Adjusting the Radar Alt warning Setting

[Lt_Jaeger]

I played a little with the radar altimeter warning settings. Normally I put the altitude somewhere around 370 and leave it there, but for some medium alt dive bombing training with the hard Deck set at 4000, I thought it would be nice to get the beeping if I break that. 

 

Long story short, too get to the higher values one has to turn way more on the knob as to the lower. I would say, without further testing, that I have to turn the knob for everything over 1000 the same amount as from zero to 1000,which would be a little more than half the circumference of the instrument, compared to what, a 1/16 - 1/32.

 

Looks to me that adjusting the value of the needle you actually need to turn a certain amount of turns per value change instedt turns per increments of the circumference. 

 

I can't find better words for it, sorry, just try and you see. 

 

Anyhow, I will most probably never again set values higher then 1000 just wanted to let you know. No biggie 

 

[RustBelt]

Also keep in mind, when dive bombing the Radar Alt antenna isn't pointing straight down at the ground so its reading is unusable anyways. Unless it's a really shallow dive. 

[Lt_Jaeger]

Yeah, was a stupid idea, even so I thought I was pretty smart at that moment 

[Sideburns]

On 1/28/2021 at 12:14 AM, RustBelt said:

Also keep in mind, when dive bombing the Radar Alt antenna isn't pointing straight down at the ground so its reading is unusable anyways. Unless it's a really shallow dive. 

 

From some Lightening pilot interviews I understand the radar alt warning was more a night time flying safety feature rather than an F16 style MSL and hard floor warning or when to pull up from diving attacks.

[draconus]

On 1/28/2021 at 1:14 AM, RustBelt said:

Also keep in mind, when dive bombing the Radar Alt antenna isn't pointing straight down at the ground so its reading is unusable anyways. Unless it's a really shallow dive. 

"The system will operate normally in bank angles up to 45° and in climbs or dives except when the reflected signal is too weak." NATOPS says unless we have some older version than AN/APN−194.

[TOViper]

22 hours ago, Lt_Jaeger said:

Yeah, was a stupid idea, even so I thought I was pretty smart at that moment 

I dont think so. If you select 4000 feet at the radar altimteter for descending at a fligthpath angle of -30° you would then get a warning at "real" ~3000 feet.

So if you would like to receive a warning at 4000 ft, you might wanna change the setting to 5000.

Why not?!

 

Regarding this: "Looks to me that adjusting the value of the needle you actually need to turn a certain amount of turns per value change instedt turns per increments of the circumference. "

Yes, I got what you wanna say. I have no idea if this represents the real aircraft or not, but either way the behavior of the knob is annoying

Edited February 3, 2021 by TOViper

[PawlaczGMD]

Bump. What OP is trying to say is:

The scale of the altimeter is non-linear, but the increment/decrement inputs are linear in altitude, not bug rotation angle. So you have to crank the knob forever to get to high altitude values. Instead, the amount the needle moves per button input should be constant, and the altitude change non-constant. This would make the altimeter easy to set at whatever value.