Baro and radio minimum knobs reversed?

[alex98 13]

Hello all,

Unlike the 777 or the 737, the BARO knob we use in the 744 to preset the decision altitude is scaled 10ft by 10ft and the RADIO knob foot by foot. This seems to me kinda odd since most approach charts specify decision altitudes with numbers like 217' or 675' and decision heights like 200' or 700'. Is there a reason why Boeing choosed to do this? Just curious...

Happy flying

Alexandre Giordan

[Ralgh 43]

I may be misunderstanding what you are asking but I am able to adjust both BARO and RADIO settings by a single digit. Actually decision heights aren’t always even numbers. Example LAX CAT II 24R is 118 ft. 

[alex98 13]

8 minutes ago, Ralgh said:

I may be misunderstanding what you are asking but I am able to adjust both BARO and RADIO settings by a single digit. Actually decision heights aren’t always even numbers. Example LAX CAT II 24R is 118 ft. 

Hi Ralph,

Thank you for your reply. Actually you did understand me correctly 😊 May I ask how you adjust BARO setting by a single digit? Btw I always use the ROTARY option and not SLOW/FAST.

Cheers,

Alex

[skelsey 765]

I don't know about the PMDG 744, but in the real thing this (10ft/1ft increments) is a customer option. You would simply round up to the nearest 10 ft and certainly Lido charts do the same (can you read your altimeter to the nearest 1' on a marginal approach and will it make any difference?)

1 hour ago, alex98 said:

most approach charts specify decision altitudes with numbers like 217' or 675' and decision heights like 200' or 700'.

The DHs shown are barometric heights (i.e. on QFE) above the threshold. 200 ft above a runway with threshold elevation 17 ft gives a DA of 217 ft -- they are NOT radio DHs 🙂

Radio DHs are applicable only to CAT II and III approaches and will be specifically noted as RA (e.g. 97 RA)

 

Edited July 10, 2018 by skelsey

[Ralgh 43]

On 7/10/2018 at 8:51 AM, alex98 said:

Hi Ralph,

Thank you for your reply. Actually you did understand me correctly 😊 May I ask how you adjust BARO setting by a single digit? Btw I always use the ROTARY option and not SLOW/FAST.

Cheers,

Alex

I use the slow/fast method. I checked it again and am able to adjust it by a single number.

[alex98 13]

On 7/11/2018 at 6:56 PM, Ralgh said:

I use the slow/fast method. I checked it again and am able to adjust it by a single number.

I tried the SLOW/FAST option and yes actually it works. Thank you!

[Ephedrin 418]

Also imagine the time you had to hold the knob to dial in an MDA (baro) of 5370 ft if it was seperated into 1 foot increments ^^

[skelsey 765]

1 hour ago, Ephedrin said:

Also imagine the time you had to hold the knob to dial in an MDA (baro) of 5370 ft if it was seperated into 1 foot increments ^^

The rotary selectors IRL have some acceleration depending on how fast you spin the knob - so a quick 'flick' of the knob around might result in a change of several hundred feet whereas slowly clicking it around will only increase in 1/10 ft increments depending on the option selected by the airline.