DC-6 navigation without navaids

[19AB67 16]

Hi folks, 

 

waiting impatiently for the FSX DC-6 and after having read many of the 1950s DC-6 timetables (see my other thread http://www.avsim.com/topic/492268-dc-6-routings-timetables-lets-collect/ with most helpful links) now I wonder how navigation was done preGPS and preINS and preNAT. 

 

Maybe I should be more specific.

Of course I know about navigators using sextants etc. See also on Wiki article on 'Transatlantic flight'. This is on 'Where am I?' 

 

My question is more on the *aviate* in aviate-navigate-communicate. 

 

If I know where I want to fly to, how to set the heading appropriately? 

Without GPS or weather charts I know little about the actual wind situation outside and the drift resulting from it. In the aforementioned article we learn:

'To aid aircraft crossing the Atlantic, six nations grouped to divide the Atlantic into ten zones. Each zone had a letter and a vessels station in that zone, providing radio relay, radio navigation beacons, weather reports and rescues if an aircraft went down. The six nations of the group split the cost of these vessels.^[47]'

 

However, before these radio navigation beacons, -- and within FSX -- there were/are no navaids. 

 

If I take the route from Shannon to Gander as an example, the great cycle is roughly: 

EINN N5320  N5330  N5240  N5050 CYQX 

 

The magnetic headings for 'no wind' are a starting point:

EINN 286° N5320  283° N5330  278° N5240  273° N5050 263° CYQX 

1. Did the pilots simply fly this route until they picked up first navaids on the other side of the pond?
2. What if the navigator calculates at e.g. 30W that you hit rather 52N or 54N? Correction to 282°/274°? Or rather extrapolation of the last section to the next, not knowing whether the wind is significantly different? 
3. Did they make use of incoming aircraft, which just had been probes in the wind at a given, i.e. their crossing altitude? 
4. A mixture of 1.-3.? 
5. BTW: Did they already fear mid-air collisions and flew altitude separation?
6. If we know the wind, e.g. taken from skyvector.com wind barbs, we can calculate with some trigonomy the heading to fly. 

Noooooo, I won't ask when the FSX DC-6 will be out.... but I start flying in my imagination!  B) 

[19AB67 16]

Ups, the true waypoint across the Atlantic are of course ...

EINN 286° 5320N  283° 5330N  278° 5240N  273° 5050N 263° CYQX

... with the 'N' at the end. 

[scandinavian13 5,192]

 

 

Did the pilots simply fly this route until they picked up first navaids on the other side of the pond?

 

They attempted to fly whatever route they deemed suitable, yes. This could either be out over the waters, or an arc (with/without stops) over NE Canada, S Greenland, Iceland, Ireland and the UK.

 

 

 

What if the navigator calculates at e.g. 30W that you hit rather 52N or 54N? Correction to 282°/274°? Or rather extrapolation of the last section to the next, not knowing whether the wind is significantly different? 

 

Course corrections were normal, and usually involved calculating what pushed you out of position to help you make a better correction to continue.

 

 

 

Did they make use of incoming aircraft, which just had been probes in the wind at a given, i.e. their crossing altitude? 

 

You could, but their calculations of the actual wind are no better than yours, and weather constantly changes.

 

 

 

If we know the wind, e.g. taken from skyvector.com wind barbs, we can calculate with some trigonomy the heading to fly. 

 

Correct. Even without the wind barbs, you can still figure it out, and are encouraged to do so. This is best done prior to losing your ground references and navaids, as well: known positions, time to drift, etc. Navs all had slide rules (similar to, or exactly like, the E6B of today).

[19AB67 16]

Thanx Kyle, this gives the insight. 

 

 

 

They attempted to fly whatever route they deemed suitable

 

... but based on some early weather charts? 

 

 

 

but their calculations of the actual wind are no better than yours, and weather constantly changes

 

... right, but the incoming aircraft at EINN just had experienced the latest weather (the weather probe), while those heading from EINN to CYQX had to rely on whatever weather charts. 

[downscc 1,327]

They had a navigator on board and an astrodome to shoot the sky. Celestial navigation was the primary means of getting across water. The NDB sites were unreliable in bad weather but that was it.  Good old fashion pilotage was and still is an art.

[kevinh 409]

Over land they also had the LFR Radio Range system for airways flying. There was also Decca navigator system which could be used over the ocean.

[19AB67 16]

 

 

Decca navigator system

 

Again, I assume this support knowing where you are. 

I'd like to learn more which methods where used to set the right course with the knowledge of your position, deviation from wanted position, but not knowing the winds outside. 

[kevinh 409]

Yes the Decca navigator could only identify current position. It's up to the flight crew to plot the course, estimate drift and compensate for it. That's why long range aircraft usually had a navigator in the crew.

[skelsey 765]

As has been mentioned, there would be a navigator on the crew who would be trained far more comprehensively in the art and science of navigation than any pilot, then or now. The various means of fixing position have been discussed -- celestial nav (including using the sun, during the day) could be used, as could the various radio-based systems described by Kevin.

 

Regarding applying a wind correction -- if you knew where you were, and you know your present position, you can plot the course you have flown on a chart. You can then use the time taken to get to from where you were to where you are now to determine your ground speed, and it is a simple matter of trigonometry to calculate the wind drift -- you have the actual ground track (if you knew your previous and current position) and you have the speed.

 

You could use either a computer (slide rule/E6B) to come up with a precise answer or you could use various rules of thumb such as the Maximum Drift (http://www.jenxs.co.uk/Navfiles/Maxdrft.html) method to approximate the required correction.

[scandinavian13 5,192]

 

 

... but based on some early weather charts? 

 

Not likely. If there was one, it was not usually trusted very well.

 

 

 

... right, but the incoming aircraft at EINN just had experienced the latest weather (the weather probe), while those heading from EINN to CYQX had to rely on whatever weather charts. 

 

Right, but unless you're on top of that aircraft, you're going to be later than it. If you're right behind it on approach, then sure, but the skies were not filled with aircraft back then like they were today.

[19AB67 16]

 

 

BTW: Did they already fear mid-air collisions and flew altitude separation?

 

Any knowledge on this? 

000° to 180° FL190, 210, 230, 250?

180° to 360° FL180, 200, 220, 240? 

[scandinavian13 5,192]

 

 

Any knowledge on this? 

 

What about it? What you've listed is the current separation standard.

[skelsey 765]

Any knowledge on this?

 

I would assume there was some sort of convention, if not necessarily mandatory, but I would have to do some research to find out for certain.

 

Mid-air collision was certainly a concern, though there was a lot of (perhaps justified to a certain extent) stall placed in the 'big sky' theory -- ie the sky is a big place and aeroplanes are relatively small. Arguably mid-air collision didn't really enter the forefront of consciousness until the Grand Canyon mid-air of 1956, which led to a number of changes in the ATC system to reduce the risk.

[19AB67 16]

 

 

What about it? What you've listed is the current separation standard.

 

Did they already adhere to something like this? Or a different agreement?

 

 

but I would have to do some research

 

That'd be great, Simon. 

[soerennielsen 35]

Over land they also had the LFR Radio Range system for airways flying. There was also Decca navigator system which could be used over the ocean.

 

Sorry Kevin,

But I have to correct you on the Decca Navigator System.

Decca was only covering on land and =Coastal waters= up to 400 nm in day and 200 to 250 nm at night, and only in certain area of the world, thus could not be used on an entire ocean crossing.

A very nice description of the Decca Navigator System can be found here:   http://www.wow.com/wiki/Decca_Navigator_System