Standby ALTIMETER SETTING CHANGE

[LEM]

Some people say:
During climb, leave the STBY altimeter setting to departure field setting, it could be useful in case you have to come back in a serious emergency.

Other people say: At transition (European transition, quite low) change ALL altimeters to 1013, to have one more crosscheck available for the other two altimeters during cruise, and above all not to have a false, misleading setting during descent ("Have we updated the setting to destination or not?").
If you have to come back in emergency, you will have to update anyway the whole cockpit, and if unable to talk to ATC you have the setting written down on the flight log.

I agree with the second philosophy.

What about you?

[Captain Stable]

In small aircraft, particularly if unpressurised, thus making it far more likely that you will be operating below TA, I'd leave it on QNH of airport of departure, thereafter on regional QNH (or for any other unusual situation).

Everything else, yes, put all altis on the same setting.

[Max Angle]

We set all three to QNH before take-off.

Main altimeters to 1013 when cleared to a level, stby to 1013 as part of the 10000ft checks.

stby goes to QNH when going down through 10000ft and mains when cleared to an alt. Not sure what the long haul boys do in US airspace.

[LEM]

I strongly agree with you not to follow the academic rule of changing altimeters AT transition, but to always have them set in accordance with the altitude you have in the altitude select window.
Unfortunately, there are still many guys out here who strictly observe the transition level/altitude, and it's GUARANTEED soon or late they will forget to change, and with low pressure in the approach area the result will be:{ !

:yuk:

LEM

[rightbank]

I generally agree with MAX whereby you set 1013 as soon as you are cleared to a flight level in the climb and QNH as soon as you are cleared to an altitude in descent. However companies I have worked for required the Standby to be left on QNH for the duration of the flight, as both MSA and driftdown are altitudes not FL's. The exception to this is if you are operating above FL290 where RVSM checks require all 3 to be set to 1013.

[Miserlou]

You do as the SOP says and the SOP probably says this-

Change to 1013 when passing TA when climbing (then you know where you are with regard to MSA in case of an emergency) and all three at the same time.

Change to QNH as soon as you're cleared to an altitude when descending then the autopilot will (should) level out at the correct place and not infringe any MSA's.

Having them set to different settings as a reminder is BS because the autopilot will tell you if it has a problem deciding who has the correct setting and they'll have to be set the same anyway.

If you need to remember something WRITE IT DOWN!

[fireflybob]

Yes you should do what your company SOPs say but I thought that, on climb, you should set 1013 (on all but the standby altimeter) as soon as you are cleared to a Flight Level. Not to do so risks a level bust.

[Miserlou]

Now let's think about it for a moment.
My base airport's SID ends at FL70. Should I set 1013 before take-off then? Of course not.

Some people try to get their after take-off checklist done asap even though you should be clear of the departure zone.
If you do it at or around the TA you've got yourself covered.

What if you get a "Stop climb at 4000'" instruction?

Doesn't make sense. When PASSING TA in climb and when CLEARED an alt. when descending. All three together.

[fireflybob]

>My base airport's SID ends at FL70<

Miserlou, does that mean your SID is unrestricted climb to FL70, or is there an altitude restriction prior to this, eg. cross x at 4,000ft?

If so, then after the 4,000 ft restriction then you should be setting 1013.

If the SID is unrestricted climb to FL 70 then there is still an option to set 1013 before TA and, I say again, this may prevent a level bust if you omit setting 1013.

Would you st 1013 on the standby in this case if your MSA/SSA was, for example, 9,000 ft amsl?

>What if you get a "Stop climb at 4000'" instruction?<

Assuming you are cleared to a FL then ATC should be aware of this and the fact that you may have 1013 set (in theory) but since you would still have QNH on the standby why should this be an issue?

[galaxy flyer]

As a pilot in the American Air Farce, I've never understood why the rest of the world does not agree to the American standard of FL180. No, we certainly are not right all the time in the Land of the Free, but changing altimeters to FL at 3000 feet seems to invite terrain clearance problems. It's so late in the approach that it can be missed and causes the problem on departure of "stop climb at 4000" instead of climbing to FLs. FL 180 is high enough that you are well away from any terrain.

Can't wait for the hoots.

[PakoSpain]

As an ATCO and in order to keep vertical separation I expect pilots to fly altitudes (local QNH) below TL and TA, an flight levels (1013) above. In the event one departure has to stop climb at a certain altitude due to inbound traffic, if both altimeters are not set to local QNH, the 1000 ft separation is not granted.

[overeasy]

Here is another one for you, and I am sure we are not unique. In cruise we set the Standby to line up with the other altimeters. 1013 does not give a very accurate reading and useless in RVSM. At least if the others go down you have something realistic to follow and in RVSM ayou are less likely to bump into someone comming the other way !

[Spank me baby!!!]

As an ATC I cannot make any comment on the use of multiple altimeters in aircraft, so, from a controller's perspective, I'm separating my aircraft on the assumption that everyone at or below the Transition Altitude has an altimeter set to QNH, and everyone at or above the Transtion Level have altimeters set to 1013.

I don't care which altimeter you use, as long as when I ask you to report the level you're passing, its based on the correct setting above or below the Transition Layer. That way, when you tell me you're 1000FT apart, YOU ARE 1000FT APART!!!

This is even more critical when 500FT separation is in use. I often correct 300FT variations in Mode C altitude information on radar due to incorrect pressure settings on altimeters.

300FT variation (Aircraft A) + 300FT variation (Aircraft B) = 600FT

500FT Separation Standard minus 600FT total variation = :{

Remember, my radar cannot measure what altitude or level you're at, only you and your transponder can give me that information...:ok:

[fireflybob]

Different states may have different requirements but here is a quote from the UK AIP ENR 1-7-2 (24 Jan 02) under Altimeter Setting Procedures:-

5.1.4. ....When cleared for climb to a Flight Level, vertical position will be expressed in terms of Flight Level, unless intermediate altitude reports have been specifically requested by ATC.

I would be interested to know what the ICAO Pan-Ops says these days - it's a while since I looked but I suspect it's the same as the UK AIP.

By the way, Galaxy Flyer, point well taken about having a higher TA but it's only 3,000 ft in the UK outside controlled airspace. Go to places like LHR etc. and it's 6,000 ft although the lack of commonality would make good for another thread!

[Spank me baby!!!]

firefly, so you have more than one Transition Altitude in the UK?

Throughout the Australian FIR, the Transition Altitude is 10000FT, regardless of the class of airspace you're in, be it Controlled Airspace or Outside Controlled Airspace.

:8

[Spitoon]

As a controller, I would expect the pilot of any high-performance aircraft to be able to follow my instructions/requests. If the cleared level is an altitude, I would expect level reports etc to be QNH-based, if it's a FL, I would expect level to be referenced to 1013. If it's vital to be certain what setting is used I'll double check by asking the pilot (and use Mode C if it's available).

I'll do my best not to swap between the two settings (e.g. having cleared the pilot to a FL to then give a stop your climb at an altitude) but these things can and do happen for various reasons. If I have to do it I'll always give the QNH again if it's a stop at an altitude. Whilst it may be an inconvenience, pilots seem able to comply with instructions in these cases whatever altimeter setting procedures are used.

I've always got half a mind on vertical searation when I'm working around the Transition Layer and will build in a buffer to a clearance that will at least ensure a degree of vertical space if the wrong pressure is set.

No, it's not fail-safe and, no, it's not the perfect situation. And certainly building in a bit of extra vertical can't be done all the time (and probably never at some places). As a side issie, I kinda like the 10000ft or 18000ft Transition Alt idea but I'm wary of saying 'let's do it' without giving it a lot of thought to see what other problems might emerge because the rest of the UK's airspace and procedures are based on the lower levers.

My attitude may seem insular but reading this thread clearly shows the range of altimeter setting procedures that are used. Sitting on the ground, I'm not going to try and second guess what altimers are set at what pressure setting on any particular aircraft! If you're a pilot and feel happy that you could comply with the (sometimes messy) level instructions that a controller gives because you've always got altimeters set up to let you, this is good. If not, is it something to raise with your Ops?

[Captain Stable]

It appears to come as a surprise to controllers and pilots who are used to the situation in other countries (Oz and the USA in particular) that the UK does not have a standard TA/TL, and that it tends to be a lot lower than in those other countries.

What you need to bear in mind is the size of the UK, which, together with the density of population, the density of airports and therefore density of controlled airspace and density of air traffic, requires active Air Traffic Control down to a much lower level.

Furthermore, we do not have fantastically high lumps of cumulo-granite so above 4,406' there isn't so much of a problem with inadvertently bumping into the terrain. It does happen, of course, but you need to try a bit harder than you do in some parts of the world.

In my previous airline when the SID ended at a FL, we took off on QNH and setting 1013 was one of the post-take-off actions (which triggered the request for the after take-off checks). For reasons that, I am sure, most people here can understand, I am not entirely happy with the concept of SIDs ending at a FL rather than an altitude.

I believe (I may be wrong) that PANS OPS says you can set 1013 when less than 2,000' from TL and cleared to a flight level. You may be making difficulties for yourself if you set 1013 immediately you are cleared to a FL since you may be asked for your passing altitude on the way. In some machines I've flown, climb performance was not brilliant, so getting to within 2,000' of TL could take a while!

[BOAC]

Oh yes SMB, 3/4/5/6 and Naples Italy 8 for starters! Need more?

Spitoon - FYI - BA's procedure (737) is to set 1013 when above acceleration altitude (normally 1500' QFE) and cleared to a FL (no mention of within 2000'), but the standby remains on QNH until above MSA and TA, so is normally available for an altitude check.

[DFC]

Re the US system of flight levels above a comon very high transition altitude, I have the following questions;

An aircraft flies from the east coast to the west coast IFR at 14000ft. What are the laid down procedures that ensure;

a) The pilot has access in flight to the most appropriate QNH?

b) The flight does not hit a VFR flight coming the other way that hasn't reset the QNH for the past 1000nm?

Do Area Control Sectors have a QNH that they use for all flights within their sector?

When is this QNH updated and how much R/T time does it take to tell everyone on frequency and get an acknowledgement of the new QNH including some "say again"'s.

Since the QNH could be different in every sector how often do pilots change QNH on average per flight?

Finally, if the QNH in two sectors is measured at the centre of the sector, and the distance from the QNH source to the sector boundaries is 200nm, what is the worst case separatin minima of opposite direction aircraft on vastly different QNH and planned 500ft vertical separation plus some mode C error?

Of course, it looks like a great idea. However it seems to me to be an extra burden because - leaving FL350, passing FL190, set the sector (area) QNH which ensures separation from other enroute traffic then, before making the approach, set aerodrome QNH.

Seems like extra altimeter setting requirement to me.......like going back to using QFE again!

Regards,

DFC

[LEM]

Across Europe there are many different transition altitudes, and some are ridicolously low!!
And if you consider that (many?) Airlines do the Approach cklist
AT transition altitude....
:yuk:

[eyeinthesky]

As a Pilot and an ATCO:

When departing and cleared to a flight level, I will set the main altimeter to 1013 when passing MSA and leave the standby on the aerodrome QNH.

I expect a similar approach from the traffic I control. If you are cleared to a flight level, it should be terrain safe and it is the FLIGHT LEVEL, not the ALTITUDE which is providing your separation against the traffic above which is, presumably, also operating on 1013. If cleared to a FL and not asked for intermediate altitude reports, set 1013 as soon as you are above MSA.

In times of low QNH, a delay in setting 1013 until TA can end in tears.

Consider this:

High performance biz jet departing on a QNH of 983mb. Initial SID level is 4000ft, and the aircraft is subsequently cleared to FL 80 against traffic at FL90. TA is 6000ft. The crew, with the a/c climbing at 3000fpm, delay resetting altimeters until passing 6000ft.

6000ft on a QNH of 983 mb is approx FL 69. By the time the crew have set the altimeter to 1013 passing 6000ft at 3000fpm, the aircraft will be passing FL75 or more, with 6 seconds or less for the autopilot to capture the new level and start the level off. Chances of a level bust or worse very high.

There have been more than a few Airproxes in just this scenario. :eek:

[LEM]

Right!
So let's launch a new topic: " Do You Reduce Your Climb Rate In The Last 1000 ft?"

[Miserlou]

Fireflybob.

The climb instruction is "climb with min gradient 6.6% to FL70". The TA is 5000'.

Having the QNH in the standby alt isn't going to get the autopilot to level off at an altitude.

Now, with the input of some ATC types, we can see a pattern emerging. If you have the QNH set up to TA then you can stop the climb and report alt passing. Then at TA set 1013 and do the after take-off checklist.
Everything gets done at an appropriate time, nothing gets left out and you can comply with any request or necessity at any time.

I don't have plates handy for anywhere with a 9000' MSA, but I can't find any TA lower than MSA.

[galaxy flyer]

Well in the US with its altimetry, the controller has QNHs for the airports in the area and it is transmitted upon initial contact, if operating below FL180. The QNH is given with the descent clearance below TA/TL for the area. Yes, controllers forget and pilots ask, so its not perfect, but FL180 gives everyone time to straighten it out. VFR pilots are responsible to periodically get a QNH, how well that works I'm not prepared to say.

Usually on the hand-off to arrival control, you'll get a QNH for that airport. For the crew, it works because you can do the approach/in-range check early enough for the altimeters to be set prior to getting vectors or prior to the IAF.

I was an Eastern Airlines (dearly missed) and we used QFE almost to the end and had all sorts of peculiar altimetry procedures using QFE on the main altimeters and QNH on third altimeter. We both had to refer to the third when being vectored and change over to the mains for the actual approach.

There is nothing sacred about FL180, but, as a pilot, I like the idea of being on QNH once I've descended below the highest terrain.

[DFC]

MIserlou,

Check out Scotland north of Glasgow.

Highest obstacle is Ben Nevis (over 4000ft) and the transition altitude away from the main airports is 3000ft.

One thing that I have noticed in the UK is that the transition level is calculated as the flight level closest to and above the transition altitude. Thus there is no vertical separation between the transition altitude and the transition level.

When flying in Ireland, the transition level is quoted on the ATIS and is always separated from the transition altitude.

Perhaps people from other countries could state if their "transition level" is separated from the transition altitude or not.

Why with the same (ICAO) definition of transition level do two adjacent FIRs use totally different methods for it's calculation?

I must admit that I am in favour of having the transition level separated from the transition altitude for obvious reasons. I am also in favour of having the TL on the ATIS so that we can get a mental picture of how deep the transition layer is...............if TA is 5000ft and the TL is FL75..........we can instantly see that having changed to 1013 after being cleared to a FL, we are at the MSA of 3500ft after passing FL50. easy.

Regards,

DFC

[Tinstaafl]

TA in Scotland is A060, not A030 like England (except under London CTA where it's A060, apart from alternate Thursdays in months ending in '...er' unless you have 7 altimeters & specific JAR-OPs/CAA approved dispensation to operate.... ) :rolleyes:


Oz TA is A100, TL is F110. This gives 1000' buffer. As QNH reduces below 1013 the minimum available FL for use increases to maintain at least 1000' separation between the two systems eg min allowable FL could be F115, or F120 etc.

Very like the US system. A100 works well. The highest mountain is less than 8000' & A100 is a nice, easy to remember number.

[DFC]

Inverness, Scotland.....TA 3000ft unless the Jepp is wrong. (Hope not!! ) :oh:

As far as I am aware, in the UK the transition altitude is 3000ft except where in the vicinity of an airport a higher altitude is notified.

So the Australian system also ensures that the TA and TL are verticaly separated.

I can't figure out why the UK does not ensure that an aircraft at the transition level is vertically separated from an aircraft at the transition altitude.

IMHO, this could have safety implications where outbound aircraft climb on a SID to the TA.......if an inbound descends to the transition level in the UK, it will get very close to the outbound.

Perhaps, getting the calculation of transition level standardised would be a good first step. After all, not much point having a common TA if every FIR calculates the TL differently.

Regards,

DFC

[arrow1]

Spitoon

"As a controller, I would expect the pilot of any high-performance aircraft to be able to follow my instructions/requests. If the cleared level is an altitude, I would expect level reports etc to be QNH-based, if it's a FL, I would expect level to be referenced to 1013."

Spitoon, how would you manage a (fairly common) scenario where one aircraft is cleared to an altitude and the next one to a FL by approach control. Isn't the idea of the first reporting altitudes and the next FL's liable to lead to confusion regarding their actual separation?

[eyeinthesky]

arrow1

In the UK at least, we usually calculate the flight level which will give at least 1000ft above the highest altitude.

In the London TMA, where the maximum SID altitude is 6000ft, the lowest FL will be that which equates to an altitude of 7000ft or more. So in times of low pressure, the lowest FL might be FL80. Conversely, in times of very high pressure we never use less than FL70. So it can take a long time to get from 6000ft altitude to FL70 or above, and this can prove embarrassing if you're not ready for it.

(For example: QNH 1040. 6000ft Altitude is approx FL 52. To climb and get separation of 1000ft above traffic at FL 70 you need to climb 2800ft instead of 2000ft. It can cause some tightening of the sphincter if you're trying to jump the stack!! :eek: )

So to answer your question more succinctly, the controller should know which flight levels are separated from altitudes and which are not.

[Capt H Peacock]

This is one of these things that there really shouldn’t be an SOP on. The setting should be up to the Captain for his own requirements. For many ‘standby’ quality altimeters, setting 1013.2 won’t give you the same indication as the main altimeters because it’s not derived from a digital air data computer, and CERTAINLY won’t be accurate enough for RVSM compliance.

If you feel that standard is a good setting then fine, over the Pond there might not be anything better to set, but don’t read into it more than is there. Personally I prefer to have the lowest QNH over the route I’m flying, and Zurich, Salzburg, Barcelona QNH respectively in those areas where terrain is a factor.

A good dose of Commanders discretion required.
:hmm:

[arrow1]

eyeinthe sky

Thanks for the input. We have a similar system, while having QNH below the TA and 1013 above the TL and altitdues/FLs are reported accordingly. This means that the situation covered by "spitoon" wherein two aircraft on the same side of the the TL are reporting altitudes/FLs depending on what they are cleared to does not arise.