Question regarding the A320 EGPWS.

[flame_bringer]

I understand that mode 4 is about warning the pilot when either coming close to terrain while landing gear or flaps are up, Or if the flaps aren't in full config or landing gear is down at ceratin airspeeds and radio heights.
On the cockpit there supposed to be a button on the EGPWS panel that says LDG flap and another button that says LDG flap 3.
LDG flap inhibits all landing flap warnings associated to mode 4 and LDG flap 3 inhibits the LDG flap warning when in config 3 and is mainly used when pilots want to land with flaps in the 3 position.
So both of these buttons practically do the same job except that ldg flap 3 p/b does the job at a less degree (meaning inhibiting the warning when flap is on the 3 selection) and the same thing can be done by the LDG flap p/b, Whats the point in having the LDG flap 3 p/b if the ldg flap p/b does the same thing :S, Am I mispercieving things here???
Anyone please explain
Thanks in advance

[jb5000]

From a 320 driver rather than engineer:

The LDG Flap 3 pushbutton will still warn you should you intend on landing in flap 3 (common these days for fuel saving) but you have flaps 1 or 2 selected only.

The LDG Flap pushbutton is more useful in cases of Flap / Slat Jams and other computer failures that result in landing with a reduced flap / slat setting. It is used only in non-normal situations.

Hope that is clear?

jb5000

[flame_bringer]

Thanks for the reply.
If it will still warn you at config 3 even if its pressed then whats the reason to having it in the first place???

[Dan Winterland]

I think JB5000 has confused you. You press the Ldg Flap 3 button on the O/H panel to prevent a warning in the landing config. As you know, you can land in either config 3 or full, but the ECAM landing memo defaults to full. By pressing the button, you stop a config warning if you try to land in 3 and there will be no blue items on the ECAM landing memo.

You also have to tell the MCDU in the landing PERF page that you want to land in config 3 so it can recalculate V approach.




My employer tried for a while to save a bit of fuel landing in config 3, but gave it up after a while. It turns out the fuel saving was negligable, especially when increaded brake wear and reverser landing in config 3 was taken into account. Airbus recommend config 3 if windshear is forecast as you get better roll response, and this is about the only time I ever use 3.

[flame_bringer]

Thanks for the clarification.
I'm still kinda confused about why having the LD flap p/b 3 when LD flap p/b can do the same job which is inhibiting the 3 config warning though.

[tom775257]

Because if you were to just use the flap p/b you would not have any warning if you were planning to land Conf3 and had Conf 2 or 1 selected. Sure you would still achieve the aim of not getting any 'too low flap' warning of landing in Conf 3, but you wouldn't be warned about any other config set either.

By using the landing flap 3 p/b you retain the protection that warns you aren't in conf3 for landing. Belt and braces...

[flame_bringer]

tom775257
Thanks that makes sense now and sums it up very well.
Regards