ATC Operations at Ronaldsway
since my retirement in September 2014
An attempt to record
some of the changes to ATC operations from then up to the present day.
ATC is a constantly evolving operation with new equipment and procedures
being introduced on a regualr basis. As I am no longer working there,
I am using various sources to keep up with the changes.
For a detailed explanation
of day to day ATC at Ronaldsway see ATC 2014
Airspace Revision - November
With effect from the
13th November 2014 all class 'F' Advisory Routes within UK airspace were
abolished, either completely or replaced with another category of Controlled
Airspace. Around the Isle of Man route W2D to Pole Hill (for Blackpool
& Leeds), W911D to Dean Cross (for Newcastle) and W928D to BLACA (for
Prestwick & Glasgow) were abolished and becambe Class G airspace.
Aircraft formerly using these routes now leave the air route structure
as soon as they cross the Isle of Man Control Zone boundary, unless they
choose a longer less direct route. Ronaldsway Radar can provide a
service until around 40 miles away and then hopefully hand the aircraft
off to another agency. In many cases Scottish Control are happy to
provide a service to these aircraft, depending on controller workload.
Route W911D from IOM
to BOYNE (for Dublin) changed to a class 'E' airway and was renamed Y911
with a base level of Flight Level 75, the airspace is also a Transponder
Mandatory Zone (TMZ) for VFR aircraft wishing to operate within its confines.
Aircraft operating under the Visual Flight Rules can cross the airspace
without a clearance so long as they have an operational Mode-S radar transponder,
making them visible to ATC.
The base level of FL75
can cause some additional workload to Ronaldsway controllers, particularly
when runway 08 is in use as the Manual of Air Traffic Services states that
controllers should keep aircraft with Controlled Airspace if at all possible,
but with a short distance to touchdown from the Control Zone boundary it
is almost inevitable that pilots will request to descend below the airway
to avoid additional routing and wasting fuel, the ATC service being provided
to them might then change three times within around 20 miles.
around the Isle of Man from 13th November 2014
Changes to Ronaldsway's ATC
Radio Frequencies and remote Approach Radar Radio Station - December 2014
A project that dates
back to the 1990s to improve Ronaldsway's VHF radio coverage at lower levels
over the north of the island became operational towards the end of 2014.
Originally planned and tested with an additional transmitter/receiver station
on 120.850 at Jurby, revised plans have re-located the main Approach/Radar
radio station to Snaefell summit from the airfield at Ronaldsway. Due to
the new location and mountain top elevation, this required alterations
to the main operating frequencies for Ronaldsway to prevent interference
to other aeronautical radio stations. On the 22nd September 2014 'Radar
2' frequency 118.2 MHz was permanently withdrawn from service to allow
engineering work to commence for the main frequency changes. With effect
from the 11th December 2014 the new operating frequencies are:
- 135.9 MHz
on Snaefell Summit, with standby at Ronaldsway
- 119.0 MHz
Transmitters & receivers
remaining at Ronaldsway
Other (when instructed
by ATC) frequencies are 120.850 and 125.3 and can be used for a second
radar position or Ground Movement Control when traffic requires. The old
Tower frequency of 118.9 was replaced by 119.0 and is no longer available
at Ronaldsway. This change to the primary Approach and Tower frequencies
was the first since they were introduced into service on the 16th January
Replacement of ATC Surveillance
systems at Ronaldsway - 2011 onwards.
A requirment that was
identified around 2010 was to replace the 15 year old Watchman PSR &
Cossor SSR radar systems. The Watchman would have required extensive
refurbishment to continue in operation and the Cossor Mode A/C SSR needed
to be replaced by the start of 2012 to comply with requirements to operate
only Mode-S systems. The replacement systems chosen were a Selex
ATCR-33S Primary Surveillance Radar to be installed at Ronaldsway with
a Wide Area Multilateration Mode-S SSR system operating from multiple sites
around the island. Part of the project included a ground surveillance
system showing aircraft and vehicle positions on the airfield.
The equipment was installed
in 2011 but due to various unforeseen technical issues, the project
had an extended development period to try and bring it up to an acceptable
performance level before it could be used by ATC. As a result of
this the Watchman radar had to be modified (in common with all existing
ATC 10 Cm radar systems) to prevent interference from 4G mobile phone transmissions
that were planned to operate at frequencies adjacent to those of ATC radars.
The Cossor Secondary Radar System suffered a major fault and was temporarily
withdrawn until a new aerial could be installed and the system returned
to service. Temporary permissions had to be obtained from the UK
CAA to continue operating the Mode A/C SSR system.
The new system went
'live' on the 3rd September 2017, operating in a combined Primary Surveillance
& Multilateration Secondary radar only mode.
The new radar system
is completely processed with no primary radar 'blips' displayed on the
screen as with the older system. Instead, different symbols are used
to show the source and type of information displayed. The primary and secondary
radar is combined electronically and aircraft tracks are then displayed
to the controller.
A primary radar only
contact is show as a vertical cross +
An MLAT only contact
is shown as a diagonal cross x
A combined contact (PSR
& MLAT) is shown as a star *
is provided to the controller based on information being downlinked from
the aircraft Mode-S transponder, depending on the type of transponder fitted
into the aircraft. The most basic information displayed shows the
aircraft radio callsign, either as a Flight Number for airline flights,
Aircraft Registration, or Military Callsign. This information can
be stored in the transponder in the case of aircraft registration, or has
to be entered by the crew before each flight in other cases. The
aircraft vertical level (Flight Level) is also transmitted and displayed
either as a flight level or an altitude if the aircraft is operating at
or below the Transition Altitude, 3000 ft in the case of Ronaldsway at
present, although this is due to change to 18,000 ft in the future.
More advanced transponders
also downlink 'Enhanced Parameters'. This can include, selected level
on the autopilot, aircraft indicated airspeed, actual aircraft heading
and the barometric pressure set on the altimeter. These can be displayed
on the controllers display as required. From the Selex Primary Radar, digitized
weather returns can be overlaid on the display to plan for weather avoiding
requirements by pilots.
Selex ATCR-33S Radar
Selex Wide Area Multilateration
Selex data on the
Mode-S two line Data
Mode-S three line
Radar Interference from Wind
It is an unfortunate
fact that the growing number of both onshore and offshore wind farms are
causing problems to ATC radar surveillance capabilities. Most ATC
radars cancel out unwanted 'static' returns by using filters that detect
the difference between stationary and moving targets. Wind turbines,
by their very nature are presented to the radar processor as moving targets
and it is therefore are difficult to remove them as clutter on the display.
The older Watchman radar at Ronaldsway suffered from this from time to
time, even though the nearest wind farms at the time were technically over
the 'radar horizon'.
Primary radar returns
from rain showers around the Isle of Man
Mandatory Zone (TMZ)
The problem with newer
fully processed radar systems is that when sufficient levels of data processing
are introduced to remove the unwanted clutter from windfarms on the display,
the actual aircraft returns can also be removed. Secondary Surveillance
Radar returns should be unaffected by the wind turbines and a Transponder
Mandatory Zone (TMZ) has been established over the wind farm for the benefit
of Warton airfield, located near to Blackpool and operated by BAe for the
production and flight testing of Typhoon and Hawk aircraft. The TMZ
only operates during Warton's notified hours of opening from Monday to
Friday and any aircraft that wishes to transit through the airspace must
either be fitted with a serviceable Mode-S transponder or contact Warton
for a clearance to transit. At present, Ronaldsway is having to restrict
radar services offered outside controlled airspace.
on the Watchman Radar Display
in the northern Irish Sea around the Isle of Man
including the Walney
Transponder Mandatory Zone (TMZ)
Rationalization of the UK Ground
Navigation Aid Infrastructure - 2014 onwards.
With a major change
under way to 'Performance Based Navigation' (PBN) using GPS (backed up
and checked by other systems, e.g. DME beacons) as the main navigation
source for aircraft there is a program by NATS En-Route Limited to reduce
the number of ground based radio aids. Around the northern Irish Sea area
the VOR at Dean Cross (DCS) was withdrawn from service in December 2014,
leaving the DME in operation and plans indicated that the VOR beacons at
Glasgow (GOW) and Turnberry (TRN) would be removed in 2016 and Manchester
(MCT) in 2017. In fact, all of these beacons remain in service as of November
2017. The New Galloway Non Directional Beacon 'NGY' was scheduled
to be withdrawn in 2016 but remains in service as of November 2017.
The VOR/DME beacons at Isle of Man (IOM), Belfast (BEL) and Wallesey (WAL)
are scheduled to be replaced with new equipment. The Isle of Man
beacon was re-furbished during the summer and autumn of 2017 and was due
back in service on the 15th December. Where the VOR beacons have
been removed, the Distance Measuring Equipment (DME) element remains, as
this is an important component for area navigation sytems in aircraft.
They can be used to determine an aircraft's exact position automatically
by using the DME ranges from two or more beacons and this can be used to
check the integrity of other naviagtion systems.
The 'IOM' VOR/DME
beacon undergoing work in July 2017
Aerial view of the
'IOM' VOR/DME in 2018
A near vertical view
of the 'IOM' VOR/DME
Changes to agreed levels for
Ronaldsway traffic on Airway L10 to the south east.
'Agreed Levels' are
long term arrangements between different air traffic control agencies to
reduce coordination requirements, every flight being climbed or descended
to the agreed level, usually by a certain geographical location.
The agreed levels with Scottish Control for traffic operating on airway
L10 to the south east of the Isle of Man had fo a long time been set too
low for many modern high performance aircraft.
The previous agreed
outbound level for traffic heading south east towards Liverpool was Flight
Level 70 (7,000 ft) which often caused a problem with higher performance
aircraft such as the FlyBe Dash8s and EasyJet Airbus's reaching it rapidly
after departure from Ronaldsway, resulting in a lot of extra telephone
co-ordination between Ronaldsway and Scottish Isle of Man Sector.
Also inbound aircraft were being forced to descend earlier than they would
like to achieve the agreed inbound level of FL80 (8,000 ft) abeam point
KELLY, 15 miles to the south east of the airport and about 20 miles from
touchdown if runway 26 was in use but 40 miles from touchdown if runway
08 was in use. Raising the inbound agreed level to FL100 (10,000
ft) allowed outbound aircraft to be climbed up to FL90 (9,000 ft) without
any co-ordination between Ronaldsway and Scottish Isle of Man Sector.
Another change still
'in the pipeline' is to raise the top level of the Isle of Man Control
Zone from FL65, which would enable radar controllers at Ronaldsway to vector
inbound aircraft for runway 26 away from the confines of airway L10 (now
part of the Holyhead Control Area) while they are at a higher level, reducing
the number of track miles needed to be flown and hence conserving fuel.
The revised 'Agreed
Levels' with Scottish Control on Airway L10
Airspace changes to the
south east of the Isle of Man
Introduction of RNAV-1 routes
- 9th November 2017
In 2016, NATS
notified that there was going to be a big change in the way airspace below
FL245 (24,500 ft) was to be designated. The existing 'Airways' structure
dated from the early 1950s (see ATC
1950s for more information) and in recent years the designations had
been in contravention of international agreements. With the move
to more Area Navigation (RNAV) systems and the removal of many of the old
radio beacons, multiple routes were being designated within the same volume
of airspace. To correct the anomalies, a rolling program of re-designation
of the old Airways to Control Areas was started and the airspace to the
south and east of the Isle of Man was changed in early November.
Airways L10 and L70 (amongst others not affecting Ronaldsway) have had
their airspace status changed from Class A to Class C and been re-designated
as the 'Holyhead Control Area'. The rather strange and short Class
E Airway 'Y911' to the southwest of the Isle of Man also becomes part of
the Holyhead Control Area, but retains its Class E status.
Within this airspace
there are various routes designated, including one called L10 which in
fact just follows the old airway centreline. There are also new routes
to the north and south of L10, M146 which is for northwest bound traffic
and Q39 for southeast bound traffic. There are yet more, but these three
are the only ones affecting Ronaldsway traffic. The reason
for such a plethora of routes is that the newer ones require aircraft navigation
performance to RNAV-1 (with a higher accuracy required) whereas there are
still many aircraft around that can only manage RNAV-5, which has a lower
accuracy requirement, ATC radar being used to ensure separation between
the two classes. Eventually it will be a requirement for all aircraft
using the Controlled Airspace System to carry RNAV-1 when, presumably,
the structure can be simplified.
is to link these routes to an airport via Standard Terminal Arrival Routes
(STARs) and Standard Instrument Departures (SIDs) which are pre-programmed
into most modern aircraft Flight Management Systems (FMS).
The pilot then just has to select the appropriate SID from his departure
airfield, then the relevant routes until connecting with the STAR at his
destination which in turn connects to the Instrument Approach Procedure
for the runway in use. At present Ronaldsway does not have STARs
and SIDs, which can cause some confusion to visiting aircrew as to how
they connect with the en-route structure.
Northern Irish Sea
Airspace classes from 9/11/17
Lower Airspace ATS
Routes from 9/11/17
Manual of Air Traffic Services
7th Edition published
- Effective date 28th December 2017
The MATS Part 1 is effectivley
the 'bible' of Air Traffic Control in the UK (and Isle of Man) and the
First Edition was published in 1974, not long after I had started my career
in ATC the previous year. Before then the publication had been known
as the Manual of Air Traffic Control. To quote from sections of the
forword of the latest version:
'The Manual of Air Traffic
Services contains procedures, instructions and information, which are intended
to form the basis of ATS within the UK'.
Part 1 of the Manual
contains instructions that apply to all UK ATSUs and is published by the
UK CAA. Part 2 contains instructions that apply to a particular ATSU
and is produced locally but are approved by the CAA. A copy of the
latest edition of Part 1 can be downloaded
New editions are published
when there are major changes to ATC procedures and Edition 7 is mainly
concerned with changes associated with the move to a Standardised European
Rules of The Air (SERA).
Communications Frequency Changes
11th October 2018
All ATC frequencies
within Europe have been gradually changing from 25 Khz separated channels
to 8.33 KHz separation, in order to provide a much greater number of available
frequencies. Area Control was the first to implemement these on a
rolling program starting some years ago, with UK airfields changing during
2018. In some cases new frequencies have been allocated, but in others
the only change is to the designation of the frequencies to indicate that
they are 8.33 KHz channels.
In Ronaldsway's case
there are no actual changes to the frequencies, just the channel designations:
- 135.905 MHz (Actual carrier frequency still 135.9)
on Snaefell Summit, with standby at Ronaldsway
(when instructed by ATC) 120.855 (Actual carrier frequency
(when isntructed by ATC) 125.305 (Actual carrier
frequency still 125.3)
- 119.005 MHz (Actual carrier frequency still 119.0)
Transmitters & receiver
123.880 (Actual carrier frequency still 123.875)
Transmitter at Ronaldsway