Altimeter setting procedures

[CirrusF]

Do you change altimeter calibration to STD exactly as you climb through transition altitude and to QNH exactly as you descend through transition level? Or do you change to STD as soon as you are cleared to climb to a Flight Level and to QNH as soon as cleared to descend to an altitude?

I have always done the latter but at a recent simcheck I was picked up on it and told to do the former. Anyway, does it actually matter from the point of view of separation?

[dbee]

Generally one does as you said: when cleared to a FL (provided that no more alt reports are required) set 1013; similarly in descent set QNH when cleared to alt provided no more FL reports etc. Don't forget to call the pressure setting change and ensure that the alt call from your oppo shows the he/she has done so. dbee

[potkettleblack]

I fly the bus around Europe and our SOP's are when cleared to a FL (and out of SRS) we set STD. Similarly when cleared to descend to an altitude we set the QNH and the PF will cross check their altimeter by verbalising with the PNF. Something like 3,000 on 996 gives me xxxft. The PNF will confirm with a "checks" or something along those lines.

Our SOP's differ for flying in the US since the TL is much higher than what you find in Europe but its probably not relevant to your question.

[Checkboard]

I used to change at transition in Australia, but Australia has a single, standard transition altitude of 10,000 feet. In Europe, with such a plethora of transition levels, it is smarter to change on receiving the clearance - it gives you a trigger to change, which makes forgetting (with the consequent level bust) a little less likely.

Where this may change is on P-RNAV SIDs and STARs, In this case limiting levels or altitudes may be published on the chart. You may be cleared on descent to an altitude, but with an intervening level restriction, so you need to define a point to change from QNE on descent.

[BelArgUSA]

Altimeter changes

I would recommend (contrary to what some of you do) to remain on QNH for departure, until reaching TRANS ALT, and, during descent and approach, to remain on QNE/STD until reaching TRANS LVL for a few reasons.
xxx
The reasons are simple.
xxx
(1) If you have to come back for immediate landing...? Better have QNH preset, is it...?
(2) If ATC asks you to level-off "due to traffic" during your climb or descent...?
(3) If waypoints on the SID or STAR are published with QNH (or QNE) and is not what your altimeter shows...?
(4) If ATC calls you and requests "say passing ALT (or LVL)"... during your climb or descent...?
(5) If you have to play around with QFE in Russia or China...?
xxx
TRANS ALT is one thing clearly briefed for our departures (as well as the SID) rather than spending time "bla bla bla, we abort if... bla bla bla before V1 etc..." that we know well since years ago. Same for TRANS LVL during the approach briefing, and they are written on our "bug cards" for takeoff and landing.
xxx
To mention also, about the altimeter, is that we do not "short-out" the digits of the setting (like saying "987" for 29.87 inches, a habit of some of our Yankistan friends) and we say/readback the name in full of the setting units - such as HECTOPASCALS or INCHES (although this old fart still pronounces "hPa" as "millibars") - After all, our altimeters still have "mB" printed next to the Kollsman window in our old 747s.
xxx
The only crewmember setting his altimeter "in advance" is our F/E, for management of cabin pressurization. He sets QNE before departure, and QNH at top of descent.
xxx
Our 747 airplanes have an "extra altimeter" to the right of the captain's instruments (metric) - I preset that one to QNE prior to departure, and QNH at top of descent, as my "personal reminder" of proper QNH setting. That is the one I read to tell the passenger how high they will have to jump with their parachutes... (and they do not listen to the PA anyway).
xxx

Happy contrails

[763 jock]

Just do what your company SOP's require. If you have a better idea then raise it with management. Simple really..............

[411A]

BelArgUSA has it right, and that is precisely what we do in our small airline.

[BOAC]

CORRECTION: 763 jock has it right.

[CirrusF]

I agree with all the points that BelArgUSA makes - but I have always taken care of all the points that he raises by leaving QNH on the third altimeter, just as he does. So if ATC asks me to report at such and such an altitude, I can quickly check the third altimeter. I generally update the QNH on the third altimeter throughout cruise whenever I pick up the local QNH through radio traffic, so that I permanently have an accurate readout. It is also useful because I get an idea throughout the flight of whether I am flying towards low-pressure or high-pressure, and all that helps with understanding weather and winds ahead.

But I've always (until now) changed setting on the principal altimeters as soon as cleared to a new altimeter setting by ATC on the grounds that, as others point out, it is easy to get distracted while passing transition altitude or level and end up doing a level bust.

Good point BelArgUSa about including transtion altitude and level on pre-departure and pre-descent briefings.

[Denti]

Many ways to skin that cat obviously.

We change to STD at transition altitude and yes, we do brief it during our normal departure briefing as it is different at nearly every airport. However our standby altimeter remains on QNH until top of climb for a possible return. In case we have an extra metric altimeter on the classics (dont need that in the NG anymore) it is allways set at standard except when operating in metric countries.

Back down we set well before top of descent the standby altimeter is set to QNH of the destination (QFE operation is not allowed anymore), values from the ATIS or ATC. The main altimeters are switched to QNH once we get a clearance to an altitude. Of course if we get a reclearance to a FL we have to switch them back to STD.

[BelArgUSA]

"Third" altimeter

Cirrus -
xxx
For me with my planes, the problem is that the "3rd altimeter" is metric...
You probably fly with a 3rd altimeter in feet - a good cross-check. Fully agree with your ideas. I flew many contracts with different companies, most if not all of them had altimeter procedures same or very similar to the one I described.
xxx
I remember American Airlines had an extra altimeter they kept on QNH, since they flew QFE for takeoff and landing (in US airspace...!) until the 1990s... Eastern Airlines used QFE as well. I got trained to use QFE OR QNH as early as my PPL days as a teenager... and PanAm had excellent optional QFE procedures training for Russia/China operations. Was required for all pilots operating these routes.

Denti -
xxx
Of course if you cannot use a QFE procedure, apply your QNH procedure. The last time I went to Moscow (2005) - I did use QFE/Metric - I believe it can be quite dangerous to "convert" QFE to suit a "QNH" procedure in that airspace. I recall many "horror stories" about wrong altimeter settings and erroneous levels or heights to maintain in Russia or China airspace, at least with old "classic" avionics. If your NG equipment permits, of course, must be a great convenience. Meters for QNE levels and QFE heights, meters/second for winds, or rates of climb, kilometers/hour for speeds... is much of a headache even if I am quite proficient in flying with such numbers, TRANS LVL and TRANS HEIGHTS...
xxx
In Russia/China, I always decided to be PNF and being extra careful in my conversions, just telling the PF "what to do next"... unless you do fly that airspace and these procedures twice a month. I never had problems.
xxx

Happy contrails
xxx

[763 jock]

My point was that in an airline environment you can't have hundreds of pilots all doing what they think is best. In my outfit, we set standard when cleared to climb to a Flight Level and QNH when cleared to descend to an altitude. A cross check is compulsory when a change is made. The standby altimeter remains on QNH until passing FL180 going up and has destination QNH set prior to TOD. It can therefore be used for "passing altitude" reports if required.

If a stop climb/descent clearance is subsequently issued it is up to the crew to make sure the subscale is properly set.

Plenty of other ways of doing it, but this works well for us.

[Checkboard]

Just do what your company SOP's require. If you have a better idea then raise it with management. Simple really..............

The point of a discussion like this on a "Professional Pilot's" website, is to see if there are any better ideas out there.

[BOAC]

Indeed, CB, but the ONLY correct answer is to follow your company SOPs as 763 says, isn't it? Otherwise you probably should change your job?

No-one is trying to stifle 'ideas', just to point out that that is the only way it will work in a multi-crew environment. I have no argument with the logic provided, but "BelArgUSA has it right" is only true in BelArgUSA's airline. BelArgUSA and 411A would not be allowed to operate in mine and many others. Simple?

Yes, I know they don't want to...............................

[Jumbo Driver]

UK ATC will, in the climb and after you have been cleared to a FL, reference any subsequent requests to FLs and conversely, in the descent and after you have been cleared to an altitude, reference any subsequent requests to altitude (i.e. QNH). I imagine most other countries' ATC would adopt similar procedures.

Therefore, it is sensible to set 1013mb when cleared to a FL in the climb and to set QNH when cleared down to an altitude in the descent. If you have an autopilot engaged and you are selecting a cleared altitude/FL, then it becomes essential to set the appropriate subscale at the same time to avoid a potential "level bust". As has been said, many (most?) IFR equipped aircraft will have a third altimeter set to QNH during CLB/DES anyway for reference if needed - unless, of course it is metric!

In any event, I think 763 jock has it right - if you are operating under an AOC, stick to your SOPs.

I have respect for BelArgUSA's postings but I must correct him on one point.

Contrary to common belief, QNE is not a subscale setting (1013mb). QNE is an altimeter reading (i.e. height) and is defined as what the altimeter will indicate at the surface (usually at an aerodrome) when 1013mb (STD) is set. It is little used now but it had its uses at high altitude airfields for operators who used QFE, when QFE was very low. It was an alternative used either to avoid a very long wind-down of the subscale to QFE or if the QFE was less than the lowest subscale setting of the altimeter.

To use the term QNE in discussion as if it equated to "setting 1013" is therefore wrong.


JD

[BelArgUSA]

Again about altimeters...

To Sir BOAC
xxx
At no time did I imply, to reset altimeters in a manner or form contrary to SOPs applicable to any given airline. Obviously, if I would takeoff, I would preset the QNE, if departing a sea level airfield, to maintain FL 040 with a transition altitude published to be 3000 ft QNH... as we would be very unlikely to be restricted during the initial climb clearance.
xxx
My recommendation simply illustrates what I was trained to do in altimeter management ever since my intial IR training, long ago in the past century, which apparently has been acceptable to the numerous airlines and operators for which I have held a pilot position.
xxx
A procedure, defined by SOP, or a technique, are two different things. And in any case, my first concern is flight safety and observance of precise altitude/level profiles as published and/or required by ATC.
xxx
If your airline so requires, I assume your said SOP, must probably specify which fingers shall be used for rotating (is it clockwise or counterclockwise?) the altimeter setting knob with finger nš 1 and nš 3 (?) similar to sheet music used by piano students practicing Clementi Sonatinas...? Or, is it acceptable to use fingers nš 1 and nš 4, with the pinky held up, in the classy vertical position, as per social standing applicable at the 10 Downing Street, when sipping a cup of tea...?
xxx
As to be allowed to operate at your airline, and the "many others" you mention, I do not think that 411A, nor myself would consider the honor. You might hold, Sir, more aircraft type ratings, or have flight experience of more hours than I have logged, but I have probably flown, by far, with many more different air carriers or operators than you, and many others, at times maybe several during a calendar year, depending on contracts.
xxx
Having worked with many different operations, has given me quite an insight in comparing and criticizing the merits and caveats of their individual SOPs, reason why I have occupied numerous TRE, TRI and flight standards positions.
xxx
Yours respectfully,

Happy contrails

[Jumbo Driver]

If I may be so bold, I find that to be not one of your better posts, BelArgUSA ...


JD

[BOAC]

Thank you JD for bothering

[Pilot Pete]

xxx
Are you becoming 'son of 411A' Bel?
xxx
Does it matter which fingers I use to pick up your teddy and hand it back into your cot??
xxx
PP

knob with finger nš 1 and nš 3

[411A]

What it would appear here is that we have a few European pilots, whom are so enmeshed in their SOP's, that they then cannot think for themselves, let alone comprehend what other pilots, in other airlines, in other parts of the world, have been doing for years, and all quite safely, in full compliance with their specific airlines SOP's....simply because the European folks are perhaps far too narrow minded to understand.

Gosh, why am I not surprised?