AP-BDZ Incident

[Amaad Lone]

I recently traveled to Frankfurt on PK763. Till Amsterdam Captain T.P Ahmed was a passenger, taking over the leg between Amsterdam and Frankfurt.

During our conversation he informed me that the AP-BDZ incident was a computer malfunction. It reported to the autopilot that speed has decreased to 90 knots, which is close to stall.

To avoid stall the autopilot put the nose of the aircraft down, in an effort to increase speed. The pilots had to disengage the auto pilot to take over to save the aircraft.

The aircraft did cross some perimeters, after which it is required by airbus that certain tests are carried out. Those tests were carried out in Karachi and the plane was declared fit to fly.

I have some great shots of the cockpit (AP-BEU) was operating the flight, and will post them soon. I am in Paris, leaving for Lahore on the 18th, so if anyone knows the captain of the flight, make sure he allows me some nice shots once again.

[Abbas Ali]

Thank you Amaad for sharing info. We look forward to see the photos and wish you have a nice flight.

Abbas

[Adnaan786]

To avoid stall the autopilot put the nose of the aircraft down, in an effort to increase speed. The pilots had to disengage the auto pilot to take over to save the aircraft.

Interesting that the aircraft pitched down for the stall recovery. As I remember the aircraft lost quite a bit of height. One of the main objectives in a stall recovery is minimum height loss. I would have expected the autopilot to pretty much hold the attitude and apply full thrust. I'm not 100% sure on this however, I wonder if anyone else can clarify this.

Thanks.

[umar744]

my dearest friend,
salam
hello
yes my old best good friend of mine captain name is AZIZUDDIN can you please give my message and my name to capt.azizuddin.
message is
hello salam Capt.Azizuddin, I am Umar Anis. How are you? Hope you well. I am fine. I tell you to please call my friend to see meet you and please let him sit jump seat to see your take off and landing also please photo your cockpit and anything. I will fly PK758 with capt.shahid hussain from LHR to LHE on new 773 thursday 18th Jan to arrive Lahore on Friday mornng 19th January and I will fly back to London on 25th january. I will meet you at PC hotel or Flt Ops LHE airport. Have nice flight
with lots of love
Umar Anis
List of Crew on Flight 750 on Thursday 18/01/2007
ID Name Base AC Pos DHD
40099 AZIZUDDIN ISB 310 CP
54880 BIJARANI ISB 310 FO
54894 IMRAN SOHAIL KHI 310 FO
35798 IFTIKHAR AHMED KHI 772 SP
41730 MANSOOR AHMED LHE 772 FP
47679 SHAMAILA ASGHAR LHE 733 FP
61774 AHMAD AMAD LHE 743 FS
61100 MALIK OMAR AKBAR LHE 743 FS
55653 USMAN QAYUM MIAN LHE 772 FS
61834 ANEELA SHABBIR LHE 733 AH
52115 AREEBA BUTT LHE 733 AH

[AN]

Stall recovery taught anywhere on any aircraft is always two things. NOSE down and full power. Simply put power alone cannot cause the aircraft to recover from a stall. Once a certain angle of attack has been exceeded, and the wing has stalled, the AoA must be reduced to recover from the stalled condition.

as in the case of gliders or aircraft that have had engine failures, it is ofcorse the pitching down that is essential.

[AM]

AP-BDZ conducted a test flight yesterday at 0230pm till 0430 pm.All flight parameters were checked .On board were aircraft engineers,CAA representatives and Fltop engineer. All phases of flight were satisfactory.Airbus has also cleared the aircraft after reviewing raw fdr data of last two flights and test flight.No defects reported except nose wheel shimmy on landing.

[Adnaan786]

Yes you're right you do put the nose down, but you still hold a positive nose attitude don't you? In the Piper Seneca you put the nose down to about 8 degrees nose up attitude and apply almost full power (not full because of overboost) and it would come out of the stall very nicely with minimum height loss.

In a jet I was told to hold the attitude at about 15 degrees nose up and apply full thrust. Mind you it was really difficult to hold 15 degrees while the stick shaker was rattling like mad.

[AN]

sorry never heard of any stall recovery (except during stick shaker caused wind shear on final approach) where you have a positive nose attitude.

[R.F.]

Gentlemen, ' when ever a certain angle of attack is exceeded the airflow surrounding it is disturbed resulting in a loss of lift and the wing stalls'.

On an A310 stall recovery is as basic as any other aircraft however the procedure differs as on a basic trainer the pilot has to lower the nose to in order to decrease the angle of attack. On high speed jets the idea is to recover with minimum loss of height as ground contact may be a factor.

A310 has safety feature called the alpha floor where in upon activation i.e after exceeding the angle attack vis-a-vis certain pitch angles depending upon what configuration has been selected, the thrust engages into a protection mode called the Thrust latch or alpha floor.

The dilemma is that on a nose high attitude and with the engagement of alpha floor a jet upset can and may occur, however with the disengagement of the autpilot a recovery procedure can be initiated.

Normal stall recovery when close to the ground on an A310 fully configured is +10 degrees of pitch and above 20,000 is 0 to -5 degrees.
Below 20,000 feet if in clean config with ground contact not a factor slats are extended for recovery. Ofcourse all these manouvers are done with full thrust.

I hope that clarifies the query.

[AN]

full configured =?
do you mean landing config?

in which case the flaps will be deployed causing the center of pressure to shit rearwards on the wing giving the aircraft a lower angle of attack than in a clean config to stay level. This account for the increased pitch angle during recovery in landing config/ on approach.

[R.F.]

Affirm, indeed full config is the landing which is 30/40 on the A310/306.
The centre of pressure always moves rearwards when a stall occurs. Increased pitch during landing stall recovery is due to the thrust increment as you must have studied and experienced in your basic flying.
The Nose goes up when power is increased and down when decreased.

What I presume is that you mean 'Shift' !

[Adnaan786]

Interesting, thank you R.F.

One more question: Why did the autopilot put the nose down for the stall recovery, was this because it actually got into a stall?

Thanks.

[FULLTHRUST]

Because, with the AP engaged, the Auto Trim order (of Horizontal Stablizer) work opposite to pilot control inputs.