Bashkirian Airlines Flight 2937

sr4470 said:
Saw the documentary about this a while back. The pilots should have followed their flight computers, and ignored the controller's instructions.
Click to expand...
At the time, Russian aircrew were used to following ATC over TCAS as it was always standard operating procedure for Russian airlines. That has now changed since the Uberlingen incident.

This incicent is a perfect example of the famous 'Swiss cheese model'. It wasn't one mistake which caused the incident, it was a series of mistakes in circumstance, action and procedure which led to the incident.

I can empathise with Nielsen, his life ended the second he realised there had been a mid air :(
 
Scuzi said:
At the time, Russian aircrew were used to following ATC over TCAS as it was always standard operating procedure for Russian airlines. That has now changed since the Uberlingen incident.

This incident is a perfect example of the famous 'Swiss cheese model'. It wasn't one mistake which caused the incident, it was a series of mistakes in circumstance, action and procedure which led to the incident.
Click to expand...

Oh I know, just saying I thought it was the most significant contributor.
 
Scuzi said:
At the time, Russian aircrew were used to following ATC over TCAS as it was always standard operating procedure for Russian airlines. That has now changed since the Uberlingen incident.
Click to expand...

So it is now the rule of thumb to use TCAS because it will have more 'local knowledge' than ATC?
 
Lysander said:
So it is now the rule of thumb to use TCAS because it will have more 'local knowledge' than ATC?
Click to expand...
Air traffic control provide separation but when ATC or the pilots make an error and aircraft end up on a collision course, TCAS can detect the collision and will offer traffic information on average 45 seconds before collision. If ATC or the pilots do not correct this, TCAS will provide what is called an RA (Resolution Advisory) within ~15-20 seconds of a collision. An RA will command the aircrew to either climb, descend or monitor vertical rate. TCAS only works in the vertical plane as it is very inaccurate in the horizontal plane. A TCAS RA takes priority over an ATC instruction.

When aircraft are what we call 'on top of each other' on the radar, i.e. within one mile of each other, it is hard for an air traffic controller to provide avoiding action as the radar display displays a range of anything from 35 miles up to 120 miles. Radar derived information is also subject to an approximate dealy of 6 seconds so what you see on the radar is the position of the aircraft 6 seconds ago, not exactly great information to go on if the aircraft are within 1 mile of each other at a closing speed of up to 1000+ mph.

In the vast majority of cases, controllers will issue avoiding action when they spot the confliction long before the aircraft get that close however in the case of pilot error, controller error or equipment error where the aircraft do get close enough, TCAS is a last resort, 'belt & braces' system which has saved lives.

It is the opinion of some ATC incident investigators that had TCAS not been introduced, there would have been a mid air collision in UK airspace in the past few years.

It's a great system which I thankfully haven't had to rely on to get me out of a pickle (touch wood!) although I have been controlling some aircraft which have had what we call nuisance RA's. These occur when an aircraft is climbing below an aircraft which is descending, both at high rates, to separated levels. TCAS, however, does not know what level the aircraft are climbing/descending to and as such issues an RA, even though the vertical clearences are perfectly safe.
 
What frightens me most is the amount of planes in our skies.

In Brussels I once counted no less than 15 planes in the sky all going in different directions. The sky constantly looks like a etch-a -sketch board.

Still by a long chalk the safest mode of travelling but when things go belly up it causes the most destruction and death. It's not our proximity to the airport than increases our chances. It can happen at 36000 feet
 
Can you think of a situation in the last few years where a TCAS has definitely prevented a collision?

One other question on a slightly different level. How does an aircraft land? Coming back from Holland the other day I noticed - again - the the aircraft seemed to have some kind of guidance system which automatically adjusted its speed and angle. That's how it felt anyway. I've noticed that a lot in the last few years.
 
jas72 said:
What frightens me most is the amount of planes in our skies.

In Brussels I once counted no less than 15 planes in the sky all going in different directions. The sky constantly looks like a etch-a -sketch board.

Still by a long chalk the safest mode of travelling but when things go belly up it causes the most destruction and death. It's not our proximity to the airport than increases our chances. It can happen at 36000 feet
Click to expand...
Look to the skies just north of London, you'll see more that 15 planes on the quietest of days! :eek:

Useless fact of the day - Here in the UK, the London TMA (Terminal Control Area - The airspace which sits above all the major London airports from ground level to 24,500ft) is commonly regarded as the busiest, most congested and complex block of airspace in the world. :cool:
 
Lysander said:
Can you think of a situation in the last few years where a TCAS has definitely prevented a collision?
Click to expand...
I'm afraid I can't divulge any such information.

Lysander said:
One other question on a slightly different level. How does an aircraft land? Coming back from Holland the other day I noticed - again - the the aircraft seemed to have some kind of guidance system which automatically adjusted its speed and angle. That's how it felt anyway. I've noticed that a lot in the last few years.
Click to expand...
Within 50-ish miles of major airports, most aircraft will be vectored by ATC into an orderly fashion and directed to the approach, usually to establish on what is called an Instrument Landing System. Most modern aircraft can fly the approach to a certain height after which the pilot has to take over and most new airliners are CAT IIIB equipped, meaning the plane can land itself without any human input:eek:

ILS - http://en.wikipedia.org/wiki/Instrument_Landing_System
 
Don't think this has been mentioned, but don't flame me if it has because I haven't read the entire thread! There's an episode of Air Crash Investigation, shown on national geographic about this exact crash. Very sad situation :(
 
355F1512TR said:
Don't think this has been mentioned, but don't flame me if it has because I haven't read the entire thread! There's an episode of Air Crash Investigation, shown on national geographic about this exact crash. Very sad situation :(
Click to expand...
Aye, thats a very good show. It goes into quite a bit of detail. Highly recommended for anyone with an interest in this incident.
 
I dont understand this. Were they never on a collision course to start with then? :confused:

Very sad, and an interesting read none the less
 
Butters said:
I dont understand this. Were they never on a collision course to start with then? :confused:

Very sad, and an interesting read none the less
Click to expand...

Both planes were originally on a collision course. Neilson in Air Traffic Control instructed Flight 2937 to descend, though seconds later the Traffic Collision Avoidance System on the other flight instructed the pilot to descend also.

Though Flight 2937's TCAS was now instructing the pilot to ascend, they followed the advice of ATC. Neilson was unaware of the TCAS alerts since maintenance was being carried out on the radar and he was using a slower system.
 
Scuzi said:
Aye, thats a very good show. It goes into quite a bit of detail. Highly recommended for anyone with an interest in this incident.
Click to expand...

that program in general i think is excellent. i find it fascinating how they piece everything together and get to the cause. when i was in uni i had a module called "crisis management" which detailed some of the methods (models mainly) that investigators use to get to the route cause of a problem, and how often many small failures can occur regularly with no adverse consequences and how it is often something seemingly innocuous that leads to catastrophe.

the union carbide bhopal disater was one of the events we studied, as was the manchester runway fire, which the lecturer actually investigated.
 
Scuzi doesn't this kind of thing scare the **** out of you? I'd have a nervous breakdown if I had to work at ATC every day of the week, knowing that despite all the precautions and safety systems you can have, sometimes accidents do unfortunately happen.
 
You must log in or register to reply here.
Back
Top Bottom