A2A Cessna C172 any news on this?

[sdflyer]

Are guys going to model any kind of failures? It looks like failures are becoming pretty popular feature nowdays :_

I had two alternators failures one in VFR and one another one in IMC. Ironically, the one electrical failure in IMC was in C-172R. Right after climb out I noticed "VOLTS" on annunciator panel. The was no way to turn back and land VFR because I was already in the clouds. I estimated (conservatively) my battery life for another 20 minutes (given age and electrical usage)

Ideally I would turn off unnecessary electrical equipment but since I was flying instrument I opted to turn off only GPS. ATC did a great job to set me up on localizer asap. To make long story short everything turned out ok even improvised ILS vectoring along extreme descent rate were kind of fun.

The lesson learned - even if you check your ammeter loading on run up by flipping your alternator switch on/off you still can loose it 5 minutes later LOL

So I bet you guys probably have on your bucket list...water/debris in the fuel tank, vapor locks, shimmy wheel, buffeting during forward slip with full flaps?

[sdflyer]

temperature corrections required for altimeters, and so on, are not there

I don't remember any temperature correction for an altimeter gauge. Perhaps you referring to some airspeed indicators which have TAS window and knob associated with it where you can adjust pressure altitude and temperature ?

[AKar]

temperature corrections required for altimeters, and so on, are not there

I don't remember any temperature correction for an altimeter gauge. Perhaps you referring to some airspeed indicators which have TAS window and knob associated with it where you can adjust pressure altitude and temperature ?

Hi sdflyer,

No - I'm referring to the altimeter temperature correction. That's caused by variations of density of the air above the points of measure. One of those being the static connection of the altimeter, and another the level on which the reference pressure (= current local altimeter setting) is measured. Put simple, the temperature error is caused by the more/less dense (in colder/warmer than in ISA respectively) column of air between you and the level of reference weighing more/less than in ISA. That affects the difference in static pressure between you and the reference point. And that difference is what the barometric altimeter indicates. It's not an altimeter per se, it's a pressure gauge calibrated approximately in feet of altitude in ISA atmosphere.

Not being a pilot and not keeping myself current with this, I stand ready to be corrected, but if I recall, an approximate way to estimate your temperature correction would be ~4 ft per 1000 ft above point of reference per degrees of Celsius under ISA (+15'C)

For example, if you're flying 5000 ft indicated above your airfield with local altimeter setting, in a temperature of, let's say, - 20 degrees centigrade being 35 degrees under ISA - a typical northern winter day, that would make a true altitude being approximately: 4 ft x 5 kft x 35'C = 525 ft less than indicated - that being an error of a significant degree.

I should add that the discussion above would obviously assume standard lapse rate at least, probably some other simplifications also.


Edit: The same effect of temperature to air density is also what causes the IAS to be a bit dependent on the air temperature, as the density of the air affects both dynamic pressure, or 'ram pressure', and static pressure of the air.

[sdflyer]

temperature corrections required for altimeters, and so on, are not there

I don't remember any temperature correction for an altimeter gauge. Perhaps you referring to some airspeed indicators which have TAS window and knob associated with it where you can adjust pressure altitude and temperature ?

Hi sdflyer,

No - I'm referring to the altimeter temperature correction. That's caused by variations of density of the air above the points of measure. One of those being the static connection of the altimeter, and another the level on which the reference pressure (= current local altimeter setting) is measured. Put simple, the temperature error is caused by the more/less dense (in colder/warmer than in ISA respectively) column of air between you and the level of reference weighing more/less than in ISA. That affects the difference in static pressure between you and the reference point. And that difference is what the barometric altimeter indicates. It's not an altimeter per se, it's a pressure gauge calibrated approximately in feet of altitude in ISA atmosphere.

Not being a pilot and not keeping myself current with this, I stand ready to be corrected, but if I recall, an approximate way to estimate your temperature correction would be ~4 ft per 1000 ft above point of reference per degrees of Celsius under ISA (+15'C)

For example, if you're flying 5000 ft indicated above your airfield with local altimeter setting, in a temperature of, let's say, - 20 degrees centigrade being 35 degrees under ISA - a typical northern winter day, that would make a true altitude being approximately: 4 ft x 5 kft x 35'C = 525 ft less than indicated - that being an error of a significant degree.

I should add that the discussion above would obviously assume standard lapse rate at least, probably some other simplifications also.


Edit: The same effect of temperature to air density is also what causes the IAS to be a bit dependent on the air temperature, as the density of the air affects both dynamic pressure, or 'ram pressure', and static pressure of the air.

Ok I see what you mean...
The only way you can adjust actual altimeter is via Kollsman window were you set current altimeter setting (inHg in US). Altimeter shows so called indicated altitude. There is also true altitude (MSL - above sea level ), absolute altitude (AGL - above the ground), pressure altitude (and density (those are commonly use when calculating aircraft performance) Most of the time GA pilots fly with ATC guidance, so ATC provides them with new altimeter setting every time they hand you over next controller. When aircraft crosses so called transition altitude (18,000ft in US) altimeter is set to standard pressure 29.92. So there is nothing fancy here.

The only time pilot can check altimeter parameters is at the airport. When altimeter setting is obtained altimeter suppose to show altitude within 75 feet of airport elevation (MSL)

If pilots can't obtain current altimeter setting they should be aware and temperature or pressure difference when transitioning from area high pressure/temperature to low pressure/temperature . Here is the primary concern is true altitude (AGL) not indicated. There is also saying associated with that phenomena "flying from high to low look out below"
Here is a good illustration what actually happens with true altitude


Pressure altitude or density altitude is something what influence aircraft performance take/ landing off distances, climb rates and so on. There is no way to find them out out of altimeter gauge (although you can obtain pressure altitude by setting altimeter to 29.92 at any time). To figure those altitude there is wizwheel aka E6B or any valid interpolation method used in pilots head:)

As you mentioned the standard lapse rate 2 degrees C per 1000 feet. The lapse rate more concern pilots weatherwise. If this rate is increasing that there will be unstable air, possible temperature inversion or convective activity. Nonstandard temperatures also affects aircraft performance aka take off/ landing distances, climb rate and so on

So the only real thing you can do with actual altimeter is to check airport elevation with in +/- 75 feet. So A2A team is off the hook here I guess. However, flying wise pilot should be aware transitioning from high temperature/pressure to low temperature/pressure without adjusting altimeter settings. Here is primary concern is true altitude specially in the are with high elevation terrain..

[AKar]

...

I need to clarify that the temperature correction for an altimeter is all related to local altimeter setting and temperature at station reporting the setting. Not at all to flying between different meteorological conditions. It's very easy to mix these two things, of which the pressure variation between different places is far more often relevant, especially when flying in moderate temperatures. Also, and importantly, there is no adjustment knob or anything, except perhaps a combination of an ADC and FMC input in some aircraft I've got no experience of, that could make the adjustment for you - you just need to be aware that farther you are away of your airport elevation, and more the temperature at the airport deviates from ISA of +15'C, more your altimeter is off from your true altitude. That is due to reason I wrote about earlier: the difference of static pressure between the point the airfield measures the QNH for you, AND the point you are depends on the mass ('weight') of the air column in between you two in vertical axis.

It's often assumed, that the concept of QNH setting takes care of this. Well, 'to take care of' such a difficult phrase is. Let's take an example. Let there be an airfield, that is 500 ft above MSL. And let's say that the airfield is situated on a top of a cliff that drops 500 ft to the ocean, and just say that the ocean will be at our MSL.... Also, suppose that the temperature at the airport is that -20'C. (Not sure what the place would be in real world... perhaps in Antarctica, but let's not stick to that!) Now, you're at the runway, and set the altimeter setting reported by ASOS or whatever. What does the altimeter read? Well, it would read 500 feet, because the QNH setting refers to the pressure setting that indicates a correct altitude above MSL of the position. Now, when you take off, and climb to 5000 ft above your airfield, what would your altimeter indicate? 5500 ft? No, it would not. It would indicate approximately 4975 ft or so, that being the 525 ft (that I calculated earlier) less than the correct altitude of 5500 ft. Only in ISA conditions of +15'C (and standard environmental lapse rate etc...) would the non-zero difference in altitude, in atmosphere, between the point of pressure reference and the point of measurement be indicated correctly with an instrument that is based on comparison with a reference pressure. That being the state of an aneroid calibrated at ISA conditions.

To elaborate the concept, let's say that you remove the altimeter and hike down the cliff with the instrument to sea level in the aforementioned conditions of temperature of -20'C. What would the altimeter indicate? Well, not the 0 ft. Using the earlier, and as it appears, very approximate 'formula', it would read about 4 ft x -0.5 kft x 35'C = -70 ft, that is 70 ft less than the correct altitude. The reading is therefore obviously -70 ft, as we are at sea level. That's again being due to the column of air between the point of reference (the airfield) and the point of measurement (in this case the sea level) being more dense than in ISA, and therefore weighing more, and causing more increase in static pressure when descending a given distance below the level of pressure reference. The QNH setting means just that your altimeter reads correctly at the level of given QNH measurement, the exactly correct reading at any other level requires a coincidence of conditions of those at ISA.


I found this:
http://www.skybrary.aero/index.php/Alti ... Correction
..though it's a bit brief discussion.


Hope this makes sense, and we are not mixing too many concepts.


Nice chat by the way! It's been a while since I've last blown the dust off my notes. Great community besides the fine products here, makes me to return to too-long-ignored basics and to think about how it really was when I tried to first learn the stuff!

[sdflyer]

Ok I think you make things more complicated than they are

I've been flying in Southern California for the past 10 years. So you can say I deal mostly with temperature higher then standard.

I can tell you that there is no any kind of conversion involved in this sense during actual flying other than I mentioned in previous post. Yes I would figure density altitude on hot day departing Palm Springs. Or minimum accelerated to stop distance due to pressure altitude departing Big Bear. But that is about it.

As of for instrument flying most of safe altitudes (MSA, MEA ,MOCA and so on) are usually 2000 ft AGL above highest point in the sector. So any minor deviation from indicated altitude vs absolute altitude will be covered by conservative clearance from possible obstacles.

Don't get confused between true altitude, absolute, and indicated. If climb at 5000 ft at current altimeter settings it always will be 5000 indicated. For instrument flying (in US) pilot allowed to deviate +/-100. In real life ATC would probably start worry if pilot deviate more than 500 ft, and advice to check altimeter settings. Although sometimes thing get bad due to weather and airplane may deviate +/-500 due to turbulence, downdrafts, mountain waves and so on

Now the only concern area would minimum altitude designated for certain type of instrument approach. Depends on type of aircraft equipment and approach speed minimum decision altitude/height may vary. However, there are many tools such as GPS, radio altimeter and other ground equipment that can help pilot to make a safe approach to the minimums or discover inop equipment, but I wouldn't worry about those things in C-172R shooting approach at 90-80kts.

If for example look at this ILS to CRQ
http://155.178.201.160/d-tpp/1307/05310ILD24.PDF
You see fix called CIDRU with little lighting sign next to it? This is glide slope intercept altitude. Normally I would cross check my altitude at this predesignated fix. For that particular approach CIDRU can be identified via GPS, DME (or I can ask ATC identify it for me). If find myself not at 2300 at this point I would terminate approach and assume that my altimeter incorrectly set or unreliable. It simple as that. When you fly there no time to figure out a lot of things, so good ground planning is a must

Now If there is any hypothetical significant weather phenomena which effect ILS approach there will be NOTAM and amendment on minimum decision altitude/height for that particular approach.

Now I'm not claiming to know everything, but at least I have an idea about basics since FAA issued me flight instructor certificate. Although I think any license is license to learn after all, and I still do.

[cornell blok]

Please just don't make the failures unrealistic, lets be honest how many failures have you encountered as a pilot ?

16 years down the line as a commercial pilot I can tell you my failures

1. Gear not extending ( used emergency gear extension no problems)

2. 2 X Radio failure

3. Vacuum pump failure in VFR conditions

4. Engine not producing full power on take off

5. Electrical failure

These aircraft where made to last


Cough Seafury next on my Knees Please Cough

[AKar]

Hi sdflyer,

Yes I'm aware of different ways to set your barometric altitude and the results you get. And of course I do not argue that the error caused by the temperature differing from ISA is often irrelevant. No way I mean to question your knowledge on this stuff, hope you did not get it that way!

The temperature below ISA and it's effect on altitude indication vs actual altitude above the level of reference has very often to be taken into account however up here in northern Europe, when flying according to IFR in cold temperatures, and it it appears to be well described in ICAO publications at least. The "correction" is just to add x feet to your altitude targets, that is, if you're to fly 4000 ft with QNH setting, you'll fly at a bit higher indicated altitude to compensate in cold weathers. You find prepared tables that give you some values for reasonably many conditions. Perhaps the ISA DEV input to your FMC in tubeliners do that for your VNAV profiles automatically, though not sure.

And as you said, it mainly affects you on your approaches. That's why many RNAV procedures add a small print of stating a minimum temperature for uncompensated, barometric-only VNAV systems. For example, an RNAV approach to a quite familiar airport for me: https://ais.fi/ais/eaip/aipcharts/efiv/ ... 04_GPS.pdf
You find ones like this in US also, they also add a maximum temperature, though it appears to be usually irrelevant (>+40'C).


But all this goes way outside my original point! Though I don't mind the conversation at all, I actually just randomly picked a few, usually subtle things that affect your instruments that at least I've not seen in FSX. Some of those are way more visible than the effect of temperature to altimeter. Really in this case it's more about an atmospheric property than an instrument error. I just recall a single time when messing with FSX when it annoyed me that the effect was not there (flying up a mountain in a chopper when just quickly testing one). Can't even claim for sure that I just didn't mess with the weather settings and accidentally hid an effect that actually is there..

[Lewis - A2A]

Hey guys,

the failures will be there as they have been in all the accu-sim aircraft since first created prior to 2008

For those not familiar with the Accu-sim simulations you can check them out on our you tube page;
http://www.youtube.com/user/ShockwaveProd/videos

More details on the C172 specific details will be coming in due time.

thanks
Lewis - A2A

[sdflyer]

Please just don't make the failures unrealistic, lets be honest how many failures have you encountered as a pilot ?

16 years down the line as a commercial pilot I can tell you my failures

1. Gear not extending ( used emergency gear extension no problems)

2. 2 X Radio failure

3. Vacuum pump failure in VFR conditions

4. Engine not producing full power on take off

5. Electrical failure

These aircraft where made to last


Cough Seafury next on my Knees Please Cough

lol I got all of that plus in flight fire

[sdflyer]

And as you said, it mainly affects you on your approaches. That's why many RNAV procedures add a small print of stating a minimum temperature for uncompensated, barometric-only VNAV systems. For example, an RNAV approach to a quite familiar airport for me: https://ais.fi/ais/eaip/aipcharts/efiv/ ... 04_GPS.pdf
You find ones like this in US also, they also add a maximum temperature, though it appears to be usually irrelevant (>+40'C).


But all this goes way outside my original point! Though I don't mind the conversation at all, I actually just randomly picked a few, usually subtle things that affect your instruments that at least I've not seen in FSX. Some of those are way more visible than the effect of temperature to altimeter. Really in this case it's more about an atmospheric property than an instrument error. I just recall a single time when messing with FSX when it annoyed me that the effect was not there (flying up a mountain in a chopper when just quickly testing one). Can't even claim for sure that I just didn't mess with the weather settings and accidentally hid an effect that actually is there..

Are you from Finland? I think Finland is one of few countries that recognize FAA pilot license!

I bet flying close to polar circle would be way different fm SoCal. we are spoiled with good weather most of the time LOL

[AKar]

Are you from Finland? I think Finland is one of few countries that recognize FAA pilot license!

I bet flying close to polar circle would be way different fm SoCal. we are spoiled with good weather most of the time LOL

Yes, I'm from Finland, and currently living here for studies also. Been occasionally working with different fields related to aviation, mostly commercial but also some private stuff, with almost exclusively European perspective unfortunately. If I recall, in the EASA countries (and in most others also) the validity of pilot license is basically related to the country of registration of the aircraft. That is, if an FAA license is what you've got, you may fly an N-registered aircraft also here in Europe. With an European license, you can fly an EASA-registered aircraft. Recently I've seen quite many N-registered aircraft flying in Europe, perhaps because the trouble of having your license validated to FAA and all the other stuff that comes from it, are in some occasions still less of a problem than some EASA regulations that would apply if registered locally. That's just a guess anyway.

Concerning the weather, Finland is not that bad for aviation I suppose. Of course it might get very cold for a few days a year and sometimes there might be quite a bit of snowfall, and you have to know how to deal with winter conditions - both ground people and flight crews. But overall I'd guess that northern Canada and Alaska for example are usually much harder on you. And quite flat terrain around here helps a lot too.

lol I got all of that plus in flight fire

Ouch! Was it electrical, or something else?


-Esa

[FHS]

Please just don't make the failures unrealistic, lets be honest how many failures have you encountered as a pilot ?

16 years down the line as a commercial pilot I can tell you my failures

1. Gear not extending ( used emergency gear extension no problems)

2. 2 X Radio failure

3. Vacuum pump failure in VFR conditions

4. Engine not producing full power on take off

5. Electrical failure

These aircraft where made to last


Cough Seafury next on my Knees Please Cough

HI folks

Well I think having the option of deliberately simulating a specific failure would be really cool. This way, you could make a mission, on which something (plausible in the real world) would happen and you would have to react accordingly.

I had the chance to have some hours on Swissairs training simulatiors (DC-9, MD-81, A300, A320,..) through a good friend of mine who was instructor for the airline on the given types of aircraft. For instance on the A320 on the touch screens for the instructors you have this option to select failure of any given part of the aircraft. So you can access a menu for each main system and from there you can go down to an idivividual component. In this case I couldn't refrain from selecting "engine fragmentation left" while I was explained the pattern of LSZH in flight. And surely the christmas tree lit up in the cocpit and my friends face went sour. (I was specifically told not to "damage" the virtual plane. Swissair considered this as much as fun as wrecking a real plane). But with pushing the right switches and buttons all wennt well further on. I took it very much as a relief to see the ease in which he handled the situation. That's what makes a passenger feel safe...

So I know there are much less systems on the C172 so there is probably less importance to simulate failures on a plane. Espcially as some (quiet rightfully I after my experience too) state here that those planes kind of always work well.

Still I think it would be a great way for making missions challenging. The flight sim does have random failures that can be selected, but as the systems are modelled in accusim, wouldn't it be interessting to have these options there too? It could be in a further Shift-Menu or be accessible through a script. So I'm really talking about using smething that is already there in accusim, and not a further component.

Cheers,
Florian

[Wiqvist]

I do not think anyone need to be afraid that failures will be overdone on any of A2a's products.

Yesterday I saw a bit of a program on Discovery HD, the flight program about the flying Company(and Family) from Unalakleet. There they had an interesting failure on one Cessna 180, a rudder pedal broke down on the pilot side but the pilot was alone and switch side and flew home the aircraft from the right seat. A mechanic later explained it that this happens 'relatively often on bush planes', but most often discovered on the ground. The reason for it to more often happens on bush planes is that they use the rudder more active than what is common(when you fly with the side in front there is much more pressure on the rudder). It was realy interesting to see how calm the pilot was when he discovered that the rudder pedals did not work, and that he relatively quick shifted seat to test if they worked from the co pilot seat. Such failure is of cource wellcome, I think.

[sdflyer]

Yes, I'm from Finland, and currently living here for studies also. Been occasionally working with different fields related to aviation, mostly commercial but also some private stuff, with almost exclusively European perspective unfortunately. If I recall, in the EASA countries (and in most others also) the validity of pilot license is basically related to the country of registration of the aircraft. That is, if an FAA license is what you've got, you may fly an N-registered aircraft also here in Europe. With an European license, you can fly an EASA-registered aircraft. Recently I've seen quite many N-registered aircraft flying in Europe, perhaps because the trouble of having your license validated to FAA and all the other stuff that comes from it, are in some occasions still less of a problem than some EASA regulations that would apply if registered locally. That's just a guess anyway.

Ok so it's similar to what experienced in Australia when tried to fly!

Ouch! Was it electrical, or something else?
-Esa

Oil line in Mooney M20C.