Duplicate altitude callouts

[jfjoubert]

Hi,

I often get duplicate altitude callouts when on short final. I'm in a steady descent and tracking the glideslope and will hear for example 500 and very soon thereafter another 500 callout.

Anyone else experiencing this?

[mmerelles]

You may experience this when overflown uneven ground on final surrounding the runway. Remember the aural callouts comes from a RADIO altimeter (not from the barometric altimeter), thus the eco bounce readings -aircraft radar antena to ground- will vary based on rough terrain.

 

On modern jets you may also use barometric altimeter for callouts.

[mmerelles]

an example of radio altimeter limitations for monitoring approach.

 

[jfjoubert]

Hi mmerelles,

Thanks for the info... I'm getting these repeated callouts on even ground around the airport. I will see what happens with an autoland. Maybe my "manual flying" is too erratic.

Regards

[mmerelles]

yes, flying the approach glide like a rollecoster will make it go crazy as well