A320 Normal Law Protections

Today we take a look at some of the flight envelope protections the A320 has available in normal law. We will look at the protections in the following order:
00:15 Bank angle protection
01:35 Load factor protection
01:35 Pitch attitude protection
02:20 High speed protection
03:15 High angle-of-attack protection clean
04:30 High angle-of-attack protection in landing config
Acronyms used in this video:
PFD - Primary Flight Display
TOGA - Takeoff - Go-Around thrust.
VLS - Lowest Selectable Speed
VMO - Maximum Operating Speed
Trivia:
- Pitch trim on the Airbus is mostly automatic!
- In normal law movement of the sidestick controls the elevators to demand a load factor (a level of G) proportional to sidestick deflection. This is also true of degradation into 'alternate' law. The aircraft requires further system degradation for 'direct' law to result in a direct stick-to-elevator relationship such as in a conventional aircraft which requires the pilot to trim in the normal manner.
Interesting Stuff / Further Reading:
- You may note that these manoeuvres were flown without the use of the Flight Path Vector aka the ‘bird’. During dynamic manoeuvres the bird is directly affected by aircraft inertia as it is computed from IRS data and static pressure information. It thus has a delayed reaction making it less suitable as a flying reference for these sorts of manoeuvres.
- Degredation of protections from Normal to Alternate law - no pitch and bank angle protections are provided. Load factor protection remains. High speed protection is replaced by a high speed stability. Angle of attack protection is lost and replaced by a 'low speed stability'. Alpha-floor is no longer available.
Manual references
- A320 FCOM/Aircraft Systems/Indicating/Recording Systems/Indications on the PFD/Flight Path Vector
- A320 FCTM/Aircraft Systems/Bird
- A320 FCOM/Aircraft Systems/Flight Controls/Flight Control System
- A320 FCOM/Aircraft Systems/Auto Flight - Flight Augmentation/Flight Envelope Function/Alpha-Floor Protection.
- A320 FCOM/Aircraft Systems/Flight Controls/Reconfiguration Controll laws/Alternate Law
Note: This video is published for familiarisation purposes with our simulator only and any views expressed within this video are our own. Some calls and checks have been omitted for brevity. Always refer to your company documentation or appropriate flight crew manual as the primary reference.
For bookings, further information and to learn about our simulators visit manchesterflightsim.com/

[@mba7454]

Best demo seen yet since my A320 training in 2010!

[@manchesterflightsimcentre]

We enjoyed making this one!

[@realavio]

This is great stuff guys! Thank you.

[@babyface1956]

Gentlemen! Thanks a lot. Appreciate this demonstration.

[@manchesterflightsimcentre]

Glad it was helpful!

[@josipbacinski5965]

Good job explaining

[@paulschmidt2820]

very clear explanation ! Thanks

[@GustavoDelacruzEscobar]

Good job explaining...the best.

[@tordenbob]

Brilliant 👍

[@derrick1707]

Great explanation, thanks.

[@manchesterflightsimcentre]

You're welcome!

[@sticky737]

Thank you!

[@alialmansoori4141]

Alpha-pitch-gLoad-rolland speed protections

[@philippegleize3037]

Is that FSlabs software on it?

[@bazokazoro4563]

Alpha floor & angle of attack protection isn’t the same case?

[@KhoiNguyen-ny7fz]

Alpha floor is trigered when you’re entering a stall, after stall recovering you will have toga lock

[@stevenwest000]

Is there no audible alert for the bank angle

[@1Gadspeed876]

I wonder too

[@ax.f-1256]

Nope.
Because why would there be a bank angle warning when you are flying with all Protections available when the airplane is on normal Law ?
The airplane will never allow more than 67° of bank angle. And those 67° will only ever be flown if you purposefully push the Sidestick to the left/right.
The Moment you let go of the sidestick the airplane will itself roll back to the more modest 33°.
And the autopilot will never command such a steep turn anyway, so you have to purposefully make control inputs to get the airplane to those 67°. And if you are doing it on purpose anyway, what would be the point of the warning ?
So there is no reason why the computer would ever sound the warning sound
"bank angle" when all protections are fully available.
Because you just can't bank the airplane steep enough to endanger it.
So no reason for the warning to sound.

[@stevenwest000]

@@ax.f-1256 ok

[@9LimaAlpha7]

can all of this automation be disabled?

[@Newberntrains]

intresting fact is you use alpha floor and the flight laws to escape windshear

[@mba7454]

Norm even on norm planes. MaxthrustXCLMax! Nothing new there

[@MungunzagasJargalsaikhan]

I thought it was called vne not vmo

[@JasonSchwerin]

Depends on the altitude, if you’re up high using Mach numbers, it’s VMO.

[@unknownuser-pb1io]

It's called vne on smaller aircrafts like C172

[@0utsider_]

​@@JasonSchwerin actually no. VNE (Never exceed speed) is a limitation usually more related to pistons. Airliners have different limits: VMO (Maximum Operating Speed), when flying below the crossover altitude (the altitude at which you stop flying at an Indicated Airspeed and start using Mach Numbers instead, as you pointed out). Above the crossover altitude, MMO (Maximum Operating Mach Number) becomes the limit.
There are even some additional limitations placed below the MMO and VMO to provide a safety margin towards them, like VNO (speed for normal operations), which must not be exceeded under normal circumstances.
It really get's a bit complex as there actually way more limitations and V speeds that are used in airlines :)