VOCA

An aviation researcher, writer, aviation participant, pilot & agricultural researcher. Author of over 35 scientific publications world wide.

Categories

Good reads

Oil Prices

#ozaviation

“Nothing to see here” – #asa, #atsb, #icao

“Nothing to see here” – #asa

That #asa would take the view that a failure of the radar and say that the reversion to “voice seperation” is astounding. Remember #MH370, where the only remaining reliable remaining data is that provided by radar.

This demonstrates that #asa has no idea about how to properly use the technology. Further, that #atsb has not recorded these incidents and later downgrades the classification system to not record ‘incidents” is quite amazing.

Perhaps not quite so as the #atsb has history.

The history is #atsb’s failure to understand the basis of the Reason [Swiss Cheese] model and apply it. The answers given to the Senate inquiry into #pelair is relevant reading and must be looked at, as to how things can go wrong once a single thing is missed in a causal accident chain.

I have interrogated the #atsb database and come to the conclusion that #atsb and #asa may be colluding to not record data for public scrutiny.

Maybe this is similar to the report on #pelair going missing in #icao.

In this case, Mathew [Australian article below] reports dozens of incidents, yet #asa explains this away using a statistical approach.

This approach does not answer the issues of :

“Why have these continuous failures in Tasmania occurred?”


 

Tasmania air surveillance: Unreliable radar sees planes go ‘missing’

Failures in Tasmania’s $6 million air surveillance system — including planes disappearing from radar screens for minutes on end — are still occurring ­almost monthly, as air traffic controllers warn the system is “unreliable”.

Reports previously missing from the public record but provided to The Australian show the Tasmanian Wide Area Multilateration (TASWAM) radar-like surveillance system failed 38 times between June 2013 and last month.

There have been 14 failures reported this year, including on June 18 when an aircraft near Launceston disappeared from radar screens “for several minutes”. That was the third such ­occurrence since June 2013, ­including an August 9, 2013, ­report of an aircraft departing Hobart not being visible on screen for 20 minutes.

These latest failure reports are in addition to more than 90 faults reported between 2010 and May 2013 and revealed last month.

They include blunt assessments from clearly frustrated and concerned air traffic controllers that TASWAM’s “unreliability” is sapping “confidence in their surveillance ability”, adding to their workload and even delaying flights.

While the earlier data was publicly available on the website of the Australian Transport Safety Bureau, the more recent data — post-June 2013 — had not been made publicly available.

It was released on request to The Australian, with the bureau saying it no longer classified such radar failures as “incidents” ­requiring inclusion in its incident reports database.

“In 2013, the ATSB changed its Australia-wide coding practice for classifying infrastructure reports,” a bureau spokesman said. “As a result, notifications of infrastructure failures are only included in the aviation safety occurrence data if the event ­affected the safety of an aircraft.”

The 38 post-May 2013 ­failures in TASWAM occurred in June, July, August, October and December of 2013; every month of 2014 except August through to October, and; every month of 2015 up until and including July. Outage times varied from one minute to seven hours.

Bureau media manager Marc Kelaart said none of the reported TASWAM failures — even where planes disappeared from radar screens — were regarded as having compromised aircraft safety.

“The aircraft were still under full communication and control by ATC and there were no losses of separation (planes flying too close to each other) or other ­safety related incidents,” he said.

The failure reports made by air traffic controllers show a level of frustration and concern about the apparent fragility of the TASWAM system, introduced in 2010 after concerns about several near misses. One report, dated January 25, 2013, relating to intermittent failures, warns “controllers are losing confidence in their surveillance ability” because of the frequent faults.

Further failures a day later led a controller to report: “Controller confidence in the system is very low. They’re basically using procedural techniques for separation (of planes) due to the unreliability of TASWAM.”

On December 19 last year, the system’s failure forced controllers to delay all flights between ­Tasmania and Melbourne by five minutes as a “mitigation” strategy.

In May last year, controllers complained that TASWAM’s 14 ground stations were not monitored for power failure, unlike other radar or radar-like systems, and that a failure in just one or two receivers was enough to down the entire system. On July 8 this year, Hobart airport reported 11 of the ground receivers went down at a time of high air traffic, with “complete loss” of surveillance across the state.

Mr Kelaart said some of the failures were due to problems with aircraft transponders, which send signals from planes to the TASWAM ground stations, rather than the infrastructure itself. “In addition, Airservices has advised the ATSB that controllers were encouraged to report everything, regardless of whether the TASWAM was being used at the time, and that some reports were associated with lack of controller awareness around the areas of coverage,” he said.

Airservices Australia, the government business that is responsible for TASWAM, said it was “confident that Tasmanian airspace is safe”. “In the past five years the TASWAM network availability has consistently exceeded 99.95 per cent,” said Greg Hood, an Airservices air traffic chief. “There have only been three instances where the target was not achieved and the lowest level of service availability was 99.80 per cent.

“Of the TASWAM faults ­reported by Airservices to the ATSB, none were assessed as ­impacting on aircraft safety or ­requiring further investigation.”

There were 14 ground stations, using signals to triangulate aircraft position, and “multiple layers of redundancy in place to safety manage any technical faults”. “In the event of a single ground station fault, there are ­numerous other ground stations fully operational to ensure surveillance is maintained,” he said.

The number of failures had ­declined over time as controllers grew “more aware of the system parameters”.