MLS Airports facilities

[Gustavo Guido]

Hi everyone,
I'm doing some studies regarding "Microwave Landing System", and could
anybody tell me were I can find a list of airports around the world
that operate with MLS of any category? tks

[Jon Woellhaf]

Gustavo,

The FAA's new _Instrument Procedures Handbook_ has this to say about MLS:

MICROWAVE LANDING SYSTEM

The MLS is a precision instrument approach alternative to the ILS. It
provides azimuth, elevation, and distance information, as well as a back
azimuth capable of providing guidance for missed approach procedures and
departures. In addition to straight-in approaches, the MLS system can also
provide three-dimensional RNAV type approaches in both computed straight and
curved paths. It was initially designed to replace the ILS system and it
provided inherent flexibility and broader reception range with the greatest
limitation being the capabilities of the airborne equipment installed in
individual aircraft.

The MLS has multiple advantages including an increased number of
frequencies, compact ground equipment, and complex approach paths. For a
variety of reasons, particularly the advent of civil use GPS, MLS
installation was deferred, and by 1994 it was officially cancelled by the
FAA. Today there are few MLS installations in the U.S. and currently there
are no plans for further installations. Furthermore, the MLS equipment
required for an MLS approach was not widely installed in aircraft, whereas
most new aircraft produced today come with GPS systems. With the limited
number of MLS installations around the country, it is highly unlikely that
most pilots will ever encounter the MLS approach, and if they do, it is even
less likely that the proper equipment would be installed in the aircraft.

Like the ILS, the basic MLS approach requires the final approach course
alignment to be within 3° of the extended runway centerline. This type of
approach uses a glide slope between 3° and 6.40°, and provides precision
landing minimums to 200 feet HAT. Obstacle clearance is based on the glide
slope angle used in the approach design. The design criteria differ for each
type of MLS approach and incorporate numerous formulas for the derivation of
specific course criteria. This information is contained in FAA Order 8260.3
Volume 3, Chapters 2 and 3.

Boise, Idaho, is an example of an MLS installation still in use in the U.S.
[Figure 5-46 on page 5-56] In the front of the TPP, there is a page
containing additional information pertaining to the use of an MLS system.
The MLS Channeling and Frequency Pairing Table cross references the
appropriate MLS channel with its paired VHF and TACAN frequencies. Ground
equipment associated with the MLS operates on the MLS channels, while the
MLS angle/data and DME is required to operate using one of the paired VHF or
TACAN frequencies. In the case of Boise, the DME system operates on 113.65
MHz, the paired VHF channel for MLS channel 626.

Jon

"Gustavo Guido" > wrote in message
om...
> Hi everyone,
> I'm doing some studies regarding "Microwave Landing System", and could
> anybody tell me were I can find a list of airports around the world
> that operate with MLS of any category? tks