Sunday, November 30, 2014

South Asian and Southeast Asian Nations (SASEAN) Defence Chief’s Dialogue

Press Release

No PR263/2014-ISPR Dated: November 29, 2014 
 
CJCSC with general jagath jayasuria, chief of defence staff, sri lanka during the sidelines of SASEAN.
 
Rawalpindi - November 29, 2014: General Rashad Mahmood, Chairman Joint Chiefs of Staff Committee (CJCSC), is visiting Sri Lanka to participate in SASEAN (South Asian and Southeast Asian Nations) Defence Chief’s Dialogue. While speaking at the forum, CJCSC highlighted the role played by Pakistan to achieve peace and stability in the region through a perennial resolve against terrorism in its all manifestations. He also dilated upon the functioning of Higher Defence Organization in Pakistan and the synergetic effects of strategic thinking at the highest fora.

Chairman Joint Chiefs of Staff Committee also held wide ranging bilateral talks on the sidelines of SASEAN with host country’s Chief of Defence Staff, General Jagath Jayasuria and delegates from other countries which included, Hon Anatoly Antonov Deputy Minister of Defence of Russian Federation, General Zulkifeli bin Mohd Zin Chief of Defence Forces Malaysia, Lieutenant General Wang Ning Chief of General Staff Peoples Liberation Army China, Major General Dato Paduka Seri Mohd Tawih bin Abdulla Commander Royal Brunei Armed Forces and Major General Ahmed Shiyam Chief of Defence Forces Maldives. During these meetings matters related to bilateral interests came under discussion.

The SASEAN forum is a conclave of Defence Chiefs of 18 regional countries which also constitutes SAARC and ASEAN. This being the first session is significant due to its regional peace, stability and confidence building goal setting agenda, and the coming into prominence of the region due to its natural geographical foray into Indo-Pacific Ocean. Delegates from China and Russia also attended the dialogue as observers.

Wednesday, November 26, 2014

5 Most Fastest Jet Aircraft of The Sky

The concept of jet aircraft was first given by two engineers, Frank Whittle of UK and Hans von Ohain of Germany. Jet Aircraft are powered by jet engines and move much faster as compared to the propeller-powered aircraft.

They are the most fastest beasts in the sky, and they evolved secretly sometimes. Now they are the legends of the ages.

Deferentially they're: 

V. XB-70 Valkyrie

It has a max speed of 3.1 Mach and is produced by USA. It is powered by 6 General Electric YJ93-GE-3 afterburning turbojet machines.
 

IV. Mig-25 “Foxbat”

It is produced by Russia and is really pragmatic in functioning at high altitude above 80,000 feet. Its max speed is 3.2 Mach and is powered by twin Tumansky R-15B-300 afterburning turbojets.
 

III. SR-71 BlackBird

It was developed by Lockheed Corporation, USA in the 1960’s and is the upgrade version of U-2 reconnaissance aircraft. It is powered by 2 Pratt $ amp; Whitney J58-1 continuous –bleed afterburning turbojets with a capability to supply 32,500 lbf thrust each. It can fly as high an altitude as 100,000 feet with 3 times the speed of sound (3.5 Mach). It was in use by USAF for 40 years and was retired in 1998.
 

II. X-15

With the max speed of 6.72 Mach, X-15 is the 3rd fastest jet aircraft. Its engine is Thiokol XLR99-RM-2 liquid fuel rocket engine that uses liquid oxygen us fuel. It can fly as high as 354,330 feet.
 

I. X-43A

This jet is fueled by Hydrogen and can move at a speed of 9.8 Mach. The credit goes to the supersonic-combustion-ramjet. It is produced by USA.
 
 
Source: Internet
 

Tuesday, November 25, 2014

PAF To Get Extra Military Hardwares From USA

A recent post from defence.pk suggests that Pakistan will get some crucial military hardwares from various US sources. These includes:

I. 8 Block 52+ F-16 C Fighting Falcons fighter

Pakistani F-16 Block 52+ Fighting Falcons.

II. 3 Oliver Hazard Perry-class frigate

Oliver Hazard Perry class frigate infographic.

III. Requested the sale of AH-1Z Viper attack helicopters to replace the AH-1F/S Cobras 

 

A devastatingly handsome (and lethal) beast, AH-1Z Viper attack helicopters.
It is likely that Pakistan will exercise the option for the total 18 extra F-16s or buy more surplus ones from the US. Many would say this as the diplomacy of the COAS, but still there something to observe.  Pakistan those AH-1Z Viper attack helicopters, because for both type of war scenario of Pakistan Army, in the east or north-west, they need these attack birds very urgently. 

Recently Pakistan approaches firmly with Russian firms to acquire Mil Mi-35 HIND-E attack choppers in a countable number from Russia.
 

Monday, November 24, 2014

A Big Punch: Snapshot of The Potential Pakistan - Russian Relationship

A listfull of recent Pak-Russia relationship elements:


Pakistan has signed a milestone defense pact with Russian federation which may entail the following. 


* Acquisition of Mi-35 Hind-E assault helicopters for SSG's Special Operations Task Force.

* Joint Counter-terrorism training of Special Ops units

* Joint Air Force training

* Pakistan will participate in Russian tank warfare competition

* Russia will be allowed to have regular port calls and docking at Pakistani ports

* Russia has elevated Pakistan from category D to B for arms sales.

* Smooth supply of RD-93 turbofan engines and its upgraded MA variants for JF-17 Thunder aircrafts.

* Pakistan has just established an upgrade and overhaul facility for its Mi-17 helis, which Russians will help with.

* Both states have agreed to work together in Afghanistan to make sure another civil war doesn't take place

* On economic side, Russia is interested in building a gas pipeline from Nawabshah city of Sindh to Gwadar in Balochistan which will be connected with Iran when the sanctions on Iran are lifted.

* Russia is also interested in rebuilding Pakistan's steel mills, helping with Railways and in building the Tajikistan, Afghanistan, Pakistan, India gas pipeline.

* Russia will also invest in Pakistan's oil and gas exploration sector which is seeing increased activity.

* Increase in bilateral trade which currently stands at just $542 million.



Source: Pakistan Defence.

General Raheel Sharif At Stanford University

General Raheel Sharif spoke at the Stanford University to a committee including scholars and academia like Dr Kiron Skinner and Dr Abraham Sofaer among others. 
 
 
He highlighted Pakistan's role in combating globalized terror and asserted that Pakistan is a nation of resilient people who have defended themselves at great cost.

Greece To Ask U.S. for Two Arleigh-Burke Destroyers: A News From Last Decade

Less than three years after the retirement of the Themistoclis, the last Charles F. Adams-class guided missile destroyer, the Hellenic Navy is ready to officially request two newer vessels from the U.S. Navy. 
 

Navy officials have prepared and will soon send a letter of request for a pair of used Arleigh Burke-class guided missile destroyers under a government-to-government agreement, said Navy Capt. Stefanos Gikas, a spokesman for the Ministry of Defense here. Details about schedule, cost, transfer conditions and weapons would need to be worked out.

“The response of the U.S. administration in the letter of request will be the decisive factor for the implementation of the program,” a high-level Hellenic Navy official said. “What can be said at this initial stage is that the number of the ships should eventually increase to three or four; only at this force level would the introduction of a highly capable and complicated weapon system be worth the initial investment.”

Greece also is asking the United States for four Osprey-class mine-warfare ships and a number of P-3C Orion maritime patrol aircraft. “All these requests will be managed in the framework of the Greek-U.S. Defense and Industrial Cooperation agreement, which governs the military relations of the two allies,” Gikas said.

The destroyers, which carry the Aegis weapons system, are far more capable than anything in Greece’s current fleet. Adm. Panagiotis Chinofotis, chief of the Hellenic National Defense General Staff, said the Burkes would improve Greek and NATO capabilities by:

• Increasing the interoperability of the Greek military and NATO allies.

• Giving Greece a tactical ballistic missile defense capability, thereby allowing the country to participate more actively in similar allied efforts.

• Strengthening NATO’s southeast region, where hot spots and increasing asymmetric threats have drawn more and more alliance attention over the last decade.

• Helping Greece participate in allied missions overseas.

Chinofotis emphasized that “the transfer will also signal the expansion of the Hellenic-U.S. cooperation in the armaments field and the strengthening of the bonds between the two navies, which are more than 100 years old,” he said.

The transfer of the Burkes also may affect the Hellenic Navy’s effort to buy new frigates, the service’s largest program. A proposal to buy one ship with an option for a second is being included in the preliminary drafts of the next five-year unified armaments procurement plan — known as the 2006-10 EMPAE.

The frigate effort will replace the corvette program that was canceled because of excessive costs in November 2002. Some 588 million euros ($722 million) had been planned for the corvettes in 2006-10.

“The picture will become less obscure when the formal process for the 2006-10 EMPAE starts,” the Navy official said. “Until then, everything is a matter of speculation and alternate options.” But he said Greece was determined to maintain a fleet of 14 major surface combatants.

The Navy now operates four Hydra-class (German MEKO-200HN) and 10 Elli-class (Dutch Standard) multipurpose frigates. Six of the Ellis are getting a midlife upgrade under a 386 million euro contract awarded in 2003 to Thales Naval Nederland, Hengelo, the Netherlands, and Hellenic Shipyards, Skaramanga, Greece. A midlife upgrade for the Hydras will begin in 2010. •

The point is...

Are these good or bad news?

Sunday, November 23, 2014

More 5 Mi-171sh Attack Helicopter for Bangladesh Air Force

Bangladesh Ministry of Defense concluded with the company "Rosoboronexport" contract for the supply of five military transport helicopters Mi- 171SH . On this, as reported by ITAR - TASS news agency, said the director of the Special Assignments "Rosoboronexport" Nikolai Dimidyuk . Transaction amount is not specified. Supply helicopters will be on account of export credit in the amount of a billion dollars , issued by Bangladesh Russia .
 
A Mi-171Sh aircraft similar to those to be delivered to the Bangladesh Navy by 2015.

Agreement to provide export credit Bangladesh signed in January 2013. On account of the same transaction will be delivered to Bangladesh combat training aircraft Yak-130. Their transfer to the customer , according to Dimidyuk begin in the second half of 2015 . In total, the Bangladeshi military should get 15 Russian aircraft.

Early last year , when it signed an agreement on the allocation of export credit Bangladesh , Russia also agreed to provide the country $ 500 million for the first phase of construction of nuclear power plants " Ruppur ." It began last fall.

India Must Prepare For A Two-front War: NSA Ajit Doval

India has to be prepared for a two-front war and build deterrence that ensures conflict is not an option for its adversaries, said National Security Advisor (NSA) Ajit Doval, while speaking on future threats at the Hindustan Times Leadership summit on Saturday afternoon.
 
Indian Armys' Female Members.

“India has two neighbours, both nuclear powers (which) shave a strategic relationship and a shared adversarial view of India,” the NSA said. He also confirmed that the government had received reports of Chinese personnel working in Pakistan Occupied Kashmir (PoK) to build infrastructure and New Delhi had already expressed concern to Beijing and Islamabad.

Taking a cue from former foreign secretary Kanwal Sibal, who was chairing the talk, Doval expressed concern at Pakistan’s continued use of terrorism as a part of its foreign policy. “Pakistan’s inter-Services Intelligence (ISI) can bleed India but it cannot “degrade a strong civilisational nation like us,” he said.

However, the NSA expressed optimism that India has been able to engage both countries and “economic inter-dependence” can prove to a frame work to build peace in South Asia.

But clearly the NSA was keen to reinforce Prime Minister Narendra Modi’s plans for a new economic paradigm. “Economic development is the best way to ensure security and a 9% growth will make us totally secure,” Doval said. According to the NSA “a strong economy is the surest means of protecting the country and creates vested interests which will ensure India’s protection.”

Echoing Prime Minister Narendra Modi’s call ‘Make In India’ Doval stressed on the need to put manufacturing on India’s highest priority. “We have a strong decisive government, considerable clout in the international arena and world calls human resources.

Doval, a former Director, Intelligence Bureau, and a much decorated intelligence office also provided context for Prime Minister’s diplomatic whirlwind taking him to the US, Australia, Myanmar and Fiji besides engaging South Asia with vigour. “In a changing world order India is engaging powers who have conflicting views. So we engage China and Japan as well as Russia and the United States.” The reason for this sustained engagement is driven by the fact that India’s economic engagement with the rest of the world had grown from 14% to 40%.

Covering a slew of issues that has dominated India’s security concerns, the NSA also underlined the Modi government’s focus on emerging technological threats from cyberspace. “We are seized of it, we have huge experience, scientific capabilities but we have have lost out on technical issues. Root servers are in other countries, mostly in the USand even private corporations have become very powerful,” he said.

With cyber space emerging as an engine for powerful economic growth,the government will continue to keep a sharp eye on it, the NSA assured.

TAI - TFX Ffth Generation Turkish Fighter: InfoGraphic Video


Saturday, November 22, 2014

United Arab Emirates To Purchase 150 VP11 4x4 Mine-Resistant Ambush Protected Vehicle

United Araba Emirates (UAE) has expressed intrest in purchase of 150 NORINCO's VP11 4x4 Mine-Resistant Ambush Protected (MRAP) vehicles.

The VP11 MRAP vehicle is designed using a 4x4 light truck chassis for reconnaissance, search and rescue operations in urban environment by homeland security forces. VP11 4x4 Mine-Resistant Ambush Protected (MRAP) vehicle is equipped with a remote weapon station which is mounted on the rooftop of vehicle. 
 

Thursday, November 20, 2014

Y-9 Military Transport Aircraft

The Y-9 (Yun-9) is a medium-sized, medium-range turboprop multi-purpose transport aircraft designed and manufactured by Shaanxi Aircraft Corporation. Derived from the Y-8 (An-12 Cub) transport aircraft, the Y-9 features improved engines and modern avionics including a ‘glass’ cockpit, and is believed to be comparable to the U.S. Lockheed Martin C-130J in general performance.


Development History

Shaanxi began to develop a new military transport designated Y-8X in 2001 to meet the PLA’s requirement for an advanced medium transport aircraft to replace its ageing Y-8 fleet. The aircraft later received a new designation Y-9. The Ukraine-based Antonov Aeronautical Scientific-technical Complex (ASTC) aircraft company provided some assistance to the Y-9 development, including the design of the airframe and wind tunnel testing.

Key Data

  • Number in service: Unknown
  • Designer: Shaanxi Aircraft Corporation
  • Manufacturer: Shaanxi Aircraft Corporation
  • Maiden flight: 2006?
  • Crew: Four
  • Powerplant: Four WJ-6C turboprop engines
  • Max payload: 20 tonnes
  • Max take-off weight: 65 tonnes

Design

The Y-9 has a similar aerodynamic layout to the Y-8, with high-mounted wings and four turboprop engines mounted under the wing’s leading edge. The rear cargo door also serves as a ramp to allow quick load/unload of cargoes. The tail flats and fin are mounted high. Additional small vertical stabilisers are installed on the tailplanes.

The aircraft has a two-wheeled nose landing gear and two four-wheeled main landing gears. The aircraft has a four-man crew, including two pilots, a flight engineer and a loadmaster.

Cargo System

The Y-9’s cargo bay is 16.2 m in length, 3.2 m in width, and 2.3 m in height, with an internal volume of 155 cubic metres. The payload requirement includes a range of military vehicles, cargo containers, pallets, and paratroopers. With a maximum payload capacity of 20 tonnes, the aircraft is capable of carrying 98 paratroopers, or nine international standard pallets of 108” X 88”, or eight 125” X 96” pallets. The cargo bay is also equipped with cargo handling rollers and tie-down rings.

Avionics

In addition to radio communication and navigation systems, the Y-9 features a ‘glass’ cockpit and modern avionics including ground proximity warning and collision avoidance systems. An electro-optical turret containing forward-looking infrared (FLIR) and TV sensors is mounted under the fuselage for day/night, all-weather operation.

Engines

The Y-9 is powered by four WJ-6C (Wojian-6C) turboprop engines each rated 5.100hp. The engine features a six-bladed JL-4 propeller.

Specifications

CARGO BAY DIMENSIONS
Length 16.2m
Width 3.2m
Height 2.3m
WEIGHTS
Empty 39t
Normal take-off N/A
Max take-off 65t
Fuel capacity 23t
Max payload 20t
PROPULSION
Powerplant 4X WJ-6C turboprop
Thrust (dry) N/A
PERFORMANCE
Max level speed 570km/h
Cruising speed 550km/h
Cruising altitude 8,000m
Service ceiling 10,100m
Range 5,000km
Take-off/landing distance 1,350m

China Conducted 3rd Missile Interception Test

China had successfully conducted another ground-based mid-course missile interception test on its territory on 23rd July. No further detail about the test was given. This is the third exo-atmospheric missile interception test conducted by China, following the two successful tests in January 2010 and January 2013.

China’s missile defence programme can trace its origin to Project 640, a multidisciplinary strategic defence programme launched in the late 1960s. The programme was cancelled in 1980 but researches on relevant technology were being continued under Programme 863 since 1986. These researches began to yield results after 2000, which has led to a number of high-profile weapon tests since 2007.



The missile interception test at a night in January 2013 was witnessed by many people in western China.
 
China conducted an anti-satellite (ASAT) weapon test in January 2007, destroying a retired satellite in low Earth orbit using a booster-carried kinetic kill vehicle (KKV). The same technology was believed to have also been used in the two mid-course missile interception tests in 2010 and 2013, and possibly the latest test too.

The 2013 missile interception test was conducted in the missile impact zone in Xinjiang in western China, with a booster-carried KKV (reportedly designated SC-19) successfully intercepting a ballistic missile launched from the Jiuquan Satellite Launch Centre.

What Actually Is The Poland's Stealthy PL-01 Tank?

Has Poland's OBRUM and its partners designed the tank of the future? The PL-01 does pack some incredibly valuable features into a fairly compact and modular concept, and yes, it also looks cool as hell.
 
 
The idea of the PL-01 is to try and eliminate the infrared, radar and visual signature of the traditional tank to a large degree, while also relying on guile to take identity masking a step further. In addition, the PL-01 concept aims at brining to market a tank packed with relevant modern features, many of which already exist off the shelf, while others are still on the developmental horizon. The vast majority of targeting sensors on the battlefield today rely on the infrared band of the electromagnetic spectrum to do their bidding. The PL-01 attempts its almost magical infrared signature reduction via the installation of temperature controlled wafers that blanket its exterior. This chameleon's skin of sorts, allows the tank's skin to match the infra-red signature of its surroundings. It does this by processing what small infrared sensors mounted around the tank detect, and then displays a pattern on the tank's honeycomb-like covering that best matches the infrared data collected. As a result, the tank all but disappears to infrared sensors. Even more outstanding, these wafers can also be used like pixels, as each can be manipulated in temperature. This allows for the tank to use active infrared camouflage, such as tiger stiping its infrared signature in the jungle, or making it flat like the sand in the desert. The PL-01 also lowers its infrared signature through cooling and dispersing the exhaust from its 940 hp diesel engine.

The PL-01's proposed active infrared camouflage system can even go a step further, from concealment to trickery. The tank can even make itself look like a car or another common object, via matching the temperature of its surroundings and then displaying a preprogrammed image on its temperature controlled wafers. This is an amazing countermeasure that, if reliable, can make enemy detection and the creation of a firing solution almost impossible during nighttime operations for a large percentage of any enemy's anti-tank weapon systems. Active camoflauge for military vehicles is nothing new, in fact it has been tested as far back as the 1940's via mounting lights on aircraft, and later ones that change intensity and shade depending on their background. There are rumors that "visual stealth" was tested on aircraft as late as the 1990's. Even Boeing's Bird Of Prey program was said to have tested some forms of visual signature reduction. We have also seen YouTube videos of LED suits that use light sensitive receivers to "cloak" an object, or even more incredible this new capability that is straight out of the Predator movie franchise. This is precisely what the PL-01's designers say they are working on for their tank now, and future models are claimed to offer both infra-red and visual "cloaking" and "spoofing" capabilities. Such a technology would work in the same way as the tank's infrared masking capability, basically by using data from video or light sensitive receivers mounted around the tank and displaying the image taken from one side of tank on the opposite side. This is similar to putting a camera behind a flat panel TV and viewing the camera's feed on the TV. If the magnification was right the TV would all but disappear from a distance.
 

With the miniaturization of technology, I would not doubt if a similar system has been tested on aircraft and even ground vehicles in the US as well. Infrared, and even visual detection, remains a low observable aircraft's "achilles heel," and so called "silver bullet" platforms, meant to kick down the enemy's air defenses, or to spy on an enemy without being detected, could greatly benefit from this technology. Although putting such an elaborate system on a 40 ton tank is very different than installing it on a 15 ton fighter, where weight is always an issue. The infrared spectrum continues to dominate the ground side of the modern battlefield, especially after dark, so having the ability to blend into your thermal surroundings, or to even look like something totally different than what you actually are, should drastically increase your survivability. The PL-01 tank is also said to be almost entirely coated with radar absorbing material, and the vehicle's very low-profile and faceted design is said to reduce radar returns in a sizeable manner. This could be quite valuable, as detection of armored formations via standoff strategic platforms using ground moving target indicator (GMTI) radar will increasingly be proliferated throughout the world. Additionally, radars and missiles that use millimeter wave radar for detection and guidance, such as what is found on the Mi-28N and the AH-64D attack helicopters, are also becoming more common place as a means of attacking armored targets under adverse weather conditions.

Finally, modern fighter and attack aircraft can use their radar systems to detect, and even target armored vehicles, even while those vehicles are moving. With this in mind, lowering the radar signature of a main battle tank, thus decreasing its detection range, can mean the difference between life and death when a roaming pack of enemy multi-role fighters is out hunting for tanks to plink. The PL-01 is also quite intuitive and efficient with its general design, as it only uses three crew, and has an auto-loading system in its turret that carriers 16 rounds (24 more are stored in the hull). The turret, which is unmanned, is modular in nature, and may allow for different turrets, with different capabilities, to be to be interchanged if need be. The PL-01 was designed to field a 105mm or 120mm smoothbore cannon, that will be capable of firing sabot, high explosive, or guided missile rounds. In addition to the main gun, the PL-01 will have a 7.62mm coaxial gun internally mounted turret right next to the main gun, in a similar configuration to the Abrams, as well as a detachable remotely controlled 7.62 or 50 caliber independent gun turret system.
 
 
For the tank's commander, gunner and driver, the latest multi-spectral sensor and targeting systems from BAe and its affiliates are also proposed to be integrated into the stealthy tank. This may include a distributed aperture system (DAS) like spherical situational awareness visual system, similar to what is found on the F-35. Similar systems, albeit of a less complex design than the one found on the F-35 Joint Strike Fighter, are now being adapted for nautical and land-based applications. In the case of a tank, this could mean that the Tank Commander could potentially wear a helmet mounted sight that would allow him to "see clearly through" the walls of the tank, day or night. This is done by taking a constellation of staring camera sensors placed on the outside of the vehicle, and then stitching their video images together using software and sheer processing power. This virtual visual sphere can then be projected into the tank commander's helmet mounted site. Think of a virtual tour of a room in a home, but real-time imagery. In effect, such a system would provide a tank commander a full 360' day or night view of the outside of his tank. Additionally, this system could also automatically detect targets, both in the air and on the ground, or even movement around the tank if it is set to do so. The PL-01 will also sport active defenses in the form of a Trophy like system, where electronic actively scanned array (AESA) radars will be installed around the turret. Once a high-speed projectile is detected moving at a threatening vector, the system will fire one of its countermeasure rockets to intercept and detonate infront of the incoming projectile, thus killing it, or greatly decreasing its kinetic energy, before impacting the tank. Also, laser detection sensors will be distributed around the tank so that early warning of an imminent enemy attack could initiate automatic ejection of infrared and laser masking smoke mortars, which are mounted flush with turret to keep the tank's radar signature low.

The PL-01 basic tank will come stock with level 5 ceramic-composite armor installed on its frontal hemisphere, with level four armor on its flanks. Additional plug and play armor is said to also be an option for working in extremely high-threat environments, such as urban battlefields. Currently the PL-01 weighs in at about 33 tons, with the additional armour it is projected to weigh close to 39 tons. This would put it in at about 3/5's the weight of an Abrams and about ten tons lighter than the fully loaded Russian T-90 main battle tank. What is also very exiting is that the PL-01, which is based on the Combat Vehicle 90 chassis, will be offered in multiple formats, including a command vehicle, an armored repair vehicle and a mine clearance vehicle. This will allow a forward deployed armored column to work as a single team, using common parts, to accomplish various tasks. What is also smart, is that designers did not include an ambulance, an armored personnel carrier and other disparate capabilities that would have compromised the effectiveness of its baseline design and most certainly would have added to the PL-01's final cost and overall complexity. 
 

The PL-01 seems like a fantastic concept as it takes a modular approach to proven and effective tank design, while also incorporating new technologies and signature control capabilities that are very intriguing to say the least. Although, as with so many "concept" vehicles and weapon systems, it will be interesting to see if BAe and OBRUM can delivery on their many promises and successfully integrate all these attributes into a reliable and effective weapon system. With that said, the choices as to what technologies to integrate into the PL-01, and how to properly integrate them, seems to be incredibly well thought out and truly intriguing. A full working prototype will be fielded in 2016, with initial production beginning near the end of the decade according to OBRUM, so we will just have to wait and see if Poland and their British friends have truly revolutionized the tank as we know it.



Is it possible to fly 4 helicopters anywhere in a country without official knowledge?

If a helicopter is flying low, and not "squawking", there is no way that any civilian radar will pick it up. Especially in a mountainous region such as Pakistan. Simple mechanics of radar as illustrated by this picture from Answers.com. Note that mountains between the radar site and aircraft will further block the ability of the radar to detect an aircraft.
 

Keep in mind that if they can't be seen, they can't get shot at either. And these are some of the best helicopter pilots on the planet. Most radars are unable to detect anything flying contours, but I would wager that for part of this they were flying nap of the earth. The below image is taken from the Global Security Website (the exact image is from Figure 28 on this page) where they discuss many modes of flight for helicopter safety from enemy fire.

Even larger aircraft like the FB-111 would use this technique to avoid detection without the need for stealth technology.

So even though the airspace is monitored, if they can't be seen, it doesn't matter. Also, I don't think this was "allowed" or "disallowed" by the Pakistani government. Some covert operations are carried out, and then back-briefed if the target (such as Osama bin Laden) is important enough.

ADDED INFO:

Now, several folks have asked about the helicopters used, and some of their performance characteristics. The most likely aircraft (as reported in a couple of other answers as well) is the MH-60 Pave Hawk (a Blackhawk variant modified for special operations). Again, to quote Global Security, the performance characteristics are:

Primary Function Infiltration, exfiltration and resupply of special operations forces in day, night or marginal weather conditions.

Power Plant Two General Electric T700-GE-01C engines

Thrust 1,630 shaft horsepower, each engine

Length 64 feet, 8 inches (17.1 meters)

Height 16 feet, 8 inches (4.4 meters)

Rotary Diameter 53 feet, 7 inches (14.1 meters)

Speed 184 mph (294.4 kph)

Maximum Takeoff Weight 22,000 pounds (9,900 kilograms)

Range 445 nautical miles; 504 statute miles (unlimited with air refueling)

Armament Two 7.62mm mini-guns

Crew Two pilots, one flight engineer and one gunner


In particular, note that these aircraft are mid-air refulable from a KC-130 (NOT KC-135), thus they have a nearly unlimited range. I highly doubt that they took off from anywhere inside Pakistan (i.e. Ghazi) but rather originated in Afghanistan. I cannot say where exactly though, but no matter where they took off from, if they received refueling prior to entering Pakistan, the range is more than adequate to get to Abbottabad and back on one tank of gas (looking at google maps, it appears that the distance is less than 350 KM from Kabul, or about 200 miles). So a little less than 400 mile round trip, at about 200 MPH would be about 2 hours total (add in the actual assault and there you have your timeline). These figures are approximate though because things change with load-out and other configurations. These aircraft would probably have flown in a formation that would probably helped to disguise their true numbers.

Someone mentioned that ATC must have a squawk to paint these aircraft. That is overstated, however as previously mentioned, they were probably well below the radar, and aided by the mountainous terrain. Add in they were most likely using EMCON 4 procedures, and then it would be even more difficult to pick them up by any means. As the cited article also mentioned, the noise reduction and additional radar absorbent paint just added to the stealthiness of these aircraft (as if SPEC OPS flight patterns were not enough).

And thanks to Kit Sunde, we have further info: Here's Pakistan denying having known about the raid http://bbc.co.uk/news/world-south-asia-13268517 which also states: "US helicopters entered Pakistani airspace making use of blind spots in the radar coverage due to hilly terrain."


Source: skeptics.stackexchange.com