Near miss ?

[AGPwallah]

Was recently flying to LAS, in the cruise at 38,000 somewhere over N. America, when Mrs Wallah pointed out an aircraft out to our right approaching at 90 degrees to our flight path and it appeared to be at our height. The time taken for us to fly through it's contrails, after it disappeared from our view was about 15 seconds. As we were flying at 500mph, according to the in-flight movie screen, I estimated that it must have passed about two miles in front of our aircraft. Would this qualify as a near miss?

:confused:

[Final 3 Greens]

It's notoriously difficult to make such estimates and I doubt very much that you experienced an "air prox."

[PAXboy]

Non-pilot speaking.
You say, "the time taken for us to fly through it's contrails" but did you mean to say, "the time taken for us to fly ACROSS it's contrails". In other words, OVER and ABOVE them?

There are many such questions in various forums in PPRuNe (probably one a month) and the professionals usually say that it is very difficult, even for a pro, to accurately judge height - whether the observer is on the ground or in another a/c.

[AGPwallah]

Paxboy,

I did actually mean through - as in at same altitude. And the 15 second estimate was an over- rather than under-estimate according to Mrs Wallah.

[Hand Solo]

Contrails are very wide and tend to descend. If you flew through the contrail then you were probably 1000ft below the other aircraft.

[exvicar]

Isn't a near miss a hit?

[Globaliser]

I would have thought that if there was any possibility of a conflict, the TCAS on both aircraft would have been screaming blue murder. The fact that neither crew appears to have reacted to any TCAS warning, which is what your account implies, strongly suggests that there was no possibility of a conflict. As PAXboy says, even those who fly for a living know that it's very difficult to judge these things by eye.

[JazzyKex]

The visual cues you have to compare other aircraft positions are incredibly deceptive. You would be surprised, (or maybe not) at how often visually aquiring an aircraft and comparing its position to that on TCAS provides a surprised look. I've only been flying commercial jets for 9 years and I find it almost impossible to judge relative altitudes +/- 1000ft. It's only when you actually see the other aircraft pass within 1-2 miles you can be absolutely sure of their relative position without the aid of TCAS.

As for passing through contrails - it can be almost as deceptive, but if our eye witnesses are entirely reliable then 15 seconds is not long enough for a contrail to descend 1000ft. So you must have been at the same level. And if you did pass through a contrail less than 15 seconds behind another jet at 38000ft, you would have noticed some pretty serious vortex associated jolts much more than the contrials! Assuming both aircraft had their mandatory TCAS unservicable which must have been the case for them to pass within 3nm (the minimum separation at the same levels under the most accurate radar control (sorry maybe UK Watchman only not sure about US ability to reduce below 5nm)) a distance which must have been breached even if both aircarft were travelling 7nm per minute at 90 degrees to each other (normalish to high cruise speeds for most airliners).

I'd contact Mulder and Scully, seems too hard for simple aviators to explain!

[AGPwallah]

Maybe if I post flight number and date we can get some input from the flight deck - always assuming that they are Ppruners, of course.
;)

[PAXboy]

I sit to be corrected on these points:

If the flight paths were that close, then an Air-Prox would have been filed?
If that is the case, it will eventually become public?

[6chimes]

Was the in flight movie that bad!

6

[Avman]

Hello from a nice warm & sunny Algarve where Avman is on his hols! AGP, please believe me when I tell you that you had the required separation. For the ignorant (I don't mean this unkindly) it's easy to think otherwise. On my way here I just happened to look out of my A330 window and see a Royal Air Maroc B737 go by opposite direction 1000 feet (I expect) below and approx 0.1nm away. An amazing sight, but we were legally seperated.