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DGAC
10th Aug 2010, 15:54
Can anyone recall the details of a Qantas crew helping out a pilot lost somewhere over the Pacific, I think? There was something about the Qantas crew asking the guy to hold his arm out and count the number of knuckles between the horizon and the sun followed by some other very clever pilot nav techniques.

If anyone has the full details I would be most interested to read them again

MG23
10th Aug 2010, 18:56
I don't know about the historical details, but I do remember a movie I saw on TV some years ago where an airliner flying over the Pacific finds a lost pilot and leads him to the nearest airport in New Zealand. Can't remember what it was called, but it sounds like the same story and it was supposed to be based on real events. I'd be interested to know what movie it was, becasue I'd like to watch it again sometime :).

hoodie
10th Aug 2010, 19:52
Here's the story (http://www.navworld.com/navcerebrations/mayday.htm). (ANZ, not QANTAS)

“Mayday mayday.” This message of a pilot in distress on radio three days before Christmas 1978 is heard by Auckland ATC. The saga of how Jay Prochnow was finally located by the innovative navigational techniques of Captain Gordon Vette aided by Malcolm Forsyth both of Air New Zealand, Auckland ATC, Norfolk Island and the crew of the Royal New Zealand Air Force (RNZAF) Orion is made into a Brain Game. The Penrod, a towed oil rig with running lights, served as a beacon which enabled Captain Vette to rendezvous with Jay Prochnow.

The film was in 1993: Mercy Mission: The Rescue of Flight 771 (http://www.imdb.com/title/tt0107556/)and starred Scott Bakula of Quantum Leap fame.

wrecker
10th Aug 2010, 19:52
Flashes from my memory.
Lost a/c was a Pawnee
I have a feeling the crew assisting were flying a DC10, which could make them Air N-Z and the time maybe early 80s.

In rough terms an arm held outstretched with the fist clenched, each knuckle subtends an angle of about 1 degree and provides an approximate way of measuring the sun's elevation. Check difference of elevation between lost a/c and seeking a/c at same time this will give a indication of difference of lattitude, you have one position line, difference of sun's azimuth will give differnce of longitude. all very approximate but in that case it worked. A great bit of work from the ANZ crew.I think they were recognised by the Institute of Navigation.

forget
10th Aug 2010, 20:03
All here;

Mayday in December (http://www.navworld.com/navcerebrations/mayday.htm)

DGAC
11th Aug 2010, 10:36
Thanks "forget". Just what I was looking for.

hoodie
11th Aug 2010, 17:09
Errr....

Nah, never mind. :}

forget
11th Aug 2010, 17:43
Oops. Sorry Hoodie. I did check that no-one had posted that link. Obviously not well enough. :\

DGAC
12th Aug 2010, 15:06
Likewise, Sorry Hoodie. But it's such a good story that it's well worth repeating http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif

forget
12th Aug 2010, 15:28
I have to admit, I didn't get this the first time I read it years ago - and I still don't.

Since the heading of the Cessna to the Sun was 274 degrees it was greater than the 270‑degree heading of the DC‑10, that meant that the Cessna was south of the DC‑10 as shown in Figure 20.

Different elevations dependent on longitude yes, but 'heading to'.

PS. I can already feel that I may regret posting this.

HEATHROW DIRECTOR
12th Aug 2010, 17:44
I've read the story a few times: The most amazing airmanship by the ANZ crew.

hoodie
12th Aug 2010, 19:54
Likewise, Sorry Hoodie.

Absolutely no problem. In fact, I enjoyed telling the missus that "Yes, I can be too subtle sometimes - look!" :ouch:

But it's such a good story that it's well worth repeating http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif

100% unarguable, that is. I'm with HD - amazing airmanship.

PS You'll note that I am artfully avoiding an attempt at answering forget's question.

sycamore
12th Aug 2010, 20:50
Forget, forgotten it`s S Hemisphere ?Sun is always to your `North`.....

David Layne
12th Aug 2010, 22:35
This part of the story doesn't make sense to me...............

"The Cessna landed safely after being airborne 23 hours and 5 minutes arriving at close to midnight 8 hours beyond its 1600 ETA. Prochnow had stretched the Cessna’s twenty-two hours of fuel by 5 percent through cruise control."

A Cessna 188 Agwagon wouldn't have fuel for that long in the air unless it was carrying extra tanks where it would normally carry it's agricultural load.

Anyone know if the Cessna had some kind of tanks for ferrying?

hoodie
12th Aug 2010, 22:46
This 2007 thread Dunnunda thread about Capt. Gordon Vette is worth our time, I think:

http://www.pprune.org/dg-p-reporting-points/278620-congratuations-gordon-vette-nzom-obe.html

Groundloop
13th Aug 2010, 09:19
Anyone know if the Cessna had some kind of tanks for ferrying?

It was a trans-Pacific ferry flight - of course it had ferry tanks fitted.

forget
13th Aug 2010, 09:44
This is what's bothering me. I thought that, for all practical purposes and because of the sun's size and distance from Earth, light rays reaching the Earth are parallel. So, at any instant, it doesn't matter where you are on Earth the (true) heading to the sun is the same.

Like I said, I know I'll regret asking this.:hmm:

http://i21.photobucket.com/albums/b270/cumpas/mayday6.gif

PS. Sycamore, Southern Hemisphere? Sun is always to your `North`.....

Not if it's southern summer it ain't. Tropic of Capricorn?

The Tropic of Capricorn lies 23° 26′ 16″ south of the Equator. It marks the most southerly latitude at which the sun can appear directly overhead at noon. This event occurs at the December solstice, when the southern hemisphere is tilted towards the sun to its maximum extent.

forget
14th Aug 2010, 16:52
No navigators here? I got the words below from a sunset/sunrise primer. It says the same as I'm trying to say; Figure above can't work. I'd like to be shown I'm wrong.

The Azimuth of sunrise/sunset is the compass bearing. North is 0°, East is 90°, etc. On the equinox (approx March 21st/September 21st), the sun rises due east and sets due west (all over the world). At other times, the sun rises north or south of due east.

Brian Abraham
18th Aug 2010, 01:08
Morning forget, if you google "sun azimuth" you may find your answer. There are azimuth calculators to be found there so you can play with figures.

John Hill
18th Aug 2010, 04:01
In the same part of the world and a few years later a ferry pilot in a small aircraft was heading south towards Pago Pago (which is where the other aircraft being discussed had taken off from) but he never found the island and continued on until he was able to contact me at Niue (I dont recall exactly but I think that must have been on VHF). He could not find Niue and of course we had nothing on the ground to help him. Eventually he said he would be ditching while the engine was still running and he still had some daylight. He also said that if he managed to get into his life raft he would turn on his EPIRB at sunrise.

A RNZAF P2 went up from NZ and was in the general area are sunrise when the beacon came on and he was located in a very short time. He was not much further than over the horizon from Niue, maybe 60 miles I forget exactly, be we had no boats able to navigate out of sight of land and there was no commercial shipping located in the area by the Orion. It was arranged by the RCC that a Coast Guard cutter from Pago Pago would go and pick him up but they left without return fuel arranging instead that a tug would follow along behind with more fuel, however the tug returned to Pago Pago for some reason and of course the cutter was left helpless in the South Pacific but with the pilot on board. After a week or so the Orion was back in the area searching for the cutter!

I cannot swear to the accuracy of the bits of this story which did not immediately involve me but I believe it is essentially correct.

John Hill
18th Aug 2010, 04:05
Regarding sun azimuth, yes that would be right. The azimuth of sunset would give you an idea of latitude and comparing the time of sunset would give you an indication of relative longitude. Altitude of the two aircraft would play a part and maybe the Air NZ crew were able to calculate that in.

forget
18th Aug 2010, 10:04
Brian, I've got it, I think. What threw me was the sequence of events, as written. I thought that the Cessna being South of the DC-10 was determined on the magnetric headings only, which isn't possible. (Is it :confused:) If the events are reversed, sun elevation first, then heading, it's obvious - sort of.

Like I said, I knew I'd regret asking. Brilliant bit of work though - bl**dy genius.

Captain Vette, a qualified navigator, contacted Prochnow and asked him to head toward the Sun and to report his magnetic heading. Prochnow pointed the Cessna to magnetic heading 274 degrees as Vette steered his DC-10 toward the Sun and read his magnetic heading as 270 degrees. Next Vette instructed Prochnow to determine the elevation angle of the Sun above the horizon using his partially outstretched arm and fingers as a sextant. Prochnow established the elevation of the Sun as four fingers as Vette measured the elevation of the Sun as two fingers.

Brian Abraham
18th Aug 2010, 16:48
Just to make sure you got it :p Say the sun was directly overhead the equator at the 0° meridian. To an observer on the equator at 90°E or W, or at either of the poles, the sun would be on the horizon (assuming perfect sphere, no refraction etc etc). To each of the four observers the suns azimuth would be,
South Pole - 000°T
North Pole - 180°T
90°E - 270°T
90°W - 090°T
Each of the four positions lie on a circle, centred at the suns position, of radius 5400NM (assuming 1°=60NM). As the suns altitude increases, as observed by the observer, the radius of the LOP decreases. No matter the radius, unless it's zero, somewhere on the LOP circle the azimuth of the sun will run the full gamut of 360°.

A navigator can even use the sight to determine his compass error.

Had to get out D. C. T. Bennetts "Complete Air Navigator" to make sure I got it as well.

sycamore
18th Aug 2010, 17:32
BA, I used a couple of sites,`gaisma.com`,and the NOAA site to sort out sunsets ,azimuths ,and back timed the variation. The link to the story is a little short on detail,ie what time was the Mayday made, and so on. Another curiosity is that it was picked up by Auckland,so presumably on HF ,as Jay was out of range from NI.Later it says that an HF position line was obtained by the DC10 to confirm position(line). I would have thought that it could have been earlier . I recall reading the full article in the early 80s ,which I`m sure had a lot more detail....Anyway all the more reason to make sure your Standby compass is swung accurately...not sure if an AgWagon would have a full system....
Nevertheless,a truly outstanding bit of flying ,and navigating,by both parties,so never go with fuel left in the bowser....

John Hill
19th Aug 2010, 06:22
I have often wondered if anyone tried to predict the position of the Cessna by using known winds. At least one report said the pilot had not deviated from his planned heading but had missed Norfolk Island due to the winds not being as forcast, therefore someone who later knew the actual winds shoud have been able to predict the position of the Cessna.

Whatever, for all I know Captain Vette may have included that anyway.

gileraguy
19th Aug 2010, 06:44
now if someone would be so kind as to explain how he used the radio reception to find the longitude, i would be thankful.

from the diagram in the story i would have though that the reception would be lost on the opposite side of the box, not the side it shows the lost aircraft was closest to?

forget
19th Aug 2010, 09:17
From the diagram in the story I would have though that the reception would be lost on the opposite side of the box, not the side it shows the lost aircraft was closest to?

The radio boxing diagram looks OK to me. The DC-10 has already worked out a very rough location from the sun and is flying towards that location, heading South West and maintaining a constant altitude for the exercise. The Cessna is asked to transmit on VHF, let's say, a 2 second burst every 10 seconds.

At Point 1 reception of VHF by the DC-10 begins to increase, from nothing. At Point 2 it decreases to nothing. From this, the Cessna is abeam track 1-2, half way between 1 and 2, but it can be to the North of 1-2, or the South.

The DC-10 then turns left at Point 2 and then does a 180 after which the VHF signal starts to increase from nothing at Point 3. At Point 4 the signal decreases to nothing. From this, the Cessna is abeam track 3-4 and half way between 3 and 4, thus resolving the question, North or South of track 1-2.

Had the Cessna been North of 1-2 then the circle simply shifts North West.

http://i21.photobucket.com/albums/b270/cumpas/mayday10.gif

(Note that initial aircraft/aircraft calls would have been by long range HF radio, but no mention is made of this. Note also the comment, 'VHF Aural boxing depends on continuous transmission on VHF otherwise a silence can be construed as loss of contact'. The Cessna would almost certainly have been fitted with ARC VHFs. I wouldn't trust one to provide a continous transmission for that period, it'd burn out and I'll bet the Cessna pilot knew that too. Transmission bursts are more likely.)

forget
19th Aug 2010, 09:47
PS. I've just remembered. Not long after Vette's save Air New Zealand, and I think QANTAS, installed electrical meters at Flight Engineers' stations. These meters were connected to the Automatic Gain Control test output of a VHF transceiver. The higher the reading the stronger the received signal; accurate, and great for radio locating. I wonder if they were ever used.

gileraguy
21st Aug 2010, 01:19
thanks mate

I misunderstood and thought the Jet was flying the circle, not the straight legs.

Wunwing
21st Aug 2010, 06:01
Forget
Yes they were known as search meters and were in fact a signal strength meter and were normally operated by the FE.When plugged in to (I think) VHF#1, the gain was automatically increased.Strange setup because we monitored "guard " on VHF #3.

Personally I've used them about 5 times in anger and we found 3 downed aircraft, including 1 fatal in the Blue Mountains near Sydney.In most cases we were steered into the search site by ATC.

When Qantas was privatised the management decided to remove them.

Additionally to all the above mentioned lost aircraft, I seem to remember a ferry aircraft going down near Tahiti. The Qantas crew were talking to him all the way down and he was never heard of again. From memory the Captain of the Qantas aircraft was Ben S.

Wunwing

forget
21st Aug 2010, 12:12
Which reminds me, in the '70s a transatlantic flight picked up a 121.5 ELT signal, mid ocean. Either Shannon or Gander asked all flights to monitor 121.5 and to report their INS positions when the signal was first heard and when it was lost. After a couple of hours they had several dozen plots and were able to divert a Shell tanker to a spot in the Atlantic. The tanker found a lone yachtsman with a broken mast. If I remember rightly a Concorde was even more involved in the airborne plot production - anyone?