were also five collisions that occurred near the circuit area (that is, within 5 NM of an airport and with at least one aircraft arriving at, or departing from, that airport). These included one aeroplane-aeroplane collision at 1,500 ft with both aircraft on departure, one aeroplane-helicopter collision at about 1,500-2,000 ft with both aircraft on arrival, and three aeroplane-glider collisions at less than 2,000 ft with the aeroplane climbing.
Of the 20 aeroplane-aeroplane collisions that occurred in or near the circuit area, 25 aeroplanes were on training flights, 12 were on private flights, two were on passenger charter flights, and one was on an aerial work flight. At least 21 of the aeroplanes were being used for circuit training or practice. The aeroplane-helicopter collision involved two aircraft on aerial work flights, and the aeroplane-ultralight collision involved two aircraft on private flights. The seven aeroplane-glider collisions involved five aeroplanes being used as glider tugs, although only one was actually towing a glider at or just prior to the accident. The other two aeroplanes were engaged in private and aerial work operations.
Fifteen of the collisions in or near the circuit area occurred at one of the five major general aviation airports; that is, Archerfield, Bankstown, Jandakot, Parafield or Moorabbin. Thirteen of these collisions occurred during tower operating hours7, although in one of these collisions neither pilot had yet contacted the tower (Moorabbin, 1970). Of the other two collisions, one (Jandakot, 2002) occurred just after the tower controllers had handed over to an air ground operator. The other collision (Moorabbin, 2002) occurred at night when the control zone was classified as a mandatory broadcast zone (MBZ). No other collisions have occurred in MBZs in Australia, which commenced in 1991.
Remembering this report was written in 2003 before MBZ’s became CTAF’s, and the recommended vice mandated became the norm! ….. how many since then!!!???
Most (10) of the 15 collisions at the major general aviation airports occurred prior to the introduction of General Aviation Aerodrome Procedures (GAAP) during tower hours in 1980.8 The major change to operations at these airports in 1980 was the introduction of simultaneous contra-rotating circuit operations onto parallel runways (contra-circuits) at those airports with parallel runways. The previous procedures (known as a secondary control zone) involved all aircraft flying circuits in the same direction on the same side of the runways. Due to the high aircraft movement rates, tower controllers were only required to provide a limited service at secondary/GAAP airports, with aircraft separation being primarily a pilot responsibility. A review of the 10 collisions that occurred prior to 1980 found that many of them were unlikely to have occurred if contra-circuit operations to parallel runways had been in use. Only one of the 37 collisions occurred in controlled airspace where air traffic services were providing a full control service. This collision occurred in the Coolangatta primary control zone in May 1988.
There were six collisions involving pilots deliberately flying close to another aircraft. All were aeroplane-aeroplane collisions, and four involved formation flying activities. Seven of the aircraft were operating in the private category, two in the aerial work category, and three in the charter category.9 Only two other collisions occurred away from the circuit area. One involved two aeroplanes on private sightseeing flights (at 1,500 ft), and the other involved two aerial agricultural aeroplanes about to commence swathe runs (at approximately 50 ft).
It is not surprising that most of the collisions occurred in the circuit area, as this is generally where the traffic density is the highest. Of particular note is that at least 11 of the collisions in the circuit area occurred on final approach, where there is relatively little variation in the position of aircraft.
hmmm….
3.4 Other characteristics and contributing factors
The 30 midair collisions since 1969 not involving ‘deliberately close’ activities were reviewed to identify common characteristics and contributing factors. The 1968 collision at Moorabbin could not be included due to a lack of information. This review noted that there was a wide variety of contributing factors in the collisions, but there were no dominant factors. The circumstances of the majority of the collisions were consistent with the inherent difficulties in sighting aircraft in time to avoid a collision.10 More specifically, the review noted the following:
• All of the collisions occurred during good weather conditions, with visibility
being 10 km or more (when recorded). There were no reports that problems with visibility contributed to any of the collisions. Only one of the collisions occurred at night (Moorabbin, 2002). Sunglare was cited as a possible factor in four of the collisions.
• Most (18) of the collisions involved one aircraft colliding with another from
behind, or both aircraft converging from a similar direction (less than 30 degrees difference in heading), and only six of these collisions resulted in fatalities. Twelve of these collisions occurred at a height of 250 ft or less above the ground, with only three resulting in fatalities.
Of the 12 collisions with collision angles 30 degrees or greater, 11 resulted in fatalities.11 All of these collisions occurred at heights greater than 250 ft. Figure 2 provides a diagrammatic representation of the collision angles involved in the midair collisions.
• At least eight of the aeroplane-aeroplane collisions involved pilots conducting different sized circuits, but none of the pilots flew paths that were considered to be contrary to procedures. Two of the aeroplane-glider collisions involved glider pilots conducting unusual circuit patterns, with one of them entering the circuit from the wrong direction. The Bankstown collision in May 2002 was the only collision involving contra-circuit operations to parallel runways.
See comments re base joins on the other thread!
The point I make to you is that this report predates current CTAF op’s and only reports on ‘collisions’!! It does not include statically relevant airprox’s that could have been collisions except for blind luck! … that is why your reliance on this data is fundamentally flawed in the context of collision probabilities!
Do you get it yet? .. I think you do, you just cannot accept being wrong!!
The US experience
In terms of general location of midair collision accidents in the US between 1981 and 2003, 16 could not be classified due to a lack of information. Of the remaining 368 accidents, 169 (46 per cent) occurred in the circuit area, and 56 (15 per cent) occurred near the circuit area. Of the remainder of the US collisions, 46 (13 per cent) involved ‘deliberately close’ flying, and 97 (26 per cent) occurred away from the circuit area.
These rates were essentially the same for the periods 1981-1990 and 1991-2003.
Most of the accidents in the circuit area involved one or both aircraft on final
approach. Fifty-nine (26 per cent) of the accidents in or near the circuit area occurred at airports with a tower. The accidents away from the circuit area involved a mix of both aircraft in cruise flight, one or both aircraft climbing from or descending to an airport, or both aircraft involved in airwork activities. Of the 384 midair collision accidents in the US, 225 (59 per cent) involved fatalities. There was a total of 754 fatalities (or 2.0 fatalities per accident). If the accidents involving RPT aircraft are excluded, there were 220 fatal accidents and a total of 628 fatalities (or 1.6 fatalities per accident).
The US Federal Aviation Administration (FAA) recently conducted a similar review of midair collisions in the US for the period between 1983 and August 2000, involving a total of 329 collisions.19 Findings of this review included the following:
• All occurred in visual meteorological conditions. Only six occurred at night and four occurred at dusk. Bright sun was on the only commonly sighted factor related to weather.
• About 88 per cent of pilots involved in midair collisions do not see the other aircraft in time to avoid a collision.
• Most midair collisions involve low closing speeds, as one aircraft usually strikes the other from behind, above or from a quartering angle.
• Most midair collisions occur near airports, especially airports without a control tower. Midair collisions at high altitudes are rare events.
• A common factor in midair collisions was pilots using inappropriate entries into the circuit and failing to use radios at non-towered airports.
• The 329 midair collisions indicate that see-and-avoid has inherent limitations as a tactic or strategy for avoiding midair collisions.
4.2 Midair collisions in other countries
The Bureau d’Enquetes et d’Analyses pour la Securite de l’Aviation Civile conducted a review of midair collisions that occurred in French territory between 1989 and 1999 and involved at least one civil aircraft.23 The review excluded formation flights and glider-glider collisions. Results of the review provided included:
• There were 17 collisions, which resulted in 42 fatalities and 27 aircraft destroyed.
Air transport aircraft were involved in three collisions, and gliders were involved in four collisions.
• All of the collisions occurred during daylight in visual meteorological conditions. In two cases, pilots reported poor visibility conditions, and in six cases one of the pilots had ‘the sun in his face’.
• Seven of the collisions occurred near an aerodrome with aircraft in the circuit. Another eight collisions took place in areas where aircraft concentration was high, such as near an aerodrome, overhead a radio navigation device, or where there were a large number of gliders. Only two occurred during cruise.
• Twelve collisions occurred in uncontrolled airspace and the remaining five in
controlled airspace, although communication was not compulsory for three of
these situations. Non-use of radios or other communication problems was an issue with several of the collisions. Only one of the aircraft did not have a radio.
In a recent accident investigation report,24 the Transportation Safety Board of Canada noted that in the 10 years prior to August 1999, there were 17 midair collisions in Canada. Of these, ‘8 involved some form of formation flight, 3 occurred in practice training areas, and 6 occurred in the vicinity of uncontrolled airports’. None occurred in a control zone where an advanced level of air traffic control was being provided.
Figure 4: Comparison of midair collision accident rate between Australia and the US for general aviation
• Australia had a general aviation midair collision accident rate 1.1 times higher than that of the US in or near the circuit area during the period 1981-2003. This comparison excluded collisions involving aircraft deliberately flying close to each other. This difference was not statistically significant.28
• The US had a general aviation midair collision accident rate 5.8 times higher than that of Australia away from the circuit area during the period 1981-2003. This comparison excluded collisions involving aircraft deliberately flying close to each other. The test of the difference between the two countries was not significant.29
However, this test had a low level of power to detect differences in the rates as the Australian rate was based on only one event (Moreton Bay, 1988). The fact that only one event also occurred during the period 1961-1980 (Cecil Plains, 1980) suggests that the Australian rate may be reasonably reliable. There was a significant difference in the hours flown per collision involving general aviation between the two countries, indicating that there was a higher collision risk in the US away from the circuit area relative to Australia.30
It would be reasonable to expect that the US had a higher rate of collisions per flight hour away from the circuit area as it is generally accepted that it has a higher traffic density in this airspace relative to Australia. For example, the US had 17.5 times more general aviation flight hours than Australia during the period 1981-2003. However, quantifying the difference in traffic density is a complex issue and beyond the scope of this study. The extent of any difference in the average traffic density for general aviation aircraft in or near the circuit area between the two countries was also beyond the scope of this review.
... like I said .... Keep it up boys!!!
