A few questions about UK airspace

[VRB03KT CAVOK]

Hi there,

I'm just trying to learn a thing or two about the different classes of UK airspace and have a few questions for anyone willing to answer them:

1 - I’ve read that RVSM is only possible for aircraft properly equipped, are there still a few airlines flying aircraft that aren’t RVSM approved and do flightlevels above and below them become unusable while it’s transiting?

2 - Are there any types of controlled airspace that DON’T require a mode C transponder?

3 - In Class F airspace are flightplans and radios only required by IFR flights on advisory routes? and do VFR aircraft treat the Class F as uncontrolled airspace?

Thanks

[Chilli Monster]

1) No - the aircraft are not permitted entry into RVSM airspace.

2) Class 'D' or less does not require it at the moment.

3) Yes to both

[VRB03KT CAVOK]

Does this mean that even a 30 year old Boeing 727 gets RVSM approval so it can fly around Europe?

Are there ever any close calls with IFR aircraft descending through cloud and finding a VFR aircraft infront of them when they are clear of the cloud?

Thanks again, just trying to get a better understanding...

[Spamcan defender]

Hi VRB03KT, Its my understanding that if an aircraft meets RVSM approval standards then it may be approved regardless of age. So in theory an old Comet or Trident with the mandated equipment could fly RVSM. (I stand to be corrected :D )


Spamcan

[Widger]

1) No - the aircraft are not permitted entry into RVSM airspace.

Not quite correct. Those that are Exempt are also allowed in RVSM airspace and yes they do block off two levels or more.

[5milesbaby]

If any a/c wants to fly in RVSM airspace then it needs approval which involves carrying the correct fully functional equipment. There are some airlines with non-approved aircraft, ie City Ireland (dont know the proper airline name) B146's but for the sake of a couple of 1000 feet I don't think they need to bother. There are older aircraft compliant, I think even John Travolta's B707 is approved! As Widger says some a/c can get exemption, mainly military flights, but these will only be accepted subject to workload. Formation flights CANNOT be RVSM approved under any circumstance.

[Pierre Argh]

Are there ever any close calls with IFR aircraft descending through cloud and finding a VFR aircraft infront of them when they are clear of the cloud? VRB03KT CAVOK... I can't quote any precise incidents, but theoretically it is possible? To explain the theory...

(i) ALL pilots are ultimately responsible for the safety of their aircraft, which includes collision avoidance.

(ii) In unregulated airspace, the basic principle is "See and Avoid". Difficult if you're IMC in cloud, I know but read on...

(iii) The VFR criteria, generally, requires a pilot to maintain a certain minimum distance horizontally and vertically from cloud and have a minumum inflight visibility... So the IFR pilot popping out of cloud should have some separation from the VFR pilot, and both should have time to "see and avoid". But...

(iv) In some instances, v.slow aircraft VMC is "clear of cloud, in sight of the surface", i.e. no minimum separation from cloud is specified! This is where, IMHO, it starts to get a bit woolly?... Separation now relies on...

a. The airmanship of the VFR pilot i.e. not getting so close to cloud that'd (s)he'd be surprised if IFR traffic came out of the cloud.
b. The "Big Sky Theory"

But before you get into a panic about IFR Vs VFR, to put it into perspective... think about the IFR pilot, flying in cloud, who encounters another IFR pilot on a crossing heading? There's nothing at all in the IFR for un-regulated airspace to prevent them colliding... apart from luck!

[Pierre Argh]

Since the above post, I have received a PM from a member questioning my statement on IFR vs IFR, claiming that the quadrantal rule will separate a/c?

Unfortunately... whilst it gives some protection, it's limited. For example... Two aircraft, the first is heading 020. It has an aircraft in it's left 10 o'clock position hdg 080... Both a/c are on a collision course, and as both are flying at a correct quadrantal FL, which would be an odd level e.g. F70. The Quadrantal Rule reduces the liklihood of collision but there is still a risk.

[bookworm]

The Quadrantal Rule reduces the liklihood of collision but there is still a risk.

One could say exactly the same of Air Traffic Control, but of course I'd never say that on the ATC Forum... ;)

[Spitoon]

And when the military finally get their way and fly UAVs all over the place ........

[terrain safe]

Doesn't the quadrantal rule only apply to IFR, VFR fly at a level that they wish in order to comply with VFR?

[VRB03KT CAVOK]

So with VFR remaining 'clear of cloud' in Class E airspace (which could well be just 100' below broken cloud), would you advise an IFR aircraft of a primary return if they were at the top of their descent?

Even with quadrantal rules they are going to be descending through these heights anyway aren't they?

I've tried Googling to find the UK's radar coverage, are there just a few remote hilly areas that miss out on low level traffic?

[VRB03KT CAVOK]

Any answers?

(Sorry, just had to reply to my own to get the topic closer to the top again!)

[Tweety]

rrrrrrrrrrrrrrrrr

[Pierre Argh]

VRB03KT CAVOK... would you advise an IFR aircraft of a primary return if they were at the top of their descent? if they were in receipt of a radar service we'd advise them of any traffic VFR or IFR, known or unknown. If they hadn't asked for a service they might not be idenitified, so ATC couldn't give traffic info as they probably wouldn't know the confliction existed?

I'd refer you to my first post re: airmanship... Next time you're flying VFR 100ft vertically clear of cloud, quite legally, just ask yourself if you are allowing yourself time to avoid something descending out of the cloud in front of you?

I'm not surprised you couldn't find a chart of radar cover as it will depend on range and height. Rule of thumb for radar coverage is approx 1000ft/10nms from the radar head... this is a very basic guide that can be applied to determine LARS radar cover (different rules apply at longer range)... and this does NOT take into account local terrain effects. Every radar I have worked in the UK and abroad has areas of poor cover (beyond the above ROT).

Yes of course, when climbing or decending the Quadrantal rules don't work... to give them their full title they are "Quadrantal Cruising Levels". IMHO the quadrantal rules are designed to REDUCE the chance of collision to a negligable risk... and they do that quite well.

Bookworm... I sense this is said light-heartedly, but there have been many more mid-air collisions by pilots flying VFR than those receiving an ATC service and until this stat is reversed I think that justifies my job?

Spitoon... before "the military fly UAVs all over the place" (i.e. outside danger areas or segregated airspace) the military will need to develop sensors that will allow the UAV to "see and avoid" other aircraft... someway off yet, I'd suggest?

[DFC]

Spitoon... before "the military fly UAVs all over the place" (i.e. outside danger areas or segregated airspace) the military will need to develop sensors that will allow the UAV to "see and avoid" other aircraft... someway off yet, I'd suggest?

That depends on what one defines "see and avoid other aircraft" as. Sensors other than visual ones can be and are used to detect "targets"!

Regards,

DFC

[Pierre Argh]

DFC Sensors other than visual ones can be and are used to detect "targets"! But, I believe, these sensors are not sufficiently "fail-safe" to allow flight alongside manned-aircraft yet. If they are, then where's the problem in being up there with them? But this is getting off thread...