PPRuNe Forums - View Single Post - Automation Bogie raises it's head yet again
Old 20th Jan 2011, 11:19
  #170 (permalink)  
RAT 5
 
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Greetings, to my mind this was not an automation issue. Bubbers44 says, perhaps rather sarcastically, he didn't want to show how easy the NPA was. Indeed any NPA can be easy if planned, prepared and briefed properly. However, they are a disaster waiting to happen when attempted without proper preparation. The worldwide CFIT stats bear that out. Situational awareness goes out the window as you slide ever more behind the a/c. You are a passenger on a sled ride. Sometimes you are saved by busting out of cloud, in an unexpected place, breath a huge sigh of relief, wipe the seat and spray some airfreshner, then land. No-one except you and the FDM monitor is any the wiser. Another statistic avoided. On the other hand...
An a/c at altitude has an amount of energy; This has to be reduced drastically to land safely. Our god given computer used to do this; now we trust VNAV/LNAV, but hopefully monitor it to make sure it is doing what we would have done ourselves. It is a great reducer of workload, when used properly. In this case the a/c was too high on energy; it was too high, too fast and too short of time to reduce the energy sufficienly to make a safe approach and landing. That would have been true for a needles & dial a/c or an EFIS a/c. It's physics and aerodynamics. Situational awarness told them how far they were from the rwy, the altimeter told them their height and the ASI told them their speed. Added all together they had too much energy. Without proper planning they did not have enough time to set up safely. Why they made a decision to defy energy I have no idea. Were there causal factors at play, e.g. behind schedule, tight on FTL's, commercial pressure, poor training culture etc. etc. I do not know. Some guys can push the boundaries and so learn, by mistakes or by successes; some guys stay in the middle of the box and are considered stodgy, but safe. The hairs on the back of my neck are a good barometer. I've pushed boundaries in many things, but usually with an escape route. When I've got close to the edge, unitentionally (= mistake) it's scary. Knowingly going into a cul-de-sac usually alerts the hairy sensors and I back off. I just cannot see this having, as a root cause, a mis-managed automation conclusion. In daylight, airfield in sight, perhaps it was worth a go. At night, PF on 1st visit, IMC, high on energy, NPA, it just seems a very odd human decision to even atempt such a manouevre. A couple of holes had lined up when they started to consider a straight in. By saying "NO Thanks" the 3rd hole stayed closed and the cheese was back in the fridge, at least for this scenario. By saying OK the holes started to line up 1 by 1.
From the spectrum of posts I suspect this thread will rotate and continue without reaching a concensus. I'll read with interest, hopefully learn, but my tuppenyworth is spent.
RAT 5 is offline