Lakes - FL or Alt?

[mr_rodge]

Hi all,

After a poor year's flying last year due to financial constraints I'm just about back on the horse. Having gotten the IMC rating in January I'm beginning to get the confidence back and am looking at flying further afield for day trips with the girlfriend etc.

Anyway, to the point. I know there's a lot of talking going on with the transition altitude and standardisation, however I'm looking at a couple of hours flying over the lakes with my dad in a couple of days time and wondered what everyone would do. Having chatted to a few pilots down at the field the general attitude is to fly as you would any other VFR flight, only higher i.e. QNH for terrain clearance and talk to Leeming/Linton for as long as possible. There is, however, an article in the latest issue of Flyer stating that if we are to go high enough (I was looking at just a transit over at 5000' ish, no valley flying!) then it should go without saying that we should be on 1013, flying FLs using the quad rule and making sure the selected level allows for terrain clearance whilst keeping below the airways.

I've no problem doing either, but what would you do? The route is Full Sutton -> Harrogate -> Penrith -> Dean Cross -> Whitehaven -> Harrogate -> Full Sutton.

Cheers.

[BackPacker]

Actually what I would do is keep my altimeter on the QNH (for terrain clearance) and read my FLs (for traffic separation) from the transponder. It's a useful trick my aerobatics instructor showed me when we were doing aerobatics below and above the TA/TL.

Have to have a mode-C transponder at least for that to work though. And of course you need to be aware of what the TA/TL actually is, so you know whether to read back the altimeter (altitude) or transponder (FL) back to ATC.

For IFR flying obviously you need to follow IFR procedures though.

[mr_rodge]

BackPacker,

That sounds a nifty trick. As far as I'm aware it's still 3,000ft over there, so I need to be on FLs. I wish I had two altimeters/a transponder showing FLs so I could actually make use of that!

What's the opinion on the area? Would everyone fly on 1013 over the lakes?

During IMC training we were regularly flying above the TA at 5/6000' on QNH. In fact, I don't think we ever used 1013 during the IMC course. Would that be because we had a LARS and were squawking Charlie, so ATC could see our level anyway? Then we wouldn't have been flying the quadrantal rule... Is that because the instructor was VFR and I was only simulated IFR?

Thanks again.

[Genghis the Engineer]

Just look at the chart. If the bottom of the class A you're dodging is expressed in feet, set QNH, if it's set as a FL, set 1013. (And then set your No.2 altimeter to QNH for terrain avoidance.)

G

[mr_rodge]

Genghis,

That's what I was looking for. Thanks. No second altimeter though, so it'll be the one upstairs I think! The pressure at the minute is forecast to be high so easy peasy.

Thanks again.

[Whopity]

It will all be solved soon when the transition altitude goes up to 18000ft. Above transition you should fly at an appropriate flight level, if possible, but if you are sight seeing I would have thought that you could be below the TL and therefore on QNH.

[Genghis the Engineer]

Genghis,

That's what I was looking for. Thanks. No second altimeter though, so it'll be the one upstairs I think! The pressure at the minute is forecast to be high so easy peasy.

Thanks again.

Glad to help.

If I were you, I'd also just work out the correction between QNH altitude and 1013 on the day so that you have a quick check on MSA / terrain if flying 1013. If on QNH, no issue really.

G

[tmmorris]

It will all be solved soon when the transition altitude goes up to 18000ft.

This may sound like a dumb question, but what happens to semicircular/quadrantal rules under these circumstances? I do a lot of flying IFR OCAS and while I know it's not quite separation, I get a small amount of comfort from the quadrantal rule.

Tim

[Genghis the Engineer]

This may sound like a dumb question, but what happens to semicircular/quadrantal rules under these circumstances? I do a lot of flying IFR OCAS and while I know it's not quite separation, I get a small amount of comfort from the quadrantal rule.

Tim

Use altitude instead of flight level. This is perfectly normal already in the USA where the transition level is up in "mandatory oxygen" territory, and on occasion in the UK.

Would be a good opportunity at the same time to get rid of the UK-only quadrantal rule and implement the ICAO standard semicircular rule. But I don't suppose that will happen.

G

[mrmum]

I think Quadrantals will disappear anyway pretty much, as they only apply up to FL190, after which it's the semi-circular rule already. When the TA goes to 18,000ft, that leaves only a small band applicable to Quadrantals, it would probably be sensible to get rid altogether.
They're pretty much a waste of time anyway as far as collision avoidance in IMC OCAS goes, much better to just let people spread out randomly at various altitudes.

[10W]

If you're flying during the day (which I am sure you will be under VFR) and stay South of the Solway Firth and North of Kendal, there is no Controlled Airspace below FL125, which is WAY above the 5000' you are planning on operating at.

On that basis, I would personally fly VFR in the area on a QNH rather than a Standard Pressure Setting. It saves the mistake of making an error when calculating terrain clearance if you are flying using the altimeter with reference to Flight Levels.

If you need to start drifting up towards 10,000' for any reason, then would be a good time to change to 1013HPa on the subscale in case you creep up higher towards the base of the Airways. Very unlikely to be a problem though, unless there is a massive low pressure area. If you are at 10,000' on a low 970HPa, you are still going to be below the base (at 11,290' approximately or FL112).

[GeeWhizz]

Without contesting any of the above there's an interesting slant to the question of FL or Alt. As long as I know the terrain clearance it doesn't matter whether the sub scale is set to 950hPa or 1050hPa.

For instance if I take off from the top of a mountain (highest elevation in 100nm) and the sub scale is set to 950hPa with the altimeter reading +800ft then as long as the altimeter reads +1300ft I'm 500ft above the highest obstacle within a 100nm radius.

That said if I were to go sightseeing locally within perhaps 1-2 ASRs, flying an altitude is probably more sensible than a FL as only one or two sub scale setting changes are required. But flying through 4-5 ASRs or more sometimes in quick succession would mean 4-5 (or more) pressure changes followed by the necessary climb/descent adjustment when a FL altimeter indication would remain the same (notwithstanding terrain clearance minima).

In sum: local sightseeing its more useful to fly an altitude affording liberal descent/climb manoeuvrability, for long legs crossing several ASRs use a FL for simplicity. Simples!

GW