The critical question of locating MH370’s black box comes down to determining the turn at or after IGARI waypoint. This is a timeline of events we know leading to what was likely a decompression event while climbing before, at, or after IGARI waypoint to an unsafe flight level.
I am assuming that at IGARI, the Captain & Co-pilot had either a bet of some sort, or a filed flight plan based saving time and/or fuel by using a higher flight level, which may or may not have been approved by the airline. This would then have had to occur without ATCs approval (which they appear to have not been able to get from Malaysian ATC as evidenced in the transcript).
Therefore, the logical stream of events would assume that at IGARI, they both agreed to disable the transponders, ADB, and ACARS to data mask (other than the black box) their unapproved higher flight level. This is the only logical way you get the ACARS not being damaged, but turned off without damaging the FMC and keeping engine management going.
When and where they then encountered a decompression event is important because that tells you when they may have started their (presumably left) turn to the closest airport, which is the 11,000 foot runway 22 at WMKN airport (98 nm away). Yes, they had time to descend to this airport. This runway didn’t have ILS and this was at night so they may have wanted to arrive at this airport at a higher flight level to spot the airport. And they may have wanted to arrive at this airport with energy in case of engine problems. However, since we know that the plane had no engine problems, they may have felt confident to descend and prepare for landing.
NO, they didn’t go west to VAMPI.
See: how Inmarsat data disproves Malaysian western radar track. This radar track is a plane (not MH370) leaving Singapore, headed inland Malaysia, before exiting on air corridor to middle-east. The reason that that Defense Ministry offered this radar of another plane is because they wanted to link MH370 to terrorism, based on the two Iranians with the stollen passports. However, they have no actual radar evidence that connects MH370 at IGARI spotted by Thai radar to the western track.
As they headed southwest towards TGGX1 waypoint to line up for WMKN airport, if they lost control, it seems unlikely that they would have programmed a missed approach w/a climb. They would have had to antcipate that they’d get knocked out. If they did it would be somewhat futile regardless. So, I’d assume that any missed turn to runway 22 would have left the plane on AP heading mode at a fixed altitude that remained for the rest of the flight. This heading, this speed, and this altitude, the airplane’s weight at the time, and the winds along the way are the crucial variables that would be all you’d need to determent he likely impact area.
Here’s the star of timeline:
Somewhere their FMC levels them off above FL100. They accelerate past the 250kts <10,000 foot restriction before climbing to FL350. Then they’d climb based on whatever best climb speed for their weight
Crew confirms FL350
They would be accelerating to .84 cruise
Transponder ranges MH370 at:
Relay is attempted from Japan-bound plane “30 minutes ahead”
Last possible moment ACARS could have been active
Unconfirmed: Last primary radar contact by Malaysian military
320 km northwest of Penang
The image I’ve seen has a time of 02:22H on it, 18:15 UTC is 02:15 local.
Last partial Inmarsat handshake
Missed arrival in Beijing (2500 nm trip)
In addition to the Inmarsat ping times, which I may cover separately, this is the extend of our knowledge until they find some debris. Therefore, there is one of two good tracks you can take. I’m assuming that the WMKN track makes a lot more sense, especially since they’ve moved the search area 1,000km to the northeast. This coincidentally matches a 1.3-2mph drift rate over 19 days.
WMKN diversion track:
2932.9nm over 7h 31m at average of 390 kts
3384nm over 7h 31m at average of 450 its
To have reached the MEKAR waypoint (the farthest western point in the radar) by the time Malaysia claims (in 1h 34m), it would have to had an average ground speed of 470 kts. Then, with the remaining (7:30-01:40) 5h 50 minutes of the trip (based on the last handshake, it would have had to travel roughly, 2643.1 nm at an average speed of 480 kts.
Now, factoring in a 30 kts tail or crosswind from the east, indicated airspeed will be the same (ground speed adds the wind). Ground speed will be different.
For the first track to IGARI from WMKK, you have 274.8 nm. The last reported radar contact is 6.920833, 103.578611, which happens to be precisely where the IGARI waypoint is located, which is curious. Is this accurate? Or, are they estimating the location of IGARI? Or, was IGARI chosen because that’s were transponder radar cuts out? Unless there was a freak coincidence of accident, or that they left the cockpit at that waypoint and there was a waypoint, you need a good reason why the transponders are shut off at this precise location.
The wiki says that the transponder cuts out two minutes after the radar contact is lost, and three minutes after ATC voice contact.
If you assume that they disabled ACARS themselves temporarily to mask their desire to go to a higher flight level, then they would have continued past IGARI for some distance as they climbed before a decompression event.
If they’re at FL35 @ .84 mach, this converts to 555 kts. At a heading of 239 at 555 kts with a 30 kts 90 deg headwind, groundspeed is 580 kts with a 2 degree wind correction. They would have then started to climb at an unknown feet/min. Let’s say they select the limit FL430, that’s a different of 8,000 feet. If they want to get there quickly, they might select 2000 feet/min, which would bring them to their desired FL over 8000/2000 or 4 minutes. If we assume that they lost 30kts or so during the climb, we’re looking an at average ground speed of 550 kts over 4 minutes past IGARI, which is a distance covered of 36.7 nm.
This coincidentally brings you to BITOD waypoint, it’s the same distance of 37nm
I’m then guessing that at IGARI they started for their next way point, BITOD. They started to climb for 4 minutes over 36.7 nm to a higher FL and they decompressed near the limits of the plane.
If you assume that the 184 missed approach is the more likely track (because it’s closer to the transponder cut), then this means that the plane would have remained in a fixed state from about TGGX1 or closer, depending how close they wanted to be to the airport before turning. TGGX1 is about 20nm out from the runway (777 is a big plane). This this leaves you with a remaining, roughly, 2503 nm of distance to reach the current search area based on Inmarsat data, on a course of 184.
Based on this track, if you average the speed over 7.5 hours, you get 380 kts. This is for the whole flight, so the last speed could have been slower along the final leg. I’m therefore initially estimating, based on the 184 IGARI turn track (assuming that they may have started climbing sooner than IGARI, or that their left turn around brought them back around close to IGARI), that they then flew on a course around 184 for 2502.7 nm over 6h 35m, leaving them somewhere near -36°4.15’S 99°49.22’E or -36.067778°S 99.817403°E.
First prediction: -36.067778°S 99.822803°E (-36°4.15’S 99°49.22’E)
New search area: -37.443724°S 102.424284°E (-37°26'37.41”S 102°25'27.42”E)
The distance between these two points is 150nm on a bearing of 320/140. So this then depends on the drift of the currents in the area, whether debris would go as much as 1000km or less depending on eddies. Depending on the currents in the area, we can then go back to the prediction and assume that the plane continued on to BITOD and turned at a point where the souther track would correspond to any debris drift rates, once it’s located.
However, on a head of 184 with AP mode set and no FMC waypoint, there would be no automatic wind correction. Therefore, if we calculate an average true airspeed of 380 kts, the correction for a 90 degree 30 kits crosswind would be a 5 degree correction. We can then go back and re-plot the true heading from TGGX1 at 184+5 (to the west)=189 degrees over 2503 nm. And the answer is:
Corrected prediction: -37.566690°S 95.509453°E (-37°34.08’S 95°30.64’°E)
New search area: -37.443724°S 102.424284°E (-37°26'37.41”S 102°25'27.42”E)
This new distance between a wind-correct predicted impact and the search area is 350 nm on a bearing of 310/130. If debris drift rates need more distance, we can then assume that the turn occurred later on it’s climb to BITOD or assume a different ground speed from the average of 380 kts.
What then becomes questionable is the heading, altitude & fuel consumption at a given speed that MH370 was at coming into TGGX1 with. I’ve assumed a 380 kts ground speed. As a plane descends, there is a maximum safe speed that can reach. And if we work backwards and assume a correction for a 30 kts crosswind, then true airspeed would have been a bit less, like 379 kts. If we then assume that a waypoint was used for TGGX1, after which they went to heading hold mode, then that means that their last heading would have been their wind corrected course from the FMC.
If they then desired a heading to TGGX1 of 184 with the ~30 kts E crosswind, and their speed was ~376 kts indicated, FMC would have course corrected -5 degrees and they would have been actually heading 184 degrees at a grounds speed of 380 kts.
Then we’re left with altitude and fuel consumption, for a 777-200ER based on the performance charts, for a 2503 nm range over a 6h 35m flight (380 kts ground speed or 376 kts indicated).
At flight level FL120 with 280 KIAS and an 380 KTAS, the fuel burn may have been in the range of 6,600-6,900 PHH/Eng. Over 6.5 hours * 6750 PPH/Eng gives you 43,875 Lbs/Eng of fuel burn per engine. Doubled, you get 87,750 lbs. If MH370 is said to have 49,100kg of the fuel load, at a specific gravity of 1, that translates into 108,000 lbs of fuel or so. Therefore, based on this prediction, we’d assume that the plane would have already burned 108,000-87,750 lb = 20,250 lbs fuel for both engines having taken-off, climbed-out, & flown from WMKK to IGARI TGGX1. The turn & descent from FL350 IGARI to TGGX1 would have used less fuel.
A Trent 892 powered 700-200ER at 648,000lb take off weight uses something like 14,400lb/h for both engines. Since we’re 1 hour into the flight, perhaps this makes sense to have burned 20,250lb of fuel to have taken off to FL350, then cruised for about 20 minutes?