Pitch Attitude in Percent Instead of Degrees
 

Just reading an accident report on a Partenavia P68 and they have a discussion about the required pitch attitude at a certain point in flight. They say that they were informed by an experienced pilot at an 11%(6.3 degrees) pitch attitude is required.

Are there some aircraft types or artificial horizons that use percent as pitch attitude rather than degrees?

It’s a little hard to comprehend without any further context.
Percentage of what exactly?
A pitch instrument could be marked with anything really, apples for up and oranges for down.
Being called an “attitude indicator” or “artificial horizon” it would mean show the difference between level flight and higher or lower pitch attitudes.
Considering everything else which is measured or indicated in degrees: flight control defection, roll rates and pitch rates.
It would be most logical to have a degree scale.
I have flown with angle of attack indicators that were color coded.
You also need to consider international design standards and certification requirements.
Doesnt answer your question I guess.

Fully aerobatic percent indexed AI would be interesting. After 100% / 45° NU/ND the scale would became logaritmic (and infinite at 90° NU/ND)!

Maybe that’s what happened during the accident and it opened up a rift in Spacetime?

11% of what ?!

Measuring slope in percentage or permille is pretty common in railway especially if you're using metric, as it makes some of the maths easier. E.g. at 1 permille, you gain/lose 1 meter per kilometer. 50‰ = 50m per km.

I could see the Russians using it but I don't think I've ever heard of it.

Sounds more useful for flight path/glideslope than for AoA or actual deck angle, though.

57.273.

Of course, it's used exclusively for departure flight path requirements and calculations. I assume because the numbers are easier to deal with than umpteen decimal numbers if using degrees.

Slope is easier to determine directly - measure the vertical rise and divide by the horizontal run and the above number is the result. It also directly converts into climb rate vs. ground speed which would also take into account wind speed. As long as the latter ratio is bigger than the former one, whatever obstacle there is to clear will be cleared.

In over 45 years as an avionics systems developer and over 45 years as a pilot (some overlap but not coincident) I never saw pitch attitude expressed as a percentage of anything. I was always degrees with a range of -90 to +90.

What was the context of the referenced report?

"The Investigation was also provided with information from an experienced P68 pilot. The pilot informed the investigation that to maintain a speed of approximately 90 kts, a pilot would need to hold the aircraft at a pitch angle of approximately 11% [6.3 degrees]."

Page 33 of this report:

2025-001.pdf

Thanks for the reference. It still makes no sense to me but I do note that "%" only has one instance in the report and that is in the quoted paragraph. I can only assume it was a typo but I have no idea what was intended.

JOKE
Why use those silly. outmoded, inaccurate degrees?

“If it needs to be complicated …..it’s worth making it really, really complicated!”

Hey, why not use an Attitude indicator and Dg marked in Mils up/down , left/right as used by the military for Land Nav, Artillery Spotting and suchwhat.

”Ok Bloggins, at rotate I will raise the nose to 180 mils! At 1000 feet I will bank 360 Mils to port to join our course of 4500 mils.”

Here's a more detailed breakdown from AI

• Mils as a unit: A mil is a milliradian, which is one-thousandth of a radian.
• Theoretical value: There are approximately 6283 mils in a full circle.
• Practical rounding: Military compasses and instruments often use 6400 mils, simplifying calculations.
• Application: Mils are used for measuring angles, especially in military applications like artillery, aiming, and navigation.
• Relationship to distance: One mil corresponds to one meter of displacement at a range of 1000 meters.
• One degree = +/- 18 mils (my edit)

JOKE OVER.

Many civilian aircraft have an AoA indicator which shows not actual AoA but a 'normalized AoA' with a range of 0 to 1. 0 is zero g and 1 is stall speed.

https://www.code7700.com/angle_of_attack.htm#section3

And I have an AOA system that beeps with increasing rate as AOA increases. How does a discussion of AOA help explain Pitch in percent? AOA is not pitch attitude.

The Investigation was also provided with information from an experienced P68 pilot. The pilot informed the investigation that to maintain a speed of approximately 90 kts, a pilot would need to hold the aircraft at a pitch angle of approximately 11% [6.3 degrees]

Surely not a typo when the stated % and degrees matched? Just accurate reporting of the pilot's statement, and conversion for consistency with the rest of the report?

document: a pitch angle of approximately 11% [6.3 degrees]
angle converter program: An angle of 6.3 degrees converts to: 11.04 Percent of a Slope

I had not attempted to calculate it but I agree with the conversion. However, expressing pitch attitude as a slope still makes no sense. Why would any pilot do that?

Dazed and Confused
 

Good question. Why indeed?

Not a joke but feel free to laugh at me.

Now if and that’s a big IF what is being referred to is that 100% of Pitch up or down is 90 degrees then what % of 100 is 6.3 degrees?
So IF 90 degrees = 100% 1 degree is 100/90 or 1.111% so 6.3 degrees is 6.3 x1.111 should equal 6.999 % .( pretty darn close to 7 degrees of pitch)

Using this completely illogical theory 11% of 90 degrees of pitch = 9.9 degrees of pitch. ( I even asked Google what 11% of 90 is to confirm.)

However I found this site which purports to reflect truth regarding % of slopes that an 11% slope agrees with the 6.3 degree figure from the test pilot and now my head hurts.

( Convert Percentage slope/gradient/pitch to Ratio or Degrees

11% = 9.1 Ratio or 6.281 Degrees )

Link to the site below.

https://www.mountainpassessouthafric...d=449&catid=48

You don't need any special slope calculator. Simply take the Tangent of 6.3 deg and multiply by 100.

Very True. EXDAC but I was trying to just use basic back of the cocktail napkin math to see what trail that would lead me down.