I thought I was getting the hang of this until............

[Peter Grey]

For some perspective in the airline world airliners have equipment called TCAS which generates alarms (called RAs) that the pilot has to respond to. This alarm happens around 25 seconds before point of closest approach if the aircraft is going to cross within 600' vertically AND .55NM horizontally (this varies with altitude, these are the values for flight between 5000 and 10000').

An aircraft directly under or over by 1000' will not produce an RA alarm. An aircraft directly below by 500' will, but the alarm will simply tell the pilot not to descend.

[rgrazian]

Hi Peter,

My buddy lets me fly his 1978 Lance II. I blame him for my renewed passion for flying and lighter wallet. However, I'm getting my instument rating in a C172 G1000. Amazingly, the G1000 has what sounds like a similar traffic feature. Garmin calls it TIS. Similar alarms, etc. So much has changed in GA from the early 90s when I learned to fly.

[Peter Grey]

Yes the G1000 (either via TIS or ADS-B) has a similar feature (I was instructing in G1000 C172 and DA-42s about 4 months ago). The biggest difference is that TIS and ADS-B isn't actually supposed to be used for avoidance maneuvers (it doesn't have the highest level alarm, but the second highest, which yells "traffic, traffic").

[Ryan B]

In that pic I wouldn't say you're close to that SWA 737... just my opinion though.

Slight deviations are fine for traffic avoidance, but I agree a drastic +/- 1000 ft might mean an error for the controller (loss of separation). For light planes I'd ask to deviate. In larger planes, equipped with some sort of TCAS, they might receive an RA (resolution advisory) aka guidance telling the pilot to turn and or climb/descend the plane. In this situation, the controller is not responsible for standard separation (but provides traffic advisories) until the acft is finished with the RA maneuver.

Also I'd issue a traffic alert if it looked like you might smack the other unidentified aircraft(s). Something like "Traffic Alert, N12345, traffic 12 oclock 2 miles, opposite direction, altitude indicates 11,200, advise you descend immediately to 10,000." That was a little wordy... what I say in real life would be more like "Traffic Alert, N12345, advise you descend immediately!" Then once I have him descending I'd continue to issue the traffic until no factor.

[Daddy O]

I guess one of the questions that was asked and not answered was how to deal with the issue. Let's examine it logically. When you are flying at cruise altitude up to 18k, you are always within 500 feet of traffic heading in the iopposite direction. If you are flying VFR, just above you is IFR traffic flying blind in the opposite direction, so you don;t want to go there.

But diving has its downsides. Aircraft can take positive Gs better than negative Gs. If you happen to be flying in the yellow, with a full bag of gas and passengers, a sudden push over could Vmax the airframe.

Had a near miss once. MoNW, I had allowed my altitude to increase a little too much while I was playing with luggage behind the seat. B200 passed off my left wing so close I could see that the pilot was wearing Rayban Aviators. Planes are often hard to see when you have a 340 knot closing speed. In Xplanes and FLX, other aircraft are rendered better than in real life. In the RW other aircraft are much harder to see.

If I remember correctly, the SOP for a head on approach is both planes veer to the right. Same when overtaking another craft?

[Anthony Santanastaso]

If I remember correctly, the SOP for a head on approach is both planes veer to the right. Same when overtaking another craft?

Yes, according to FAR 91.113.

http://www.ecfr.gov/cgi-bin/text-idx?c= ... 3.10.2.4.7