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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 12th Mar 2014, 01:47
  #1981 (permalink)  
 
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I have never flown an airliner, and I can't remember any corprate jet where you had to switch the transponder to standby before changing codes.
The idea of switching to STBY between codes was to avoid inadvertently hitting a 7000 code during the code change.
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Old 12th Mar 2014, 01:50
  #1982 (permalink)  
 
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Scribe Marks......

http://www.dca.gov.my/Division/Airwo...es/AN%2091.pdf

Will the DCA re-issue a follow up of this Airworthiness Notice, if this aircrafts last repaint took place in the mid to late 2000's?
Will the DCA direct the operator/MRO to conduct immediate inspections of its fleet to discount this possibility?
Will the DCA investigate whether the MRO continued to have, or took disciplinary action against employees who were found to have unapproved implements in their possession in the years following the issue of this AN?

Last edited by Acute Instinct; 12th Mar 2014 at 02:00.
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Old 12th Mar 2014, 01:52
  #1983 (permalink)  
 
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Pigboat

Great Handle.

I have run across the concept you mention. I think the original post was questioning whether it was a requirement to go to standby before changing codes, or a procedural one like you mentioned.

Maybe someone here with knowledge of MH procedures could clarify this.

It may he helpful in determining why the transponder was turned off.
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Old 12th Mar 2014, 01:52
  #1984 (permalink)  
 
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in my opinion from the little evidence available, it had a depressurisation problem rendering the flight crew and passengers unconscious, resulting in the aircraft flying solely on autopilot and completely unmonitored from the malacca straights on an approximate track taking it over the indian ocean towards the island of madagascar via diago garcia, where at some point it ran out fuel.
Very unlikely. If the cabin altitude went to even 10,000', there would be a loud aural alert in the cockpit plus an EICAS message telling the flight crew that there was a pressurisation problem. I'm sure the pilots are regularly checked for health and wouldn't find 10,000' much of a problem. If they did succumb to lack of oxygen without realising there was anything wrong with pressurisation, the autopilot would have taken them to their destination and beyond (at their current cruise altitude). Also, as previously stated, depressurisation shouldn't have affected their transponders.
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Old 12th Mar 2014, 01:53
  #1985 (permalink)  
 
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transponder

The reason one switches to standby before changing the code, is that if one cycles the code numbers it does flash other transponder codes.
Which is also a reason for having "Ident".
The transponder is a radar aid, it is not a training line to air traffic control.
If there is no transponder, or its off , ATC just read a target: no identity, no altitude no TAS/IAS.no supplementary information
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Old 12th Mar 2014, 01:56
  #1986 (permalink)  
 
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Originally Posted by Ian W
The aircraft also underwent an extended maintenance ~ 2 weeks ago at which corrosion/cracking around the SATCOM mount should/would have been checked for.
No doubt this plane was taken care of - MAS typically has things in order. On the other hand, what about the aspect that the plane was last "touched" as short as 2 weeks ago?
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Old 12th Mar 2014, 02:05
  #1987 (permalink)  
 
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Surely the 777 does not have those steam-driven transponders with rotary code select knobs. Surely it would be fitted with the newer push-button code entry controllers that donít change the transmitted code until the fourth number in the code is entered.
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Old 12th Mar 2014, 02:08
  #1988 (permalink)  
 
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With the older rotary Transponders the policy of turning the unit to STBY has merit but with modern keyboard Transponders the likleyhood of an incorrect code is slim and is easily rectified.
The problem with turning the Transponder unit to STBY is that TCAS protections are now lost which in my mind is not an ideal situation.
By all means turn it to STBY but just realise the repercussions whilst it is off and god forbid if it is not turned back on.
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Old 12th Mar 2014, 02:18
  #1989 (permalink)  
 
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Turning it off is only one explanation, out of numerous, for a transponder ceasing to operate.
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Old 12th Mar 2014, 02:23
  #1990 (permalink)  
 
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Surely the 777 does not have those steam-driven transponders with rotary code select knobs. Surely it would be fitted with the newer push-button code entry controllers that donít change the transmitted code until the fourth number in the code is entered
Quite right Creamie.

Also in some jets I fly with the rotary code selector knobs, as soon as the knob is turned to change the code the TCAS/Transponder goes to standby mode until all digits are selected and set for something like 3 seconds, not sure of exact timing.

As far as this thread goes...Never have so many understood so little but written so much about it!
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Old 12th Mar 2014, 02:24
  #1991 (permalink)  
 
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Jet we don't know that. Both transponder antennas are close together. It the section of skin they are both mounted on departed the aircraft.....

Just as likely a major loss of electrics....or for some reason multiple databuses went down at once.

IMHO: until we recover her, were gonna drive ourselves crazy guessing.

Asking again any 777 or 767 drivers remember what the load shedding scheme is?
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Old 12th Mar 2014, 02:24
  #1992 (permalink)  
 
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Just to point our on some of the information provided by the Malaysian military last night around its last know position, more so around the fact the the aircraft descended to around 3000ft would this simply be to maintain VFR , cloud base in kl usually sits between 3000ft and 10,000ft

this would indicate the the PIC certainly had control of the Aircraft
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Old 12th Mar 2014, 02:32
  #1993 (permalink)  
 
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The stream of news and rumors is ridiculous

Malaysia's air force chief denied a media report that the military last tracked a missing Malaysia Airlines jetliner over the Strait of Malacca, far from where it last made contact with civilian air traffic control when it disappeared four days ago.

"I wish to state that I did not make any such statements," air force chief Rodzali Daud said in a statement on Wednesday.
Malaysia air force denies tracking missing jet to Strait of Malacca
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Old 12th Mar 2014, 02:33
  #1994 (permalink)  
 
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Reagarding the transponder and why it was not returning a secondary paint on radar could be as mentioned above. If a decompressurization did occur, and in the process of changing the code from assigned code to 7700, the PNF left it in Standby mode and not return it to TA/RA mode due to increase in workload or partial or deteriorating awareness due to hypoxia, it may explain why the transponder was 'off'. Quite plausable and we all know how overloaded we can become during simulator proficiency checks for similar scenarios.
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Old 12th Mar 2014, 02:43
  #1995 (permalink)  
 
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It's the only scenario which I can piece together which fits the evidence. The aircraft could be anywhere from the last primary radar return to 3000nm west of there. - and may not be found for a very long time.
Given the arguably chaotic S&R response thus far - with zero results - you'd think it might be worth at least one attempted ariel or surface sweep along that path... if not already too late.
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Old 12th Mar 2014, 02:45
  #1996 (permalink)  
 
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I have never switched the transponder to standby before changing code.
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Old 12th Mar 2014, 02:50
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ACARS via SATCOM

On the B777, if the SATCOM antenna is damage as a result of fuselage mount cracking could this disable ACARS transmission as well!??
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Old 12th Mar 2014, 02:51
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I have never switched the transponder to standby before changing code.
@ManaAdaSystem, I agree. In my 20+ years of flying, I've never done that. In fact, every time I changed code, I'd hit the 'ident' button (or toggle switch) to give out a pulse.
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Old 12th Mar 2014, 02:52
  #1999 (permalink)  
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Ok, let me ask you this...Any of you had ever turned off the transponder on the flight for any reason? If so why?
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Old 12th Mar 2014, 02:53
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Latest:

@STForeignDesk: #Malaysia official replies "it's not the right time yet" to question from #MH370 families if govt is hiding military data
#MalaysiaAirlines
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