Garfly

Yeah, I don't think it'd apply particularly well in this case. The uneven slope and variable surface of the 'runway', alone, would make it unreliable. But still, just having any such performance/acceleration check in mind - on any unusual take-off - ought to give pause enough, you'd think. If I was ever so adventurous as that chap, I'd try a solo take-off first and then assess if any more load was feasible and safe. Maybe helped by another rule-of-thumb: For a given situation, for every 10% increase in T.O weight you need 20% more T.O distance. I'm not sure how reliable that one is, either, but one could confirm it, for one's own a/c, experimentally by taking note of two max performance take-off runs (in identical conditions) one with, and one without a load - an instructor, say. The numbers could be extrapolated to roughly prove (or not) the rule, no?

Juan Browne on the 50/70 rule:

Few, if any, doubt it.

Oh, aye ... "All the world is queer save thee and me, and even thou art a little queer."

https://au.news.yahoo.com/pilot-crashes-into-ocean-while-trying-warn-surfer-of-giant-shark-221716311.html

What had he done wrong, exactly?

A very straightforward scenario and a very smart PIC. Warning not waving. Too late.

But also potentially, possibly, about bending a rule to save a life.

Sure it is. Which is why Pprune had a long, impassioned thread on the subject a while back, running the gamut from the 'very straightforward' brigade to posters of the 'very complicated' persuasion. Never the 'twain shall meet. ;- ) https://www.pprune.org/pacific-general-aviation-questions/501671-mercy-flights.html

Hmmm ... visions of would-be rescuees bleeding-out as our scrupulously law abiding aviator attempts to get through on the blower to announce his 'declaration'. But I seem to remember reading that even the old Mercy Flight declaration no longer pertains; that it's now covered under the broader category of a May Day call. Not sure. Something to clarify. In either case, lives could well be hanging in the balance due dodgy radio comms. And given the Air Law joys of strict liability the judge may have to discount any kind of common sense defence. Heck, you might even get done, at the same time, for failing to render assistance. Catch 91.

Mercy flight? (Are they a thing any more?)

An interesting depiction of just that in this happy-ending video from Dan Gryder. But if you object to being toyed with for 20 mins - in the name of 'suspense' - I suggest watching the first minute, jumping to 22:00 for the completion of the forced landing and, if you've a mind to, returning to 'go' for the analysis and discussion with the pilot concerned.

Yes, I suppose flying beyond the J-curve in WAC land (and out of range of real time layer updates) it'd be nice to have PRDs showing up on the chart - paper or tablet versions. I wonder how many such areas are out there, and how many are only activated by Notam. So it may be an improvement after all, especially given that where the clutter is the worst the need for WACs is the least (as Yenn was saying, above).

OME, I can see that if you want to have your contestants limited to WACs, say, for the navigation trial, then having the boundaries of your local Danger areas right on them would be a help. So yes, these new charts might be handy for remote area PRDs ... saves you drawing them in yourself on paper charts like the good old days ;- )

PenName, can you expand on this? What 'layer cake' do you mean? The 36 DME Class C step? That won't be on the new WAC. They're talking PRD areas only. So, presumably, Pine Gap will be there - as it is already on Visual Terminal Chart. And as to FIR frequencies, I'd have thought your OzRWYs/AvPlan plus the ERC Low chart had you well covered in that department. If you want WACs to be all things to all people - especially nowadays - they will lose their particular usefulness. It doesn't take much magenta ink to cover useful detail at 1:1,000,000

Well, yes, I guess that's the point. So you wonder, why would they have bothered. In any case, if only PRDs are shown then the new style WACs are hardly of any use regarding all the other types of restricted airspace. In practice it probably won't be much of a problem for anyone on their EFB charts but there are many places where the Hybrid VFR maps give over to the WACs from VNCs. And I think there may be a lot of PRD boundaries - at some level or another - extending out that far. I just hope it doesn't mean a lot of misleading and useless magenta lines cluttering up those areas.

I enquired with ASA's Aero Charting about this news and they were kind enough to send me this sample image. According to ASA: "The PRD boundaries have been added to bring the WAC series closer to ICAO compliance for this chart type." And "We are hoping that with a planned change in software to create these charts we will be able to update them on a more regular basis in the future." As I understand it, the printing of Aeronautical charts and other documents has now been outsourced to https://www.aipshop.canprint.com.au/ where the new WACs can be bought. On first impressions, I'm not all that impressed. It seems like a lot of unnecessary clutter (given that we have VNCs and VTCs ... and EFBs to boot). Anyway, these will be incorporated in OzRWYs in December. I've heard tell that some in the OzRWYs team are not thrilled by the innovation either. CLICK TO EXPAND: This is the feedback I sent to ASA Aero Charting, yesterday. "On first look at this new WAC format, I wonder how it will be generally viewed by the flying community. To me they look pretty cluttered and I would have thought that the beauty of WACs has been that they were unfussed by airspace detail and dealt mainly with ‘existential’ geography. Also, so much magenta might get a bit much when used with EFBs - which, of course, use magenta lines for other things. I’d have thought that we already have all the airspace info we need in VTCs and VNCs as well as real time overlays (on any and every map) of active PRD areas on EFBs. The boundaries of these, of course, can change on an hourly basis so the electronic real time display is very handy. Anyway, I’d be interested in the thinking behind this move and any discussion within ASA. I’m surprised to hear that WACs do have all that airspace info on them in other ICAO regimes. In any case, at first glance, I'm thinking I might miss the old, uncluttered WACs. But maybe when I get used to them I will come to appreciate the upsides. 🙂 "

Agreed ... or as I'd put it: "with all the variables at play in take-off performance, our sense of normal can be confused ..." And, to paraphrase Nev, with P-charts, it's garbage-in/garbage-out. To me that says a backstop rule is handy. True, but I don't think the video really misses that point. Gryder stresses that a sick engine is only one of several possible causes of unexpected poor acceleration and his 50/70 rule of thumb is meant to catch them all. And, as you say (and the video, too), it's only good as a last line of defence. Nobody denies that stopping immediately anything seems wrong is the way to (not) go. And sure, in the real world, like taking off at Mt. Hotham on a hot summer's day (P-calcs duly done), having a backstop rule-of-thumb to counter "inaccurate feelings" might help. Even - turning it the other way - to prevent a dangerous reject situation which was never, in fact, necessary. (Visions of a cliff-hanger ;- ) Also, you might say that this video demonstrated a case where pulling it off the ground may well have improved the situation. According to the pilot's story, the alternative could have been plowing into the school pick-up event unfolding in front of him. Of course, he's the first to agree that an early reject was what was called for - if only he'd learned 50/70 earlier, he reckons. But yes,, as Dan G says in the video, actually living to tell such a tale is not at all common.

I suppose the most available abnormal-acceleration check is our own sense of what normal feels like. But we need to listen to the inner "something's wrong" voice - and be ready to reject in good time. But with all the variables at play in take-off performance, our sense of normal can be confused (assuming all due P-chart compliance) especially operating away from home. I suppose that's why the 50/70 Rule (70% of take-off speed by 50% of runway length) was invented. As a rule of thumb, it accounts for most of those variables (variations in slope and/or surface along the run excluded). Of course, it means the PIC has to mark (mentally, at least) the midway point in advance and have the 70% number in mind. Seems like it'd be worth experimenting with. Anyway, old Gryder swears by it ... and the pilot in the video is a keen, if recent, convert.

Very TRUE (and closer to education than revelation ). Though Gryder and the (800 hour) aviator involved were at pains to explain that such a check had not been part of his (the incident pilot's) education heretofore. Revelatory to him, at least.

Dan Gryder's talk with a pilot whose perfect P-chart calcs let him down due to a sick, underperforming, engine:

Call me easy-to-please but I reckon all RAAus aircraft are 'fun'.

This video shows some interesting mods being done on a classic Ranger"

Ross, I don't know if that's an AvPlan/Android version bug but on OzRwys/iOS the SE2 device does not shut out internet access. This is how OzRwys Support explained it to me: "The SkyEcho doesn't advertise itself as a gateway, so your iPad will not try to use this as an internet connection. Instead it'll automatically fall back to other available options, such as your iPad's SIM card (if one is inserted) or Hotspot from phone (has to be connected via bluetooth). So there's no need to disconnect from your SkyEcho to obtain updated weather information or OzRunways cellular traffic. These features and any other cellular services will run in parallel with the SkyEcho connected."

I think few would disagree with you on this, Turbs, but to me your story goes right to the point. Despite your (presumably) having studied and been tested in a pretty good licensing system, it actually took experience down the track for the theory that you knew (or, at least, once knew) to sink in - to become real for you. I doubt, though, that any PPL course could ever cover all contingencies and phenomena in every subject that might come up in one's flying career. But yes, I think we all agree that weather and its perils for small aeroplanes could, and should, be taught, in some fashion, from the get go. But just cramming - once - for a 20 question multiple choice quiz is never going to cut the mustard.