Near Mid-air Incident

[straitman]

As an ex aviation professional I beg to differ (both PIC and ex ATC), the choice of content borders on sensationalism and the lack of knowledge is rather obvious, case in point is the incident mentioned, those aircraft should never have been given the same altitiude when they are on conflicting lateral paths, odds and evens (Quadrantal rule) do not apply above FL290 owing to the requirement to have 2000 ft separation. In fact the rules applicable here are the Semicircular/Hemispheric rules, that is,

Eastbound - Magnetic Track 000 to 179° - odd flight levels (FL 290, 330, 370, etc.)
Westbound - Magnetic Track 180 to 359° - odd flight levels (FL 310, 350, 390, etc.)

As there is no mention of RVSM, its inappropriate to say an even flight level should have been assigned. Aircraft on conflicting tracks assigned the same flight level is a very serious matter, especially when its under a non radar environment, the fact the CX crew picked up on the issue is a big credit to them!

markis10,

I'm not disagreeing with your post above regarding the detail but disagreeing with regard to 'said article.' I do not believe the article 'borders on sensationalism' and whilst having some inaccuracies, that I also slipped up on, with regard to vertical separation was actually written in a way the average person could understand rather than being full of the aviation jargon that only a select few of us actually understand fully.

 

[markis10]

markis10,

I'm not disagreeing with your post above regarding the detail but disagreeing with regard to 'said article.' I do not believe the article 'borders on sensationalism' and whilst having some inaccuracies, that I also slipped up on, with regard to vertical separation was actually written in a way the average person could understand rather than being full of the aviation jargon that only a select few of us actually understand fully.

Straitman,

The case in point was referring to the usual inaccuracies to be found in such articles, there is no sensationalism in this case, in fact it is trying to tone down what is a very serious loss of separation, I am sorry if my comments indicated otherwise.

The article dwells on the fact that TCAS was not reporting issues, yet does not mention the fact TCAS Class II is limited to around 40 miles in range, which is not much when you have two aircraft closing on each other at a rate of Mach 0.9, in fact it would have given less than 60 seconds warning depending on the actual closing speeds. Whether TCAS went off or not is hardly the point, its interesting to note the crews both took diversionary action regardless once the issue came to a head, the fact the ATSB classed it as Cat 5 is also irrevelent and not a true indication of the seriousness either, just an indication or admission by the ATSB that they could not add value with another investigation on top of that being done by CASA.

Generally there is a lot of sensationalism in Mr Sandilands blogs, I suppose it helps sell advertising and gets page hits, in this article there was none, and while it was a good explanation of the use of different flight levels its a pity that it was incorrect in the context of the incident.

 

[harvyk]

The article dwells on the fact that TCAS was not reporting issues, yet does not mention the fact TCAS Class II is limited to around 40 miles in range, which is not much when you have two aircraft closing on each other at a rate of Mach 0.9, in fact it would have given less than 60 seconds warning depending on the actual closing speeds.

They would have just under 1 minute 20 seconds, based on a ground speed of say 480kt per plane, each plane with 40nm range on their TCAS, and flying directly at each other.

That said, the DJ 737 flying at FL370 from MEL - DRW does seem strange. I wouldn't have thought it would have been a distance or direction which being 1000ft higher or lower would have made a great deal of difference. (That said, I'm not a 737 pilot so I wouldn't know for sure). I would have expected if either plane was on a unusual flight level, the CX plane would have been the prime candidate based on direction and distance.

 

[oz_mark]

As there is no mention of RVSM, its inappropriate to say an even flight level should have been assigned.

Given the rather sparse amount of information that has been officially reported (an abstract from ATSB), is the absence of mentioning RVSM prrof that RVSM was not in operation?

 

[markis10]

Given the rather sparse amount of information that has been officially reported (an abstract from ATSB), is the absence of mentioning RVSM prrof that RVSM was not in operation?

There is a good chance that RVSM was in operation, its likely that both aircraft ops were under RVSM certification however it cannot be assumed.

Worldwide there is a trend to move routes to a one way flow scenario making the semicircular/hemispheric and quadrantal rules obsolete, along with elimating the risk of having opposite track aircraft on the same level.
It makes sense, the accuracy of aircraft navaids allows for RVSM in a vertical sense, we should be taking advantage of this to give aircraft lateral separation at the same time, two dimension separation has to be better than one, providing more protection against human error.

 

[mannej]

Came across this this morning. (Don't know how reputable the source is?)

B92 - News - Society - Planes nearly collide over Belgrade

 

[drron]

Came across this this morning. (Don't know how reputable the source is?)

B92 - News - Society - Planes nearly collide over Belgrade

Here are some more details-
Incident: Air France A318 and El Al B772 near Belgrade on Dec 28th 2009, loss of separation

 

[drron]

And this in Boston-
Incident: Continental B738 and Cape C402 at Boston on Dec 29th 2009, TCAS RA on initial climb

Happens pretty frequently around the world.

 

[markis10]

The report has now been published,looks like both crews responded to TCAS warnings at 35nm and took their own action, the report on the ATC work is somewhat damning, in summary:

On 22 December 2009, at 0253 Central Standard Time, an air traffic controller took action to resolve a loss of separation assurance that occurred on airway route J30, 222 km north-west of Tennant Creek, Northern Territory between an Airbus A330-300 (A330) aircraft, registered B-HLV, and a Boeing Co. B737-800 aircraft, registered VH-VUJ.
The aircraft were approaching each other at flight level 370 while tracking in opposite directions on the same airway route. The air traffic controller managing the airspace did not effectively control the resolution of the developing confliction.
The flight crews of both aircraft identified the traffic confliction and initiated avoidance action to maintain separation.
The investigation found that the controller did not implement a separation plan when the confliction was first identified and that action by the flight crew of the A330 prompted the controller to take action to re-establish separation assurance. In addition, a number of safety issues were identified, including that the controller had not received training in compromised separation recovery techniques and that there was no dedicated control room aisle supervisor during the then peak traffic period. Finally, ambiguity was identified between the Manual of Air Traffic Services (MATS) and the Aeronautical Information Publication (AIP) in relation to the assignment of non‑standard cruising levels and the definition of an 'operational requirement'.
In response to this occurrence, Airservices Australia (Airservices) conducted an internal investigation, which recommended a number of actions to address the safety factors and issues that were identified by the Airservices investigation. The Australian Transport Safety Bureau (ATSB) is satisfied that the action taken by Airservices to clarify the relevant content in the MATS and AIP, and recommended by the Airservices investigation will, when implemented, adequately address the safety issues identified in this ATSB safety investigation.

Investigation: AO-2009-080 - Loss of separation assurance - Airbus A330-300, B-HLV and Boeing B737-800, VH-VUJ, 222 km NW of Tennant Creek, NT, 22 December 2009