That is indeed correct, if I remember correctly from the AF447 accident report.

I didn’t know this either thx for info

Indeed, good airmanship ist the most important of all! Stabilizing your flight path is the most important aspect of this. That's why we have memory items for that while the rest is done straight from the book. My instructor always told me "survive the first 30 seconds and you'll survive the whole manouver".

28:56

@@tomstravels520 thanks :)

@@arminhansarian2268 they can be used for landing as spoilers but not for inflight to slow down in this situation

😂

Because with all ADR’s turned off the LGCIU has no idea what the speed is. Below 280 knots (I think) a safety valve opens to allow the gear to be lowered. Without airspeed the LGCIU doesn’t know if it’s safe and will not open the valve

Very good Tom!

@@A330Driver I learnt this from the MH134 final report

With the gravity gear extension utilized, can the gears ever be retracted again, say in case of a goo around?

@@francobobfred as long as you have a working green hydraulic system yes

Up until AF447 Airbus designers and engineers thought that pilots would be smart enough to know how to recognise and deal with unreliable airspeed……AF447 proved them wrong. So up until then when the airspeed was lost the aircraft goes into alternate law as the autopilots and PRIM’s have insufficient information for themselves to determine safe flight and hand control to the pilots. Airbus developed the BUSS (and later DBUS) as a way to provide another reference when anemometric data fails. However they decided to go one step further and develop something called alternate autopilot. It’s already available on the A350 and can be put in the A330. This was apparently based on the fact that on AF447 when the autopilot disconnected it caused the pilots to freeze as they did not expect it (startle factor). As part of alternate autopilot, the autopilot will now hold heading and level flight and autothrust will be “adapted”. This is still only a measure to prevent scaring the pilots and give them time to figure out what is going on. There is a video titled “Airspeed Indication and autopilot enhancing the systems” on YT.

@@tomstravels520 Thanks for that comprehensive response! But if the reason for that "alternate autopilot" is to give the pilots time to figure out what's going on, how does it even engage in the first place? I thought of it as a mode that pilots can engage/switch to, once the they have identified that the airspeed is unreliable.

@@ahaa_2917 for the alternate autopilot it is automatic. It changes to V/S+0 and HDG automatically and adapts thrust as per programming. If you watch the video I mentioned it explains in more detail

Because with all ADR’s turned off the LGCIU has no idea what the speed is. Below 280 knots (I think) a safety valve opens to allow the gear to be lowered. Without airspeed the LGCIU doesn’t know if it’s safe and will not open the valve. The reason for no steering is in order to use the gravity extension you need to cut off hydraulic fluid to the landing gear. The NWS operates on the same system as the landing gear so once you cut if off to the gear, you cut it off to the nose wheel steering as it’s downstream from the cutoff valve.

You're right Tom

@@A330Driver I did learn very recently there is a button Airbus can install as an optional extra that switches the NWS to an alternate system. Although not seen that button fitted to an actual aircraft. I know the A320’s since about 2010 now use yellow system for NWS to get around this problem

Well, when there's a fire on board there may be neither time to dump fuel nor burn any fuel so you would probably just land above max landing weight (MLW) to reduce risk

That button isn’t on the widebodies. When you select it in the MCDU the GPWS automatically knows you want FLAP 3

As Tom says, that's only a small Airbus thing.

Thank you for the reply!

In fact they still serve as our prime example for upset recovery training! Very tragic case but also one of the few ones where an Airbus actually stalled.

I think Aeroperu 306 guys would have loved to have seen this video too, altho not same aircraft, principles should apply.