Vintage vs Modern VFR flying.

[mrcapitalism]

Kind of a wandering thread, but I'll see if I can explain;

From FSAviator's description of 'Pioneer flying'

This post is explicitly about the Vintage era and is not intended to replace VFR navigation techniques being taught to real aircrew today in accordance with current requirements. Real aircrew must stick with the techniques they were taught and should make the maximum use of modern electronic aids and modern ATC to maximise safety at all times. This post is about how things worked (in general) before those possibilities existed.

Each vintage era flight is a series of time wasting turn slightly right, turn hard left, zig-zags.

so...as a flight simmer who's progressed to the status of "real aircrew," the question becomes, why? Why is what we're taught IRL so different from what was used nearly 100 years ago?

The concept of 'dead reckoning' is only relevant to Vintage era simulation in so far as it relates to ensuring that you locate the line feature to the right of the next landmark (waypoint).

As you all know, modern visual flight is heavily reliant on dead reckoning. It has almost no turns of this nature. New pilots are not taught the concept of a "line feature" in the official handbooks. It's learned as a technique during training, but not used in this way. The modern emphases is on maintaining a mostly direct track to the destination, defined by landmarks to check progress and position.

Compared to the simulated technique;

As soon as visibility is too poor to see one landmark from the last it is an error to set off directly to the next landmark, and therefore an error to choose landmarks during flight planning that cannot be located by intercepting an extended line feature leading to the next landmark. Remember visibility may reduce during the flight.

With these questions in mind, I converted the Calclassic updated Trimotor to FSX and chose a route to better understand. Washington DC to Pittsburgh PA.

My first attempt tried to follow the vintage technique, but I realized it relied too much on the modern influence.

My checkpoints have associated line features, but the routing is pretty much direct, and given that the visibility on that day was good, it was flown just like a modern flight (ignoring modern airspace and equipment limitations).
Even with that direct routing, I found (via dead reckoning) that I was behind schedule! Which I blame on a headwind and reduced performance on a hot day.

It was lawful to cruise a J6 engine continuously at 2000rpm, but far from economical, and not necessarily safe in modern terms. Most operators of the 4-AT-E are likely to have published 1750rpm as the target for economical cruise in their operating manuals

Yeah, for the last half of the flight (including descent) I was riding that 2,000 RPM limit all the way to the traffic pattern.

So, not quite satisfied with my performance, I decided to do some research.

First, the Library of Congress has available on the web the actual "strip map" for this airway segment (1926, 9 years before the timetable). Available here: www.loc.gov/resource/g3701pm.gct00064/?sp=4

It's remarked,

to simulate Vintage era navigation you do not need current Sectional and terminal charts. They should be employed when simulating the current era.

If you compare the modern sectional chart to the 1926 vintage strip map, you see they are nearly identical! It's amazing! A modern sectional is basically the same thing. Compare features such as airport and navigation symbols, cultural information, terrain depiction, and the symbols for lights (airway vs modern airport beacon). I've come to realize when you examine a modern FAA Sectional, it fundamentally hasn't changed.

So since the modern Sectional can basically substitute an old strip map, I can plot the different flight plans using Skyvector. I'll just share the links to the different flight plans here to save space.

If I follow the mileage lines shown on the strip map, I get something approximating this.

What strikes me is the marks for miles shown along the route. It seems that even in 1926, direct flight was attempted (at least along defined routes). Is this a version of the "airway" that Central Airlines claims to follow in 1935? The distance scale leads me to believe that FSAviator is right, dead reckoning is not used here. The pilot merely observes their position and uses the scale to determine miles traveled. A clock is removed from the procedure, progress is measured in ground miles traveled, like an automobile.

I had only seen depiction of such distance marks in DCS World, with the L-39 training campaign. I had thought it was a Russian military technique. I've since learned it's actually used by many military to control ETA for bombs on target. In the civilian world I guess we care about ETA for First Class Mail to Pittsburgh.

So let me plot the other airways on this strip map. Here is my best estimation of the beacon airway.

What I can deduce is that the lighted airway beacons are mostly built along the sides of roads (at least in this example). Thus, if you chose a 'line feature' such as a road between two major cities, it probably had a beacon airway running along it. Is this the reason for such a strong focus on line features? If you're following a line feature (at least a road), you're very likely following the path of a beacon airway anyways? Or at least simulating the beacon airway.. which could be considered somewhat of a 'line feature' in itself?

All very interesting. I also built a flight plan using the radio ranges, but that isn't terribly related to vintage flying or the Trimotor. Here is my guess.

So a tour through youtube found this video, where I was first introduced to a new term "Contact Flying." I have never heard this term before... contact flying. It's not in current FAA handbooks. But yet it's easy to find in various online encyclopedias and dictionaries.

contact flying noun

Definition of contact flying

: navigation of an airplane by means of direct observation of landmarks —contrasted with instrument flying

How crazy, the FAA has forgotten this phrase??? I suspect that as a safety function, dead reckoning has been combined with contact flight to become what we now call "Visual Flight Rules." But I would need more research to discover this fact. What happened to contact flying?

....just some of the things I think about flying a Ford Trimotor in a flight simulator....

I'll leave you guys with my descent into the old Pittsburgh Airport (now called Allegheny Country KAGC), riding 2,000 RPM trying to make up time.

[mrcapitalism]

Oh yeah, the times!

So the advertised cruising speed for the Trimotor is 93KIAS, which the FSAviator FDE will do at 1750 RPM on a standard day.

The scheduled departure time from Washington is 1040am (from the vintage airports, which are now occupied by The Pentagon. The modern KDCA is a great stand in as it's less than 1nm away).
The scheduled arrival time in Pittsburgh is 1225pm. This budgets 1h45m to make the run.

If I fly modern VFR direct, the distance is 162nm, and the required groundspeed is 92.8 knots.
If I fly the strip map distance lines (the turn at Uniontown), the distance is 173nm, and the required groundspeed is 99 knots.
If I fly the beacon airway, I get about the same. Distance is 174nm and required groundspeed is 99.5 knots.

So either Central Airlines didn't fly at 1750 RPM, they didn't actually follow the airways and flew direct, or they built (and bid) their schedule on the direct distance, and not how it was actually flown.

[mrcapitalism]

Hey guys,

I have some time here, and thought I would give some updates on this subject.

During some google search for "pioneer phase" navigation, I came about a curious book called Flying the Beam: Navigating the Early US Airmail Airways 1917-1941 by Henry R. Lehrer.



It's kind of a curious book. Written for a pretty obscure subject for the general public, but of interest to the aviation community ...I guess. You can see that from the reviews. It's not a history of Air Mail, not a history of Air Lines, but a history of navigation and airways. It references a large number of period sources, and goes into excruciating detail on the questions I was looking for. It's really incredible to exist for my purposes, and answers pretty much any question I could have. It's published by Purdue University, and considering it's not grossly overpriced and full of filler, I assume it's not a textbook I suspect it started as a masters thesis based on it's writing and bibliography.

Anyways, let me answer my questions, and do some more rambling:

Why is what we're taught IRL so different from what was used nearly 100 years ago?

Because the tools and techniques of simple VFR navigation are actually high technology. We loose that context when we use even more advanced systems of radio/celestial/satellite navigation.

To quote FSAviator again,

How we should conduct a realistic propliner, maritime patrol, or bomber simulation within FS9 depends on;

1) crew complement

2) the avionics being simulated

3) location

4) date

This is still true, even for the pioneer phase of navigation. But I would modify it slightly (or at least re-imagine it). "The avionics being simulated" doesn't just apply to electronics, or even those mounted to the aircraft. In the pioneer phase, the tools and equipment available greatly influence how the aircraft is operated, despite being nothing like we would consider with the modern definition of "aviation electronics = avionics."

The pioneer phase also needs expansion.

Consider the information needed to conduct a dead reckoning navigation leg:
Direction, distance, ground speed, fuel consumption.

To get direction and distance, you need a map (specifically, a chart). Charts and maps are technology.

Road Atlases such as that prepared by Rand McNally are perfectly adequate for simulated vintage era navigation right across the United States...Puerto Rico, Canada and Mexico as well. ...and to simulate Vintage era navigation you do not need current Sectional and terminal charts. They should be employed when simulating the current era.
-PT2008

This is true for a single location, date, and crew in the pioneer phase. Just like when we consider what (and who) is available in a vintage, classic, or modern flight. Consider these examples of VFR flight.

1903 - When you fly the Wright flyer simulating 17DEC1903, a road atlas is inappropriate technology.
1926+ - When flying Contract Air Mail, and simulating holding an Airway Strip Map, it's actually more appropriate to have a modern sectional than a road atlas.
In the 23 years between these dates (and later), in various places, at various times, it was most appropriate to use a modern road atlas as the map technology available. This is a choice you have to make.. what map technology is available?

In Flying the Beam, Captain Lehrer goes into great detail on the flight planning/monitoring tools available. Early plans consisted of choosing, on the ground, the line feature to be followed after takeoff. Other routes were purely textual in form, with descriptions of landmarks, mileages, and line features along the route. No maps. Other aviators exactly described the FSAviator technique, of flying a heading to identify ,and then turning to follow, a line feature to the next landmark. By the time the airway strip maps were available, mileage was displayed on the map, along with relevant line features and landmarks.

The two major infrastructure developments along the early airways were maps/charts, and emergency landing fields. The beacon airways and airfield lighting existed to facilitate night and low visibility flight. Much of the book is spent discussing the development of charts and maps. I had assumed that the airway map of 1926 proved the irrelevance of the road atlas, but the reality is the choice of navigation/planning information has to be carefully considered, just as you would choose the electronic navigation aids available.

Rand McNally actually participated as a contractor and published their own aviation maps.

Aeronautical charts of course derive from nautical charts, and their major benefit is to accurately depict the positions and directions of every location. With accurate depiction, it is possible to actually measure accurate distances and directions. Without this fundamental information, dead reckoning was impossible.

Lets take a break: Here, I decided to fly a random Trimotor along a Air Mail route from Chicago (MDW) to St Louis (STL). I neglected to check the weather, and decided to see what I would encounter once airborne. I used a sectional from Skyvector, simulating an airway strip map.

When flying in the vintage era perfectly ordinary weather that you would not even notice as bad weather when driving a car to the airport becomes a potential killer. Even moderately low visibility can kill you...The airline pilots of 1929 had to push their luck a lot further than flying in a visibility of three miles if they wanted to keep their jobs, often with fatal consequences for all aboard. Simulating what they had to do to keep their jobs is the only way to understand why the vintage era of aviation killed so many aircrew and passengers and why the classic era techniques had to be imposed by federal regulation. Trimotor - FSAviator

Now we need to talk about aircraft equipment.

Assuming you can even find the dead reckoning course and distance to fly, the next challenge is to actually fly it. The humble calibrated aircraft compass that we all pretty much ignore is high technology. Just as much technology as is the simple paper chart. A great deal of research and development was spent creating a compass that would not produce massive errors when surrounded by the metal fasteners, brackets, engine and accessories in an aircraft in flight. Without an accurate compass, it's not possible to fly the direction of a dead reckoning leg, and you're forced to rely on landmarks and line features for direction information. I have to ask, in this simulated flight will an aircraft compass be available?

The S.V.A. 5 simulates this well with only a handheld compass available, although in a flight simulator it has the same accuracy as an installed and calibrated aircraft version.

Similar development and limitations affect instruments such as airspeed indicators and other VFR paraphernalia. Airborne flight computers (Dalton E6-B)were probably available by the mid 1930's, and I suspect that by about 1935... for those crew and aircraft equipped... the modern VFR dead reckoning + pilotage regime was in place.

Here's another screenshot from my interesting pioneer flight. First, the relevant quote:

A visibility of 3 miles is, in many current jurisdictions, nothing more than the lower limit of visibility that newly qualified amateur pilots are expected to cope with, without access to any electronic aids. Vintage era simulation is all about developing that real world skill. Only after experiencing rising terrain or masts looming into view frighteningly close ahead is it possible to understand why vintage airliners had to be so slow. This is stuff that cannot be understood by reading a book. It has to be 'experienced'. That is what flight simulators are for.
Trimotor - FSAviator

See if you can notice them...



I didn't grab a screenshot of the outcome of this daring air mail sortie. I heard characteristic rumbling of some sort of winter precipitation (hail/ice?) and Active Sky decided that I had enough. All three carburetors froze simultaneously with my pitot tube, forcing a casual landing on the major highway which was my line feature. I'm sure had I been more careful, I would have either not departed, or soon diverted to the nearest government managed emergency landing field. I was probably able to cheat my certain fate for about 30 minutes...

[Tom/CalClassic]

A good example of why it was so dangerous back then. But by 1935 many airways had some sort of radio aid as well.