Velocity Vector, a better way to fly IFR?

[L.Adamson]

Originally Posted by frankh

The only thing I understood so far is that mechanical turn coordintaors are indeed paperweights....

Same here, regarding the "head hurting" title. I've read all this several times and keep thinking of other notions I've heard over the past few years, such as.......

"Don't use the GPS as the primary navigation instrument. Only as backup."

Does that make sense in this day and age? Of course not! Even some, "by the old methods" flight instructors attempt to keep GPS's out of students hands, while some advanced schools start with " GPS glass" on day one!

I'm a guy that's tracked probably all flight into terrain accidents for several decades, and am familiar with a bunch in the 50's too. I'm extremely open to new technology, and don't feel that the way "it's always been done", is always the right way now.

L.Adamson

[JohnR]

Great discussion. Keep the info coming I am learning a lot from this thread and appreciate the time people are taking to share their knowledge.

As I approach needing to make decisions on instrumentation everything I can learn is helpful. I make my living working with technology and learned years ago that technology for technology sake is a bad choice. Use it if it improves the process, increases efficiency, adds a safety factor, or a combination of the above. Otherwise it is a waste of time and can be dangerous.

[gasman]

Originally Posted by jeff122670

not to hijack the thread, but what current systems on the market offer a flight path marker (velocity vector)?

Jeff

Who has this now in their systems?..........................

[Rainier Lamers]

Originally Posted by jeff122670

not to hijack the thread, but what current systems on the market offer a flight path marker (velocity vector)?

Jeff

Our Enigma and Odyssey do horizontal velocity but not as a seperate indictation - rather by means of the synthetic terrain being based on ground track. In other words, if you are approaching an object, such as a runway, you keep it in the middle of the screen and you get there...

Based on this thread - I started thinking a little, and then I started hacking a little.

So, as of the next update for both Enigma and Odyssey - I have added a few things. You now get a vertical marker that moves up and down and is related to the synthetic view on the screen. I.e. - if you approach a runway you keep the runway in the middle and the vertical marker on the threshold of the approaching runway on the screen - and that is exactly where you will end up. The marker banks with the image so it it not dependent on attitude - just true flight path.

For those that would prefer to use the synthetic vision based on heading rather than ground track, I've added this as an option. In this case the velocity marker will of course move left and right as well as, in effect, it is ground track. Personally, I prefer the synthetic vision based on ground track - it seems more natural when flying the EFIS.

Thanks for the thread - it's been interesting and valuable...

Rainier
CEO MGL Avionics

[Msletten]

Originally Posted by REHughes

This is not to say that the instrument is not useful. It is a better global information-processing display than a separate iVSI and Turn Needle or Coordinator, but the control capabilities are basically the same.

It's interesting you say this... When flying IFR in my spam can Grumman Traveler with pure steam gages I always look primarily at the Turn Coordinator for lateral guidance.

Initially, my reasoning was if my attitude indicator failed I would have an easier time transitioning to partial-panel, turn coordinator-only instrument flight. Now, years later, I've decided it's easier to fly PERIOD using the turn coordinator for primary lateral guidance.

Of course, I take the occaisional glance at the attitude indicator (and other gages) to verify what the TC is telling me, but I find the very slight lag (compared to the attitude indicator) in response of the TC doesn't have me "chasing" an attitude like the attitude indicator.

Even should I become disoriented I believe the TC is more valuable:

-- Throttle idle
-- Trim for best glide
-- Release yoke
-- Center needle (and keep centered) with rudder
-- Wait until vertigo subsides, or you drop out the bottom of the cloud (hopefully before you hit the ground ;-))

This discussion reminds me of my experience in choosing cockpit instrumentation when outfitting the Grumman. I decided early I needed a situational awareness aid. I narrowed my choices to either an HSI or a moving map display. Since I coudn't afford an HSI I wound up with a MM GPS/Comm.

I'm glad I did, because since then I've decided a MM is LIGHTYEARS ahead of an HSI for improving SA. I know there are a few HSI hardcores out there who swear by the things, but a MM requires NO mental gymnastics to nail your position in relation to anything displayed on the map -- remember all those silly questions on the FAA IFR test?

Likewise, determining a heading for a new clearance is a snap -- just look at the map, turn generally in the direction you need to go and "fine tune" yourself after setting the freqs in the nav radios.

Much like this, I believe the new crop of VV instrumentation will prove out in the end because it eliminates the "intrepretation" step in instrument flight. I can simply look at the gage and "see" what the plane is doing and where I'm going. With conventional instrumentation I must look, then interpret (hopefully correctly) what the gages are telling me before I know.

I think the less experience one has with the "old" stuff the more useful he/she will find the "new" stuff.

Regards,
Mark Sletten

[Bill Wightman]

The correct technique for instrument flying is to set an attitude and a power and monitor the performance instruments (airspeed, altitude, heading, v/s) to assess.

Exactly spot-on correct statement. I taught basic control-performance flying from 1987-1991 in the T-37. We hammered on students all day to get this right.

The only thing you have direct, immediate control over is what you hold in your hands: stick and throttle. Or said another way, attitude and thrust. These things are called "control" parameters, and so the attitude indicator and what ever you use to indicate thrust are called "control instruments".

Everything else the airplane does is a reaction to whats done with the control parameters. Those things are called "performance" parameters, or instruments. Examples of performance parameters are airspeed, vertical speed, altitude, heading, etc. And yes the VV is also a performance parameter. Its closely tied to the attitude of the aircraft, but in the end its just another thing to chase. We don't have immediate direct control over this.

Control/Performance trained students are taught to set the controls first, and then assess the performance. Control is managed; performance follows. If performance isn't where you want it, you make a change to the controls and re-asses your performance. Its a loop.

I use VV as a matter of routine in my current line of work, but find it really only marginally useful on approaches to set descent angle. To date, with 12000+ hours, I cannot use VV to hold altitude. Its not sensitive enough.

[breister]

Originally Posted by John Collier

2) Its easy to become reliant on the technology and lose basic skills. Similar to turning off a GPS and trying to read a map, turning off your VV and forcing yourself to fly standard instruments (or just maneuver VFR) can be a humbling experience for someone "addicted" to a VV - ask me how I know

Hehe - we used to say the same thing about the F-15 pilots relying on all their newfangled technologies (I was a Phantom jock). I think it is always a good argument to have the uncorrected raw data available as an option, and to spend time training using only the raw data. "If you don't know what the interpreted data means, you can't know if it is lying to you."

I'm tossing around the idea of having a Dynon EFIS and a Tru-trak in my RV8...so thanks for the thread and I look forward to your article.

That's what I'm installing, along with a GNS-480 which should drive the TruTrak through any approach without possibility of pilot error - err, for the convenience of the pilot. But I still plan on flying most of my approaches referring only to the needles, attitude, airspeed, and VV etc. The other stuff is there to measure how WELL I fly the basics...

Cheers,

Bill

[Bugsy]

In the back seat of an F-15 I couldn't fly without the VVI, In a pitch sensative aircraft VVI really helps you stay ahead (sts) of the aircraft. VVI is constantly in my crosscheck. Boys up front get the HUD with flight path marker that much like the VVI gives you instant trend forcast. F-16 doesnt seem to have that same pitch sensativity, of course I get a HUD repeater when flying Viper bravo, so I use flight path marker instead of VVI.

Seriously, from a human factors prospective, in a pitch sensative airframe you need something to provide instantaneous trend or you'll be chasing the needles. I wont be adding a VVI to my panel but will rely on trending from EFIS much like you describe.

[REHughes]

Originally Posted by Bill Wightman

The only thing you have direct, immediate control over is what you hold in your hands: stick and throttle. Or said another way, attitude and thrust. These things are called "control" parameters, and so the attitude indicator and what ever you use to indicate thrust are called "control instruments".

Everything else the airplane does is a reaction to whats done with the control parameters. Those things are called "performance" parameters, or instruments. Examples of performance parameters are airspeed, vertical speed, altitude, heading, etc. And yes the VV is also a performance parameter. Its closely tied to the attitude of the aircraft, but in the end its just another thing to chase. We don't have immediate direct control over this.

In all the Tactical Aircraft Head-Up Displays that I am aware of, the Velocity Vector (or Flight Path Marker) is THE control parameter used to set attitude. The Angle Of Attack symbology, Approach guidance cues, and Potential Energy indicators are all referenced directly to the VV/FPM symbol. Fuselage Pitch Angle, if displayed at all, is generally not used for anything as long as the Flight Path system is working.

A Level Speed Change maneuver can demonstrate how the two different control parameter systems function:

With an Attitude Indicator, you start out with, say, 10 degrees nose up at 100 KTS, and as you add power and accelerate, you roughly adjust a constantly-changing AI to maintain a constant Altitude value (using the VSI as a leading-indicator) and you eventually wind up at 3 degrees nose down when you have accelerated to 180 KTS.

With a Velocity Vector system, it is a whole lot easier. Keep the VV on the Horizon Line as you accelerate, making tiny changes up or down as you reference the performance parameters, the Altitude and VSI.

I am assuming that your Flight Guidance commands in the Boeing are referenced to the Waterline Pitch Symbol, making it the control parameter, and relegating the VV to an accessory Descent Path type indication. It might be the result of my background, but I much prefer the Velocity Vector referenced systems, even in Head-Down displays.

[CarlosF@grtavionics]

Originally Posted by gasman

Who has this now in their systems?..........................

GRT has it.

At first you may ask what it (VVI) is doing especially in strong manuvers. Once you know what it is telling you it makes flying easier.

A couple of examples, on final in a strong crosswind you put the VVI on the runway on the PFD and that is where the airplane will go. The nose of the airplane will be pointed away from the runway (depending on the strength of the crosswind) but the track will be to the runway. The GRT shows both lateral and vertical vector in one indicator. Put the VVI where you want to go, it's that easy.

Another example is leveling off after a climb or descent. Simply put the VVI on the artificial horizon at your target altitude. Once the VVI is on the artificial horizon theres no climbing or descending, you are level at the altitude you want, no guessing. If you want a 3 degree descent, put the VVI on the 3 degree pitch line.

It makes steeps turns under the hood a none-event.


Regards,

Carlos Fernandez
GRT Avionics