OK -- why

[Liquid Charlie]

Simple question -- why do we not use flight levels across all cruising altitudes in North America unless you are in northern airspace -- at the very least they should be used in all uncontrolled airspace but why not expand it to encompass all -- it seems to me it is the only accurate way to maintain separation when we are playing with 500 feet --

[nbinont]

For avoiding other aircraft, sure, I agree flight levels are simpler. However for avoiding the ground, flight levels are pretty much useless. So near the ground, I'd much rather have a good idea how close to the ground I am.

Given the two needs served by the two systems: avoiding the ground and avoiding other aircraft, we just need to have a simple way where we switch between them. Someone arbitrarily said 18,000ft, and it seems reasonable enough given the different ground elevations across the country, however it is arbitrary - if someone has a better approach, by all means try to explain it simply so pilots can easily and accurately follow it.

[Rockie]

I can envision a time when barometric altimeters will be a backup system only. Already WAAS provides 3-dimensional position accuracy better than barometers and that capability is being used today in LPV approaches using a common reference and free of the kind of atmospheric errors barometric altimeters are subject to. Only a matter of time until somebody discovers the benefits of enroute vertical separation.

[nbinont]

Already WAAS provides 3-dimensional position accuracy better than barometers.

I don't know if I'd go so far to say WAAS altitudes are better than barometric altitudes. WAAS is slow to react without a barometer (which is why your barometer is used as an input to WAAS GPS units). And there are many cases where the barometer altitude can be better (sea level, far away from WAAS ground stations). Conversely the WAAS altitude has many cases where it is better (high altitudes, nearer WAAS ground stations). Though you can certainly mess up an altimeter setting with very bad results. Over all I'd say they are just comparable. This is also supported by the decision heights on LPV vs ILS I approaches - they are comparable. To get lower, ILS CAT II wants a radar altimeter.

[swordfish]

For avoiding other aircraft, sure, I agree flight levels are simpler. However for avoiding the ground, flight levels are pretty much useless. So near the ground, I'd much rather have a good idea how close to the ground I am.

Given the two needs served by the two systems: avoiding the ground and avoiding other aircraft, we just need to have a simple way where we switch between them. Someone arbitrarily said 18,000ft, and it seems reasonable enough given the different ground elevations across the country, however it is arbitrary - if someone has a better approach, by all means try to explain it simply so pilots can easily and accurately follow it.

Lame argument, IMHO. They don't have any problems all over Europe avoiding planes and ground when they switch to QNE a few minutes after takeoff - anywhere between 3000' and 6000' AGL as assigned. Pretty well the only time you're on QNH is when you're in a the control zone of the airport, and separation there is provided by radar.

[nbinont]

For avoiding other aircraft, sure, I agree flight levels are simpler. However for avoiding the ground, flight levels are pretty much useless. So near the ground, I'd much rather have a good idea how close to the ground I am.

Given the two needs served by the two systems: avoiding the ground and avoiding other aircraft, we just need to have a simple way where we switch between them. Someone arbitrarily said 18,000ft, and it seems reasonable enough given the different ground elevations across the country, however it is arbitrary - if someone has a better approach, by all means try to explain it simply so pilots can easily and accurately follow it.

Lame argument, IMHO. They don't have any problems all over Europe avoiding planes and ground when they switch to QNE a few minutes after takeoff - anywhere between 3000' and 6000' AGL as assigned. Pretty well the only time you're on QNH is when you're in a the control zone of the airport, and separation there is provided by radar.

swordfish: Note that I only argued that we need some regions to be on QNH/altimeter setting near the ground and a simple way to switch to QNE/flight levels. I'm not sure how this is lame.

As I don't fly in Europe, I'm unfamiliar with how they handle it. Could you enlighten us? When would an aircraft switch between QNH/QNE when there's no tower? How about NORDO aircraft?

[Rockie]

This is also supported by the decision heights on LPV vs ILS I approaches - they are comparable. To get lower, ILS CAT II wants a radar altimeter.

WAAS in its present form has limitations especially across the poles, but look how far we've come in the last 25 years. GPS technology and its enhancements are revolutionizing the way we operate aircraft and in 2020 the US is taking it all another giant step upwards with NextGen. There are currently 3404 LPV procedures in the US versus 1284 CAT I ILS's, and 856 of those LPV's have a 200 foot decision height - the rest are 250'. There are also 11 GLS approaches with work continuing apace worldwide to develop that ability with the eventual goal of full CAT III autoland. GLS provides I believe 1 meter resolution.

By the time new pilots today retire in 40 years chances are good the next technology beyond GPS (whatever that turns out to be) will be a reality, but at the very least the current technology will be refined and enhanced to the point we won't recognize it any more.

[photofly]

As I don't fly in Europe, I'm unfamiliar with how they handle it. Could you enlighten us? When would an aircraft switch between QNH/QNE when there's no tower? How about NORDO aircraft?

Different transition levels (going down) and transition altitudes (going up) are assigned per airspace block. From a GA perspective, it's hideous, compared to the North American way of doing things.

Anyone who thinks the biggest error in their indicated altitude comes from not updating their altimeter setting as they fly along shows an almost laughable faith in the accuracy of their instrument.

[swordfish]

It's 15 years since I flew there, and have done all my subsequent flying in Canada.

Over there the transition level at each airport is decided by the QNH (I believe; I'm not sure how this worked. All I remember is that it changed from day to day, and place to place) and you switch to it as soon as you go thru it after takeoff, and you switch to QNH when you're handed over to the tower on arrival. I didn't fly into places that had no control. Indeed it would surprise me if there are any places like that these days, as the airspace is so congested over there. And if there ARE, they will be controlled indirectly by Eurocontrol.

I also doubt that NORDO aircraft are permitted there, or permitted within a tight range of geographical and vertical limits. NORDO is a primitive permission.

The concept of 18,000 being "arbitrarily" selected as the TA makes me wonder. ("Why...?") North America clings to many primitive concepts, to permit "backwards compatibility", none more underscored than the new CAP charts, which seems to be getting dragged - kicking and screaming - into the 21st century (we have relatively few ILS approaches in Canada, yet TC/NavCanada is clinging tenaciously to hundreds of step-down NPAs, instead of SCDAs "Why...?").

LC is bang-on. We should be using flight levels (QNE) for all flight after you clear out of a CZ/MFZ in North America. And while I'm on a tear...the confusing different procedures for changing between QNE and QNH need to be tossed in favour of standardization, together with adopting harmony with the JAA countries and standards.

[Shiny Side Up]

I also doubt that NORDO aircraft are permitted there, or permitted within a tight range of geographical and vertical limits. NORDO is a primitive permission.

NORDO is awesome. Just you and the airplane noises. No silly chatter.

All seriousness aside though, I think you guys are forgetting that North America ain't Europe. Vast swaths of uncontrolled airspace, no radar coverage, the altimeter as a tool of separation just isn't something to be counted upon. Enjoy it while you can.

[swordfish]

Think: "International Standardization", and that will assist your perspectives

[Liquid Charlie]

As I don't fly in Europe

--

It is only Canada and the United States that don't have "low level" flight levels -- btw FL180 is not standard in all of Canada either -- look at Northern Airspace -- and to depend on people to reset their altimeters while flying from a to b unless you are under IFR is a joke -- I have seen 3 to 4 hundred feet differences in stations 100 miles apart -- Canada is a large area with poor weather reporting for the vast majority of that and the only place you can get reliable altimeter settings is in that airspace within 100 miles of the US border -- when I am flying IFR altitudes and mixing with VFR traffic I have no faith in the VFR guy religiously updating his altimeter -- the rest of the world makes it work and my opinion it's far safer for enroute aircraft -- especially in the vastness of our uncontrolled southern airspace -- works in the arctic and works great why not in the northern part of the provinces as well --

[justwork]

it seems to me it is the only accurate way to maintain separation when we are playing with 500 feet --

That's what "conflicting traffic please advise" is for.

[Shiny Side Up]

Think: "International Standardization", and that will assist your perspectives

So when are they going to become more like us?

[digits_]

For avoiding other aircraft, sure, I agree flight levels are simpler. However for avoiding the ground, flight levels are pretty much useless. So near the ground, I'd much rather have a good idea how close to the ground I am.

Given the two needs served by the two systems: avoiding the ground and avoiding other aircraft, we just need to have a simple way where we switch between them. Someone arbitrarily said 18,000ft, and it seems reasonable enough given the different ground elevations across the country, however it is arbitrary - if someone has a better approach, by all means try to explain it simply so pilots can easily and accurately follow it.

Lame argument, IMHO. They don't have any problems all over Europe avoiding planes and ground when they switch to QNE a few minutes after takeoff - anywhere between 3000' and 6000' AGL as assigned. Pretty well the only time you're on QNH is when you're in a the control zone of the airport, and separation there is provided by radar.

In Europe they do almost exactly the same as in the US and Canada. Transition altitudes are usually defined per country. You look at the highest obstacle and add a few thousand feet. The only difference is that Canada and the US as a country are bigger than the whole of Europe combined. So the Rockies give you ridiculously high transition altitudes.

Good thing they ignored Alaska, or we would have transition altitudes of 25000 ft

[Liquid Charlie]

That's what "conflicting traffic please advise" is for.

who in their right fuking mind makes that mindless statement -- lmfaooooooooooo --

Alps do create a bit of an obstacle --

[Illya Kuryakin]

That's what "conflicting traffic please advise" is for.

who in their right fuking mind makes that mindless statement -- lmfaooooooooooo --

Who says that? Pretty much everybody. Drives me nuts!
Another one I love.."Expecting Armpit Lake in 15..." Or the dumbest one ever ..."Wheels down in ten.." WTF? Where'd that moronic line come from? Then the fools leave the wheels UP!
As far as low level flight levels go, too many can't set an altimeter in the first place, let alone remembering to set field barometric for approaches. The carnage! Think of the children!
Illya.

[ragbagflyer]

The concept of 18,000 being "arbitrarily" selected as the TA makes me wonder. ("Whi]") North America clings to many primitive concepts, to permit "backwards compatibility", none more underscored than the new CAP charts, which seems to be getting dragged - kicking and screaming - into the 21st century (we have relatively few ILS approaches in Canada, yet TC/NavCanada is clinging tenaciously to hundreds of step-down NPAs, instead of SCDAs "Why...?").

LC is bang-on. We should be using flight levels (QNE) for all flight after you clear out of a CZ/MFZ in North America.

I doubt it's a totally arbitrary designation. It has something to to with obstacle clearance. The highest US or Canadian mountain outside of the Saint Elias range in the Yukon/BC/Alaska is 14500 and you can make a good argument that if there is a chance you're flying close to terrain you might want your altimeter to reflect your actual altitude.

[Liquid Charlie]

It has something to to with obstacle clearance.

I beg to differ -- so we can't fly over mountainous terrain at flight levels -- seems we do it all the time -- ifr ATC will assign the transition level or minimum crossing level -- the eastern arctic and Greenland are designated mountainous areas and flight levels are flown all the time -- as for VFR -- what does VFR mean -- pretty simple concept -- but Canada is so far behind in most aspects of aviation -- what else could one expect

[swordfish]

At the risk of boring everyone to death, may I quote a couple of extracts from a Eurocontrol pdf? (Eurocontrol has actually launched an initiative to establish a "common" transition level, as the discrepancies in standards are causing headaches for crews, operators, and Air Traffic Control)

"19 EUR States have two or more transition altitudes for the same aerodrome depending on the
departure/arrival direction. Some have up to 4 at the same aerodrome. One EUR State has 118 different TA values for the airports listed."


"Denmark
The TA for the whole FIR is set at 3000 ft AMSL except for the Copenhagen Area where it is set at 5000 ft
AMSL.
The TL is variable by ATC based on QNH.
The TL is changed in 1000 ft increments using QNH bands of 34 to 36 hPa

The Netherlands has it’s airspace divided into four Altimeter Setting Regions. The QNH of the
airports of Schiphol, Maastricht, Aachen and of two off-shore platforms is used. VFR and IFR
traffic have a different transition altitude (3500 ft and 3000 ft respectively).

Belgium uses the term Regional QNH as sole reference for the enroute portion of a flight below
the transition altitude. This means that the lowest value is taken from a certain number of
reporting stations.

Switzerland is divided into three Altimeter Setting Regions: Zurich, Geneva and Ticino.

Norway includes the ICAO table for the altimeter correction when operating in extreme cold
temperatures. It does not apply the Altimeter Setting Region concept. For terrain clearance, the
QNH of the nearest aerodrome along the route should be used. These are available from all the
controlled aerodromes and from aerodromes where flight information services (AFIS) are
provided.

Belgium and Germany have one value for the transition altitude, although Belgium uses 4500 ft
which does not conform with ICAO PANS-OPS (Doc 8168-Ops/611, Volume I- Flight
Procedures)"

[Chaxterium]

At the risk of boring everyone to death, may I quote a couple of extracts from a Eurocontrol pdf? (Eurocontrol has actually launched an initiative to establish a "common" transition level, as the discrepancies in standards are causing headaches for crews, operators, and Air Traffic Control)

"19 EUR States have two or more transition altitudes for the same aerodrome depending on the
departure/arrival direction. Some have up to 4 at the same aerodrome. One EUR State has 118 different TA values for the airports listed."


"Denmark
The TA for the whole FIR is set at 3000 ft AMSL except for the Copenhagen Area where it is set at 5000 ft
AMSL.
The TL is variable by ATC based on QNH.
The TL is changed in 1000 ft increments using QNH bands of 34 to 36 hPa

The Netherlands has it’s airspace divided into four Altimeter Setting Regions. The QNH of the
airports of Schiphol, Maastricht, Aachen and of two off-shore platforms is used. VFR and IFR
traffic have a different transition altitude (3500 ft and 3000 ft respectively).

Belgium uses the term Regional QNH as sole reference for the enroute portion of a flight below
the transition altitude. This means that the lowest value is taken from a certain number of
reporting stations.

Switzerland is divided into three Altimeter Setting Regions: Zurich, Geneva and Ticino.

Norway includes the ICAO table for the altimeter correction when operating in extreme cold
temperatures. It does not apply the Altimeter Setting Region concept. For terrain clearance, the
QNH of the nearest aerodrome along the route should be used. These are available from all the
controlled aerodromes and from aerodromes where flight information services (AFIS) are
provided.

Belgium and Germany have one value for the transition altitude, although Belgium uses 4500 ft
which does not conform with ICAO PANS-OPS (Doc 8168-Ops/611, Volume I- Flight
Procedures)"

See?! Clear as mud!

[rxl]

Now there's a forward-thinking, logical system for us to emulate.
There's no chance of someone having their altimeter set incorrectly with that simple set of rules.

[cyeg66]

The whole world should just use YYZ's QNH setting, since it's the centre of the universe, no?

[digits_]

Now there's a forward-thinking, logical system for us to emulate.
There's no chance of someone having their altimeter set incorrectly with that simple set of rules.

It is actually pretty easy since the transition altitude is usually set on the ifr charts as well. And when you descend the transition level is provided by ATC. One of the advantages of having ATC and radar coverage everywhere.

[rxl]

Two different ways to skin the same cat. Each one is adapted to two completely different environments.

The only people who think YYZ is the "centre of the universe" are those who don't live there.