Theory: Why Zaharie Left the Cockpit

I have to confess that I made a blunder a month or two ago. I fell victim to the easy Google search, and snagged what I thought was a picture of the overhead circuit breaker panel (CB) for the B777. In that image, it showed CBs for the passenger O2 system, both the deploy and sensing circuit. Seemed easy enough to reach up there and pull 3 CBs and disable the passenger oxygen.

But a nagging thought was that it did not seem right. It was too easy.

So I started another search a few days ago, and could not come up with confirmation that those CBs were indeed on a B777. I found study guides and images of the CB panels, but the O2 CBs simply were not there. I was upset with myself in part because I was wrong, and in part because I try to be honest about what I do and do not know.

I also could not find the cockpit voice recorder (CVR) CB in any of the study materials. That made me even more upset. I was convinced that Boeing left the CVR CB in the cockpit so it could be pulled to preserve data in the event of an incident. At least that's how my B767 works. I knew the B777 is a more modern aircraft, but Boeing does such a good job in commonality even in diverse aircraft.

But I was back to basics. I was wrong about the CVR CB, and I was wrong about the passenger O2 CBs being in the cockpit. I was reasonably sure the flight data recorder (FDR) was downstairs in the Main Equipment Center (MEC) below the floor behind the flight deck. This is the area that cannot be reached from the cockpit, but could be accessed from the main cabin through a hatch in the floor. It was the reason I felt Zaharie made a mad dash to the MEC—to disable the FDR.

The B767 has a similar place. It's cramped. But it's jammed packed with all kinds of cool stuff, racks, wire bundles, and fans whirring. It's a kind of a tech kid's tree house, but below decks. I often pop down there during maintenance activities just because...well, just because.

I assume the B777 MEC is a little more roomy, but not by much. Making something like that roomier and more comfy for the mechanics won't sell more seats. My airline does not have B777s...or I would have been below decks putting eyeballs on the stuff I've been talking about.

I feel confident I've made a reasonable case in my last post that there's a clue Zaharie left the cockpit soon after leveling off at FL350. Literally there is a full 14 minutes that Zaharie could have been out of the cockpit, and there's no reason we would know about it.

Except young FO Fariq's stumbled and unusual radio call made around 17:08 UTC.

That was such an unusual call because Zaharie would be "working" the radios as the pilot monitoring (PM). It strongly suggests to me that Zaharie was not in the cockpit. If he was, he would not allow young Fariq to make that call, since he called in earlier, and if he was, HE should have made that call. This was a training flight, and Zaharie should be following standard cockpit protocols.

No, my surmise is that Z was out of the cockpit. I presumed it was for the FDR CB that I was convinced was below decks. This is the graphic I put together to make my case. If you follow me, you've seen this before:

So this evening, I decided to take some time, and really press on to understand just where those CBs are. I am well familiar with something airline manufacturer's publish called Component Locator Guide (or sometimes Manual). It's a goldmine of stuff that pilots rarely need to look at, but if you teach aircraft systems as I do, it's a treasured resource in preparing training materials.

Lo and behold! It was not the Twitter Gods who brought me the needed tablets, but Scribd. I found the B777 CLG published there, and downloaded it and started pawing through those electronic pages like a kid digging under the Christmas tree, looking for the right package size for that expected gift.

It did not take me very long, and I discovered all that I needed to know. I feel I know why Zaharie needed to get below decks, and into the MEC. Everything he needed to disable is located down there. Everything. Those passenger O2 deploy systems. The flight data recorder. And yes, the cockpit voice recorder.

The Component Locator Guide, it's sorta like a roadmap. Everything you need to find has a numbering system and an illustration that will help you find it (for you Millennials a roadmap is sorta like Waze). I quickly found my way through the tables and found this:

Right there in the middle of the list are the passenger oxygen CBs I was looking for. The Left, Center, and Right passenger oxygen. The A and B channel CBs to deploy the passengers oxygen...and to the right, in the column PANEL/RACK, it tells me where to find it: P310.

Next step is to find P310. That was not difficult. I knew where it would be—down below decks, in the MEC. Panel 310 Standby Power. That's where you put things that you're gonna need when you're down to your last trick. Like making sure the O2 masks deploy when you need them.

The illustration shows it labeled in the top-left graphic.

Moving on to other issues. What about the flight data recorder? Can I confirm that? Yup. Right there in the component locator, dutifully telling me the CIRCUIT BREAKER FLT RCDR AC CB is found on panel P210. The Boeing 777 FDR runs both on AC power and DC (battery) power. I won't bother including the image, but on the next page we find CIRCUIT BREAKER FLT RCDR DC CB. Pull both of those, and the FDR goes dumb.

And yes, the P210 panel is below decks (you can see it in the above graphic).

Plane made dumb, now the plane must be made deaf.

The cockpit voice recorder was my next search. I had a hard time finding that. There was no CVR or Cockpit Voice Recorder in the list. I knew it had to be. It was not in the "INDICATING/RECORDING SYSTEMS" as I expected. But with some persistence, and being not young, I found it under CIRCUIT BREAKER VOX RCDR CB in the COMMUNICATIONS system. Back in my younger years, VOX was common term for "Voice Activated Switch" (or variations of that). In other words, the CVR. Where was that? Panel P110. Where is Panel P110?

Down in the MEC, next to P310 where the passenger oxygen CBs are found.

Bingo!

I now feel I know why Zaharie left the cockpit. IF my hunch is correct, he left the cockpit, and under some kind of "I'm the captain" sorta thing, opened the floor hatch (highly, highly unusual), and headed below decks. Once there, he would have known exactly where the CBs were to be found, and would have pulled them, making MH370 deaf, dumb, and dangerous (no O2 for the passengers).

The maximum of 14 minutes he could have been out of the cockpit is MORE than enough to pop into the cabin, open the hatch, do what he needed to, and get back topside prior to reaching IGARI. When Zaharie made the first call as they leveled off at FL350, he knew exactly when they were going to reach IGARI. The flight computer would have told him that.

He had the time to go below, and he would have known the time he needed to be back before reaching IGARI. He just had to have time to order young Fariq out of the cockpit for some reason (any reason, it would not matter).

He may have even sprung it suddenly on FO Fariq, who quite possibly left his mobile phone on the right side glareshield.


NOTE: Everything I put in the blog can be found with minimal effort on the Internet. This is not some kind of state secret. Bad actors who might be interested in such things, already know such things. Safety and security are important to me. I'm going to have some discussions with my airline about securing that hatch (I hope that some airlines already do).

PREDICTION: If the CVR and FDR is found in the debris field, both will have stopped working sometime after 17:05 UTC but before 17:14 UTC.