Malaysian Airlines MH370 contact lost

[Lonewolf_50]

Compromised cockpit remains an open possibility.
So do a few other not so happy scenarios.

The transponder thing was true in my fledgling days, but I doubt that 777 has such archaic avionics.

It is amazing how quickly the mods are ditching posts. Wow.

jet noseover:
Yes. Was trouble shooting mine. Turned it off, recycled the CB, turned it back on to stby to warm it up. A few minutes later, with the code assigned, it seemed to work based on ATC getting a good squawk out of me. This was over 20 years ago.

[Australopithecus]

Ditto re stndby on ATC TX. When I learned to fly that was the accepted procedure. Forty-three years ago. Time has marched on since then.

[Pitot Probe]

No never.

Only xpdr change I can think of is a checklist action to go from TA/RA to TA Only following ENG failure/shutdown.

[LASJayhawk]

Jet, I did work on a KA200 that had a duel transponder failure coming into KLAS.

The seal on the R/H cheek panel was no good and they flew through rain.

Both TDR-90s had water pour out of them when I pulled them.

Unless they have added some wiz-bang feature, it is also possible that A transponder failed. And if they were busy, or ATC didn't call them to point it out, I doubt they would know.
No reply does not mean they were turned off...

[Australopithecus]

The common element for the transponders, VHR COMM #1, the GPS recvrs and the Satcoms is the antenna locations on the fwd fuselage.

That said, and with the understanding that there is a lap joint AD in effect, and with the alleged transmission of cabin disintegration received in Utapao yet one more theory emerges.

The Aloha 737-200 was very much shorter and only just held together apparently, so the scenario of a fuselage failure on a 777 being possible, and then allowing for another hour of flight would be astonishing. Although it would explain many data points.

[B777FD]

If the transponder is turned off/on standby, do ATC (civil or military) still get a contact with no associated information? A primary return?

I'm a little confused by the impression I am getting from various posts that a large jet can go "invisible" by switching squawk to standby. Can SSR work where PSR cannot?

[Stanley11]

Ok, let me ask you this...Any of you had ever turned off the transponder on the flight for any reason? If so why?

I regularly operate within Military airspace. We turn it off (Standby) when operating within the circuit. When operating low in the training areas (definitely out of radar and transponder coverage), we turn it on but sqwark a common code.

To add (not relevant for this case), when we operate in such locations, it's known as 'flight monitoring'. I.e. the control agency will not be able to see us but know that we are somewhere in that area. We will call in every half hour to report. If we fail to do so, they will call to check. SAR will be dispatched only when we are way over due. I think this is very common for GA as well.

[LASJayhawk]

B777FD If you go to standby, the transponder will still hear the interrogations, but not send out any replies. So no, it would not show up on SSR.

[mattfl]

This is starting to sound like a variation of Helios Flight 522:

Helios Airways Flight 522 - Wikipedia, the free encyclopedia

The left turn may have been an attempt by one of the remaining crew-members to return to land. Some news reports claim it was a low as 3'000 after turning west - other reports say is was sill up near 30k. If it did drop from the cruse this is further evidence that possibly one remaining member of the crew was making a valiant attempt to save the lives of aboard.

[LookingForAJob]

I'm a little confused by the impression I am getting from various posts that a large jet can go "invisible" by switching squawk to standby. Can SSR work where PSR cannot?

Yes. SSR heads typically have greater range than primary heads and, for en-route surveillance, it is quite common for civil ATC to have no primary cover.

[Dendrite]

Thailand will not be wasting their tax payers money over Malaysia authority blame game, sending them to search South China Sea, Gulf of Thailand, Andaman sea, and probably Indian Ocean next.

Missing MH370: Thai Navy may cease hunt for plane

[pilotday]

All this transponder talk is silly. Why would anyone try to select 7700 and not tell ATC anything?

We won't know what happened until they find the black box…if ever.

this may go down in history as just one of those accidents where you never find the wreckage.

Its a huge ocean…..won't be the first or last time a plane disappears.

[Stanley11]

Why would anyone select 7700 and not tell ATC anything?

Yes:

1) Unable to transmit voice (headsets failure, radio failure)
2) Unable to speak - loud cockpit noise such as canopy failure, partial pilot incapacitation, cannot speak audibly due to 3rd party (terrorist situation)

we even have codes following 77xx, to mean other failures, Hydraulics, Electrical, oxy, etc...

[LASJayhawk]

Jet, it is possible a transponder failed (it happens) Unless ATC yelled at them or the failure caused a TCAS error message they may not have noticed.

The point is, no reply from the transponder does not mean someone switch it off on purpose.

[Stanley11]

@Weary

In a part of the world historically known for the cultural practice of face saving, who would confess to pulling the trigger?

It is not easy to do this in the dark and cover it up. The hoops to go through are very complex. No one would want to do that. Trigger happy loose cannons just do not sit around waiting for opportunities like this. If ever this scenario even happened, the authorities would be very quick to spin it to their advantage, saying that they need to protect the ground from a larger collateral damage. This is not a region where people are staring down each others' barrel. There are just so many ways to disprove this theory.

[jugofpropwash]

I've seen little information about the pilots, other than that the copilot was transitioning. Does anyone know if the pilot regularly flew this route? Seems like someone who "knew" the area well might react differently than someone who didn't in the event of a com and nav failure. He would, perhaps, be more able to determine his position visually based on ground lights, and would be more apt to know of other (even disused) airports. Also, did he usually fly at night? He had a high number of hours and presumably seniority?

[Old Boeing Driver]

Continuing Transponder Saga

On the 777, if a transponder fails, will it auto transfer to another transponder, or is there a message of failure and a manual transfer to an operating transponder?

The last airplane I flew auto transfered, and gave an advisory message and chime.

[TRW Plus]

Checking the back weather data, both KL and Penang were essentially calm and partly cloudy all night during the hours when this flight could possibly have been returning in that direction. Broken cloud layers were reported at or near 3000 ft. From what I recall of the satellite imagery (but I was then concentrating on areas further north) there were tropical thunderstorms quite a bit further south (probably south of Singapore) but as usual in this part of the world, dissipating and remnants drifting west. I think we could rule out weather as any kind of a factor in this event, even some theoretical last stage return to base.

[LASJayhawk]

Old Boeing Driver. I have never seen a setup on an American built plane that auto switches. Doesn't mean there isn't one....

Most failures will trip a fault that will show up but some faults in the receive path won't trigger an error, the transponder just won't know it is being interrogated, and won't reply.

Jet I agree it stinks to high heaven, but that doesn't mean it was a willful act by someone on the flight deck...

[Stanley11]

At the rate this SAR is going, I doubt the debris field, if any, would remain clustered together. I fear that we'll just have to wait patiently for the debris to wash up on some coast, hopefully populated, and then back track the currents and find the crash site.