PET,PNR,PSR

[flyingbear88]

Hello Pilots,


I was revising some of my old ground school materials as Im looking for jobs and came across the following:

PET/PNR: Point of Safe Return/ Point of no return

Im confused about the PET bit because isnt PET the Point of Equal Time and isnt that different from the Point of Safe Return PSR? And how so?

I would very much appreciate the help if anyone would be kind of enough share their wisdom and knowledge.

[hvogt]

As far as I remember from flight school, the point of safe return (PSR) is the farthest point where you could still return and arrive at your departure aerodrome with reserves intact. The term 'point of no return' (PNR) refers to the same concept but implies arriving with tanks dry. That way, the PNR defines the so called 'radius of action', a term of military origin and mostly used in helicopter SAR missions. Sometimes PSR and PNR are used interchangeably, which might have led to your confusion.

Edit:

The point of equal time (PET) is the point where the flight time to your destination would be the same as the time back to your departure aerodrome. It's got nothing to do with PNR/PSR.

[mikedreamer787]

ETP (Equi Time Point to my generation) - the point
at which to go on takes the same time as to return,
usually all engines operating.

PNR - the furthest point at which one can return with
mandatory fuel reserves intact. This can be all eng, or
eng(s) out, or depressurised all engines operating. The
DPNR was usually the more limiting fuel on long ocean
crossings than PNR3 on the Whale. So if you carried
enough gas to cover DPNR then you were automatically
covered for PNR3.

I recall my Oz SCPL Flt Planning days where ETP and
PNR were mixed up together in the sub-subject of Base
To Remote Strips. I could never get my head around it
and knew I'd lose 10 marks or so if it showed up in the
exam. Fortunately the pass mark was 70%.

[LeadSled]

Folks,
hvogt's definition of PNR is a new one to me, and I have been around the aviation business for something over 50 years, including the Sydney "college of Knowledge" courses in my early days.

PNR is the last point at which you can divert to a suitable alternate, whether it is en-route, off- route or even the departure point with "normal" reserves.. Beyond PNR you are committed to the destination, with whatever reserves are required at the destination.

Radius of action is a bit different, depending on the criteria. Radius of action to a moving base used to give me the rar-tars, what application it had to civil use was a mystery to me, as it was only applicable to returning to an aircraft carrier.

ETP is equi-time point is just that, same time out as back, unrelated to endurance. However,you can use the same basic formula to work out an equi-fuel (burn) point, which is not quite the same as PNR.

[Centaurus]

and I have been around the aviation business for something over 50 years, including the Sydney "college of Knowledge" courses in my early days.

"Le College of Knowledge" Oh boy - does that take me back in time. Although I was in the RAAF in the early Fifties, I decided that in view of my four-engine time, Qantas would welcome me with open arms. But in those days Qantas pilots had to have a Flight Navigator Licence. I don't know why since in those days proper flight navigators were carried (you know the half-wing variety). The Sydney based College of Knowledge, as it was universally known, (and I forget its true name anyway) published correspondence courses for the Flight Navigators Licence. For a sum of course.

So I signed up for the Navigators course which even in those days was bloody expensive. I vaguely recall there were fifty lessons, all of which had to be completed and sent back to Sydney for marking. The first few lessons concentrated on revision of High School standard of maths and physics. Maths and Physics rated alongside Latin as my most hated school subjects and I swear I still have the cane marks on my bum to prove it.

I opened the first page and within a few minutes decided I could never ever be a navigator. My education was sadly lacking and I never got beyond Intermediate Certificate. That was Fourth Form in High School.

I pleaded with the C of K for my money back and was told to go away - in a kindly manner you understand. I think it was about Fifty pounds sterling which was a fair sum of money in those days. I consigned every one of those red covered folders to the tip. There was no Ebay then.
And of course I never got into Qantas.

So I stayed in the RAAF and on the aircraft I flew as a lowly Sergeant Pilot, we had a real half-wing navigators down the back of the Lincoln, often sporting the gold eagle badge of a wartime Pathfinder navigator on his battle jacket. No shortage of the DFC on many of these chaps, too. As pilots we simply flew headings as ordered by the Nav and never dreamed of questioning his directions. The trouble was some of these Navs were former scrubbed pilots and most were old blokes of 30 who had been severely shot at over Europe.

Nowadays, they would be labelled as grumpy old men especially when they got real shirty if you practiced cloud flying in thunderstorms while they were in the astrodome trying to obtain Sun or Star shots with their sextants.

[john_tullamarine]

Centaurus,

I think I probably have my old College of Knowledge books in the shed somewheres if you really want to indulge in nostalgia .... I thought that they weren't a bad course albeit that the standard of publication would cause most of the new chums today to turn their noses up in disgust .. they probably don't even know what roneo means ...

[mikedreamer787]

I think Roneo went out of business many moons ago John.

[Tinstaafl]

Sydney TAFE had the School of Navigation, as it was called when I did my CPL theory there in the mid '80s, and ATPL Nav & Flight Planning in the early 90's.

I thought their courses & instructors were excellent, and relatively cheap as a bonus.

[flyingbear88]

Thanks for your assistance I just needed to get confirmation that PET and PSR are different.

[flyingbear88]

thanks Mike. you understand my confusion then

[flyingbear88]

thanks everyone for your assistance. I got the confirmation I needed.

Love to all the ozzies too!

[Desert185]

flyingbear88:

Using outer scale over inner scale:

ETP Dist? GSR
TTL Dist. GSR+GSC

PSR (hrs)? GSR
TTL Fuel-RSV GSC+GSR

ETP: equa time point (time/distance using wind at ETP3/2 altitude)
GSR: ground speed return
GSC: ground speed continue
PSR: point of safe return (fuel)

With an offtrack ETP, always measure the ETP distance from the return airport.

[compressor stall]

John, any chance of a scan of the CoK books? Or are they too large.

I assume copyright has expired.

[mikedreamer787]

Yeah me too John. I'd be interested in your CoK books
too. I can PM you my email upon request. In return I'll
send you my illustrated College of Carnal Knowledge
texts!

[mikedreamer787]

Radius of action to a moving base used to give me the rar-tars,
what application it had to civil use was a mystery to me, as it
was only applicable to returning to an aircraft carrier.

Your 'Radius of Action' Lead S sounds similar to 'Base
To Remote Strip' (as per my last post). The BTRS was
a question like this -

Given: A twin 5700kg twin with perf and fuel data.

You fly 10 pax out with 73kg baggage to a mining camp.
You dump the pax and bags and return back with 8 pax
and 220kg baggage/cargo. No fuel avbl at the camp. The
FOB after arrival was XX gals.

How far out did you fly given a 40kt H/W outbound?

The FOB on arr comprised 45min FR and 10% VR.
From there you calculated the fuel he must've burnt.

One had to take into account DPNR1 in association
with ETP.

IIRC there were 14 cases of BTRS depending on who
and what got dumped and what didn't, and fuel at the
camp or not. As I said I couldn't ever work the damn
things out.

[muralishan89]

Wind outbound?

Hi friends,

I am not clear by the term "outbound wind"

In the Jeppessen General Navigation book. under topic "PET".

Distance A – B 1240 nm
TAS 340 kt
Wind Component +20 kt outbound

In this outbound confuses me. How i should understand the term outbound?

Either as headwind or tail wind from the point A

[john_tullamarine]

Re scans of the CoK texts .. had missed these posts at the time . . mea culpa.

My old stuff is archived in a bunch of cardboard boxes until I get into into my nice new big shed/office .. if they are still legible, I can make some arrangements.

I would need to check copyright but I suspect it will not be relevant this far down the track .. that's 50 years ago, give or take a month ...

[Capn Bloggs]

In this outbound confuses me. How i should understand the term outbound?

If it's a PET/ETP scenario, that term is confusing, because the only winds that are relevant are "on" (from the PET to the destination) or "back" (back to the origin) winds. I suspect they mean the "on" wind.

In a PNR/PSR scenario, the relevant winds are "out" (from the origin) and "back" (to the origin).

[Microburst2002]

So, if you plan a flight to an "isolated aerodrome" (no alternate available) where you have to add fuel to fly for 2 hours at normal cruise and all that… Should you determine a PNR?

In EASA they have the PDP, predetermined point. It is a fuel planning for a quasi-isolated aerodrome. Is that PDP similar to a PNR?