User:Dual Freq/JPALS

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ROUGH DRAFT -Dual Freq 12:06, 10 January 2006 (UTC)

The Joint Precision Approach and Landing System (JPALS) is an all weather landing system based on differential signals for the Global Positioning System (GPS). The International Civil Aviation Organization (ICAO) calls this type of system a Ground Based Augmentation System (GBAS).

1 History
2 Operation
3 Benefits
4 Drawbacks
5 Variations
6 Future
7 See also
- 7.1 External links

[edit] History

JPALS was created to address the need for a portable precision approach system. The current standard, the Instrument Landing System (ILS), is not portable and can not be taken to a battle area. JPALS is a self contained system that can be taken to any area where a precision approach is needed.

[edit] Operation

JPALS operation is similar to the Local Area Augmentation System. Both are situated in the vicinity of an airfield and provide integrity for and enhance the accuracy of GPS. WAAS is meant to cover an entire region of the world, but JPALS and LAAS are meant to cover only a 20-30 mile radius.

[edit] Benefits

JPALS will provide additional monitoring of the GPS signal for better integrity. It will rapidly warn users of potential problems allowing for the user to execute a missed approach. It will provide enhanced accuracy by monitoring the GPS signal at several local reference points and transmit appropriate corrections to the user.

The naval version of JPALS transmits a signal that has a low probability of intercept. Meaning it is unlikely that an enemy will detect the signal and trace it back to it's source. The existing system, TACAN, is not encrypted or concealed in any way and basically tells the enemy the bearing and range of the ship is is installed on. This is not acceptable if emissions control (EMCON) or stealth are required.

[edit] Drawbacks

LAAS's VHF uplink signal is currently slated to share the frequency band from 108 MHz to 118 MHz with existing ILS and VOR navigational aids. This will require some existing navaids to be turned off. Additionally, users will require additional aircraft based equipment.

[edit] Variations

The US Navy has developed a similar project that has enhanced features to allow automatic landing of carrier based aircraft. This requires horizontal and vertical accuracies of less than 15 cm.

[edit] Future

Due to the similarity between JPALS and LAAS, the FAA may chose to adopt it instead of LAAS. The FAA's goal for LAAS is to replace the existing ILS equipment for all categories of precision approaches.