China Deploys Satellites In Search For Missing Malaysia Airlines Flight 142
EwanPalmer writes "China has begun using its orbiting satellites in a bid to find the missing Malaysian Airlines flight. The Xi'an Satellite Monitor and Control Center is said to have launched an emergency response to search for Flight MH370 after it went off radar over the South China Sea in the early hours of Saturday. The center is reported to have adjusted up to 10 of its high-res satellites to help search for the plane."
Auto-play video on linked article (Score:5, Informative)
There's an auto-playing video embedded in the linked article's page - just in case you hate that sort of thing.
Re:Thoughts (Score:5, Informative)
Radar is line of sight. So a plane at 11000 meters, can be seen about 375 km away from the radar installation, assuming a radar at ground level.
If your radar is within 200km of the plane, the plane would fall below the radar horizon at about 5km altitude.
Given the description of the plane's flight path, if it was being tracked by radar from Kuala Lumpur, then "dropped off the radar" would have been closer to 10km altitude than to 5km.
Re:Thoughts (Score:4, Informative)
IANAATC, but...
Most center surveillance radars have a range of 200 - 250NM (ARSR-3, ARSR-4, AN/FPS-117, AN/FPS-67B). Secondary beacon radars have a range of about 190NM for 1090ES equipped transponders.
You are correct in assuming most high altitude center control ops, for aircraft in cruise, rely heavily on MODE-S data. This is transponder data and not primary radar echo return data.
Terminal radar, the kind you see at your local airport, mostly relies on primary radar data. But at a shorter range (~50NM).
The reasons for the difference are many, but come down to accuracy and overlap. Center controllers use a mosaic of data from multiple radars that must average primary returns, this leads to slight disagreements on the true location of the aircraft. The MODE-S data is constant though, so it is preferred. In terminal environments, there's usually a single radar set. So the primary data is more useful in terms of accuracy for spacing the aircraft (they can pack them in tighter more safely). Terminal radar sets also have a higher scan rate.
MH370 was over the Gulf of Thailand and was under coverage of about three different radars. Even if the transponder was turned off, primary return data would still be available for the track. CrimsonAvenger has a valid point, but the last known location of the flight was far off shore and at a cruising altitude. So we could possibly speculate that line of sight was not a big factor.
There's a lot of big mysteries and speculation at this point, but we just need to give it time. They will eventually find the wreckage and hopefully determine they cause. There are many historical crashes that required more searching than has been applied to MH370 (AF447). In the meantime, grab some popcorn and enjoy the conspiracy theories...
Re:Thoughts (Score:5, Informative)
A loss of hydraulic pressure or power does not do this for a 777. It has a RAT (ram air turbine) which pops out in such cases. Basically a big propeller which gets turned by the wind as the plane glides at 500 mph and generates enough power rudimentary electronics (including radio) and hydraulic pressure. That's what happened with the Gimli Glider [damninteresting.com] - a 767 mistakenly loaded with insufficient fuel (the original boneheaded imperial vs metric conversion foul-up before the Mars Climate Orbiter). which basically turned into a 100 ton glider when it ran out of fuel mid-flight. The RAT popped out and allowed the crew to control the plane to a safe landing. (Which of course means if this did happen on MH370, the search area needs to be much larger than where they're currently looking).
Hydraulic failure usually involves structural damage which compromises all the hydraulic lines. Most commercial aircraft have 3 independent hydraulic systems; some have 4. If there's damage which severs lines in all of those systems, the plane can "bleed" hydraulic fluid until there's not enough left to control the flight surfaces. I believe the 777 used a hybrid fly-by-wire + hydraulic system though, where pilot commands are transmitted to the flight surfaces by wire, and a hydraulic pump there moves the flight surface. So severing the hydraulic lines may have killed one control surface, but not all. (Severing the wires OTOH...)
Anyway, I'm skeptical that it broke up at altitude too. That usually generates a lot of floating debris (papers, luggage, clothing, bodies, etc.) scattered over a wide enough area that the crash area is quickly located. The pingers [benthos.com] should be firing away so it's just a matter of one of the search boats traveling within a few miles from the plane's resting location. (KAL007 wasn't located because the Soviets knew from their radar tracks where it went down, and set up decoy pingers far away to get the U.S. and South Korea to search the wrong location).