US Pilots detained (not arrested) in Brazilian Crash

[rpadula]

A picture is worth a thousand words, right?

While looking up some info on T-routes for the red board, I found a link that contained the attached picture. It shows the reduction of ATL's flight path dispersion because of the change from 0.3 nm to 0.1 nm accuracy. Increasing precision is exactly what GPS does for us, so it's easier to see how GPS could increase the odds of a mid-air.

-Rich

P.S. Dick, glad to see you back. I always appreciated your thorough analyses.

 

[Henning]

A picture is worth a thousand words, right?

While looking up some info on T-routes for the red board, I found a link that contained the attached picture. It shows the reduction of ATL's flight path dispersion because of the change from 0.3 nm to 0.1 nm accuracy. Increasing precision is exactly what GPS does for us, so it's easier to see how GPS could increase the odds of a mid-air.

-Rich

P.S. Dick, glad to see you back. I always appreciated your thorough analyses.

That would be air carriers using coupled autopilots inbound from predetermined entry fixes, but even at that, if people follow cardinal altitude rules, the only increase we'd see is rear end collisions of fast movers hitting slow. It reduces chances of merging into traffic outside your periferal vision. Flying off altitude does nothing for you because you won't be the only one with the idea so it becomes a crap shoot. If everyone flys accurately to altitude, you know what level you need to look at for traffic. The graphing you found is not indicative of low altitude GA traffic now direct podunck to pudunck rather than podunck to XYZ VOR, V7,V256,V3 ABC VOR to pudunck. In GA we still have the same problem as demonstrated and as always by traffic entering the pattern, that hasn't and won't change. The whole concept of choosing your own secret altitude is rubbish, there's no good logic in it.

 

[Dick Madding]

Traffic Effects of GPS

That doesn't make any sense, at all. GPS doesn't concentrate traffic (by your own admission) enroute, and most of the danger is near the airport traffic area. How does GPS concentrate traffic around the airport? Are people flying their crosswind, downwind and base legs using the GPS for reference? I doubt it.

I have a hard time trying to wrap my mind around the idea that because of GPS, suddenly there will be more traffic flying between say...Podunk, IL and West Podunk, IL. The same number of planes are flying (not many).

GPS causes VFR airplanes to use almost exactly the same route between navigational points, decreasing the randomness of lateral separation of both opposing and same-direction traffic. Do you recall the CessPer sandwich, where the landing Cessna stuck to the top of a Piper and they landed together? So the risk of collision during the climb/descent phase around airports is increased somewhat. [The Sandwich occurred on final, and is mentioned here to show that same-direction collisions can easily occur.] Out there where you fly, it doesn't mean much. Even around Dayton, OH, where there is some kind of airport every 10 miles it doesn't mean much, because as you point out, there isn't much traffic. But fly in the Northeast, Florida, California, Chicago, Atlanta, or other similar congested areas, and the traffic between airports becomes significant. I once had a near collision successively with a glider then a Piper Tripacer during a descent into the MGY traffic pattern while under ATC. Of course neither had a transponder or was visible on radar. The weather was great, it was a weekend day, and everyone who could was out flying. Traffic congestion means a lot.

The high altitude collisions in Brazil and Germany illustrate how the decrease in lateral separation can become a key factor in a collision, even when traffic is 'light'.

Evidently I failed to make myself clear in the earlier post. The airport traffic area mid air risk far outweighs any enroute risk even with the increase due to GPS. The pattern is where those risk avoidance practices I mentioned should be used, regardless of where the airport is or the traffic volume it has. It only takes 2. Greenwood, IN [URL in previous post] and Norfolk, NE
http://www.ntsb.gov/NTSB/brief.asp?ev_id=20001211X12827&key=1
aren't real busy places, but collisions occurred. [I still can't figure out why the Piper who took off to the north was southeast of the airport unless he circled in the pattern before departing that pattern to the east.]

Keep that landing light on.

 

[tonycondon]

well at least you ill know where to look with everyone flying the same line.

 

[mikea]

... Flying off altitude does nothing for you because you won't be the only one with the idea so it becomes a crap shoot... In GA we still have the same problem as demonstrated and as always by traffic entering the pattern, that hasn't and won't change. The whole concept of choosing your own secret altitude is rubbish, there's no good logic in it.

Reminds me of the story of the old guy who when dirivng at night on unlighted two-lane roads would turn car headlights off at intersections. His theory was he could see the headlights of any car coming on the crossroad. That works great until two drivers use the same technique. It's similar to a VFR pilot not worrying about being in a cloud with no clearance because the autopilot will keep you upright.