Automation questions - AIRBUS

[zhtm475]

To all A318/19/20/21, A330, A340 pilots,

I urgently need answers for the following questions regarding Airbus (A318/19/20/21, A330, A340) aircraft for my human factors research project. I appreciate all of your help.

(1). During an ILS approach and when autopilot is engaged:
What happens if glideslope signal is lost? Will the aircraft continue the descent and the FD bars disappear? Is the outcome difference between above and below 1,500 feet when glideslope is lost? Any changes in the mode indication?

(2). Is the go-around mode only available after descending below certain altitudes or anytime once the localizer and glideslope is captured?

(3). Is this correct that when autopilot is engaged:
The Flight Control Unit (FCU) window is, the last step in the altitude change process, to be changed after the clearance has been received. The autoflight system will not depart the FCU altitude, even if the FMGS is programmed for a different altitude.

(4). When autopilot is engaged and V/S mode is used for descent:
If excessive rate of descent is used and result in a potential of over-speeding the aircraft, will the automation automatically revert to the “OPEN Descent” mode to protect the target airspeed? Is this true?
Similarly, is this true that during a climb using V/S mode with a very high positive vertical speed selected that results in the airspeed decreasing below Vls + 5knots, the automation will revert to a “OPEN Climb”, which allows the aircraft to regain the target speed.

(5). When autopilot is engaged during an ILS approach:
If a go-around is initiated by setting the thrust levers to TOGA and autopilot remains engaged, does the aircraft fly the defaulted “runway track” before you hitting the Managed NAV or HDG mode?

(6). Does the FCU heading window shows “dashed lines” when APPR or managed NAV mode is on?

(7). When the aircraft is manually flown with auto-thrust engaged and at least one FD on while on “OPEN Descent” mode, if the pilot fails to follow the FD bars (i.e. when the pilot is not descending quick enough to achieve the descent rate shown on the horizontal FD bar), the aircraft will decelerate until reaching Vls. Is this true that at this point the auto-thrust system will revert to speed mode (i.e. thrust will increase to re-capture the target speed) and “OPEN Descent” will revert to V/S mode automatically and maintain the rate of descent at the moment of transition?

(8). During an approach without ATC speed restriction, do you only engaged “managed speed” after activating the APPR?

[Hand Solo]

These all refer to A319/320:

1)Can't find any specific reference to this scenario in my manuals but I think the aircraft will revert to the instantaneous V/S at the time of G/S signal loss and continue descent either down to the FCU selected altitude or to the ground if already below said altitude. In terms of indications, the Glide scale should flash on the PFD, the FD pitch bar will flash to indicate the change to V/S mode, the FMA will change from G/S to V/S, there'll be an aural 'triple click' to indicate the downgrade in landing capability and below 200 ft radio, if LAND mode is annunciated, the autoland warning light will flash.

2)Go around mode is available when flap lever is at least in position 1, aircraft is in flight or has been on the ground for less than 30 seconds. No reference to specific altitudes or LOC-G/S capture.

3) Depends whether you operating in selcted or managed mode. For example, lets say your flying a SID with an initial stop altitude of 6000 feet, then expect to climb to 10000 feet thereafter. On take off the aircraft will go from SRS mode to managed Climb. If the FCU window is set to 6000 the aircraft will level at 6000 and remain there. If you set the FCU to 10000, the aircraft will stop at 6000 as thats the constraint in the FMGS, but once past the constraining point in the route it will then climb to 10000 and level off there. If you operate in selected mode, you dial up your level in the FCU window, pull the dial and engage Open Climb mode which will climb directly to the selected level ignoring FMGS constraints. However the FCU altitude does limit the FMGS and the aircraft will not climb above or descend below the FCU altitude regardless of what the FMGS thinks you should be doing. So I suppose the answer to your question is yes.

4)a) Partly. Our CFM powered aircraft will revert to OP DES and target descent speed on reaching Vmo -5 (clean) or Vfe + 4 (other than clean). Our IAE powered aircraft, upon reaching whatever particular Vmax will remain at Vmax but will abandon the V/S target. Significantly V/S is still the annunciated descent mode.

4)b) Similar situation regards CFM/IAE differences. The CFMs revert to OP CLB at Vls+5, the IAEs revert to a lower V/S to keep climbing at Vls.

5)No. The aircraft flies the 'Go Around Track' (G/A TRK), which is what ever track it was flying when the go around was initiated.

6) Yes.

7) Exactly right for our CFM powered aircraft. The IAE aircraft will engage speed mode but the FDs will both disengage so the aircraft will just hold its current attitude and not attempt to capture any specific V/S. Note that the aircraft should not be flown with only one F/D engaged as Airbus say that is naughty.

8) This is generally very good practice as to do otherwise opens you up to forgetting to activate the approach phase. The sudden roar of power as the speed target leaps up to 250kts can be very embarassing. However, in theory the FMGS will calculate a deceleration point and should activate the approach itself as you pass that. It should also activate automatically when you activate the LOC mode, but not many people like to leave this to chance.

Just in case you're a bit confused by the CFM/IAE signifance, our CFM aircraft are very early 320-100s and 200s, wheares our IAEs are brand spanking new A319-100s and A320-200s, so these should have the latest Airbus software on them. Hope this helps a bit.

[zhtm475]

Hand Solo,

Thanks so much for all the information, they are really useful for me. Cheers!!

[Johnman]

Failure Of both localizer and glideslope receivers :-
The PFD and ND ( rose ILS mode ) display red LOC and G/S flags .
LOC and G/S scales disappear from the PFD .
If LOC or G/S modes are engaged and at least one AP/FD is engaged
- The AP disengeges
- The FD reverts to its HDG-V/S or TRK-FPA modes .
Failure of localizer or glideslope transmitter ( when captured )
- The LOC and G/S scales and FD bar flash
Below 200 feet RA , AUTOLAND warning

[zhtm475]

I've got two more questions here, any reply will be appreciated!

1. Will changing the landing runway erase all previously entered altitude constraints (those requested by ATC, not those in the STAR) in the FMGS?

2. Is this true that “OPEN Climb/Descent”, “EXPEDITE” and “V/S” mode does not honour altitude constraints programmed into the FMGS? However “Managed vertical NAV” has altitude constraint protection.

Many thanks:)

[exeng]

zhtm475,

1) Yes, if those altitude constraints were a part of the original star. Any altitude restraint that had been inserted prior to the star will remain. Of interest it will also annoyingly erase any holding pattern you may have inserted even though the holding position is common on the star to the new runway.

2) Yes, but I'm not sure about 'expedite climb'. It is a mode I have very rarely used as I prefer 'selected speed', entering a lower target than managed.

Scince operating buses I've developed a considerable callous on the tip of my right forefinger!

The lack of the need to 'execute' an action having selected it (as per FMS) was not a good idea in my opinion.


Regards
Exeng