Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

Question on transponder / MH370

Tech Log The very best in practical technical discussion on the web

Question on transponder / MH370

Old 16th Mar 2024, 17:38
  #1 (permalink)  
Thread Starter
 
Join Date: Nov 2022
Location: Paris
Posts: 28
Likes: 0
Received 0 Likes on 0 Posts
Question on transponder / MH370

Hi everyone,

After watching an interesting video on the MH370 flight that disappeared, I have a simple general question.

1) When the transponder on the XPNDR/TCAS panel is set to STBY, does it mean ATC can't see you on his screen and you fly undetected, the only way to detect you being primary radar pulses ? Or you can still be detected but without altitude, speed etc...
2) It leads to my second question regarding flight MH370: did the flight do what I said in 1), or did they do other things to remain undetected, like tripping CB's, or disconnecting from ACARS ?

Thank you for your answers
Aperture is offline  
Old 23rd Apr 2024, 04:44
  #2 (permalink)  
 
Join Date: Apr 2024
Location: Oslo
Posts: 4
Likes: 0
Received 0 Likes on 0 Posts
Originally Posted by Aperture
Hi everyone,

After watching an interesting video on the MH370 flight that disappeared, I have a simple general question.

1) When the transponder on the XPNDR/TCAS panel is set to STBY, does it mean ATC can't see you on his screen and you fly undetected, the only way to detect you being primary radar pulses ? Or you can still be detected but without altitude, speed etc...
2) It leads to my second question regarding flight MH370: did the flight do what I said in 1), or did they do other things to remain undetected, like tripping CB's, or disconnecting from ACARS ?

Thank you for your answers
From my understanding setting the transponder to STBY prevents operation of the transponder so the aircraft would only visible on the primary radar. It’s speculation but it seems like other systems were also deactivated like company acars.
captain.ronin is offline  
Old 30th Apr 2024, 18:09
  #3 (permalink)  
 
Join Date: Oct 2006
Location: UK
Posts: 74
Received 1 Like on 1 Post
We know the transponder stopped working..Satcom stopped working for about an hour..the Autopilot appears to be off…no Comms from the pilots… the aircraft then appeared to follow a flight path resembling a hypoxic ghost flight.

All the above looks like a mechanical accident failure scenario..

No need for all this wild hijack/suicide/murder speculation
birdspeed is offline  
Old 30th Apr 2024, 18:41
  #4 (permalink)  
 
Join Date: Jan 2008
Location: Reading, UK
Posts: 15,826
Received 206 Likes on 94 Posts
Originally Posted by birdspeed
No need for all this wild hijack/suicide/murder speculation
There's never any need for speculation, but in the absence of a definitive answer as to probable cause, speculation is just human nature.
DaveReidUK is offline  
Old 30th Apr 2024, 20:23
  #5 (permalink)  
 
Join Date: Aug 2010
Location: sussex
Posts: 114
Likes: 0
Received 2 Likes on 1 Post
I take it, birdspeed, that you are speculating it was a 'mechanical accident failure scenario'?
42go is offline  
Old 1st May 2024, 08:41
  #6 (permalink)  
 
Join Date: Dec 2003
Location: Tring, UK
Posts: 1,847
Received 2 Likes on 2 Posts
Originally Posted by birdspeed
the aircraft then appeared to follow a flight path resembling a hypoxic ghost flight.
No, not really, unless you call flying for hundreds of miles in a straight line, making a turn, then doing the same again normal for a “ghost flight”?
All the above looks like a mechanical accident failure scenario.
Having looked at this from many angles, as 777 rated pilot, I can’t think of anything that would produce the recorded flight path with no pilot input.
No need for all this wild hijack/suicide/murder speculation
IMHO the wild speculation is mostly centred about trying to explain what happened by trying to shoehorn sequences of improbable failures into the recorded flight, without much understanding of the technical ramifications. Unlawful interference fits without any contortions and this is not an isolated one-off, unfortunately.
FullWings is offline  
Old 1st May 2024, 09:06
  #7 (permalink)  
 
Join Date: Oct 2006
Location: UK
Posts: 74
Received 1 Like on 1 Post
[QUOTE=FullWings;11646665]No, not really, unless you call flying for hundreds of miles in a straight line, making a turn, then doing the same again normal for a “ghost flight”?

FullWings, that’s the big misconception. The raw primary radar data shows a meandering flight back towards Penang and then a lazy gentle turn at Penang. Then after 18:01z we have NO radar evidence how it flew. In early reports, straight lines were drawn, but they have never been backed up by evidence. It took 4 years before the actual primary raw data was released, and of course, by then everyone had made up their minds it was nefarious.
birdspeed is offline  
Old 1st May 2024, 09:25
  #8 (permalink)  
 
Join Date: Dec 2003
Location: Tring, UK
Posts: 1,847
Received 2 Likes on 2 Posts
From this same primary radar, it flew along N571 for a considerable distance after turning Penang, which is astounding work for a ghost ship with no crew or autopilot. For this to happen in real life, it would need LNAV + AP or someone at the controls tracking the airway manually.
FullWings is offline  
Old 1st May 2024, 09:41
  #9 (permalink)  
 
Join Date: Oct 2006
Location: UK
Posts: 74
Received 1 Like on 1 Post
FullWings, that is the big misconception. There is no evidence it flew the centreline of N571. The best that can be said, is it possibly went roughly in that direction.
The Malaysian military have never released raw radar data from this part of the flight- I suspect they don’t have it!
birdspeed is offline  
Old 1st May 2024, 10:22
  #10 (permalink)  
 
Join Date: Dec 2003
Location: Tring, UK
Posts: 1,847
Received 2 Likes on 2 Posts
Originally Posted by birdspeed
FullWings, that is the big misconception. There is no evidence it flew the centreline of N571. The best that can be said, is it possibly went roughly in that direction.
The Malaysian military have never released raw radar data from this part of the flight- I suspect they don’t have it!
Oh. 10 seconds on Google turned up this, which shows it tracking towards a point on an airway then following the airway:




FullWings is offline  
Old 1st May 2024, 11:02
  #11 (permalink)  
 
Join Date: Oct 2006
Location: UK
Posts: 74
Received 1 Like on 1 Post
FullWings, that is a screen shot from a press conference to the relatives…it has never been included in any official report… there is nothing that can confirm what that picture is showing.

And even if that is the correct target, you can’t tell how it is flying(autopilot on or off).

The last group of self appointed experts determine that the autopilot is OFF and the aircraft is meandering.

Last edited by birdspeed; 1st May 2024 at 11:17.
birdspeed is offline  
Old 1st May 2024, 11:24
  #12 (permalink)  
 
Join Date: Dec 2003
Location: Tring, UK
Posts: 1,847
Received 2 Likes on 2 Posts
Originally Posted by birdspeed
FullWings, that is a screen shot from a press conference to the relatives…it has never been included in any official report… there is nothing that can confirm what that picture is showing.
Well, obviously, it’s an EasyJet flight to Corfu that’s avoiding weather. That would make absolute sense at a press conference for the relatives of those lost aboard MH370.

If you selectively disregard actual evidence/data (radar, satellite) in favour of things which have no evidence or data (various outlandish stacked failures), then that falls more into the realm of conspiracy theory. For the aircraft do do what it did, requires human intervention or a sequence of events so improbable that it can be ruled out almost immediately.
FullWings is offline  
Old 1st May 2024, 12:19
  #13 (permalink)  
 
Join Date: Mar 1999
Location: big green wheely bin
Posts: 907
Likes: 0
Received 18 Likes on 1 Post
Originally Posted by FullWings
Well, obviously, it’s an EasyJet flight to Corfu that’s avoiding weather. That would make absolute sense at a press conference for the relatives of those lost aboard MH370.

If you selectively disregard actual evidence/data (radar, satellite) in favour of things which have no evidence or data (various outlandish stacked failures), then that falls more into the realm of conspiracy theory. For the aircraft do do what it did, requires human intervention or a sequence of events so improbable that it can be ruled out almost immediately.
Got any proof of unlawful interference?
Jonty is offline  
Old 1st May 2024, 12:41
  #14 (permalink)  
 
Join Date: Oct 2006
Location: UK
Posts: 74
Received 1 Like on 1 Post
Originally Posted by FullWings
If you selectively disregard actual evidence/data (radar, satellite) in favour of things which have no evidence or data (various outlandish stacked failures), then that falls more into the realm of conspiracy theory. For the aircraft do do what it did, requires human intervention or a sequence of events so improbable that it can be ruled out almost immediately.
I’m being very careful to only focus on actual evidence. That includes there is no evidence the autopilot was ever re-engaged and the aircraft may not have flown on the centreline of airway N571. So it looks like it could have been a hypoxic ghost flight.

As for the cause, there is a ‘single point of failure’ that doesn’t need to be shoehorned too much to fit the evidence. So what is that evidence? L transponder stops, Satcom stops for about an hour, autopilot appears to be off, no Comms from pilots, hypoxic flight path(possible).

All the above failures would likely happen if an oxygen bottle were to rupture in the left side of the avionics bay.

But, of course, it has always been much easier to blame a nefarious pilot.
birdspeed is offline  
Old 2nd May 2024, 05:52
  #15 (permalink)  
 
Join Date: Dec 2004
Location: 4 seasons hotel
Posts: 269
Received 5 Likes on 4 Posts
Fullwings,

From the very beginning, the term ‘Ghost Flight’ was used to describe ‘silence’ and lack of data to the portion of flight beyond the primary radar detection to the end of flight, which could possibly be a straight line.Not any portion prior.

There is no evidence of:

-Autopilot disconnect
-Autopilot reconnect
-Transponder being ‘switched off’
-Hypoxia
-Following any airways
-Unlawful interference
-Tripping transponder CB
-“Satcom stopped working for about an hour”
-“Mechanical accident failure”
-Nefarious pilot

Dave,

Speculation is only natural for human who can’t refrain from making a statement before having their own thoughts sorted.
flightleader is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.