Most ATC in the world rely primarily on secondary radar to know where planes are. This requires that the transponder on the plane works correctly.
This means that maintenance and deployment of primary radar is no longer a primary concern for airspace regulation. It becomes at best a secondary backup system before they need to pull out the flight progress strips and airways charts.
Where are the spots that is not covered by primary radar? I understand that some military ships have primary radar and can act as a mobile radar during operations.
There are a few spots not covered by primary radar. Here are a few I can think off:
Afghanistan, not really what you'd expect from flying between Europe and South East Asia. I was told though by the pilots that the Americans were keeping an eye on us. I'd imagine there are a few holes in the CIS countries as well.
Multiple areas in Africa, but this is improving I believe. There's a post on PPrune. Apparently known as the 'dark continent' for spotty coverage and consistency. South Africa has good coverage, and I'd guess the same for much of northern Africa as well.
A few remote areas in South America, then again, improving.
Oceans are not covered.
Determining factors are population density, aircraft density and economic development.
As more you Malaysia map, if there's a radar at Kota Bharu [KBR] airport, here's the map assuming a range of 200 Nm for the radar. It should in theory be well within reach.
And an extended version:
SGN Ho Chi Minh City (Saigon) [Tan Son Nhat Intl], VN
KUA Kuantan [Sultan Abmad Shah Airport (Pedang Geroda Airport)], Pahang, MY
KUL Kuala Lumpur (Sepang) [Intl], Selangor, MY
KBR Kota Bharu [Sultan Ismail Petra], Kelantan, MY
Just for the interested, here's a map showing Japanese military radar, just to get an idea of coverage in a country full of people and planes.
Maps from http://www.gcmap.com/
There are large gaps in radar coverage in the Gulf of Mexico. The FAA sponsored a study that looked into receiving ADS-B reports from aircraft in the surveillance gap and reformatting them to look like radar reports from a fake radar sensor in the Gulf so they could be ingested by their existing air traffic control software systems.
A lot of airspace is not covered with primary radar, at least not for ATC purposes.
Most airspace above seas and oceans are not covered by ATC primary radars. ATC relies mainly on secondary radar for surveillance, primary radar is used mainly for airspace infringement protection and airport surface surveillance. Over oceans and remote areas procedural control is used, without any surveillance.
Most primary radars used for long range surveillance in ATC are operating in the L-Band. L-Band signals do not follow the curvature of the earth very well; at low altitude the range is limited because the aircraft are below the horizon. At higher altitudes the range is up to about 250NM, but only when the radar is operated at very high power, which is costly both in design and electricity bill. In many cases it is not needed to operate at long range. Radar is also shielded by terrain; in mountainous areas it is difficult to cover the valleys. In Europe, and I believe also in the US, high altitudes are well covered by primary radar, at low altitude there are many gaps.
A lower band (HF - UHF) radar can be used to look over the horizon (OTH radar). This type of radars is used for Air Defence purposes. The resolution is very poor compared to radars used for ATC but it serves well as an early warning system for incoming enemy aircraft and missiles. This type of radar requires huge antenna arrays, over a kilometre long and they consume enormous amounts of power.
The effective range is typically about 3000 km. For example Australia has the Jindalee Operation Radar Network, that can see past Jakarta, Indonesia. JORN coverage
In case of the missing Malaysian MH370, and the latest suspicions that the aircraft ended up West of Perth, I wonder whether the flight was tracked by the OTH Air Defence radars of Australia.
In relation to missing flight MH370, and the radar coverage of that region, please see the link to the Department of Civil Aviation Malyasia's primary and secondary (SSR) radar services in the region.
The first page lists all the Primary and Secondary (SSR) civil/military radar services and then page 10 graphically represents the 200NM SSR ranges of each station.
So to determine how much of the map is covered by primary radar only, you can match the names of the stations on the map with the table on page 1, and use the 200NM area as a guide to determine the primary radar reach of each station.
As an example, the BBC website shows how flight MH370 changed course with this graphic:
If we look at the radar coverage map again, we can see that this means the flight passed through the primary radar station coverage of Kota Bharu, listed as 1.1.4(g).
Hope this helps, and I hope all the people are found safe.
Primary target: An aircraft not reporting mode-C, the only thing the controller has is the return on the radar. When a controller reports a primary target as traffic to other aircraft, the controller does not have the altitude of the target. Given this, I conclude that ATC radar does not have the altitude (angle-up) to the target, and only provides azimuth. So then without the altitude, how does the radar-system know where to put the target laterally on the screen? Example, a radar picks up a target that is 10 miles from the station. If the target is 0 AGL, the proper position would be 10
Most ATC in the world rely primarily on secondary radar to know where planes are. This requires that the transponder on the plane works correctly. This means that maintenance and deployment of primary radar is no longer a primary concern for airspace regulation. It becomes at best a secondary backup system before they need to pull out the flight progress strips and airways charts. Where are the spots that is not covered by primary radar? I understand that some military ships have primary radar and can act as a mobile radar during operations.
Are airspace violations (e.g. entry to class B without clearance) based on primary radar and/or Mode C transponder, or something else? I read that Mode C altitude is based on pressure altitude, i.e., set to 29.92" ... but presumably that's adjusted at the ATC facility based on the current pressure before being used for altitude enforcement. This begs the question, what would stop one (hypothetically), just winding back the altimeter pressure reading to appear to be at a lower altitude? So to summarize: How are airspace violations detected: What data input is used? If Mode C reading
Based on the reading I've been doing of FAA's Next Generation Air Traffic Control (NextGen) plans, I've been wondering if and how radar systems will continue to be used for ATC as NextGen rolls out? Questions include: Is it correct to assert that radar coverage will effectively become a less precise, backup only, data feed? I am suggesting this because my understanding (which could easily... be phased out? Seems unlikely due to airspace security issues alone. But are there any other reasons to keep radar coverage?
covered mesh with an aluminum sheet embedded. This would be easier than seat cushions to see from satellites and planes, and the aluminum layer would reflect radar and make it easier to find. This alone...Without getting into the mess of redesigning existing Flight Data Recorders, I have a simple proposal that I think would help in deep water crashes. I propose that several floating cushion sets.... This is just so we can find plane crashes in the sea when we don't know precisely where they went down (and to get basic data when the black boxes are too deep to get to immediately). Malaysian flight
Aircraft certification is covered by 14 CFR 23 and 25, what parts cover aircraft engines?
Is it legal for a pilot with an FAA license to fly a foreign registered aircraft within the United States? Is it covered by FAA regulations, or the country of aircraft registration?
In remote areas that have no radar (oceanic airspace, etc.) how is aircraft separation maintained so that airplanes don't get too close? What do areas that normally have radar do when there is a sudden radar outage? There are airplanes going everywhere, not necessarily on standard airways, and a lot of them are being given radar vectors. What happens when the screens go dark?
I just finished reading an interesting post where the author suggests that the missing Malaysian Airlines flight 370 could have 'hidden' under the cover of Singapore Airlines flight 68 to fly to a covert airstrip. I've read multiple thrillers where submarines have hidden behind the acoustic signal of large cargo vessels to mask their sound over sonar arrays, and this (at least in the book) sounds plausible. I also read another book where a bomber (flying under the identity of a commercial jet) masked a business jet to get it into an area without detection. Naturally, both examples are taken
What is the average range, accuracy, and update frequency of radar systems used to monitor airspace in the USA? I'm primarily interested in capabilities for tracking smaller general aviation aircraft without enhanced return data channels like ADS-B, etc. Please include sources, if possible. As an example, by looking at TRACON/ASR data exports (CDR), these systems appear to update an aircraft echo at about a 4.7 second frequency, give or take a few tenths. However, I not been been able to source or verify my findings or similar statements made by expert witnesses in litigation cases.