10. UK EQP - SSR & Nav Aids Flashcards
What are conspicuity codes?
Non-discrete codes may be used (‘squawked’) by
more than one aircraft at a time and some non-
discrete codes are allocated as general codes to
certain classes of operation.
E.g., the General conspicuity code for aircraft in
Class G and VFR in Class E in UK is 7000.
In the UK, other conspicuity codes are allocated for
Special purposes, which have specific meanings.
These are contained in the AIP and MATS 1.
Examples of special purpose codes in the UK
0020 Medivac
0023 SAR ops
0030 FIR lost (and contact 121.5MHz)
0033 Para dropping
0035 Selected helicopter flight
0036 Helicopter pipeline/powerline survey
0037 Royal helicopter flight
1177 London Control (Swanwick) FIS
7010 Aerodrome traffic pattern conspicuity
What is D & D?
DISTRESS AND DIVERSION CELL
Aside from the use from an individual unit,
pilots in UK can make use of a positioning
service called Distress and Diversion.
D&D use frequency 121.5MHz for Civil and UHF
(UDF) 243MHz for military triangulation.
D&D respond immediately, but aircraft may be
below cover. D&D may call you to request you
provide them with a DF bearing from your DF
display. (by selecting 121.5mHz on your DF)
D&D is located at Swanwick ACC; and is staffed
by RAF ATCOs/ATCAs.
The primary role of D&D is to provide pilots with
an emergency aid and position fixing service.
VDF accuracy
Class A – Accurate within +/- 2 degrees
Class B – Accurate within +/- 5 degrees
Class C – Accurate within +/- 10 degrees
Class D – Accuracy less than Class C
Your station will have a notified accuracy -
NDB Accuracy
Bearing accuracy is to within 5° (ideal conditions)
but can be downgraded.
Maximum promulgated range in UK is 50 nm.
Withdrawal of En-Route NDBs
Removal of the 10 NERL operated NDBs
commenced 2010.
There are only 2 remaining NERL NDBs are
scheduled to be withdrawn in the near future
originally 2020: – Henton (HEN) & Woodley (WOD)
VOR Accuracy
Accuracy is plus or minus 2º in the UK
– ICAO =1.25º
Spaced between 50nm and 100nms apart to ensure low level coverage.
A rationalisation plan is in progress to reduce
the number of VORs. This is consistent with the
attitude to these facilities in much of the world.
UK VOR Uses
UK rationalising VOR use by downgrading from
46 VORs to just 19.(more reliance on GPS)
The current plan for future withdrawals is as
follows: Manchester (MCT), Trent (TNT),
Barkway (BKY), Detling (DET), London (LON),
Brookmans Park (BPK) & Brecon (BCN)
Of those VOR stations that have been
withdrawn most retain the DME aspect
An up-to-date list of current En-Route
navigational facilities can be found in
AIP ENR4.1.
The VOR rationalisation plan will also involve
the replacement of equipment at the 19 sites
identified for retention and this replacement
program will require each site to be taken out of
service for between 2 and 3 months.
NOTAMs are sent out regularly with the
information, together with CAA safety notices.
DME accuracy, use and errors
Accurate to within 1nm.
Can accept up to 100 aircraft interrogations
simultaneously.
Subject to slant error - the closer to the beacon,
the less accurate the readings become.
DME Separation
According to MATS 1, DME cannot be used for
separation purposes when aircraft are within 15
miles of the facility.
Within the UK for separation purposes, any
distance within 15 miles must be treated as
unreliable and rounded to 15 miles.
Hence for an outbound aircraft to be 5 miles
away from another outbound at say 8 miles, it
would have to pass 20 miles; the other aircraft
would be rounded to 15 miles.
Therefore, an aircraft at say 6 miles has to be
taken as being at both 0 and 15 miles, and
every distance in between.
This will become relevant once learning
about separations.
