Third radio altimeter on B737NG
Thread Starter
Joined: May 2011
Posts: 31
Likes: 0
From: Seoul, South Korea
Third radio altimeter on B737NG
Hi all,
Is there anybody to let me know optional third RA's purpose and function?
Also, if third radio altimeter system is installed, where is the radio altitude shown?
Is there anybody to let me know optional third RA's purpose and function?
Also, if third radio altimeter system is installed, where is the radio altitude shown?
Thread Starter
Joined: May 2011
Posts: 31
Likes: 0
From: Seoul, South Korea
Hi friend,
Most B737NG do not have the third RA system as you said. However, I hearded that It can be optionally installed. Two B737NG airplanes my company operate have two raised pads on the bottom fuselage near radio altimeter antennas. Please refer to blow.
Radio Altimeter On 737 NG — Tech Ops Forum | !!!!!!!!!!!!!!
Most B737NG do not have the third RA system as you said. However, I hearded that It can be optionally installed. Two B737NG airplanes my company operate have two raised pads on the bottom fuselage near radio altimeter antennas. Please refer to blow.
Radio Altimeter On 737 NG — Tech Ops Forum | !!!!!!!!!!!!!!
Joined: Mar 2001
Posts: 4,563
Likes: 35
From: I wouldn't know.
Wouldn't surprise me, the options list for a 737 is quite long and has quite a few rarely if ever ordered options. However, the third RA is not needed for fail operational installations as is suspected in the thread you linked. Two RAs are sufficient for that.
Thread Starter
Joined: May 2011
Posts: 31
Likes: 0
From: Seoul, South Korea
Hi all,
The reason why I would like to know the third RA is because of MMEL34-20. Refer to below.
SYSTEM / INTERVAL/ NO. INSTALLED / NO. REQ'D FOR DISPATCH
2) Indications, C, ㅡ, 2
May be inoperative provided
a) Independent radio altimeters operate normally for both flight crew
members.
b) Approach minimum do not require its use
C, ㅡ, 0
May be inoperative provided
a) Associated receiver/transmitter is verified to operate normally, and
b) Approach minimums or operating procedures do not require its use.
As you know, "ㅡ" symbol indicates a variable quantity of the item installed. So I am very confused because I have seen only two RA indications displayed on Capt side and F/o side. However, MMEL say that the number of RA indications can vary.
Therefore, I guess that it may be related to the third RA.
How do you think?
The reason why I would like to know the third RA is because of MMEL34-20. Refer to below.
SYSTEM / INTERVAL/ NO. INSTALLED / NO. REQ'D FOR DISPATCH
2) Indications, C, ㅡ, 2
May be inoperative provided
a) Independent radio altimeters operate normally for both flight crew
members.
b) Approach minimum do not require its use
C, ㅡ, 0
May be inoperative provided
a) Associated receiver/transmitter is verified to operate normally, and
b) Approach minimums or operating procedures do not require its use.
As you know, "ㅡ" symbol indicates a variable quantity of the item installed. So I am very confused because I have seen only two RA indications displayed on Capt side and F/o side. However, MMEL say that the number of RA indications can vary.
Therefore, I guess that it may be related to the third RA.
How do you think?
Last edited by DongJoon Choi; 18th June 2011 at 11:46.
