A320 Reversible Alpha Floor

[vilas]

Airbus introduces reversible alpha floor with FMGS2 Honeywell. Usually this protection kicks in at high AoA ending up in TOGA LK. But with this new software if aircraft is brought back within envelope the thrust will return to previous level without TOGA LK. Anyone has these MSNs?

[Sergei.a320]

Airbus introduces reversible alpha floor with FMGS2 Honeywell. Usually this protection kicks in at high AoA ending up in TOGA LK. But with this new software if aircraft is brought back within envelope the thrust will return to previous level without TOGA LK. Anyone has these MSNs?
Yes , we have couple of them in our fleet, when out of alfa-floor A/THR reverts to the mode before A.floor activation, even if A/THR was not engaged, it reverts to current lvr position.
Even so most of our aircraft are now equipped eith DBUS with SMF, it's cool thing which convert usual Unr.Airspeed.Ind from memory item to just ECAM actions :ok:

[vilas]

Yes , we have couple of them in our fleet, when out of alfa-floor A/THR reverts to the mode before A.floor activation, even if A/THR was not engaged, it reverts to current lvr position.
Even so most of our aircraft are now equipped eith DBUS with SMF, it's cool thing which convert usual Unr.Airspeed.Ind from memory item to just ECAM actions :ok:
What's DBUS and SMF?

[Sergei.a320]

What's DBUS and SMF?
SMF - Speed Monitoring Function ,its a function of FAC that enables FAC to analyze 4 different sources (3 ADRs and One DBUS(syntetic speed calculated by FAC using AOA,LOAD FACTOR,weight,GPS alt and current configuration). It compares all of these sources between each other and monitor individually each ADR in order to detect Icing Conditions. It also assigns one of 3 Validity status( RELIABLE , FAULT, UNCERTAIN) to each speed source and shows it on ECAM.

[vilas]

SMF - Speed Monitoring Function ,its a function of FAC that enables FAC to analyze 4 different sources (3 ADRs and One DBUS(syntetic speed calculated by FAC using AOA,LOAD FACTOR,weight,GPS alt and current configuration). It compares all of these sources between each other and monitor individually each ADR in order to detect Icing Conditions. It also assigns one of 3 Validity status( RELIABLE , FAULT, UNCERTAIN) to each speed source and shows it on ECAM.
A350 comes fitted with it. You have them on A320? Great!

[jaja]

SMF - Speed Monitoring Function ,its a function of FAC that enables FAC to analyze 4 different sources (3 ADRs and One DBUS(syntetic speed calculated by FAC using AOA,LOAD FACTOR,weight,GPS alt and current configuration). It compares all of these sources between each other and monitor individually each ADR in order to detect Icing Conditions. It also assigns one of 3 Validity status( RELIABLE , FAULT, UNCERTAIN) to each speed source and shows it on ECAM.

@ Sergie.a320

Airbus does not know about SMF and DBUS on new A32x. Can you please explain what you mean ?

Thank you

[Sergei.a320]

@ Sergie.a320

Airbus does not know about SMF and DBUS on new A32x. Can you please explain what you mean ?

Thank you
You must be joking when you write something like this about Airbus. DSC-34-NAV-10-30-20 explains what do SMF and DBUS mean;) cannot attach image from FCOM.

[jaja]

You must be joking when you write something like this about Airbus. DSC-34-NAV-10-30-20 explains what do SMF and DBUS mean;) cannot attach image from FCOM.

OK thank you Sergei

I only have access to legacy and Sharklet FCOM, so can’t read that chapter with the description of SMF and DBUS

Anybody else who can post description of SMF and DBUS here or PM me ?

[pineteam]

Airbus introduces reversible alpha floor with FMGS2 Honeywell. Usually this protection kicks in at high AoA ending up in TOGA LK. But with this new software if aircraft is brought back within envelope the thrust will return to previous level without TOGA LK. Anyone has these MSNs?

According to our FCOM, we have it only on our latest 2 A321 NEO.

[Sergei.a320]

According to our FCOM, we have it only on our latest 2 A321 NEO.
Initially this function was created during UAMM (Unreliable Airspeed Mitigation Means project) foe NEO fleet to cancel OEB 59 , so for now as I know it's retrofitted by operator request..

[vilas]

Basically the Airbuses(except the A350) had three pitot, static sensors providing airspeed input to three ADRs. But when all three have different values or one having failed the remaining two differ there was no other speed information independent of the Pitot static to assess the correct one or reject all three. The digital speed is a calculated speed from AoA, GW, load factor plus GPS inputs etc. which provides that independent measurement to select the correct ADR or to reject all and provide that speed itself to use. Makes life easier. Another example of automation taking over pilot function.

[Denti]

Initially this function was created during UAMM (Unreliable Airspeed Mitigation Means project) foe NEO fleet to cancel OEB 59 , so for now as I know it's retrofitted by operator request..
Isn't OEB 59 solved by ELAC standard 103 or higher?

[Check Airman]

Basically the Airbuses(except the A350) had three pitot, static sensors providing airspeed input to three ADRs. But when all three have different values or one having failed the remaining two differ there was no other speed information independent of the Pitot static to assess the correct one or reject all three. The digital speed is a calculated speed from AoA, GW, load factor plus GPS inputs etc. which provides that independent measurement to select the correct ADR or to reject all and provide that speed itself to use. Makes life easier. Another example of automation taking over pilot function.

…until it does something stupid, like yesterday

[safetypee]

Gentle questions seeking understanding: a non AB operator, no technical knowledge of this system.

From the descriptions so far;-
Does the word ‘reversible’ indicate the computational method, the reversal of the process which displays AoA as speed on the speed tape (used in alerting and control functions related to airspeed, alpha floor): i.e. reversible - use AoA to compute speed in the event of speed failure.
Does the SMF (RSF) fill-in a weakness in cross monitoring in aircraft with three identical sensors (or combined sensor computation - air data).

In ‘older’ aircraft with identical dual input, and a different standby instrument as the third system, the cross-monitoring of primary systems is a simple difference comparison, which alerts the crew to check the standby, and then they (the human) decide which main system is ‘probably’ more accurate (two out of three voting).
If both primary systems were simultaneously in error, then although the standby might be accurate the crew would not know, but at least might have an indication of which system was at fault via alerting, e.g. altitude or airspeed, etc, independently.

In other aircraft with combined Air Data this may not be as easy, but most certification requirements assume that multiple failures will be of short duration - temporary (probability).

Modern aircraft may use three identical sensors and airdata computers. Although the likelihood of failed inputs is as above, the crew may not have any indication of which system is in error or which component of airdata is incorrect, not knowing if it is the sensor, computation, or airdata subsystem; there are multiple alerts, e.g, airdata and speed, etc, simultaneously. Also, because of very high system integration many other aircraft systems can be affected and alerted.

So, the question is if a purpose of the SMF is to clarify, simplify ambiguous failures and maintain speed protections. Technology is used to aid the human with assessment;- instead of the man aiding the digital machine (dual + stby), the machine aids the man, a combined system of man and machine together (enhanced triple-mix)

Is this an extension of the ideas behind BUSS (speed), but including the suite of sensors in ‘triple’ airdata comparison; not a specific certification requirement, but acknowledging increasing system complexity and rarity of malfunction.
If so, then BZ to the design in taking the initiative in recognising the limitations of human performance and the challenges arising from the widespread use of computational technology (Vilas; not automation replacing the human, but technology aiding the human).

[vilas]

Safetypee
Reversible alpha floor and digital back up speed are two different things. Previously when AoA shown as speed on the tape, (it's ADR1+2 divided by 2) increased beyond a certain threshold alpha floor was triggered setting the thrust to TOGA and then locking the thrust at TOGA. The pilot then reduced the AoA and disconnected the TOGA LK , reengaged the ATHR and brought the thrust levers to CLB detent which is active ATHR position. So there were some actions that needed to be done otherwise the acceleration will continue leading to VFE/VMAX exceedance. Now this is automated e.i. when the conditions for alpha floor do not exist it's back to normal. Digital Back Up Speed deals with unreliable air speed it is a calculated airspeed or synthetic air speed as Boeing call it in B787 independent of the Pitot static system with some degraded accuracy. So the actions for ADR disagree are spelt out on ECAM and pilot just executes that. So no ADR Check procedure is necessary. A350 has a fourth pitot static in the engine which FADEC uses. That's known as alternate speed and the calculated speed is the fifth but less accurate option. The monitoring and switch over when required is automatic with only intimation to the pilot.

[Sergei.a320]

Isn't OEB 59 solved by ELAC standard 103 or higher?
ELAC L103+ is also a part of UAMM project,you are right)

[Sergei.a320]

Safetypee
Reversible alpha floor and digital back up speed are two different things. Previously when AoA shown as speed on the tape, (it's ADR1+2 divided by 2) increased beyond a certain threshold alpha floor was triggered setting the thrust to TOGA and then locking the thrust at TOGA. The pilot then reduced the AoA and disconnected the TOGA LK , reengaged the ATHR and brought the thrust levers to CLB detent which is active ATHR position. So there were some actions that needed to be done otherwise the acceleration will continue leading to VFE/VMAX exceedance. Now this is automated e.i. when the conditions for alpha floor do not exist it's back to normal. Digital Back Up Speed deals with unreliable air speed it is a calculated airspeed or synthetic air speed as Boeing call it in B787 independent of the Pitot static system with some degraded accuracy. So the actions for ADR disagree are spelt out on ECAM and pilot just executes that. So no ADR Check procedure is necessary. A350 has a fourth pitot static in the engine which FADEC uses. That's known as alternate speed and the calculated speed is the fifth but less accurate option. The monitoring and switch over when required is automatic with only intimation to the pilot.
Perfectly summed up!:)