MH370 - what happened
A plausible explanation for why MH370 "disappeared" and why we still can't find it.
MARCH 10, 2014
What happened to MH370?
Has anyone considered if the below FAA Airworthiness Directive could be a clue the MH370 investigation?
A November 2013 FAA Airworthiness Directive for the 777
http://www.gpo.gov/fdsys/pkg/FR-2013-09-26/html/2013-23456.htm
SUMMARY: We propose to adopt a new airworthiness directive (AD) for
certain The Boeing Company Model 777 airplanes. This proposed AD was
prompted by a report of cracking in the fuselage skin underneath the
satellite communication (SATCOM) antenna adapter. This proposed AD
would require repetitive inspections of the visible fuselage skin and
doubler if installed, for cracking, corrosion, and any indication of
contact of a certain fastener to a bonding jumper, and repair if
necessary. We are proposing this AD to detect and correct cracking and
corrosion in the fuselage skin, which could lead to rapid decompression
and loss of structural integrity of the airplane.
Update 3/12, 16:43:
It has been brought to my attention that this specific Malaysian Airlines aircraft
“9M-MRO, the aircraft operating MH370, was not equipped with the SATCOM antenna affected by the airworthiness directive.”
However, this does not discount the possibility that the aircraft flew for hours (on autopilot) after a decompression event. (The 777 had an early history of decompressions when the first planes were rolling off the assembly line in 1995.)
There may be other high-risk fuselage seams that could have worn out and affected radio equipment (and/or pressurization). There are also many low-level circuits, sensors, and valves related to pressurization could have malfunctioned. (e.g. Air/Ground sensors/circuits, an “air duct clamp”, etc.).
Ultimately, some type of decompression—slow or rapid—is still likely in this situation, given the lack of clear communication from the pilots.
[Updated] Summary: It seemed likely that a fuselage section near the SATCOM antenna adapter failed, disabling satellite based - GPS, ACARS, and ADS-B/C - communications, and leading to a slow decompression that left all occupants unconscious. If such decompression left the aircraft intact, then the autopilot would have flown the planned route or otherwise maintained its heading/altitude until fuel exhaustion.
A slow decompression (e.g. from a golfball-sized hole) would have gradually impaired and confused the pilots before cabin altitude (pressure) warnings sounded. The also likely possibility of an extremely-rapid decompression is described toward the end.
Chain of events:
Likely fuselage failure near SATCOM antenna adapter, disabling some or all of GPS, ACARS, ADS-B, and ADS-C antennas and systems.
Thus, only primary radars would detect the plane. Primary radar range is usually less than 100nm, and is generally ineffective at high altitudes.
If the decompression was slow enough, it’s possible the pilots did not realize to put on oxygen masks until it was too late. (See Helios 522)
Also explains why another Pilot thirty minutes ahead heard “mumbling” from MH370 pilots.
(VHF comms would be unaffected by SATCOM equipment failure.)
With incapacitated pilots, the 777 could continue to fly on Autopilot - programmed to maintain cruise altitude and follow the programmed route. Using the Inertial Reference System (gyroscope based), the plane could navigate without needing GPS.
Other thoughts:
The plane was [UPDATE: WAS NOT] equipped with cellular communication hardware, supplied by AeroMobile, to provide GSM services via satellite. However this is an aftermarket product; it’s not connected through SATCOM (as far as I know).
[UPDATE]: However, if the plane flew over or near land, then cellular connectivity is still possible.
Interestingly, 19 families signed a statement alleging they were able to call the MH370 passengers and get their phones to ring, but with no response.
When Malaysian Airlines tried to call the phone numbers a day later, the phones did not ring. By this time, fuel would have been exhausted.
Note: 777 Passenger Oxygen masks do not deploy until cabin altitude reaches 13,500. Passengers were likely already unconscious by then, if it was a slow decompression. Also remember that this flight was a red-eye, most passengers would be trying to sleep, masking alarming effects of oxygen deprivation. No confirmed debris has been found anywhere near the search area, consistent with the plane having flown for hours after it lost radar contact.
[UPDATE 3/12]:
Issues of Decompression:
The flight probably did not experience an or “inflight breakup” or “explosive decompression” that caused the plane to just “fall out of the sky.”
Instead, it’s more likely that a non-catastrophic decompression incapacitated the crew. It could have been a slow decompression. (This scenario is more likely if the “mumbles” observed by another MH pilot are legitimate.) It could have also been an extremely rapid decompression, forcing the lungs to exhale more rapidly than they are capable of. Either type of decompression makes it difficult for the crew to respond before becoming incapacitated.
This table from Carlyle shows that after a moderately rapid (2-6 second) decompression at MH370’s cruise altitude, the crew would have had only 30-45 seconds of useful consciousness unless they started oxygen breathing soon enough.
For all 3 types of (slow, moderate, extremely-rapid) decompression, there is substantial danger to the crew and passengers.
Provided the overall structure of the plane was still intact at the time of a decompression, the autopilot would have continued along the route autonomously. In order to descend to 10,000 feet, the autopilot must be commanded to do so or disengaged entirely.
So why does all this matter?
The aircraft may be at the floor of the East China Sea, Sea of Japan, or the Pacific Ocean thousands of miles northeast from the current search zone. [UPDATE: Basically, it could be “anywhere”, and we need to use any available radar records to help figure it out. It could have turned in any direction and continued on for hours. This is where the Vietnamese/Malaysia civilian and military radars will help.]
Recommendations:
Investigators should obtain data logs from primary radars throughout mainland China that would have been along the planned route. They may be the best clue as to the trajectory of the aircraft.
Investigators should obtain all passengers’ cell phone log and location data. The timing of the last successful cellular connection (ring/SMS/data-packet) can predict how long the plane was in the air. iPhone/iOS location (GPS) data may be available from Apple if subpoenaed. Android location data may be available from Google.
Add a secondary search space to include a 300nm+ radius around Beijing, focusing on surrounding bodies of water. Using planned routing trajectory, known autopilot logics, fuel quantities, and weather patterns, it may be possible to define a smaller 50nm * 50nm search space. Consider running the above scenario in MH’s 777-200ER full flight simulator.
Boeing should provide expertise about fuselage/antenna seam reliability and autopilot/navigation logic, so as to help plot this second search space.
For Inquiries: mh370lost@gmail.com
8:36PM | URL: http://tmblr.co/ZdLK9o19nZlt6
(Notes: 171) FILED UNDER: mh370 missing investigation
| 777-200 | 777-200ER | |
|---|---|---|
| Passengers Typical 3-class configuration Typical 2-class configuration Typical 1-class configuration | 305 400 up to 440 | 301 400 up to 440 |
| Cargo | Total volume 5,330 cu ft (151 cu m) includes up to six pallets, 14 LD-3 containers, plus 600 cu ft (17 cu m) bulk cargo. | same |
| Engines maximum thrust | Pratt & Whitney 4077 77,000 lb Rolls-Royce Trent 877 76,000 lb General Electric GE90-77B 77,000 lb | Pratt & Whitney 4090 90,000 lb Rolls-Royce Trent 895 93,400 lb General Electric 90-94B 93,700 lb |
| Maximum Fuel Capacity | 31,000 U.S. gal (117,340 L) | 45,220 U.S. gal (171,170 L) |
| Maximum Takeoff Weight | 545,000 lbs (247,200 kg) | 656,000 lbs (297,550 kg) |
| Maximum Range | 5,240 nautical miles (9,700 km) Typical city pairs: London - New York Denver - Honolulu Tokyo - San Francisco | 7,725 nautical miles (14,305 km) Typical city pairs: London - Los Angeles Tokyo - Sydney Chicago - Seoul |
| Typical Cruise Speed at 35,000 feet | 0.84 Mach | Same |
| Basic Dimensions Wing Span Overall Length Tail Height Interior Cabin Width Diameter | 199 ft 11 in (60.9 m) 209 ft 1 in (63.7 m) 60 ft 9 in (18.5 m) 19 ft 3 in (5.86 m) 20 ft 4 in (6.19 m) | 199 ft 11 in (60.9 m) 209 ft 1 in (63.7 m) 60 ft 9 in (18.5 m) 19 ft 3 in (5.86 m) 20 ft 4 in (6.19 m) |
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