IMC in the open FIR

[TotalBeginner]

I am just a lowly PPL with no ratings, so forgive me if this question is rather obvious.

I am under the impression that a suitably qualified pilot can fly in IMC outside of controlled airspace, without receiving a radar service. I am aware that the quadrantle rule is put in place to avoid collisions, but what about during the climb and descent.

e.g. An IR rated pilot takes off from an uncontrolled airfield in the open FIR. He climbs into cloud with the intention of flying on top. Another IR pilot takes off from another field, and is doing exactly the same in the opposite direction. Neither of them know where the other is, and are converging. Both are in cloud and claim that they are flying under IFR, and so are not in the practice of looking for other traffic?????

[rodan]

Yes, you are quite correct, but it's a very big sky you see.

[IO540]

The quad rule doesn't avoid collissions. It merely introduces a very slight statistical factor which reduces the probability of two targets ending up together. IMV it doesn't actually do anything much. It probably helps with visibility in VMC, again very slightly because a head-on target will be a fixed spot which won't be seen until too late.

That said, no mid-airs in IMC in the UK yet, ever, AFAIK.

Also, they don't have the quad rule abroad. It's just the semicircular one.

[Gertrude the Wombat]

If you're hiring, check your conditions of hire. It's not unheard of for a club to be quite keen on your not flying a club aircraft in IMC without a radar service.

[FlyingForFun]

I would always try to avoid entering IMC until I am positively identified on radar.

Of course sometimes it's simply not possible (many radar units shut down for the weekend, for example), and then you just have to trust the science of statistics, which says it's so unlikely it's not worth worrying about.

FFF
------------

[Keef]

My understanding is that the last midair outside controlled airspace in IMC in the UK was in 1942. Big sky, small aeroplane.

[Final 3 Greens]

Read the post about F15s and EMB 145s and then consider how big the sky really is.

[Tarq57]

I'm a controller with a PPL way downunder.
In our neck of the woods an Ifr plan has to be lodged, and r/t established with the appropriate FIS/FIO to activate the plan, at which point traffic information on potential conflicting flights will be passed. It's then up to the pilot/s to arrange a seperation. This doesn't always work too well - there was a near collision between a pa28 IFR training flight and a Gulfstream 4 at an unattended airfield a while back. Seems the PA28 PIC considered the G4 a non threat, or didn't consider it adequately. TCAS on the G4 helped save the day. Very hard to build a 3d mental picture of traffic unless used to it, especially when mentally occupied with another task.
Anybody know if the "traffic information" advice is a proceedure in the UK?

[S-Works]

i read the article f3g and dont see your point? There was no colision and the aircraft were 6000ft apart which is not even a near miss. More sensational journalism to me. The questions that need answered in that case are more about poor airmanship on the part of the fighter crews than an issue with the big sky theory.

I fly to work virtually every day and a lot of the time that is in IMC when the zone ar closed I fly MSA and big sky theory.

[DRJAD]

Markjoy, I suspect the question really refers to the sort of situation in Class G, flying from A/G fields, and in areas where there is no low level radar cover.

We have several of those in the UK. My local airport has ATC and some IAPs, but they have no radar and there is no low level area radar coverage in the area either. Flights where IMC has to be encountered shortly after take-off or shortly before landing, for example, therefore have to be conducted without benefit of radar. The use of the radio to gain a picture of neighbouring traffic, together with the big sky element, has to suffice.

I hasten to add that, where a radar service IS available, I make certain to request it before entering IMC.

[Bravo73]

i read the article f3g and dont see your point? There was no colision and the aircraft were 6000ft apart which is not even a near miss.

Er, bose-x, you must've read a different article.

According to the AAIB report (pg41):

"The [radar] recordings showed a minimum lateral separation between Tahoe 52 [F15E] and the Embraer 145 of 0.53nm..." (My brackets for clarity).

and from pg 38:

"Also at this time London Area Control Centre received a radio transmission from the captain of a civil Embraer 145 flying at FL210 from west to east along Airway P155 in the area of the two military aircraft. The captain informed ATC that they had just seen an F15 aircraft pass the nose of their aircraft about one hundred feet below and "no more than about two hundred yards ahead, descending"."

Which sounds a lot closer than 6000ft :eek: and pretty darn close if you rely on any 'big sky' theories. :sad: :yuk:

[S-Works]

I stand corrected a mere 3500ft........

The point is there was still no collision, without radar they would not even have been aware of each other.

[Final 3 Greens]

Bose-X

without radar they would not even have been aware of each other.

What part of "The captain informed ATC that they had just seen an F15 aircraft pass the nose of their aircraft about one hundred feet below and "no more than about two hundred yards ahead, descending". Did you have trouble understanding? :}

3500 ft is appx 1060M and at a closing speed of 400 Knots (assumed), represents approximately 5 seconds.

Big Sky?

[S-Works]

did they collide? No, enough said!!

If they were VMC and able to see enough to report it then "see and avoide" prevails.

Next....... :rolleyes:

[PPRuNe Radar]

bose-x

Providence is not, and never will be, the same as 'see and avoid'. In CAS where protection is expected, separation is still not guaranteed, but it is still almost a given that the system (tools, pilots, ATC) will provide sufficient barriers to prevent a collision.

Fortunately most of us in the professional industry understand that this encounter was pretty damn close, and hence extremely serious in potential, even if there was an 'overkill' in having a 5 second miss distance, which is nothing to worry about in 'your' view of the world.

Please try and avoid CAS mate ... then our conflicting ideas of safety won't be ever challenged :ok: and you can continue to prove the big sky theory to your hearts content :D

[Chilli Monster]

did they collide? No, enough said!!
If they were VMC and able to see enough to report it then "see and avoide" prevails.


Obviously your IR studies with regard to "Classifications of Airspace" and "Standard separation requirements" need a little bit of work still.

[High Wing Drifter]

F3G,
Read the post about F15s and EMB 145s and then consider how big the sky really is.
Swings and roundabouts. The 145 was in controlled airspace (an airway at FL310). However, whether that is an airway, CTA or CTR it must surely be realatively much busier as that is where the traffic is channelled? In the open FIR I would wager the chances are greatly reduced.

[Fuji Abound]

I think Bose-x's point is that the risk of collision in open FIR is very very small.

It would be interesting to randomly set a number of aircraft flying in the UK on a computer simulation and see how long it takes them to collide.

I think it is accepted that in fact the one factor that significantly increases the risk is the artificial way in which we arrange airspace. Reporting or navigation points of any description provide a choke point.

My guess would be if you are flying in open FIR and want to diminish the risk even further there are a number of ways you might achieve this.

1. Avoid overflying any VORs, NDBs or other reporting points,

2. Avoid navigating along or near the edge of CAS,

3. Fly in the worst conditions for SEP GA types, preferably when there is some icing around. It is well known that the poorer the conditions the less SEP GA types there will be airborne,

4. Fly as high as possible - GA SEP pilots seem reluctant to get much above 3,000 feet,

5. Frequently report where you are AND report your altitude. At least anyone else might take the precaution of adjusting their altitude to avoid a conflict.

As if to reenforce the point the only “close” miss I have had was in an ATZ without radar in the hold, when popping out into VMC at 4,000 feet I was somewhat surprised to see another aircraft at the same height and uncomfortably close. He was working a military controller who should had been liaising with my controller but had failed to do so. I got a very comprehensive apology back on the ground but it was the procedure that potentially brought us into conflict.

[Final 3 Greens]

HWD/Fuji

I take on board your comments about the potential choke points and it is a reasonable one. I remember listening to the after dinner speech by the ATC guy (forgot his name), where he jokes that the only way he can justify his job is to keep lots of aeroplanes close together ot fly a singleton near terrain!

The point I was making was no more or less than big sky is subject to to the influence of random events.

At a personal level, I think (like flying SEP at night or over water), it becomes a matter of attitude to risk and we all make our own decisions about what we consider a reasonable level.

Happy flying guys.

[S-Works]

Chill, clasifications, wotz that then...... Passed air law so forgot it all now!!

Fuiji.. I am glad somebody got the point I was making!

Radar, sorry mate to late........:) :)

[AerocatS2A]

Markjoy, I suspect the question really refers to the sort of situation in Class G, flying from A/G fields, and in areas where there is no low level radar cover.
We have several of those in the UK. My local airport has ATC and some IAPs, but they have no radar and there is no low level area radar coverage in the area either. Flights where IMC has to be encountered shortly after take-off or shortly before landing, for example, therefore have to be conducted without benefit of radar. The use of the radio to gain a picture of neighbouring traffic, together with the big sky element, has to suffice.
I hasten to add that, where a radar service IS available, I make certain to request it before entering IMC.

That's the situation that Markjoy was talking about wasn't it?

In that situation, in Australia, we are required to contact the ATC unit who is providing a traffic information service for the area, before take-off. ATC give us any conflicting traffic, and then we arrange separation by radio with the traffic. Normally it is along the lines, "we'll track 230 initially till 30DME then confirm clear and resume track", or "we'll maintain not above FL220 till passed." That sort of thing you know?