CASA opinion: Aircraft must be grounded in temps over 40 degrees
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Further to djpil's comments ... the important thing is can you argue your case satisfactorily if push comes to shove and you find yourself in court for whatever reason ?
So far as performance is concerned, provided there is not an OAT limitation in the limitations section of the POH, one can always get the charts redone to suit your operational needs.
So far as performance is concerned, provided there is not an OAT limitation in the limitations section of the POH, one can always get the charts redone to suit your operational needs.
Just an observation that perhaps CASA are drawing on this section of the FAR
Some aircraft have a piece such as this in the limitations section
Piper and Cessna, and others, have adopted the standard + 30 approach, with charts only going to 40C.
Question is, are you breaching the law by operating in temperatures above the certification standard when there is no limitation in that part of the manual?
Of course if you do the result can be
https://www.youtube.com/watch?v=OVM3RRd1vf0
§23.45 General
(a) Unless otherwise prescribed, the performance requirements of this part must be met for—
(b)(2) For reciprocating engine-powered airplanes of 6,000 pounds, or less, maximum weight, temperature from standard to 30 °C above standard
(a) Unless otherwise prescribed, the performance requirements of this part must be met for—
(b)(2) For reciprocating engine-powered airplanes of 6,000 pounds, or less, maximum weight, temperature from standard to 30 °C above standard
§23.1583 Operating limitations
(n) Ambient temperatures. Where appropriate, maximum and minimum ambient air temperatures for operation
(n) Ambient temperatures. Where appropriate, maximum and minimum ambient air temperatures for operation
AMBIENT TEMPERATURE LIMITS
-34°C (-30°F) to ISA plus 37°C not to exceed 49°C (120°F).
-34°C (-30°F) to ISA plus 37°C not to exceed 49°C (120°F).
Question is, are you breaching the law by operating in temperatures above the certification standard when there is no limitation in that part of the manual?
Of course if you do the result can be
https://www.youtube.com/watch?v=OVM3RRd1vf0
I remember in a previous life flying a King Air 90 into YWDH. Temp on the OAT gauge was ISA+ 42 so I told the pax we will sit in the shade and waited for the gauge to show ISA + 39. This was my decision based on the fact that IF something went wrong it would be MY fault for operating outside the certified envelope. Ultimately its a Command decision-but to operate outside the certified envelope is incredibly poor Airmanship unless under EMG/Mercy Flight conditions.
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I'm no lawyer, but CASA's insistance on "strict liability" clauses in virtually every regulation they produce makes a pilot's position quite clear. If you have an accident, and a possible/probable cause of the accident was a breach of a "strict liability" regulation, then you are in serious trouble.
Now the minutes of a RAPAC meeting do not constitue a strict liability regulation.
But if you do ding one in operating outside of the available performance data, and CASA believe that that was a contributing factor (and I'm sure they will try hard to do so), then you may fall foul of one of their "strict liability" regulations unless you can prove some reasonable means of compliance (kind of making you guilty unless you can prove innocent, which goes against most modern legal justice systems).
But also, don't ask a question unless you already know and like the answer. What else did they expect CASA to say: eg "yeah, no worries, just take off anyway, just don't ding it in..."
I'm sure a Pprune bush lawyer will pick apart what I've put, but that's my basic interpretation.
Now the minutes of a RAPAC meeting do not constitue a strict liability regulation.
But if you do ding one in operating outside of the available performance data, and CASA believe that that was a contributing factor (and I'm sure they will try hard to do so), then you may fall foul of one of their "strict liability" regulations unless you can prove some reasonable means of compliance (kind of making you guilty unless you can prove innocent, which goes against most modern legal justice systems).
But also, don't ask a question unless you already know and like the answer. What else did they expect CASA to say: eg "yeah, no worries, just take off anyway, just don't ding it in..."
I'm sure a Pprune bush lawyer will pick apart what I've put, but that's my basic interpretation.
More straightforward when we had the Australian specific DoT AFMs but they've been discarded and the requirements of CAO 20.7.4 re soft dry grass and runway slopes don't fit with an older typical FAR 23 AFM or POH and the weasel words in the CAO are not enough to hang your hat on.
Nil authority to continue to use those old P charts, if you do then you are personally responsible - I asked CASA to provide the test data and analysis for the 8KCAB Decathlon and got nowhere. I suspected that some bright person had provided an 8KCAB with 180 hp and C/S prop for the performance testing - where did that leave me with an 8KCAB fitted with the standard 150 hp and FP prop? The P chart is simply labelled 8KCAB. Manufacturers info? - that's another story.
Nil authority to continue to use those old P charts, if you do then you are personally responsible - I asked CASA to provide the test data and analysis for the 8KCAB Decathlon and got nowhere. I suspected that some bright person had provided an 8KCAB with 180 hp and C/S prop for the performance testing - where did that leave me with an 8KCAB fitted with the standard 150 hp and FP prop? The P chart is simply labelled 8KCAB. Manufacturers info? - that's another story.
Interesting question and a lot of focus on the POH...
I'm no stranger to GA in hot climates, but perhaps the question some should be asking is "how long can my human body perform in 40+ degree temperatures without a whiff of air conditioning in a c172". I've done some fairly stupid things when I've been hot and dehydrated, and when that door shuts and the sweat starts dripping, don't expect your mental capacity to be at an all time high.
I'm no stranger to GA in hot climates, but perhaps the question some should be asking is "how long can my human body perform in 40+ degree temperatures without a whiff of air conditioning in a c172". I've done some fairly stupid things when I've been hot and dehydrated, and when that door shuts and the sweat starts dripping, don't expect your mental capacity to be at an all time high.
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I can remember years ago taxiing in a Chieftain at YBDV for final destination YBOU (with stops at Roseberth and Durrie Stations) with the OAT gauge reading 48C.
On arrival at YBOU the OAT read 51C.
Struth Johnno;(if you are reading this) How did we survive this????
On arrival at YBOU the OAT read 51C.
Struth Johnno;(if you are reading this) How did we survive this????
Your decades-long trail of dangerous operations have been noted, kaz. 
I'm now wondering how the old Perf charts were created.
Looking at the Takeoff Performance chart for a PA28 I see that the OAT region goes from -40'C to +40'C, but I seriously doubt that the PA28 was actually tested at -40'C.
Performance is determined from the Pressure (Density) Altitude.
The problem is that DA is non-linearly dependent on OAT.
Back in the 60's it was easier to pre-calculate a nomograph for the 'expected' operating range and +40'C seems like a reasonable upper limit for the USA at that time.
Now if I can determine what the DA actually is (from an expanded pre-calculated DA v OAT chart, or from a formula), then I can apply that DA to the Perf chart and on that basis the 40'C 'limit' is no longer a limit.
Unfortunately we are talking about CASA and their ineffable bureaucratic wisdom, so common-sense is not allowed.
Looking at the Takeoff Performance chart for a PA28 I see that the OAT region goes from -40'C to +40'C, but I seriously doubt that the PA28 was actually tested at -40'C.
Performance is determined from the Pressure (Density) Altitude.
The problem is that DA is non-linearly dependent on OAT.
Back in the 60's it was easier to pre-calculate a nomograph for the 'expected' operating range and +40'C seems like a reasonable upper limit for the USA at that time.
Now if I can determine what the DA actually is (from an expanded pre-calculated DA v OAT chart, or from a formula), then I can apply that DA to the Perf chart and on that basis the 40'C 'limit' is no longer a limit.
Unfortunately we are talking about CASA and their ineffable bureaucratic wisdom, so common-sense is not allowed.
FAR 23 has rules about the limits for extrapolating test data to higher or lower temps and altitudes.
They (we at times) used to do a short series of takeoff and landing tests at a place like Bacchus Marsh and a fancy (for then) computer program would print those P charts.
Charts also for climb performance limits apply to some types - remember that little line on the C150 P charts derived from a goround with flap down.
Just can't wait until an FOI rocks up for some refresher training.
They (we at times) used to do a short series of takeoff and landing tests at a place like Bacchus Marsh and a fancy (for then) computer program would print those P charts.
Charts also for climb performance limits apply to some types - remember that little line on the C150 P charts derived from a goround with flap down.
Just can't wait until an FOI rocks up for some refresher training.
My other question is- why only now does CASA say that you cannot operate when the temp is outside the P chart temperature? They've been in existence for decades, and it's not a new idea.
I'm not necessarily brave enough to take on the potential battle.
The Alphabet Authority (cannot remember what they were called at that particular point of time) tried to ping the pilot for departing of the runway as it was too short based on the "P" charts that only presented calculations to a temp of 35c and a wind less that the actual wind.
But using the manufacturers charts the aircraft could depart. The Alphabet Authority pointed out that we had to use the "P" Charts. I informed the Alphabet Authority that their "P" charts did not reflect the conditions experienced in Australia and therefore we were being forced to use charts unfit for purpose.
I did not hear back from Alphabet Authority.
Lucky Kaz...all operating Auster stuff in the brain database. No book.
I have some Auster type AFMs.... J2, J5F etc. Not heavy duty tho.
8. Glider towing.
Fly as normal.
Simple and sound advice.
I have some Auster type AFMs.... J2, J5F etc. Not heavy duty tho.
8. Glider towing.
Fly as normal.
Simple and sound advice.
So at 39.99 degrees you are good to go, but not at 40.1? Makes sense really.
Go in to a pub the night before your 18th birthday, fly a charter before your new licence is issued...
Blah blah blah. There is always a line somewhere.
Ask this CASA guru for WRITTEN confirmation of this OPINION.
and CASA believe that that was a contributing factor (and I'm sure they will try hard to do so)
Moderator
I'm now wondering how the old Perf charts were created.
Further to djpil's comments ..
In days of olde .. when we had local rules (ie pre-Yates Report changes), one could either do one's own thing (ie develop equations or use the standard FT equations) or use the DCA equations (presented in an in-house document to which Industry consultants had access). Needless to say, most folks used the DCA document as that avoided much discussion in the approval process.
The DCA document (I have a copy but can't recall the ID without digging in the archives for it ..) used some pretty simple equations but, in practice, they were of sufficient accuracy that the P-charts were a reasonably good mix of a little conservatism and accuracy.
Later on, the document was revised the better to take account of turboprop performance .. and that document was a different beast altogether .. so, we ended up using the old stuff for pistons and the new stuff for turboprops.
The equations allowed for the interpolation (and limited extrapolation) of whatever data set had been captured .. not too much in the way of extrapolation as that involved a leap of faith .. interpolation was much more defensible. So far as test programs were concerned, we normally tried to get low/high and hot/cold within the realms of reasonable possibility and take it from there. Obviously, the more test data, the more accurate the end charts could be. What variable range ended up in the charts depended a lot on what range of test data could be found. This is no different to the problems faced by Mr Boeing and others ..
At the high end of the spectrum, for data capture, one could do cinetheodolite performance takeoffs and landings which provided a movie tracking record of the aircraft (allowing corrections for camera unit mistracking) and azimuth/elevation data for the camera axes (paper trace .. great fun working with that stuff).
Accurate survey data was required for the runway and camera unit position to do the geometry sums.
From these records, one could spend copious numbers of (relatively) productive hours developing a very accurate time history of the takeoff/landing distance and air distance/height. This allowed speed and acceleration data to be determined to a very good accuracy if you had a need for that sort of stuff.
Unfortunately, back in the 60s/70s, this equipment was pretty high tech (and expensive) so only the military and the likes of GAF were able to use it. Djpil and I spent numerous hours in the Fishermens Bend sweatshop doing this stuff after Nomad flight trials. Also, I had fun doing similar stuff at ARDU for a while.
Once we get out into the GA world, though, no-one was likely to have this kit sitting around waiting for some trials so the local industry, with DCA, developed a much simpler exercise using a reasonable quality still camera to take a series of exposures to get the important sections of the takeoff and landing. Not quite as accurate as the CT .. but much quicker and more than fit for purpose.
Some folk, to save on dollars, did the exercise with constant (gross weight) speeds throughout (reduced the number of flight trials required) and that produced some strange results in the P-charts which were the occasional subject of bar room discussions. For example, one saw landing P-charts where the distance increased with reducing weight (due to float at the end of the landing flare)
On occasions, if the OEM data in the POH appeared defensible, one would negotiate with the DCA gurus of the day and, sometimes, take a few points from the OEM POH data and use those to develop the P-charts.
DCA had a nice little HP plotter gadget to run up the charts .. most of us out in the Industry did it by hand .. same result... the typical P-chart presentation was dreamed up by DCA (Ron S, perhaps ?) and was just one of a range of possible presentations. It has its good and bad points, like any presentation. I did my share of GA P-charts and, I guess, so did djpil
Do keep in mind that this all predated the first of the microprocessor computers which came onto the market in the mid-70s - prior to that, if you could afford it, there was the odd TI bit of kit which allowed some number crunching capability. Needless to say, none of us had private access to the few mainframes around the place.
Spare a thought for us back then .. a computer (with a capability inferior to a modern pocket calculator, along with printers, cost me around $20k in the mid-70s but could we do things with that primitive kit compared to an old (still quite expensive) TI programmable calculator or slide rule. Would you believe I managed to upgrade the system several years later when a 5 kb hard drive came onto the market. (Maybe it was 5 mb .. whatever, it was tiny)
Further to djpil's comments ..
In days of olde .. when we had local rules (ie pre-Yates Report changes), one could either do one's own thing (ie develop equations or use the standard FT equations) or use the DCA equations (presented in an in-house document to which Industry consultants had access). Needless to say, most folks used the DCA document as that avoided much discussion in the approval process.
The DCA document (I have a copy but can't recall the ID without digging in the archives for it ..) used some pretty simple equations but, in practice, they were of sufficient accuracy that the P-charts were a reasonably good mix of a little conservatism and accuracy.
Later on, the document was revised the better to take account of turboprop performance .. and that document was a different beast altogether .. so, we ended up using the old stuff for pistons and the new stuff for turboprops.
The equations allowed for the interpolation (and limited extrapolation) of whatever data set had been captured .. not too much in the way of extrapolation as that involved a leap of faith .. interpolation was much more defensible. So far as test programs were concerned, we normally tried to get low/high and hot/cold within the realms of reasonable possibility and take it from there. Obviously, the more test data, the more accurate the end charts could be. What variable range ended up in the charts depended a lot on what range of test data could be found. This is no different to the problems faced by Mr Boeing and others ..
At the high end of the spectrum, for data capture, one could do cinetheodolite performance takeoffs and landings which provided a movie tracking record of the aircraft (allowing corrections for camera unit mistracking) and azimuth/elevation data for the camera axes (paper trace .. great fun working with that stuff).
Accurate survey data was required for the runway and camera unit position to do the geometry sums.
From these records, one could spend copious numbers of (relatively) productive hours developing a very accurate time history of the takeoff/landing distance and air distance/height. This allowed speed and acceleration data to be determined to a very good accuracy if you had a need for that sort of stuff.
Unfortunately, back in the 60s/70s, this equipment was pretty high tech (and expensive) so only the military and the likes of GAF were able to use it. Djpil and I spent numerous hours in the Fishermens Bend sweatshop doing this stuff after Nomad flight trials. Also, I had fun doing similar stuff at ARDU for a while.
Once we get out into the GA world, though, no-one was likely to have this kit sitting around waiting for some trials so the local industry, with DCA, developed a much simpler exercise using a reasonable quality still camera to take a series of exposures to get the important sections of the takeoff and landing. Not quite as accurate as the CT .. but much quicker and more than fit for purpose.
Some folk, to save on dollars, did the exercise with constant (gross weight) speeds throughout (reduced the number of flight trials required) and that produced some strange results in the P-charts which were the occasional subject of bar room discussions. For example, one saw landing P-charts where the distance increased with reducing weight (due to float at the end of the landing flare)
On occasions, if the OEM data in the POH appeared defensible, one would negotiate with the DCA gurus of the day and, sometimes, take a few points from the OEM POH data and use those to develop the P-charts.
DCA had a nice little HP plotter gadget to run up the charts .. most of us out in the Industry did it by hand .. same result... the typical P-chart presentation was dreamed up by DCA (Ron S, perhaps ?) and was just one of a range of possible presentations. It has its good and bad points, like any presentation. I did my share of GA P-charts and, I guess, so did djpil
Do keep in mind that this all predated the first of the microprocessor computers which came onto the market in the mid-70s - prior to that, if you could afford it, there was the odd TI bit of kit which allowed some number crunching capability. Needless to say, none of us had private access to the few mainframes around the place.
Spare a thought for us back then .. a computer (with a capability inferior to a modern pocket calculator, along with printers, cost me around $20k in the mid-70s but could we do things with that primitive kit compared to an old (still quite expensive) TI programmable calculator or slide rule. Would you believe I managed to upgrade the system several years later when a 5 kb hard drive came onto the market. (Maybe it was 5 mb .. whatever, it was tiny)
Cue Presidents of the USA ...
"We're not gonna make it"
"No no we're not gonna to make it"
I could well have sung this as I staggered out of Maitland Airport's runway 26 on a day well north of 40C in an old 6 cylinder 172 just shy of gross.
Somehow I drifted left to avoid old mates lounge window half way up the hill while observing the cushions on his couch. This was while planning on going under the power lines and performing a controlled crash up the slope in a clear area. While this was going on and in a state of sheer panic I somehow managed to glance at my mate next to me, intending to give him a crash brief only to discover he was engrossed in a magazine and completely oblivious to the situation. A serious slow motion event, he never did get the brief.
Somehow we made it over the hill, but it took several hours afterwards for me to regain composure and it was an event I will never forget.
Some aircraft should definitely be grounded at 40C.
"We're not gonna make it"
"No no we're not gonna to make it"
I could well have sung this as I staggered out of Maitland Airport's runway 26 on a day well north of 40C in an old 6 cylinder 172 just shy of gross.
Somehow I drifted left to avoid old mates lounge window half way up the hill while observing the cushions on his couch. This was while planning on going under the power lines and performing a controlled crash up the slope in a clear area. While this was going on and in a state of sheer panic I somehow managed to glance at my mate next to me, intending to give him a crash brief only to discover he was engrossed in a magazine and completely oblivious to the situation. A serious slow motion event, he never did get the brief.
Somehow we made it over the hill, but it took several hours afterwards for me to regain composure and it was an event I will never forget.
Some aircraft should definitely be grounded at 40C.
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Ask this CASA guru for WRITTEN confirmation of this OPINION.
We are not talking about a 747 or even a King Air where you probably do have performance data for every takeoff. The reality is, smaller aircraft are operated outside the parameters of the performance charts all the time, by necessity.
The C172 performance data goes to a density altitude of something like 12,000'. Why is it OK to operate at Mt Hotham at 35C, but not Mildura at 43C?
Density altitude was part of the PPL theory. You can in fact predict the effects with reasonable accuracy. CASA actually do that in the declared density charts. Maybe you just need to break the OAT and use the declared density?
The letter from CASA is actually claiming that the ranges specified in the performance charts forms part of the aircraft limitations. Which also suggests that the aircraft must be grounded below 0C.
https://www.casa.gov.au/files/vic170323pdf for that letter from CASA.
Want to do some more, JT?
Last edited by djpil; 12th Apr 2017 at 20:26. Reason: used the mobile version at first so needed to make the link work
