Probable Cause, Dan Gryder

[Thruster88]

I really like Dan Gryders new channel probable cause. His simple approach to airspeed management could save many lives if it was widely implemented. As he says we sometimes forget numbers when under pressure from things like engine failure. Why not have it marked on the airspeed indicator as a constant reminder. 

 

 

 

[ClintonB]

I have watched Dan on Flightchops with Steve and recommending the same idea no matter what you fly.

I think next outing I will be marking ASI.

 

[old man emu]

Never try to remember something that you can look up in print. In this case the "in print" are those simple strips of tape.

 

Isn't is amazing that airspeed indicators are marked with the white, green and yellow ranges out of the box, but no one ever says to "calibrate" them for your aircraft.

 

White Arc - Flap operating range

Green Arc - Normal operating speed in smooth and turbulent air

Yellow Arc - Operations in smooth are only.

 

Vso - Stall speed or minimum flight speed in landing configuration

Vs1 - Stall speed or minimum steady flight speed for which the aircraft is still controllable in a specific configuration

VRef - Landing reference speed or threshold crossing speed - The speed to be "over the numbers"

Vx - Speed that will allow for best angle of climb - Obstacle clearance speed

Vy - Speed that will allow for the best rate of climb

 

NOTE:

On the illustrated ASI, there is a moveable scale to allow for IAS to be converted to TAS. Remember that the Lift formula is expressed in terms of TAS, so if you have one of these ASIs that has a moveable scale, the markings for V speeds should be on that scale.

[kgwilson]

How can you calibrate something that is printed on the dial along with the numbers which are also immovable.

[aro]

3 hours ago, old man emu said:

Remember that the Lift formula is expressed in terms of TAS, so if you have one of these ASIs that has a moveable scale, the markings for V speeds should be on that scale.

The important V speeds Vs0, Vs1, VFE are IAS not TAS.

 

Maneuvering speed is IAS but reduces with weight.

 

The only speed that might be TAS is VNE.

[Thruster88]

2 hours ago, kgwilson said:

How can you calibrate something that is printed on the dial along with the numbers which are also immovable.

One "calibration" we can all do on a regular basis is to check the indicated stall speed clean and with flaps. This will verify that the ASI is working correctly at the most important end of the scale.

[skippydiesel]

14 minutes ago, Thruster88 said:

........................................................... This will verify that the ASI is working correctly at the most important end of the scale.

OOOOOooohhhh! Me thinks those fast aircraft, where Maximum Structural Cruise (Vno) is close to Never Exceed (Vne) just might benefit from being fairly accurate at the fast end of the scale. Just a slight (unnoticed) decent from high speed cruise, might put you &your aircraft over Vne , within moments, with potentially alarming results.

[facthunter]

The idea is not new. You have around 4 "BUGS" that are moveable on the rim of many ASI's. They vary with weight and flap setting(s). Note this post  as about 6 hours out of date.  Posted anyhow.

Those arcs are specific to your plane or else they are meaningless/irrelevant. .Nev

[kgwilson]

The arcs and numbers on the ASI in the picture are all fixed so that must be for a specific aircraft. My ASI had nothing so I got circles cut out of stick on vinyl the same circumference as the glass, cut bits off and stuck them on the glass. I've got plenty left over if I need to adjust it or do it again.

[old man emu]

5 hours ago, kgwilson said:

How can you calibrate something that is printed on the dial along with the numbers which are also immovable.

Probably a bad use of the word "calibrate". What I meant was that if you mark those "V" speeds on your altimeter, you calibrate it. You mark it so that you have boundaries that the indicator needle must be within, or not exceed depending on the required speed. What you are after is something that you can glance at and know without having to think that the needle is pointing where you want it. 

 

When you start your engine, don't you quickly look at the dial to see that the needle is "In the Green", so you can carry on. It might only be during flight that you actually monitor the position of the needle to assure yourself that the oil pressure is not falling (leakage, or pump failure) or rising (blockage). 

 

5 hours ago, aro said:

The important V speeds Vs0, Vs1, VFE are IAS not TAS

ARO, I specifically wrote TAS because the Lift equation uses TAS, not IAS. Also I was referring to the illustrated ASI, which is probably more flash than the type you would use in an under 600 kg plane. It probably doesn't mean a hill of beans anyway, as very few pilots want to fly on the edge of the envelope. We all add a fudge factor.

[aro]

34 minutes ago, old man emu said:

ARO, I specifically wrote TAS because the Lift equation uses TAS, not IAS.

The lift equation also uses density. It's inconvenient to constantly adjust speeds for changing density, but luckily IAS for a particular TAS also changes based on density.

 

The density components in the lift equation and IAS conversion cancel out, which means that stall speed etc. occur at the same IAS regardless of density, and we can mostly ignore TAS except when flight planning.

[IBob]

9 hours ago, kgwilson said:

The arcs and numbers on the ASI in the picture are all fixed so that must be for a specific aircraft. My ASI had nothing so I got circles cut out of stick on vinyl the same circumference as the glass, cut bits off and stuck them on the glass. I've got plenty left over if I need to adjust it or do it again.

The Savannah kit comes with an uncoloured ASI, and adhesive coloured arcs for the builder to apply.

[IBob]

FWIW I recently had to cut a large circular hole in gasket material: I was able to do it (with some practise) with multiple light passes of a compass (or calipers) with a sharp needle fitted.
(I did try sharpening a needle to a blade shape, but the unmodified needle seemed to work better.)

Whether this would work on adhesive vinyl, I do not know.

[old man emu]

9 hours ago, aro said:

It's inconvenient to constantly adjust speeds for changing density

It is hard to reply correctly to that statement because we need to specify when the density changes. Normally we fly on Area QNH. The acronym QNH is one of the Q(uestion) code names developed, circa 1909, for use in morse code. To concisely ask for atmospheric pressure at mean sea level (MSL), the operator would transmit the letters QNH. This was understood to mean "I have a question. What is the atmospheric pressure at Nil Height", i.e. at mean sea level.

 

These are the boundaries of Area QNH for Australia. http://www.pilotpracticeexams.com/courses/wp-content/uploads/2016/09/Image-2019-02-26-at-10.22.52-AM.png

 

We know that pressure systems move across Australia from west to east, so while an Area QNH is current for three hours, commencing 0100 UTC and each three hours thereafter, an altimeter set to Area QNH will be representative to within ±5 hPa of any actual QNH of any location within the defined area. If a pressure system, usually a Low, is crossing the continent, the actual air pressure is constantly changing, but we don't usually keep adjusting the subscale as we fly along within a QNH zone.

 

Interestingly, if we are flying towards a low pressure area, and our altimeter is set to Area QNH, the altimeter will gradually overread our actual height because the air pressure is dropping and the altimeter interprets that as the aircraft climbing. So if we keep flying at a constant indicate altitude based on a QNH derived altimeter reading, we could fly into the ground.

 

So, getting back to the original quote, if we fly within a QNH Zone using the Area QNH, we don't alter the sub-scale until Air Services changes it at the end of the three hour validity period. However, if we cross a QNH Zone boundary, we need to check with Air Services for the current Area QNH in that zone, and possibly adjust the sub scale.

 

If an altimeter has reminder markings to mark Vso - Stall speed or minimum flight speed in landing configuration they have a safety factor of 1.3. In practice that should take care of local air density changes on altimeter indications at airfields in Australia, which for the whole continent average out at about 1000' AMSL.

[facthunter]

Are we talking about altimetry or AIRSPEED indication?. Stall speed (and anything based on it) is (for us) generally protected  by using IAS.,  For planning, as aro points out True AS is the right one to use. Some limits like flutter speeds sometimes relate to TAS.  Nev

[Kyle Communications]

Such a simple mod too

 

I have a EFIS so obviously i can put the level marks where I like with programming but I like to have a analogue ASI in my aircraft as a backup...and I just have the normal arcs set to my speeds but I do like that tape line right across the gauge...i will be doing that to it.

 

Super simple idea that I am sure will save lives

 

[skippydiesel]

12 hours ago, old man emu said:

 

.................................... It probably doesn't mean a hill of beans anyway, as very few pilots want to fly on the edge of the envelope. We all add a fudge factor.

Bit of a sweeping statement OME - Short Field Landings require,first practice at altitude to familiarise yourself with handling characteristics of your aircraft as it approaches the stall , followed by doing the SFL. 

[old man emu]

2 hours ago, facthunter said:

Are we talking about altimetry or AIRSPEED indication?

You have to go back to read what the person who was quoted said.

 

ARO said, "The important V speeds Vs0, Vs1, VFE are IAS not TAS."

To which I replied, "ARO, I specifically wrote TAS because the Lift equation uses TAS, not IAS" to explain why I had written what I had.

 

The ARO said," It's inconvenient to constantly adjust speeds for changing density"

Then I went off topic a bit to explain that what we know about air density and how it changes, especially with the movement of atmospheric pressure systems, usually has no huge effect as we potter around within one QNH zone in good flying weather. Indicating on an ASI face where the needle should point for an airspeed that is your aircraft's normal landing speed increased by a factor of 1.3 (30%) should work for 90+per cent of the flights we make.

57 minutes ago, skippydiesel said:

Bit of a sweeping statement OME

It's getting so that before I post a comment I will have to provide a list of definitions, formulae and constraints so that people don't immediately shoot back with minute exceptions to the generality.

[facthunter]

An adjustable BUG for your TTS, target threshold speed would be advantageous. It varies a fair bit depending on the conditions. Gusts, your ACTUAL landing weight, chosen flap setting  etc.  Using INDICATED airspeed automatically adjusts for the change in density (Pressure & Temp) except for your actual speed being an issue in the amount of runway you require and the visual indication of being at a higher actual speed possibly inducing you to go slower.  Nev

[APenNameAndThatA]

On 09/02/2021 at 12:30 PM, old man emu said:

Never try to remember something that you can look up in print. In this case the "in print" are those simple strips of tape.

 

Isn't is amazing that airspeed indicators are marked with the white, green and yellow ranges out of the box, but no one ever says to "calibrate" them for your aircraft.

 

White Arc - Flap operating range

Green Arc - Normal operating speed in smooth and turbulent air

Yellow Arc - Operations in smooth are only.

 

Vso - Stall speed or minimum flight speed in landing configuration

Vs1 - Stall speed or minimum steady flight speed for which the aircraft is still controllable in a specific configuration

VRef - Landing reference speed or threshold crossing speed - The speed to be "over the numbers"

Vx - Speed that will allow for best angle of climb - Obstacle clearance speed

Vy - Speed that will allow for the best rate of climb

 

NOTE:

On the illustrated ASI, there is a moveable scale to allow for IAS to be converted to TAS. Remember that the Lift formula is expressed in terms of TAS, so if you have one of these ASIs that has a moveable scale, the markings for V speeds should be on that scale.

The V speeds are based on IAS. 

[aro]

7 hours ago, old man emu said:

Then I went off topic a bit to explain that what we know about air density and how it changes, especially with the movement of atmospheric pressure systems, usually has no huge effect as we potter around within one QNH zone in good flying weather.

 

A change in QNH doesn't generally change air density enough to significantly effect TAS. What does affect air density is temperature and altitude.

 

There is a big difference between landing at Moorabbin on a cold winter's morning and landing at Mt Hotham on a hot summer day. At Moorabbin the density altitude might be minus 1000 feet, at Mt Hotham over 6000 feet. If your Vref is 65 knots, one is 64 knots TAS, the other is 71 knots TAS. But the characteristics of the air speed indicator mean that 65 knots IAS is correct for both.

 

8 hours ago, old man emu said:

It's getting so that before I post a comment I will have to provide a list of definitions, formulae and constraints so that people don't immediately shoot back with minute exceptions to the generality.

To be blunt, it is not the definitions that are the problem. The problem is that most of your explanations are misleading or incorrect. You need to revise your BAK before trying to teach other people.

 

It is not fair to the people who are trying to learn this stuff to post so much incorrect information.

[old man emu]

8 hours ago, old man emu said:

because the Lift equation uses TAS, not IAS"

Pull out your textbook and prove that statement incorrect.

[aro]

It's irrelevant... you can pick individual elements out that are correct. It is when you put them together they make no sense.

[old man emu]

17 hours ago, APenNameAndThatA said:

The V speeds are based on IAS. 

After some more revision of the subject, I agree with that statement.

 

However, I went back to every post I made here. I never said anything about what V speeds were based on. I did say something about TAS in this statement:

On 09/02/2021 at 1:30 PM, old man emu said:

NOTE:

On the illustrated ASI, there is a moveable scale to allow for IAS to be converted to TAS. Remember that the Lift formula is expressed in terms of TAS, so if you have one of these ASIs that has a moveable scale, the markings for V speeds should be on that scale.

I suppose I should have said "could" instead of "should" to allow for personal preference in the way the information provided by the ASI was displayed.

 

 

 

[APenNameAndThatA]

On 10/02/2021 at 11:18 AM, old man emu said:

You have to go back to read what the person who was quoted said.

 

ARO said, "The important V speeds Vs0, Vs1, VFE are IAS not TAS."

To which I replied, "ARO, I specifically wrote TAS because the Lift equation uses TAS, not IAS" to explain why I had written what I had.

 

The ARO said," It's inconvenient to constantly adjust speeds for changing density"

Then I went off topic a bit to explain that what we know about air density and how it changes, especially with the movement of atmospheric pressure systems, usually has no huge effect as we potter around within one QNH zone in good flying weather. Indicating on an ASI face where the needle should point for an airspeed that is your aircraft's normal landing speed increased by a factor of 1.3 (30%) should work for 90+per cent of the flights we make.

It's getting so that before I post a comment I will have to provide a list of definitions, formulae and constraints so that people don't immediately shoot back with minute exceptions to the generality.

Your list of errors is a mile long and I'm not sure that you accept that they are errors. I can list them if you want.