FCTM UNRELIABLE SPEED INDICATION QRH PROCEDURE

Question 1

The “UNRELIABLE SPEED INDICATION” procedure has two objectives:

Answer 1

‐ To fly the aircraft,

‐ To identify and isolate the affected ADR(s).

Question 2

It includes the following steps:

Answer 2

1. Memory items (if necessary),
2. Flight path stabilization,
3. Troubleshooting and isolation,
4. Flight using pitch/thrust references.

Question 3

The flight crew should consider applying the “UNRELIABLE SPEED INDICATION” procedure when:

Answer 3

‐ The “ADR CHECK PROC… APPLY” action line is displayed on ECAM, for example due to the NAV ADR DISAGREE alert, or

‐ The flight crew suspects an erroneous indication, without any ECAM alert.

Question 4

The flight crew can suspect an erroneous speed/altitude indication, in the following cases: 1)

Answer 4

‐ A speed discrepancy (between ADR1, 2, 3 and standby indications),

‐ Fluctuating or unexpected changes of the indicated airspeed or altitude,

‐ Abnormal correlation between the basic flight parameters (pitch, thrust, airspeed, altitude and vertical speed indications). For example: • The altitude does not increase, whereas there is an important nose-up pitch and high thrust, • The IAS increases, whereas there is an important nose-up pitch, • The IAS decreases, whereas there is an important nose-down pitch, • The IAS decreases, whereas there is a nose-down pitch and the aircraft is descending.

Question 5

The flight crew can suspect an erroneous speed/altitude indication, in the following cases: 2)

Answer 5

‐ An abnormal behavior of the AP/FD and/or the A/THR,

‐ The STALL warning triggers, the OVERSPEED warning triggers, or the FLAP RELIEF message appears on the E/WD, and this is in contradiction with the indicated airspeeds.
In this case: • Rely on the STALL warning. Erroneous airspeed data does not affect the STALL warning, because the STALL warning is based on angle of attack (AOA) data,
• Depending on the situation, the OVERSPEED warning may be false or justified. When the OVERSPEED VFE warning triggers, the appearance of aircraft buffet is a symptom that the airspeed is indeed excessive.

Question 6

The flight crew can suspect an erroneous speed/altitude indication, in the following cases:

Answer 6

‐ The barometric altitude is not consistent with the Radio Altimeter (RA) height (when the RA is displayed),

‐ The aerodynamic noise reduces whereas the indicated airspeed increases, or vice versa,

‐ In approach, it is not possible to extend the landing gear using the normal landing gear system.

Question 7

Crew coordination is important. The PM should confirm any discrepancy:

Answer 7

‐ Between the standby airspeed indication and the speed indication on his/her PFD,

‐ Between his/her PFD and the Pilot Flying’s PFD.

Question 8

The flight crew must ensure a safe flight path. If the safe conduct of the flight is affected, the flight crew applies the memory items. The memory items enable to:

Answer 8

rapidly establish safe flight conditions for a limited period of time in all phases of flight and in all aircraft configurations (weight and slats/flaps).

Question 9

The flight crew must apply the memory items, if they have a doubt on their ability to safely fly the aircraft in the short term with the current parameters, i.e.:

Answer 9

‐ The flight crew has lost situation awareness, or

‐ The current pitch and thrust are not appropriate for the current flight conditions, or

‐ The aircraft has an unexpected flight path for the current flight conditions.

Question 10

When the PF has stabilized the target pitch and thrust values, the flight crew applies the:

Answer 10

QRH procedure without delay.

The flight crew must apply the QRH procedure without delay, because flying with the memory pitch/thrust values for an extended period of time can lead to exceed the aircraft speed limits.

Note: The flight crew must respect the STALL warning.

Question 11

According to the procedure, the flight crew can:

Answer 11

‐ Level off the aircraft then keep the flight path stabilized, or

‐ Keep the flight path stabilized.

Note: If the flight crew has applied the Memory Items, then the flight crew must level off the aircraft to stabilize the flight path.

Question 12

In all cases, the initial actions are to disconnect the automations. This prevents the Flight Guidance to:

Answer 12

use erroneous data for the computation of the aircraft guidance. Initial disconnection of the automation can prevent:

‐ Erroneous orders, if AP/FD are engaged

‐ Erroneous thrust change, if A/THR is engaged.

Question 13

If the A/THR automatically disconnects, the Thrust Lock function activates. The thrust is locked at:

Answer 13

its level at the moment of the disconnection until the flight crew moves the levers.

The thrust may be locked at idle, due to normal A/THR behaviour, or due to the use of erroneous data.

Question 14

To level off the aircraft, the flight crew uses:

Answer 14

Pitch and Thrust tables of the QRH, Pitch/Thrust Tables.

The GPS altitude can be used to confirm that the aircraft is maintaining level flight.

The GPS altitude remains available on the MCDU GPS MONITOR page.

Question 15

In order to identify and isolate the faulty ADR(s), the flight crew must:

Answer 15

crosscheck speed and altitude indications on CAPT PFD, F/O PFD and STBY instruments.

To help the identification of the affected ADR(s), the flight crew can use the Pitch and Thrust tables of the QRH procedure.

Question 16

The Pitch and Thrust tables provide:

Answer 16

the resulting speed for a given aircraft weight and flight level.

Question 17

When one indication differs from the others, the flight crew may be tempted to reject the outlier information. However,

Answer 17

they should be aware that two or even all three ADRs can provide identical but erroneous data.

Do not instinctively reject an outlier ADR.

Question 18

When the flight crew has identified the affected ADR(s), they must:

Answer 18

turn off the affected ADR(s).

As a consequence this triggers the corresponding ECAM alerts. The flight crew must apply the associated procedures to address all the consequences on the various aircraft systems.

Question 19

If the flight crew identifies at least one ADR to be reliable:

Answer 19

the flight crew must use it.

Question 20

If the flight crew cannot identify the affected ADR(s) or if all speed indications remain unreliable:

Answer 20

the flight crew must turn two ADRs off to prevent the flight control laws from using two consistent but unreliable ADR data. The flight crew must keep one ADR on. For flight continuation, the flight crew uses pitch and thrust tables of the QRH.

Question 21

When flying the aircraft with unreliable speed and/or altitude indications, it is recommended to change only:

Answer 21

one flight parameter at a time (i.e. speed, altitude or configuration).

Question 22

If the FPV is reliable (i.e. barometric altitude is reliable), or with the GPS altitude information:

Answer 22

‐ Maintain level flight (FPV on the horizon or constant GPS altitude),

‐ Adjust thrust,

‐ Observe the resulting pitch attitude, and compare it with the recommended pitch target in the table:
• If the pitch necessary to maintain level flight is above the pitch target of the table, the aircraft is slow. Then increase the thrust.
• If the pitch necessary to maintain level flight is below the pitch target of the table, the aircraft is fast. Then decrease the thrust.

Question 23

If the FPV is not reliable and the GPS altitude information is not available (no means to ensure level flight):

Answer 23

Adjust pitch and thrust according to QRH tables, and wait for speed stabilization. Expect a significant time to stabilize the flight path and important altitude variations during the stabilization.

Question 24

For the approach:

Answer 24

a wide pattern and an early stabilized approach are recommended.

For the final approach, prefer a standard ILS approach with a -3 ° G/S, if available. If the final descent is started with stabilized speed, on a -3 ° flight path with the thrust setting recommended in the table, the resulting pitch attitude should be close to the recommended table pitch value. If an adjustment is required, vary the thrust.

Question 25

When the BUSS is active:

Answer 25

‐ The AP/FD and A/THR must be disconnected,

‐ The F/CTL Laws are in Alternate law,

‐ The STALL warning remains operative,

‐ Cabin pressure must be controlled manually,

‐ Depending on the ADIRS standard, the FPV can be available on one or both PFDs as soon as the flight crew switch off all ADRs

Question 26

When flying with the BUSS, do not use the:

Answer 26

speed brakes.

Flying with speed brakes extended affects the relationship between the speed and AOA, and therefore the BUSS may provide erroneous data.